avigar

Who has added a Cross/X frame brace to their C4 coupe? Is there significant improvement to the handling to justify the extra $400+ expense? I use my coupe mostly on the highways and rural roads. No racing or aggressive driving; mostly at cruising speeds.

I'd like to start driving without the targa roof this summer. At about what speed does the bodyflex usually start to become noticeable? Are there other low cost alternative solutions to minimize the flexing?

jmgtp

I can't comment on any bracing that goes beneath the car but you may also want to consider a targa brace.

I had the flexy feeling with the targa off, the first time I drove it topless I pulled over immediately because I thought something was wrong with the suspension. I went with an AFSB targe brace. It feels more solid with the brace on then with the glass roof and it it looks nice too. Big benefit is you don't lose any ground clearance.

If you don't want anything on the roof at all then I guess your stuck with a brace underneath.

24695bob

I installed one on my 95 when I owned it...and it made a major difference... especially when crawling over a set of railroad tracks...

I used one out of a wrecked Convertible that I picked up locally and it sure did not cost me anywhere near $400....

BTW...I just purchased a 88ANC and I'm willing to bet that the targa roof will NEVER EVER come off the car... if I want to go topless I'll drive one of my convertibles...

Bob G.

avigar

I noticed that R-D Racing also advertise a crossbar that installs behind the driver/passenger seats. It seems to be the least expensive option. How well does it work, though? Anyone install one on theirs?

c4cruiser

The R-D Racing "Cross Bar" is designed for using a racing harness setup. It really doesn't add much of anything to stiffening the body in terms of stopping what is called "cowl flex" once the targa top is removed.

There can be issues with installing an X-brace under the car. First, there is a slight difference in ground clearance (height) between the coupe and convertible. The 'vert sits higher because of the factory X-brace. The coupe sits a bit lower simply because it doesn't have that brace.

The R-D undercar Xrace does not attach in the same way as the factory 'vret brace does. The OEM brace not only attaches to the corners of the frame, but also attaches to the floor pan. The pan has a number of studs (4 or 6, can't remember) that go thru the rear half of the brace and nuts hold the brace to the pan.

The R-D brace only attaches to the frame corners. You also have to drill some additional holes in the frame and use nutserts to attach their brace. There is something like 1 1/2" loss of ground clearance with the R-D brace.

corvetteronw

I have the Gordon Killebrew brace on my 91 coupe and love it. Feels like a new car. Got it from Vette2Vette

xole

I have the AFSB and really like it. Works really well with the rear hatch vent.

crzydrumer14

thats exactly what i have been looking for!!! I hate taking the top off and the handling feel like its going out the window. At least in my Vette, you can feel a pretty noticeable difference. WHERE CAN I GET ONE???

avigar

I guess that AFSB can be purchased here: http://www.prostreetcustoms.net/index.html

The AFSB truss seems to be the best option of the bunch in terms of looks and ease of installation.

ToniH

I installed the R-D Racing "Cross bar" and then some time later the "Camber brace". There was noticeable stiffening of the frame after each part. With both installed almost all creaks are gone. Now if I jack up one corner both tires on that side lift off the ground in unison. The car also feels much stiffer than before (not very accurate I know but after years with my car I can feel the difference).

Probably most of the stiffening is due the camber brace but I do believe the cross bar also helps (if one can judge by the frame creaks).

ggrassmid

I have this for my 85, I could not be happier with with it. Tom Gasper at ProStreet is top notch.

Sky Vette

Considering all the engineering time and money spent on designing the C4, it is hard to believe there is any technical reason to NOT drive it with the targa off. Otherwise, it wouldn't have been produced with a removable top. For "normal" driving on "average" road surfaces there should be no problem going topless.

avigar

To those that use the AFSB truss, what do you do for security when you have to park and leave the car? Do you normally carry the roof in the trunk, when the truss is used, so you can swap out as needed?

jmgtp

Don't park anywhere that you can't see it. I learned the hard way.
I was at an icecream shop one night last year. The car was street parked on the side opposite the shop, it was in sight but I didn't have a hawk eye on it. Some jerk threw his cigarette butt in. It landed on the passenger seat and burned a tiny dimple into my brand new wet okole seat covers. No real damage, but its upsetting for one that some ahole decided to try to ruin what wasnt his and I also had literally just installed expensive seat covers. What I would have done if I caught that ahole...

I do carry my roof in the trunk most of the time now but its a lot of hassle to swap roof/bar. It's more for the case that a thunderstorm catches me off guard and I have to put a roof on. It makes transporting anything really hard since you lose all trunk space. I'm trying to figure out some kind of "raincoat" that I could secure over it when parked, something that would keep a drizzle out and perhaps more importantly keep the sun out. That vinyl armerst cover can get HOT without a roof on!

proracr

IMHO, a bolt-on frame cross-brace and Targa truss brace would be more than sufficient for road/highway use. If they aren't, then you're probably driving recklessly on the public roads and should restrict that type of driving to the track. The combined cost for these two braces is under $900 at Corvette Central.

tmirisola

I have an awful shake with the targa top off. Are there any pics out there of the bolt on targa support?. Do they really work and can they be purchased.

Ron B C4

Read through this whole thread before I noticed you brought up a old thread.
Any one know if Prostreetcustoms is still in business. The link doesn't work anymore.

tombrammer

It appears that Corvette Central still carries one; https://issuu.com/corvettecentral/docs/c4_catalog/147

tmirisola

Thank You. It's difficult to google search when a newbie doesn't know the exact name of the part. Again :-) Thank You for the help.

Has anybody used one of these???? I don't see them talked about much.

tmirisola

Just heard back from Corvette Central and the part is discontinued. Availability again is unknown

I posted an ad in the wanted section of the forum.