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Old 01-15-2007, 12:19 PM   #46
jcsaleen
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Re: Structural Rigidity enhancement...

I'm going to try that as well. There are two main beams that run the course of the whole car. The X brace as shown before braces those beams but only in the front (obviously) but for the rear I'm getting a lower strut bar an see how it reacts to that.
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Old 01-15-2007, 12:58 PM   #47
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Re: Structural Rigidity enhancement...

I'm not sure if (independent) bracing at the front and rear is going to help much. It'd reinforce those elements to be more rigid transverely but it still won't help torsional rigidity (twisting between the front and rear suspension elements) or longitudinal flex (bending between the front and rear - what you seem to be describing when you talked about parking the car on a curb) in the overall chassis.
What you need, is a brace that ties the front and rear elements together. Without looking at how the car is put together, I'd say have a look at the transmission tunnel and see if there is enough space there to fit a member here. Or you can reinforce the floor pan.
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Old 01-15-2007, 01:15 PM   #48
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Re: Structural Rigidity enhancement...

Damnit, Once I get the car on the lift I will take a whole lot of shots for you guys the tunnel, front end and the whole entire underbody.

Not sure if this helps at all as far as the tunnel goes...

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Old 01-15-2007, 05:51 PM   #49
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by drunken monkey
what you need is a brace that spans the length of the car.
AKA roll cage.
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Old 01-15-2007, 06:11 PM   #50
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by KiwiBacon
AKA roll cage.
The brace would only span the monococke then not the length of the car. The foam would have a father span then the cage. Most cages made for the FD only go the rear upper strut bar an go as far foward as the firewall at most.
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Old 01-15-2007, 07:44 PM   #51
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by KiwiBacon
AKA roll cage.
i know a simple roll cage would solve all his problems.... but for some reason, he doesn't want a roll cage and seems fixated on foaming his chassis.
I suggested a brace in the transmission tunnel because I know how an RX 8 is made and there is just that in the chassis; a great big horizontal plane member.

Quote:
Originally Posted by jcsaleen
Most cages made for the FD only go the rear upper strut bar an go as far foward as the firewall at most.
err.... the front firewall section of the frame is structural and is joined to the two rails; the rear suspension is also fixed to the rails.
the roll cage uses these two points because that is EXACTLY where they need to go. I'm going to guess that there are, or there are available braces that are meant to go from the top of the front towers to the firewall as well. Which brings to mind another little questionConsidering that the actual passenger cell area/door frame is also part of the structural frame, it is that little bit more worrying that having the car with one end on a curb would cause your door not to close. That implies that your passenger cell area is compromised.
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Old 01-15-2007, 09:09 PM   #52
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by drunken monkey
That implies that your passenger cell area is compromised.
It would have happened to either side which ever was parked on the curb...

The flex was noticed before the accident.
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Old 01-15-2007, 11:15 PM   #53
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by drunken monkey
i know a simple roll cage would solve all his problems.... but for some reason, he doesn't want a roll cage and seems fixated on foaming his chassis.
Since he knows all the answers already, I'm not sure what this post is about.

If I was running a car like that up to it's maximum speed, I'd sure as hell want a rollcage. Whether it was in a competition that required it or not.

IMO foam should be used for energy absorbtion (like crash helmets), steel is the best material for adding strength and rigidity.
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Old 01-15-2007, 11:19 PM   #54
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by KiwiBacon
steel is the best material for adding strength and rigidity.
Also the best for adding weight, I'd rather take advantage of the rotaries weight factor. If nessesary titanium will be used.
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Old 01-15-2007, 11:21 PM   #55
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by jcsaleen
Also the best for adding weight, I'd rather take advantage of the rotaries weight factor. If nessesary titanium will be used.
Stiffness for weight, steel is better than titanium.
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Old 01-16-2007, 04:38 PM   #56
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Re: Structural Rigidity enhancement...



i think that a rollcage would be the best option.
if the foam cracks you will never get it out and will likely have to replace that part of the frame.

i dont know the specifics of this frame but would adding steel in specific places be an option?

for older cars, you can increase the rigidity by boxing the frame.
your frame is (i gather) made of square/round tubing.

you could weld extra metal onto the frame in the places that are flexing.

it sounds like in your case the middle of the frame is the weakest link.
blindly strengthening the suspension parts would make the problem worse.
what you need to do is put extra metal into the middle section.

i believe that someone suggested a brace along the transmission tunnel.
IMO this is the way to go.

but hey, its your car. do what you want.
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Old 07-05-2020, 07:16 PM   #57
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Cool Re: Structural Rigidity enhancement...

Quote:
Originally Posted by jcsaleen View Post
I was watching some Japanese tuner videos other an
heard about a pretty intresting technique. Since most
Japanese sportscars are hollow frame they injected liquid
foam urthane into the structure of the car. It enters the
body, fills then expands when it hits air and lasty harderens
as tight as a rock in the body. Cheap and very effective more
so then a roll cage supposedly. I might give it a shot on my
FD.

Imput & Other Techniques...
(List only uncommon no strut-bars etc)
Old thread, whaa, whaaa, I know!

I reduced the squeaks n rattles in a low mileage 1981 Buick Century I drove to and from school back early '90s simply by moving all four door strike posts in a few mm!

Prior to that, this comfy, electric driver seat, power windows 5,000mile Century Limited "Estate" Edition(you know what that means!) was a floppy, drafty barn on wheels!

Afterwards, the cabin stayed warmer in winter, and cooler in summer, even without constant blasting heat or A/C. Oh and yes, the handling actually firmed up some: steering more "Germanic", better acceleration, braking, and the thing ROLLLLLED between taps on the gas pedal!

Basically, I transformed a late-'70s designed GM mid-size into a late-model Accord, climate and handling wise, just by 'pulling in' the four passenger doors slightly. And with little more effort required to shut them. Plus - I could hear more of the music from the stereo, at a slightly more conversational volume.

Your mileage may vary, as they say. Moving the door strikers at all, on something built within the last ten model years, might be impossible. And successive decades of engineering have made today's passenger saloons - including Buicks! - as much as several hundreds percent 'stiffer'-bodied, than my '81 Century college shuttle. Modern vehicles are less dependent on door tightness for body rigidity.

In fact, I completely loosened the two hex screws on a rear door striker on my 2015 Hyundai, and the striker slid barely a hair's-breadth in any direction against the door jamb sheet metal. Where as on the old GM A-body, it could be moved in/out/up/down as much as quarter-inch. It took just one-eighth inch inward to transform the Century from a floppy drafty barn to a taught 'library-on-wheels'.

Last edited by RidingOnRailz; 07-10-2020 at 06:35 PM.
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