Need help with oversteer in my FWD

[tommyraym]

Hello, a few weeks ago I took a wide turn rather quickly on wet roads (was not speeding) and I had my first experience with oversteer. It may have been a combo of lift off oversteer and hydo planning because I was doing about 50mph.

Anyway, my car spun around twice and on the first spin the front end smacked a gaurd rail, major damage and I'm working on repairs.

I want to prevent this from happening in the future and I theorize that adding some weight in the trunk might help (empty trunk at the time). Obviously, the best way to prevent this is with safer driving, but I want to reduce my cars tendency to oversteer.I have great tred on all tires BTW.

It's a 2002 Nissan sentra GXE. The front end is low to the ground especially, when compared to the back. My first instinct was to raise the front end a tad and lower the rear a tad but, I lack the knowledge and skills to do so.

So I'm asking for help.

1. Will some extra weight in the back help?
2. Can I adjust the height or suspension of the vehicle? How?
3. Any tips for tuning my car in a way that prevents oversteer?

I am looking for an easy fix because, I lack the knowledge to do anything major.

Thanks in advance!

[liya_leacree]

Originally Posted by tommyraym

Hello, a few weeks ago I took a wide turn rather quickly on wet roads (was not spending) and I had my first experience with oversteer. It may have been a combo of lift off oversteer and hydo planning because I was doing about 50mph.

Anyway, my car spun around twice and on the first spin the front end smacked a gaurd rail, major damage and I'm working on repairs.

I want to prevent this from happening in the future and I theorize that adding some weight in the trunk might help (empty trunk at the time). Obviously, the best way to prevent this is with safer driving, but I want to reduce my cars tendency to oversteer.I have great tred on all tires BTW.

It's a 2002 Nissan sentra GXE. The front end is low to the ground especially, when compared to the back. My first instinct was to raise the front end a tad and lower the rear a tad but, I lack the knowledge and skills to do so.

So I'm asking for help.

1. Will some extra weight in the back help?
2. Can I adjust the height or suspension of the vehicle? How?
3. Any tips for tuning my car in a way that prevents oversteer?

I am looking for an easy fix because, I lack the knowledge to do anything major.

Thanks in advance!

Hi,,did you check your suspension parts, such as shock absorbers. As i know, if the shock is bad, you will find your car lean a bit and running deviation。

[tommyraym]

Good idea. I can check it in the morning but, don't think it's leaning or anything. It seems like the oversteer is from poor weight balance.

The front is low and heavy and the back is high and light and from what I understand, this setup gives the back much less traction. Which, I suspect is what caused the back to swing out (plus me lifting off the gas as I entered the turn). I should of gave it gas and counter steered but, I've never experienced this and it was unexpected.

It would be greatly appreciated if you guys could answer my questions and share your opinions..

[MikeCStig]

I think some weight in the rear might help. Put something heavy in the trunk and that might help a little.
Some FWD cars do have an inherent tendency toward lift-off oversteer, yours may be one of them. My tip for that would be to slow down enough before take a turn so you can apply a little throttle through the turn, and do not lift off.

[tommyraym]

Thanks for the advice. I know how to avoid oversteer. I just wanted to raise the threshold and reduce the severity of it (did a full 720). I wanted to raise the front and inch or two because it's closer to the wheel well than the rear (probably normal), and the bumper drags most curbs if I pull up to far.

However, this isn't in my skill set, so I'm just going to toss a couple sand bags in the back and drive more cautiously. Still, any further advice is appreciated.

[Stealthee]

FWDs inheritantly understeer. Liftoff oversteer is a different animal and can happen in the best of equipped cars. Adding weight in to the rear will only make the possibility to oversteer greater.

Your best way to avoid an oversteer situation in the future is to learn your car better. Sounds like you might have panicked a little and lifted throttle at the most inopertune time causing the spin. Lifting like that in a Corvette with coilovers and lowered to the ground would cause it to spin.

If you are hitting curbs by pulling up too far the answer is to learn when to stop, not raise the car.

[tommyraym]

"Adding weight in to the rear will only make the possibility to oversteer greater". How so? Everyone has been telling me the opposite. Wouldn't the added weight increase traction?

"If you are hitting curbs by pulling up too far the answer is to learn when to stop, not raise the car". I'm not actually hitting curbs, just saying my car would hit them if pulled up too far.

I wish my car did inheritantly understeer but, that doesn't seem to be the case. I'm not even sure if it was lift-off oversteer. I lifted off right before the turn, not in it. I know that in a FWD the front pulls the back and if I had given it gas during the turn, I probably wouldn't have spun.

There's more to the story. It was a wide left turn, it was wet and at the end it's straight then a slightly sharper right turn. Ok, so I got though the left turn and I'm on the straight part right before the right turn when, the car starts spinning clockwise. I just got out of the left turn and by looking at the gaurd rail I spun into, you can tell I hadn't entered the right turn yet. I'm confused as to why I spun clockwise. Maybe somebody can explain what happened their but, I am clueless.

I will definitely be driving slower in the rain because I know it was probably the biggest factor.

[Stealthee]

Adding weight over the rear will not increase traction since the rear tires are not under power. Anyone who told you that is not well versed in cars or their handling dynamics.

As you said, wet roads were a big cause, but from your own admission you said if you were in the gas you wouldn't have spun. A rear tire being worn, or even having low tread on rear tires could have caused the spin. I did it myself when I was a young driver.

The best mod you can do is gain experience. I made my share of mistakes as a young driver and learned from them. My lessons kept me from possibly totaling my Grand Prix a few winters ago. Long story short I was driving down a 4 lane highway in subzero temps with high winds. As I went under an overpass a combination of sidewinds and black ice caused the rear of the car to kick out at 70 mph. Combonations of countersteer and proper throttle inputs righted me before I ended up off the road in a ditch possibly on my roof.

[tommyraym]

Yes but, it is my understanding that accelerating gives the back traction by shifting weight to the rear. More weight in the back would give more traction to the rear and thus, make it less likely to slip out. TBH, much of what I've read on the matter has been extremely contradictory and I need a better understanding of how things REALLY work in a FWD.

"I made my share of mistakes as a young driver and learned from them". I'm trying to do the same but honestly, other than the rain, I don't know for certain what caused the spin.

[Stealthee]

Your understanding is incorrect. Yes weight shifts to the rear on acceleration but there is not going to be increased traction with more weight in the rear. You are taking weight off the front by adding weight to the rear. You want weight over the front on a FWD car.

Seriously, just go to Google and type the search "add weight to the rear of FWD" and you will find hundreds of responses telling people that it is not good.

[tommyraym]

You are correct. It's definitely not going to increase traction if you're accelerating or on icy roads.However, I do believe that adding weight in the back would reduce rear sliding.

Don't things like lift off oversteer occur because weight shifts to the front and the back gets light and slides out?

Also, as you said, FWDs have a tendency to understeer. Which means the front isn't getting enough traction. So adding weight to the back would be a big no no.

In this situation it seemed like the back had zero traction while the front had plenty. Until I was spinning that is.

[Black Lotus]

Just some rambling thoughts.
In a transient condition when you lift off, the front tires will momentarily gain more grip. If the higher weight condition exist for a longer period of time, the tires may then break away as the tires are now overloaded, and the tread distorts.
Called "Tire Load Sensitivity, and is the basis of suspension tuning. If the front is lowered, there is the *possibility* that the suspension is bottoming, and momentarily loading up the front tires....
If the chassis is moving around and the outside front corner drops, it may be lifting the inside rear, especially if your car has a rear sway bar. Also, your rear suspension is of the rear beam axle type, and if the locating arms are normally angled up from the axle to the body, the rear axle will steer out if the body rolls, giving it oversteering tendancies. Usually all manufacturers will make the outside front tire steer out in a corner with body roll giving the front end an understeering feel, thus balancing the car better-(in your case).
Having lots of tread on a tire doesn't guarantee much as the tire may be cheap and low quality. The better non-track day tires will usually stick like glue, even when it's wet, but not necessarily when it's cold out!
Lots of trade-offs and caveats, but that's why people buy high performance cars. They have less built-in bugaboos that get you when things go bad in a fast corner.

[tommyraym]

Great insights man. However, I don't think that the suspension is bottoming and loading up the front tires. I could be wrong though. I plan on getting the suspension checked soon. Also, plan on getting better quality tires when I can afford them.

Do you think adding weight in the rear would increase rear traction and lessen the chances of oversteer occurring?

I swear as soon as I'm done with repairs, I'm taking it to an empty lot on a rainy day and getting a better feel for oversteering. Probably practice by left foot braking. Don't wanna put an old street car through too much stress.

[harrveyspecter]

I think you should check your suspension parts, such as shock absorbers. good luck

[Black Lotus]

You could try with the weight, but my first thing to look at is the quality of the tires, and whether they match, front and rear. Then I would make some mental notes on my driving style, and see if there is any room for improvement (maybe, maybe not).
If your car has the ability, see if there is any way to add some more toe-in to the rear suspension (probably not).