Suspension Tech 101 Part 2
Dezoris
06-26-2002, 10:24 PM
Thank you for your interest in suspension tech 101 part 2.
You may or may not have covered part one, I suggest if there is any questions in the areas
Listed below you read this thread.
http://www.automotiveforums.com/vbulletin/showthread.php?s=&threadid=36019
The issues covered there are some basics of;
Shocks and Struts
Coilovers
Coilover Sleeves
Springs and spring rates
Sway Bars
Tire discussion and importance
Camber
Caster
Toe
Alignments
Index
A. Stock suspension
B. Lightly modified suspension
C. Modified suspension with an alignment kit
D. Advanced alignment practice
E. Coil-over suspension (height adjustable) with an Alignment
E-1. Corner Weighing
This piece will expand on some of these issues and discuss tuning your suspension, for race conditions and for true performance driving, and what you need to achieve this and why.
These topics will go from basic to advanced describing scenarios such as stock suspension, modified suspension, to heavily modified suspension to race suspension.
THINGS NOT DISCUSSED AND WHY
1.)The use of coilover sleeves on stock shocks
2.)The use of higher rate lowering springs on stock shocks
3.)The use of cut springs or torched springs
4.)Tuning using coilover sleeves on aftermarket shocks (Ground Controls, Skunk)
The reason I will not discuss tuning these suspensions is simple, these setups will not improve the suspension in terms of overall grip or handing, or comfort. #4 has been shown to be effective, but I still will not recognize and adjustable perch placed on a shock as a solid solution to a threaded body shock, valved and dyno’d for a specific spring rate that the shock comes packaged with. Also in my experience I have seen many problems with installs, blown shocks, voided warranties and just bad handling overall. Performance adjustability comes at a price.
A. Stock Suspensions
Q. What can I possibly do to make a stock suspension any better?
Answer:
Most vehicles are designed from the factory to maintain a smooth ride free of vibration and feedback from road turbulence. Not because they don't know how to build a performance suspension, but because that is how the average consumer judges ride quality, stable soft ride equals calm atmosphere inside the cabin, while the manufacturers try to improve steering feel, turning radius, and even on SUVs by incorporating 4 wheel steering to reduce the overall lock to lock turns for easier parking, so it "feels" more like a car. And this is not limited to cars only. So the best way to improve handling as discussed in part 1 is tires. The second way to improve handling in cars with a soft suspension is to increase the diameter of the vehicles anti-roll bars (sway bars). Sway bars help a soft suspension namely because it can transfer the weight from one side of the suspension that is being compressed or under heavy load to the side that is not, such as this car
http://www.dezoris.com/corner/bodyroll.jpg
As the control arms and shocks compress on one side the sway bar is being twisted/ or resisting this force by transferring the weight to the other side of the vehicles outer suspension, hence the term “anti-sway bar”
Adding a sway bar or larger diameter sway bar to a soft suspension can do wonders, in stability. On the contrary suspensions with very high spring rates and aggressively valved shocks may actually cause loss of traction, where the bar may un-glue the tires from the road. In many cases, roll and is not a bad thing and is necessary in providing traction as long as your alignment and tires are up for the load.
On a final note with stock suspension there is a frequent question
Will Tie bars and strut bars do anything for handling?
This has been an argument and technically, there may be ways that these bars can effect performance, namely shock/strut tower bars, can stiffen the strut towers to reduce frame flex which in some cases depending on the bars may increase spring rates, do to the reinforcement of the shock towers. This is not likely to translate in any improved performance on a stock suspension. Some people claim to “feel” a difference, while honestly they are not designed to improve performance, only stiffen the chassis, and usually this is more of an issue in vehicles with a modified suspension.
B. Lightly Modified Suspension
A lightly modified suspension would consist of lowering springs on non-externally adjustable after market shocks. Example (Eibach Prokit/Koni Reds) A drop no greater than 1.75” -This is a very good basic shock/spring combo that is very composed while giving the user a lowered stance and smooth ride.
Tuning a setup like this is not much different than the stock suspension, only in this area adding solid shock tower bars may help reduce chassis stress, from the lowering. Tie bars are all preference, I don’t consider them a suspension modification, just as I don’t consider urethane bushings a suspension modification, just merely a support piece in tightening up the frame or moving parts from flex.
Many people dropping their vehicle in the 2” and under range may be able to lower without the need for a camber correction kit. But in my opinion any type of lowering should be accompanied by a camber correction kit, because, your suspension is no longer what the manufacturer intended, which means that the factory adjustment for alignments, may come close to getting the alignment within factory specification, but likely there will be a few adjustments that will not be in spec, which can hurt performance, cause odd handling even dangerous. I tell many people that these kits are absolutely necessary and to just plan on it with the purchase of any spring/shock upgrades that lower the vehicle.
This will lead into the next area of tuning if there is a camber kit also known as an alignment kit.
C. Modified Suspension with an Alignment kit
Now things start to get interesting. Now that the user has the basic shock spring combo with an alignment kit we can get into setting up alignment specs based on the users driving habits or even set it for a specific type driving condition (high speed, oval track, AutoX)
This is the second biggest reason to add an alignment kit to a lightly modified suspension. The first and of course being able to get the suspension aligned properly.
Many people want the best of all worlds, lets face it, most of us don’t have a car in a trailer dedicated to track use, I don’t and personally that is not my objective here.
It is easy to visualize your driving conditions. That is what I want the reader to think about. How is the vehicle driven? Mine is driven very hard and fast in autox type conditions, under 65 MPH with many turns. The roads are choppy for daily driving and I rarely if ever see my car reach speeds over 75 MPH. So in my case I have my alignment set to take advantage of these conditions. This is a very simple yet complicated way to get the most grip and best steering feel from your setup, which enables the rest of the suspension to do what it needs to do to keeping the tires on the road and while making sure the contact patch of the tire is being used to its full potential
D. Advanced Alignment Practice
So now that we know the advantages of having an alignment kit we can talk about how it can change the way our car handles. Not only will this section discuss the how and why of the advanced alignment it will also touch on how the user can tweak, test and align the vehicle themselves with some special tools.
Since we have discussed what toe, camber and caster was in the Part 1, we now have an idea of what these terms mean, but how exactly do they effect drivability?
Camber
Probably the most talked about alignment angle mainly because it is associated with actual grip and usually is a headache for people who lower their cars. We hear this question daily:
Do I need a kit if I lower my car with this…
This is always referring to camber.
Camber can do a few things, there are not as many variables as in toe settings but they are
Creating negative camber on a suspension is usually a band-aid for not having a suspension that is keeping the tires upright or neutral. This is more common in double wishbone setups where by design the suspension does not compensate for compression (sending the wheel into positive camber) as the strut setups do. Although, strut setups don’t always maintain that upright camber angle either, the advantage is that the double wishbone setup makes it easy to correct this by adding camber kits, the strut setups need camber plates at the strut towers which are more expensive and the range of adjustment is not as great.
Positive camber is never good for performance driving, and can create an unstable feeling at higher driving speeds.
Having 0 camber or -.25 is best for straight-line and high speed stability. Creating more negative camber can be more effective for creating better grip although sacrificing high speed stability/straight-line stability. Reading further will help the drive decide how they can find out what settings are right.
When a vehicle is being pushed to the limit in a turn, a double wishbone suspension and even more prevalent in a Mcpherson strut setup is the suspensions tendency to create positive wheel camber. This natural tendency of the suspension geometry is an issue when the wheels are almost in the lock-to-lock position or your wheel is almost at lock position in one direction. This positive camber can be detrimental to grip and keeping the tires off the contact patch, although correction in strut based vehicles is more difficult, being that the natural design is to keep a more neutral camber angle through out the suspension travel, where as the double wishbone does not, the angles are changed based on wheel travel.
As far as optimizing camber angles we have a few things to look at. Generally more negative camber is good for handling, but bad for high speed stability or steering feel, this is a pattern you will see, what is good for grip is not always good for straight line high speed driving.
What I tell people doing their alignments is to get a printout of the factory specs and post about it or create a topic on the forums about it to discuss optimal settings. Instead of doing that, and trying some guess work the reader needs a few things.
A big thing is people seem to think dialing in more negative camber is a god send, and this is a misconception, and as one mechanic/tuner told me.
“Tire temps are the bible in racing, it does not matter if you have –50 degrees of camber, adjusting your alignment on the track should be based on tire temps, not on what you think it should be”
Before we get to that, please remember that negative camber is relative, too much can be as bad as too little if the tires are rolling off the contact patch of the tire. So this is what the reader needs to tune and get the car ready for optimal driving.
1.)Camber gauge as pictured below
Digital
http://www.dezoris.com/corner/camberguage.jpg
Standard
http://www.dezoris.com/corner/camberguage2.jpg
2.)Thermo Tire Temp Gauge or Prod type
http://www.dezoris.com/corner/thermo.gif
3.)Paper and pen and make a chart kind of like this
http://www.dezoris.com/tiremap.jpg
4.)Tire Pressure gauge (of your choice, analog gauges work best)
Record your tire temps when the tires are cold, and keep a log.
5.)Air pressure tank (for tire inflation)
6.)Chalk (for marking the tire)
7.)Floor Jack and proper tools if changing alignment angles.
Method A.
If acquiring this equipment is trouble some look no further than a piece of chalk, to mark across your tread. This will help determine whether or not your tire is rolling off the tread on to the side walls by seeing how much of the line you scraped off on your run. The line is best made on the outside shoulder of the tire and this can evaluated after a run.
Did the chalk line of the sidewall get scuffed? If so increase the tire pressure (this is assuming your alignment is in spec)
Did the chalk line not get scuffed up on any part of the outer tread? Decrease tire pressures.
This is the simplest and cheapest way, 2$ for chalk, 25$ for an air tank, and 5-30$ for a pressure gauge.
Method B.
These tools listed above will enable the user to set camber angles and to test tire temperatures in three places, outer, inner and center of the contact patch. This is best done on a track or parking lot that has been closed for this purpose, local colleges are usually able to accommodate this on the weekends when classes are not in session, or businesses that will allow you to use their lot, also getting a letter from them and alerting the local police department is very wise.
Buying some cones usually 30 will due, set up your course using a good combo of lefts and rights enough to balance out the turns so you may easily test the tire temps when you are done. Also using a Test and Tune day that a local car club has is a great way to do this, being that it is geared strictly for this purpose.
Have your alignment specs set up to be within your factory numbers, if you are not comfortable with adjusting the alignment yourself, you can have it done professionally, and then use this testing technique to obtain tire temperatures. Also another important issue is tire pressure before running. Check tire pressure when the tires have been sitting, (cold psi) depending on the vehicle namely FWD you will want to keep your front tires just a bit higher in pressure than the rear, also higher does not mean better, keep an eye on the tires max pressure, do not exceed that and keep in mind that heat equals expansion by a few psi. For most street tires using mid to upper 30s in the front and mid to low 30s in the rear is adequate for FWD. Again this is something that is up the driver, this is merely a starting guide. Some people question my use of higher front pressures, which shocks me, but it seems that these people feel that our front wheel drive vehicles do not have enough over-steer.
Have all your materials at the end of the course so you are ready to record.
So to start take a few warm up laps, just getting to know the course, when you are done warming up do one hard lap pushing the car, to whatever you can handle, this is why it is safe to do it on a lot with cones, so that if you lose control you will not hit anything or hurt anyone (know your limits, that is the point of the warm up)
When you are done running use the thermo gauge to record all of your tire temps very QUICKLY (this is where the thermo gauge is helpful) as depending on the tire and time you drove it they will cool fast. Harder rubber tires are harder to heat up, namely the tires with a larger tread wear rating or all season type tires.
Generally your V and Z rated tires are made of your softest compound, so they tend to heat up fast. Unless you are on race tires heating up a street tire is a bit more difficult. If you are running autox events that keep your runs short (less than 2 minutes a run) getting those tires hot will be a real task, so a quick fix would be to toe out your front tires slightly +.25 to start. It is really up to you based on if the car is a straight racer. If that was the case you could dial in more, to heat them up faster, keeping in mind the more + toe the less high speed stability and increased tire wear, although you gain better steering feel.
After you have recorded your temps get ready for a few more runs. Check your tire pressure after you record the temps and record the pressures to compare your cold and hot readings, make sure all is well, and adjust accordingly. Run another few laps and then record your temps again. Repeat the process 4 times or more if you feel like it.
When you are done you will be able to see what exactly your tires are going through.
Now it is time to look at the sheet how do the temps look? Lets start with the rear, do the temps for the inner and outer tire match up? Are they close for all 4 runs? Or is the inner or outer hotter than the others noticeably? You start with the rear (assuming the car is not 4 wheel drive or 4 wheel steering) because the wheels are stationary and are not needed to steer the car or provide acceleration, even it the car is RWD it is still good to start in the rear. The reason is because the goal is to adjust tire pressures to change tire temps.
Getting fun yet? If you are on the track reading this maybe, but by that time you are probably figuring it out for yourself.
If your temps are consistent on the inner, outer and middle part of the tire then really there is not much more to do with tire pressures. If one part is running hotter for instance lets say your inner tire in running noticeably hotter than the outer try reducing tire pressure, and if your outer is running hotter try increasing tire pressure, and run again while recording the results, then again. Did it get better or worse, and more importantly how did the car handle?
If your reading got worse then go the opposite way, until you can get a better balance.
Then on to the front tires using the same methods. If you are still seeing a noticeable tire temp difference, and you have tried several different temps, it is time to adjust the camber.
If you are running hot on the outside you should adjust your camber on that wheel, in -.02 to -.04 degree increments, until your tire temps even out.
If you are running hot on the inside you need to raise your camber by +.02 degrees until temps even out. When you see the numbers getting better you are closer to the goal, using the tires contact patch optimally. Adjusting the pressure in your tires will not have much bearing on the tire temps as much as that alignment will, but for example if your tires are under-inflated and they are rolling over on the sidewall excessively, the obvious problem would be that the outer shoulder of the tire will be hotter, so the quick fix is to inflate the tire. To avoid the excessive roll over and even tire temps. Using these examples should give the driver a good reason to monitor tire temps, and pressures.
Toe
As discussed in suspension 101 part 1 there is toe in and toe out, and now that you know what it means, how does it effect your vehicle.
Lets discuss the effects of it first, that way you can decide what is right for you.
Toe-In
Setting the wheels to toe in does a few things
1.)Increases high speed or straight line tracking of a vehicle
2.)Helps keep the car tracking straight on hard braking
3.)Reduces steering response (Less sensitive)
4.)Too much increases tire wear
Toe-Out
Setting the wheels to toe out does a few things
1.)Decreases high speed stability straight line stability
2.)Can make the car wonder or pull during breaking or on rough surfaces
3.)Increases steering response, feel and sensitivity
4.)Helps to heat up tires for short races
5.)Too much increases/feathers tire tread
It is very difficult to explain wear from having improper toe but this may help
http://www.dezoris.com/corner/toediagram.jpg
Picture the tire being toed-in the wear pattern on a normal 0 toe tire would be straight on the tire, when the tire is toed in or out excessively it created a diagonal wear pattern which can easily junk a tire and is hard to compensate for wear by simple rotations.
So setting toe has less to do with grip here as it does with preference, using these little tips I gave you can tailor your setup how you want it, I would start with an alignment, based on those factors and decide how you like the feel. Honda has a few models that upon breaking, toe-in the rear wheels to help with breaking to keep the car straight so many times adjusting your toe out of factory spec or moving it around within is not needed, but if you need heat
Radial Street tires operate best within their heat range 100-130 degrees F
and you cant get that when racing you can toe out the tire slightly to get those temps.
E. Coil-over suspension (height adjustable) with an Alignment kit
Now onto the next chapter, a height adjustable suspension is usually designed with a shock that has a threaded body valved to dampen a specific spring rate/spring that it was packaged with. The shock has a shortened case and stronger rod, and other performance related pieces that make it perfect for lowering and damping the race springs it was design to work with. Now that we understand the critical roll alignments play in tuning, we can understand what height adjustability gives us, which can be complicated. The major performance benefit of these suspensions pictured here-
http://www.dezoris.com/corner/adjustable2.gif
is the ability to corner weigh and weight a vehicle
E-1 Corner weighing
Corner weighing is simple and is a term many people should know-
Corner weighing is putting a vehicle on scales like this
http://www.dezoris.com/corner/scales.jpg
all four wheels are placed on these scales on the display there is a read out of the weight of each corner of the car, for example the cars weight for a FWD vehicle may look like this-
http://www.dezoris.com/corner/cornerweighed.jpg
This is a great diagram to understand what corner weighing is.
As you can see the weight distribution as with all front engine front drive cars is more weight in the front. So with the car on scales we can see how much each corner is, and we try to get that perfect 50/50 balance which may not be possible, but the goal is getting it close to that.
That example is actually uncommon for a FWD front engine car, being that it is pretty balanced to begin with, your average Acura Integra GSR is 58% front and 42% rear, which is a big difference.
Corner weighing should be done with the weight of the driver in the car.
So how do we get the weight more even? This is where the adjustable threaded body shocks come into play. The easiest way to reduce front weight is to raise the front end and lower the rear. Same with the sides, as the transmission may be on the right or left side of the car, the battery or driver which makes one side heavier. So raising one side to transfer the weight to another is a way to distribute weight, and this is the best benefit of adjustable shocks.
Ride height may be uneven, but when the cars distribution is closer to 50/50 it matters little.
Raising and lowering the car will only go so far to getting the cars weight more balanced, the next step is corner weighting This involves physically adding weight such as lead to each corner or front and rear to get more even distribution, if your front end is 1200 lbs and your rear is 1100, the easiest way to fix it would be to throw 100lbs of weight in the trunk, other factors are involved here, a good set of shocks will slow weight transfer and compensate for this weight, while some shocks may not be able to handle the increased load and change your handling characteristics, although 100lbs is not much and I would be doubt if there would be any change, but if we start throwing more weight in spring rates and the shocks ability to compress and rebound the extra weight makes things tricky, this is when externally adjustable damping settings come in handy.
If your car is a dedicated race machine there may be some other things that can be done to reduce weight in the front or rear depending on the type of machine.
Things like A/C and cruise control, become expendable removing 50+ lbs. Also moving weight around, like relocation of the battery to the trunk, the list can go on, but it all depends on what kind of car you have and how serious you want to get.
After the weight is as even as it can be, an alignment should be done, keeping in mind the issues discussed previously, also track testing for tire temps and pressures to assure even temps across the tread and adjusting alignments as needed is the final steps in setting up this type of equipment.
In the next installment Suspension 101 part 3 we will discuss
Single adjustable/Double/Triple adjustable coil-over suspension (height adjustable) with an Alignment kit, along with sway bar applications and adjusting the setup and tuning it .
Driving issues such as, pushing, over-steer, understeer, fixing a loose rear end, and other driving/vehicle specific issues.
You may or may not have covered part one, I suggest if there is any questions in the areas
Listed below you read this thread.
http://www.automotiveforums.com/vbulletin/showthread.php?s=&threadid=36019
The issues covered there are some basics of;
Shocks and Struts
Coilovers
Coilover Sleeves
Springs and spring rates
Sway Bars
Tire discussion and importance
Camber
Caster
Toe
Alignments
Index
A. Stock suspension
B. Lightly modified suspension
C. Modified suspension with an alignment kit
D. Advanced alignment practice
E. Coil-over suspension (height adjustable) with an Alignment
E-1. Corner Weighing
This piece will expand on some of these issues and discuss tuning your suspension, for race conditions and for true performance driving, and what you need to achieve this and why.
These topics will go from basic to advanced describing scenarios such as stock suspension, modified suspension, to heavily modified suspension to race suspension.
THINGS NOT DISCUSSED AND WHY
1.)The use of coilover sleeves on stock shocks
2.)The use of higher rate lowering springs on stock shocks
3.)The use of cut springs or torched springs
4.)Tuning using coilover sleeves on aftermarket shocks (Ground Controls, Skunk)
The reason I will not discuss tuning these suspensions is simple, these setups will not improve the suspension in terms of overall grip or handing, or comfort. #4 has been shown to be effective, but I still will not recognize and adjustable perch placed on a shock as a solid solution to a threaded body shock, valved and dyno’d for a specific spring rate that the shock comes packaged with. Also in my experience I have seen many problems with installs, blown shocks, voided warranties and just bad handling overall. Performance adjustability comes at a price.
A. Stock Suspensions
Q. What can I possibly do to make a stock suspension any better?
Answer:
Most vehicles are designed from the factory to maintain a smooth ride free of vibration and feedback from road turbulence. Not because they don't know how to build a performance suspension, but because that is how the average consumer judges ride quality, stable soft ride equals calm atmosphere inside the cabin, while the manufacturers try to improve steering feel, turning radius, and even on SUVs by incorporating 4 wheel steering to reduce the overall lock to lock turns for easier parking, so it "feels" more like a car. And this is not limited to cars only. So the best way to improve handling as discussed in part 1 is tires. The second way to improve handling in cars with a soft suspension is to increase the diameter of the vehicles anti-roll bars (sway bars). Sway bars help a soft suspension namely because it can transfer the weight from one side of the suspension that is being compressed or under heavy load to the side that is not, such as this car
http://www.dezoris.com/corner/bodyroll.jpg
As the control arms and shocks compress on one side the sway bar is being twisted/ or resisting this force by transferring the weight to the other side of the vehicles outer suspension, hence the term “anti-sway bar”
Adding a sway bar or larger diameter sway bar to a soft suspension can do wonders, in stability. On the contrary suspensions with very high spring rates and aggressively valved shocks may actually cause loss of traction, where the bar may un-glue the tires from the road. In many cases, roll and is not a bad thing and is necessary in providing traction as long as your alignment and tires are up for the load.
On a final note with stock suspension there is a frequent question
Will Tie bars and strut bars do anything for handling?
This has been an argument and technically, there may be ways that these bars can effect performance, namely shock/strut tower bars, can stiffen the strut towers to reduce frame flex which in some cases depending on the bars may increase spring rates, do to the reinforcement of the shock towers. This is not likely to translate in any improved performance on a stock suspension. Some people claim to “feel” a difference, while honestly they are not designed to improve performance, only stiffen the chassis, and usually this is more of an issue in vehicles with a modified suspension.
B. Lightly Modified Suspension
A lightly modified suspension would consist of lowering springs on non-externally adjustable after market shocks. Example (Eibach Prokit/Koni Reds) A drop no greater than 1.75” -This is a very good basic shock/spring combo that is very composed while giving the user a lowered stance and smooth ride.
Tuning a setup like this is not much different than the stock suspension, only in this area adding solid shock tower bars may help reduce chassis stress, from the lowering. Tie bars are all preference, I don’t consider them a suspension modification, just as I don’t consider urethane bushings a suspension modification, just merely a support piece in tightening up the frame or moving parts from flex.
Many people dropping their vehicle in the 2” and under range may be able to lower without the need for a camber correction kit. But in my opinion any type of lowering should be accompanied by a camber correction kit, because, your suspension is no longer what the manufacturer intended, which means that the factory adjustment for alignments, may come close to getting the alignment within factory specification, but likely there will be a few adjustments that will not be in spec, which can hurt performance, cause odd handling even dangerous. I tell many people that these kits are absolutely necessary and to just plan on it with the purchase of any spring/shock upgrades that lower the vehicle.
This will lead into the next area of tuning if there is a camber kit also known as an alignment kit.
C. Modified Suspension with an Alignment kit
Now things start to get interesting. Now that the user has the basic shock spring combo with an alignment kit we can get into setting up alignment specs based on the users driving habits or even set it for a specific type driving condition (high speed, oval track, AutoX)
This is the second biggest reason to add an alignment kit to a lightly modified suspension. The first and of course being able to get the suspension aligned properly.
Many people want the best of all worlds, lets face it, most of us don’t have a car in a trailer dedicated to track use, I don’t and personally that is not my objective here.
It is easy to visualize your driving conditions. That is what I want the reader to think about. How is the vehicle driven? Mine is driven very hard and fast in autox type conditions, under 65 MPH with many turns. The roads are choppy for daily driving and I rarely if ever see my car reach speeds over 75 MPH. So in my case I have my alignment set to take advantage of these conditions. This is a very simple yet complicated way to get the most grip and best steering feel from your setup, which enables the rest of the suspension to do what it needs to do to keeping the tires on the road and while making sure the contact patch of the tire is being used to its full potential
D. Advanced Alignment Practice
So now that we know the advantages of having an alignment kit we can talk about how it can change the way our car handles. Not only will this section discuss the how and why of the advanced alignment it will also touch on how the user can tweak, test and align the vehicle themselves with some special tools.
Since we have discussed what toe, camber and caster was in the Part 1, we now have an idea of what these terms mean, but how exactly do they effect drivability?
Camber
Probably the most talked about alignment angle mainly because it is associated with actual grip and usually is a headache for people who lower their cars. We hear this question daily:
Do I need a kit if I lower my car with this…
This is always referring to camber.
Camber can do a few things, there are not as many variables as in toe settings but they are
Creating negative camber on a suspension is usually a band-aid for not having a suspension that is keeping the tires upright or neutral. This is more common in double wishbone setups where by design the suspension does not compensate for compression (sending the wheel into positive camber) as the strut setups do. Although, strut setups don’t always maintain that upright camber angle either, the advantage is that the double wishbone setup makes it easy to correct this by adding camber kits, the strut setups need camber plates at the strut towers which are more expensive and the range of adjustment is not as great.
Positive camber is never good for performance driving, and can create an unstable feeling at higher driving speeds.
Having 0 camber or -.25 is best for straight-line and high speed stability. Creating more negative camber can be more effective for creating better grip although sacrificing high speed stability/straight-line stability. Reading further will help the drive decide how they can find out what settings are right.
When a vehicle is being pushed to the limit in a turn, a double wishbone suspension and even more prevalent in a Mcpherson strut setup is the suspensions tendency to create positive wheel camber. This natural tendency of the suspension geometry is an issue when the wheels are almost in the lock-to-lock position or your wheel is almost at lock position in one direction. This positive camber can be detrimental to grip and keeping the tires off the contact patch, although correction in strut based vehicles is more difficult, being that the natural design is to keep a more neutral camber angle through out the suspension travel, where as the double wishbone does not, the angles are changed based on wheel travel.
As far as optimizing camber angles we have a few things to look at. Generally more negative camber is good for handling, but bad for high speed stability or steering feel, this is a pattern you will see, what is good for grip is not always good for straight line high speed driving.
What I tell people doing their alignments is to get a printout of the factory specs and post about it or create a topic on the forums about it to discuss optimal settings. Instead of doing that, and trying some guess work the reader needs a few things.
A big thing is people seem to think dialing in more negative camber is a god send, and this is a misconception, and as one mechanic/tuner told me.
“Tire temps are the bible in racing, it does not matter if you have –50 degrees of camber, adjusting your alignment on the track should be based on tire temps, not on what you think it should be”
Before we get to that, please remember that negative camber is relative, too much can be as bad as too little if the tires are rolling off the contact patch of the tire. So this is what the reader needs to tune and get the car ready for optimal driving.
1.)Camber gauge as pictured below
Digital
http://www.dezoris.com/corner/camberguage.jpg
Standard
http://www.dezoris.com/corner/camberguage2.jpg
2.)Thermo Tire Temp Gauge or Prod type
http://www.dezoris.com/corner/thermo.gif
3.)Paper and pen and make a chart kind of like this
http://www.dezoris.com/tiremap.jpg
4.)Tire Pressure gauge (of your choice, analog gauges work best)
Record your tire temps when the tires are cold, and keep a log.
5.)Air pressure tank (for tire inflation)
6.)Chalk (for marking the tire)
7.)Floor Jack and proper tools if changing alignment angles.
Method A.
If acquiring this equipment is trouble some look no further than a piece of chalk, to mark across your tread. This will help determine whether or not your tire is rolling off the tread on to the side walls by seeing how much of the line you scraped off on your run. The line is best made on the outside shoulder of the tire and this can evaluated after a run.
Did the chalk line of the sidewall get scuffed? If so increase the tire pressure (this is assuming your alignment is in spec)
Did the chalk line not get scuffed up on any part of the outer tread? Decrease tire pressures.
This is the simplest and cheapest way, 2$ for chalk, 25$ for an air tank, and 5-30$ for a pressure gauge.
Method B.
These tools listed above will enable the user to set camber angles and to test tire temperatures in three places, outer, inner and center of the contact patch. This is best done on a track or parking lot that has been closed for this purpose, local colleges are usually able to accommodate this on the weekends when classes are not in session, or businesses that will allow you to use their lot, also getting a letter from them and alerting the local police department is very wise.
Buying some cones usually 30 will due, set up your course using a good combo of lefts and rights enough to balance out the turns so you may easily test the tire temps when you are done. Also using a Test and Tune day that a local car club has is a great way to do this, being that it is geared strictly for this purpose.
Have your alignment specs set up to be within your factory numbers, if you are not comfortable with adjusting the alignment yourself, you can have it done professionally, and then use this testing technique to obtain tire temperatures. Also another important issue is tire pressure before running. Check tire pressure when the tires have been sitting, (cold psi) depending on the vehicle namely FWD you will want to keep your front tires just a bit higher in pressure than the rear, also higher does not mean better, keep an eye on the tires max pressure, do not exceed that and keep in mind that heat equals expansion by a few psi. For most street tires using mid to upper 30s in the front and mid to low 30s in the rear is adequate for FWD. Again this is something that is up the driver, this is merely a starting guide. Some people question my use of higher front pressures, which shocks me, but it seems that these people feel that our front wheel drive vehicles do not have enough over-steer.
Have all your materials at the end of the course so you are ready to record.
So to start take a few warm up laps, just getting to know the course, when you are done warming up do one hard lap pushing the car, to whatever you can handle, this is why it is safe to do it on a lot with cones, so that if you lose control you will not hit anything or hurt anyone (know your limits, that is the point of the warm up)
When you are done running use the thermo gauge to record all of your tire temps very QUICKLY (this is where the thermo gauge is helpful) as depending on the tire and time you drove it they will cool fast. Harder rubber tires are harder to heat up, namely the tires with a larger tread wear rating or all season type tires.
Generally your V and Z rated tires are made of your softest compound, so they tend to heat up fast. Unless you are on race tires heating up a street tire is a bit more difficult. If you are running autox events that keep your runs short (less than 2 minutes a run) getting those tires hot will be a real task, so a quick fix would be to toe out your front tires slightly +.25 to start. It is really up to you based on if the car is a straight racer. If that was the case you could dial in more, to heat them up faster, keeping in mind the more + toe the less high speed stability and increased tire wear, although you gain better steering feel.
After you have recorded your temps get ready for a few more runs. Check your tire pressure after you record the temps and record the pressures to compare your cold and hot readings, make sure all is well, and adjust accordingly. Run another few laps and then record your temps again. Repeat the process 4 times or more if you feel like it.
When you are done you will be able to see what exactly your tires are going through.
Now it is time to look at the sheet how do the temps look? Lets start with the rear, do the temps for the inner and outer tire match up? Are they close for all 4 runs? Or is the inner or outer hotter than the others noticeably? You start with the rear (assuming the car is not 4 wheel drive or 4 wheel steering) because the wheels are stationary and are not needed to steer the car or provide acceleration, even it the car is RWD it is still good to start in the rear. The reason is because the goal is to adjust tire pressures to change tire temps.
Getting fun yet? If you are on the track reading this maybe, but by that time you are probably figuring it out for yourself.
If your temps are consistent on the inner, outer and middle part of the tire then really there is not much more to do with tire pressures. If one part is running hotter for instance lets say your inner tire in running noticeably hotter than the outer try reducing tire pressure, and if your outer is running hotter try increasing tire pressure, and run again while recording the results, then again. Did it get better or worse, and more importantly how did the car handle?
If your reading got worse then go the opposite way, until you can get a better balance.
Then on to the front tires using the same methods. If you are still seeing a noticeable tire temp difference, and you have tried several different temps, it is time to adjust the camber.
If you are running hot on the outside you should adjust your camber on that wheel, in -.02 to -.04 degree increments, until your tire temps even out.
If you are running hot on the inside you need to raise your camber by +.02 degrees until temps even out. When you see the numbers getting better you are closer to the goal, using the tires contact patch optimally. Adjusting the pressure in your tires will not have much bearing on the tire temps as much as that alignment will, but for example if your tires are under-inflated and they are rolling over on the sidewall excessively, the obvious problem would be that the outer shoulder of the tire will be hotter, so the quick fix is to inflate the tire. To avoid the excessive roll over and even tire temps. Using these examples should give the driver a good reason to monitor tire temps, and pressures.
Toe
As discussed in suspension 101 part 1 there is toe in and toe out, and now that you know what it means, how does it effect your vehicle.
Lets discuss the effects of it first, that way you can decide what is right for you.
Toe-In
Setting the wheels to toe in does a few things
1.)Increases high speed or straight line tracking of a vehicle
2.)Helps keep the car tracking straight on hard braking
3.)Reduces steering response (Less sensitive)
4.)Too much increases tire wear
Toe-Out
Setting the wheels to toe out does a few things
1.)Decreases high speed stability straight line stability
2.)Can make the car wonder or pull during breaking or on rough surfaces
3.)Increases steering response, feel and sensitivity
4.)Helps to heat up tires for short races
5.)Too much increases/feathers tire tread
It is very difficult to explain wear from having improper toe but this may help
http://www.dezoris.com/corner/toediagram.jpg
Picture the tire being toed-in the wear pattern on a normal 0 toe tire would be straight on the tire, when the tire is toed in or out excessively it created a diagonal wear pattern which can easily junk a tire and is hard to compensate for wear by simple rotations.
So setting toe has less to do with grip here as it does with preference, using these little tips I gave you can tailor your setup how you want it, I would start with an alignment, based on those factors and decide how you like the feel. Honda has a few models that upon breaking, toe-in the rear wheels to help with breaking to keep the car straight so many times adjusting your toe out of factory spec or moving it around within is not needed, but if you need heat
Radial Street tires operate best within their heat range 100-130 degrees F
and you cant get that when racing you can toe out the tire slightly to get those temps.
E. Coil-over suspension (height adjustable) with an Alignment kit
Now onto the next chapter, a height adjustable suspension is usually designed with a shock that has a threaded body valved to dampen a specific spring rate/spring that it was packaged with. The shock has a shortened case and stronger rod, and other performance related pieces that make it perfect for lowering and damping the race springs it was design to work with. Now that we understand the critical roll alignments play in tuning, we can understand what height adjustability gives us, which can be complicated. The major performance benefit of these suspensions pictured here-
http://www.dezoris.com/corner/adjustable2.gif
is the ability to corner weigh and weight a vehicle
E-1 Corner weighing
Corner weighing is simple and is a term many people should know-
Corner weighing is putting a vehicle on scales like this
http://www.dezoris.com/corner/scales.jpg
all four wheels are placed on these scales on the display there is a read out of the weight of each corner of the car, for example the cars weight for a FWD vehicle may look like this-
http://www.dezoris.com/corner/cornerweighed.jpg
This is a great diagram to understand what corner weighing is.
As you can see the weight distribution as with all front engine front drive cars is more weight in the front. So with the car on scales we can see how much each corner is, and we try to get that perfect 50/50 balance which may not be possible, but the goal is getting it close to that.
That example is actually uncommon for a FWD front engine car, being that it is pretty balanced to begin with, your average Acura Integra GSR is 58% front and 42% rear, which is a big difference.
Corner weighing should be done with the weight of the driver in the car.
So how do we get the weight more even? This is where the adjustable threaded body shocks come into play. The easiest way to reduce front weight is to raise the front end and lower the rear. Same with the sides, as the transmission may be on the right or left side of the car, the battery or driver which makes one side heavier. So raising one side to transfer the weight to another is a way to distribute weight, and this is the best benefit of adjustable shocks.
Ride height may be uneven, but when the cars distribution is closer to 50/50 it matters little.
Raising and lowering the car will only go so far to getting the cars weight more balanced, the next step is corner weighting This involves physically adding weight such as lead to each corner or front and rear to get more even distribution, if your front end is 1200 lbs and your rear is 1100, the easiest way to fix it would be to throw 100lbs of weight in the trunk, other factors are involved here, a good set of shocks will slow weight transfer and compensate for this weight, while some shocks may not be able to handle the increased load and change your handling characteristics, although 100lbs is not much and I would be doubt if there would be any change, but if we start throwing more weight in spring rates and the shocks ability to compress and rebound the extra weight makes things tricky, this is when externally adjustable damping settings come in handy.
If your car is a dedicated race machine there may be some other things that can be done to reduce weight in the front or rear depending on the type of machine.
Things like A/C and cruise control, become expendable removing 50+ lbs. Also moving weight around, like relocation of the battery to the trunk, the list can go on, but it all depends on what kind of car you have and how serious you want to get.
After the weight is as even as it can be, an alignment should be done, keeping in mind the issues discussed previously, also track testing for tire temps and pressures to assure even temps across the tread and adjusting alignments as needed is the final steps in setting up this type of equipment.
In the next installment Suspension 101 part 3 we will discuss
Single adjustable/Double/Triple adjustable coil-over suspension (height adjustable) with an Alignment kit, along with sway bar applications and adjusting the setup and tuning it .
Driving issues such as, pushing, over-steer, understeer, fixing a loose rear end, and other driving/vehicle specific issues.
b16aDOHCVTEC
07-26-2002, 01:15 PM
Hey people... Someone i know (i wont call him a friend) did somethin to his car (lolz a Hyundai Elantra) and i DEFINITELY do NOT agree wit it... i know itz his car and he can do whatever he wantz to it but this is just plain ƒuckin RETARDED!! He took out his springs... COMPLETELY (and unprofessionally) and replaced them with NOTHING... hez riding around on his shocks... he thinkz itz "tyte" i think itz idiotic and a disaster waiting to happen... and THEN a friend of mine (a poor helpless GIRL who knowz NOTHING about her car) saw his "dropped" car and they just took out HER springz the other day...THEYRE SPREADING THEIR STUPIDITY TO OTHER PEOPLE!! wha should i tell them?!?! i want to warn them on wha will happen on a technical point of view... PLEASE LET ME KNOW!! thanx alot people!!
oh yeah also, when they were takin out her springz (i wasnt present) they supposedly also installed "full" exhaust that only ran them $80...for an INTEGRA... is that even POSSIBLE?!!?
~Mike
oh yeah also, when they were takin out her springz (i wasnt present) they supposedly also installed "full" exhaust that only ran them $80...for an INTEGRA... is that even POSSIBLE?!!?
~Mike
hondaman-iac
07-27-2002, 03:42 PM
yeah dude that is a good post but i have to dissagree with you on polyurethane bushings. i have them installed, with some minor modifications to the suspension and i can tell you there is a very huge difference between the rubber bushings and polyurethane bushings. first will be that the front is more precise and the wheels don't tend to get underneath the car under hard cornering, while on the back i have stock bushings and the wheels are getting under the car. i almost flipped over my car 2 nights ago making a 90 degree turn at about 45mph. everything came from the rear wheels. And i must add that i have stock size wheels on the car.
SilverY2KCivic
07-28-2002, 04:52 AM
Wow, very informative article, yet once again. :cool:
So what catagory would my current suspension setup fall into according to your post? Right now as it stands, I'm running with a freshly installed set of Tein "SS" coilovers set at rughly a "2 drop, Neuspeed 4-point upper front tower bar, cheap ass Arospeed lower rear tiebar, and 13mm OEM 6th gen Civic Si rear swaybar. Oh, and I can't forget my "15, 12lbs. per rim Rota Circuit 8 wheels wrapped with 195/50 Kumho Ecsta 711's.
Also what things can I do to my suspension in terms of tweaks, not in terms of adding or replacing anything though, just pure tweaks.
So what catagory would my current suspension setup fall into according to your post? Right now as it stands, I'm running with a freshly installed set of Tein "SS" coilovers set at rughly a "2 drop, Neuspeed 4-point upper front tower bar, cheap ass Arospeed lower rear tiebar, and 13mm OEM 6th gen Civic Si rear swaybar. Oh, and I can't forget my "15, 12lbs. per rim Rota Circuit 8 wheels wrapped with 195/50 Kumho Ecsta 711's.
Also what things can I do to my suspension in terms of tweaks, not in terms of adding or replacing anything though, just pure tweaks.
Automotive Network, Inc., Copyright ©2024