mcm95403

I picked up an x-brace for my coupe yesterday. In talking with my friend about it the question came up:

For those who have an x-brace on their coupe, does it then get rid of the "cowl shake" if you run without the targa in place?

PLRX

No.

I had a 92 Vert, and that thing flexed like no other vehicle I've driven. I used to call it the titanic. I'm sure it helps, but it will not stop the flexing.

Digital Disaster

I put one on my 92 and it helped, but I'm sure not nearly as well as modern aftermarket units.
The C4 needs major bracing to be halfway solid. In doing so you're also adding a lot of weight.

H P Bushrod

I drove a '92 triple white vert (that I was interested in buying) that had cowl shake so bad, I thought something was wrong with it. The car only had 18,832 miles on it!

mcm95403

Wow, those are some spooky responses. I'm starting to wonder if it will make any difference at all then. Guess I'll find out this weekend if I have time to get it bolted in.

Frizlefrak

Well, you already have the brace....may as well find out what it will (or won't) do. Let us know.

H P Bushrod

Keep us posted.

mcm95403

Yep, will do!

ejscarfo

92ragtop

I you box the X-brace, it works even better:

Tom400CFI

X2

In my quest for a stiffer C4, I had the same idea. I drove a '90 'Vert (with the x brace) and it felt about identical to my car w/the roof off.

My conclusion: if the x-brace does something it is something that can only be measured on a machine...not by your butt.

mcm95403

It does seem odd to me that bolting an x-brace to the bottom of a one-piece frame could stiffen it up, but I also tend to think that GM wouldn't have put the R&D time and production cost into it if it served no purpose either.

Driving home this evening I was thinking about the possibility of having it welded at the X rather than just using the bolts.

I do like the idea of boxing it.......

Frizlefrak

Then again, this is the company that put the "frisbee" on the front of the L98....

aboatguy

I drove the vert once without the X brace. (getting exhaust work)

It was like driving a car made out of wet pasta. So the X brace does something.

IMO best inexpensive way to stiffen up a C4 vert is a properly installed Factory hardtop.

The best way would be a full cage....

Mike

cv67

It would seem some box rectangle tubing with some gussets would be a lot stiffer than the piece in the pic never had one in front of me though.

aboatguy

It may not be worth the extra weight to box the x brace if its under tension it may be plenty strong. (tension is the only reason I can think of why something so flimsy looking is fastened with four big ish bolts on each corner)

mcm95403

Ha, yes that's so true!

mcm95403

How would you "tension" it though? There's no adjustment, so way to tension it, other than maybe jacking it up with one end bolted down tight and letting the frame flex do the "tensioning". I think that' would require a special jig to hold the car each time you need to install it though.

Frizlefrak

The "tension" would come as the chassis attempts to flex. Those forces would (theoretically) put the brace under tension. At rest it would be under no tension.

aboatguy