effectivity of brace

futten

Active Member
Joined
Mar 19, 2010
made up word i know but i would like to ask the autocrossers of they know how effectiv a brace like the one in the link is on handeling/frame stiffness i already have a hellwig frame FX kit installed and a X brace on the rear spring/shock mounts as shown in the pic but would like to know if theres anything else i can do to stiffen the frame with out going APE with adding stuff
 

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Bracing like that is largely extra weight.

If you want to stiffen the car and make it work properly, replace the body bushings with polyurethane. These cars are thought of as full-frame, but the truth is they're a semi-unibody. The frame and body work together. Each is a flimsy piece of crap by itself, but bolted together with proper bushings in every location and it's as solid as many newer cars.
 
i have aluminum body bushings and will add some body bracing also maaaybe a roll bar
 
i have aluminum body bushings and will add some body bracing also maaaybe a roll bar
A long time ago........

I used hockey pucks as body bushings. Upper and lower. Cut and drilled to fit. I wouldn't do it again. But I was flat broke and the sporting goods store was around the block. Tightened the body bolts with big washers until the pucks compressed to bulge a little. HUGE DIFFERENCE!

Of course, it was an even more dramatic change because even though my car wasn't that "old" yet, the originals were rotted out or missing from the factory.

Today they are still there. No other change was as dramatic except maybe for the 6 point roll-bar. I have other braces in place (trunk x-brace, front frame, fender) and not a single one of them was worth the time. But I left them all in place for the hell of it.

I wish I could start over. I would frame-off and skip all the corny crap.
 
soo in other words im not gonna get that brace then
I believe the biggest problem with our frames is twist. Twist is not really addressed with horizontal bracing on the same plane as the overall frames structure. It needs to be trussed.

Take for example a 2x12 lumber square that is framed on the flat (like a picture frame). If I stood on one side and put the other on a block, I could bounce on it and twist it apart. Even with another 2x12 flat braced across it. However, if the lumber is stood up it is more structurally rigid.

Now if I X-braced it further with nothing more than a 2x4 from top to bottom, and bottom to top, left to right.......you get the point. You have seen this in between joists in a basement ceiling or under your floor.

So....the cage does this. Especially the roll bar with an X-brace in the center. Best if you could provide such X-bracing positioned vertically in the front and back as well. This is why you will get more out of a cage. If you plan to do any structural changes to the frame, changes made to the vertical elements would help more. Like boxing up the insides of the rails.

If you don't plan to drag race it, then don't worry much about NHRA rules. But it just so happens the rules do dictate the best configurations for structural rigidity.
 
I believe the biggest problem with our frames is twist. Twist is not really addressed with horizontal bracing on the same plane as the overall frames structure. It needs to be trussed.

And a lot of that twist is induced by the drivetrain trying the pull the passenger side tire up off the ground when you mash the pedal.

A panhard bar or a Watts link can fix that.
 
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well this car will be mostly driven on normal roads as a 8 months out of the year daily and road courses after i got my frame back from the welder with the frame fx put on the frame was ALOT stiffer in tortion by hand sadly also 77 lbs heavier
but i will lighten the car in other ares so
 
well this car will be mostly driven on normal roads as a 8 months out of the year daily and road courses after i got my frame back from the welder with the frame fx put on the frame was ALOT stiffer in tortion by hand sadly also 77 lbs heavier
but i will lighten the car in other ares so

Here's the thing (and this won't help you, because you've already done it, but others may read this in the future), the frame and the body work together.

Checking the frame by itself is worthless. You have to check it with the body bolted on properly. After I replaced my body bushings, the droop you get by jacking the car up under the K-member went away.

It managed this:
IMG_0556.JPG


That's pulling 1.1G laterally in that feature. Look at the door gaps. Look at the moulding. Straight as an arrow.

That's a completely stock frame with new body bushings. Without 77 pounds of extra steel.
The car's body and frame design is sound. The compromises made for cost and NVH and age are what makes it floppy. Fix that and you're good, without the extra weight.
 
Here's the thing (and this won't help you, because you've already done it, but others may read this in the future), the frame and the body work together.

Checking the frame by itself is worthless. You have to check it with the body bolted on properly. After I replaced my body bushings, the droop you get by jacking the car up under the K-member went away.

It managed this:
View attachment 295670

That's pulling 1.1G laterally in that feature. Look at the door gaps. Look at the moulding. Straight as an arrow.

That's a completely stock frame with new body bushings. Without 77 pounds of extra steel.
The car's body and frame design is sound. The compromises made for cost and NVH and age are what makes it floppy. Fix that and you're good, without the extra weight.
Bad ass. I like it!
 
well no more frame bracing then will brace the body and maybe a roll bar it will have to be bolted in and only mountings to the body i dont want to have to cut the floor and weld the rollbar to the frame
 
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