After market companies have developed different chassis bracing for the evo. Companies like NAGISA,G.T Spec, and Cusco. They are making braces for the the trunk,fender braces and lower center power braces.Does anybody have any experiences with these braces? Would these braces help our D.S.Ms. If they would we can copy them .

They work ok but a cage would be better. i could see the fender braces being utilized so you didn't have to take the cage through the firewall (and have to take weight pentalties).

The weak-point of a DSM is totally different from that of an Evo. We lack torsional stiffness between the A- and C-pillars, while the cabin of an Evo is a rock. That's why the solution for a DSM is an 8-point cage. Evos, on the other hand, don't have enough bracing for the tops of the struts. That's why they now get a front brace from the factory and people add a brace in the trunk.

- Jtoby

jtmcinder said:

The weak-point of a DSM is totally different from that of an Evo. We lack torsional stiffness between the A- and C-pillars, while the cabin of an Evo is a rock. That's why the solution for a DSM is an 8-point cage. Evos, on the other hand, don't have enough bracing for the tops of the struts. That's why they now get a front brace from the factory and people add a brace in the trunk.

- Jtoby

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Agreed, the 4 point in my car helps but the torsional rigidity is still something to be desired. The guy I bought my Laser off of has an Evo and even with the added grip of the slicks and quick transitioning of autocross the chassis doesn't budge.

Maybe this was hersay but, I remember hearing and possibly reading about a couple of rare cases of guys having the chassis basically crack around the front strut towers. Is this known as a weak are on our cars?? I have a front strut tower bar but I've been thinking of having some kind of bracing added to the area.

Zero Bar said:

Agreed, the 4 point in my car helps but the torsional rigidity is still something to be desired. The guy I bought my Laser off of has an Evo and even with the added grip of the slicks and quick transitioning of autocross the chassis doesn't budge.

Maybe this was hersay but, I remember hearing and possibly reading about a couple of rare cases of guys having the chassis basically crack around the front strut towers. Is this known as a weak are on our cars?? I have a front strut tower bar but I've been thinking of having some kind of bracing added to the area.

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I have heard of strut towers cracking on a 2g but thats because they have a mad rust problems near the strut towers.

A week ago, Pagosa DSM and I did a test on my car to see if the cabin area was flexing. My body is stock with zero additional bracing. We ran two strings crossed through the center of the car, one end tied to the rear seat latches, the other running out the front door and pulled tight under the windshield trim. The string was held tight enough to give an audible "twang" when snapped. They created a big X through the center of the car with the crossing point of the strings marked on tape so it was easy to see.

We then lifted the right rear corner of the car two feet off the ground. The results? The gap between the strings expanded by about 1/4" with the hatch closed and 3/16 with it open. Having the doors opened or closed made no difference at all. I'll post pictures of this when I get home.

So the car is flexing through the cabin area but it sure isn't flexing much. Now this could be because we were just lifting one corner but even with me sitting on the opposite corner of the trunk (I'm 220 lbs) it didn't change it one bit.

We also checked the hatch to see if it was flexing. We opened and closed the hatch while the car was on the ground and then with the corner lifted. The hatch did deflect a bit with the corner lifted, about 1/16 of an inch.

At a future date we're looking to put a car on a frame rack and really see where we can find body flex so we know exactly where to brace and how without making the car miserable for street use. I, for one, don't have the head clearance for a roll cage running along the top of the door.

Jtoby, do you have any evidence to show the flexing of the cabin area? I've read several posts where you say this is a problem but never seen anything to show it.

I have the head clearance problem as well as I'm 6'2". My Butler aluminum seat helped a ton but because of the exhaust tunnel my seat just to the left of center by about 1-2". Cutting into the tunnel and moving the seat over would alleviate this problem, but a bit drastic for most!!

Ever jack up the car from the front subframe?? Not exactly the best place to do so but you will see a lot of flex. Also if you jack the car up on stands and watch as the front is lowered onto the stands and watch the front dop down. That's just the weight of the car, now factor in 255 width slicks going around a sustained corner. There has to be a ton of force on the car. Either way chassis bracing won't hurt you and it's cheap!!

Right, bracing is great. The question is, where is the best place to put it? I don't believe a full roll cage is necessary. Look at Scott Gray's car. He pulls over 1g on a skid pad without a cage.

Here is the photo of the test we did lifting the rear of the car.



The little red dot on the line is just to help show where it crosses the tape. The mark on the left side lined up with the string best, the one on the right was too high. Like I said... almost no deflection through the center of the car. As you can see, this photo is with the hatch open.

Apologies. I wasn't clear. It's the 2G that lacks torsional stiffness. I ran something very close to the same test as you and my shifting was around an inch. I also seem to crack bolted-on polycarb sunroofs.

1Gs were homologated rally cars. It doesn't surprise me that the body is better.

- Jtoby

Jtoby
Do you think the problem with the 2nd g is the sunroof or did they change the unibody frame from the 1st g. I realize the body pannels and wheel base where change, but do you know the changes on the unibody structure changes?Did you string check a 2nd g with out a sunroof?

I did not get a chance to check a car without a sunroof, but I know several autocrossers with sunroof-less 2Gs and they report similar problems. Apologies, again, since this is close to "butt-dyno" data, but that's all I have.

- Jtoby

Ok, Nick asked me to chime in on my experiences with 1G stuff. I'd say the front strut area where the seams join is an area of interest, but past my discussions with Rick and Nick the 1G chassis is quite good. A 3 point front strut brace helps as the tires get sticky. I don't think the rear is a big deal either, these aren't strut suspension in the rear, the control arms mount to the subframe, so all wheel loads are taken there. The spring loads in the rear of these cars just isn't high enough to cause much movement. Fix the lower control arms in the rear, and replace the subframe bushings, after that its a street car. If you want F1 car stiffness, get one, otherwise I'd be impressed to talk with people that can document rear strut brace improvements with numbers. I welcome comments..

Ray

Thanks Ray! So looking at my engine bay a couple years back when my engine was out it looked like the strut towers were glued into the car. Is there any advantage to grinding those beads off and seam welding the towers? The stuff seems plenty strong (pun intended) but it is still softer than steel.

eclipsh said:

Thanks Ray! So looking at my engine bay a couple years back when my engine was out it looked like the strut towers were glued into the car. Is there any advantage to grinding those beads off and seam welding the towers? The stuff seems plenty strong (pun intended) but it is still softer than steel.

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I doubt they are glued. It is probably seam sealer over spot welds.