Joe C

i've picked up a factory X-brace to install on my 96 coupe. seems like i got most of the hardware, spacers, nuts/bolts, etc, but as i'm looking at the rear mounting, and for the life of me, i can't see how this will attach to the frame. seems like i may have to fabricate some sort of nut plate and weld it permanently to the frame - OR AM I MISSING SOMETHING? so has the title goes, anyone install the brace on a late model C4? if so, can you provide some details, pics, or whatever. from the FSM, it almost looks like there should be four (4) permanently mounted nuts (both sides) up in there somewhere, but i just don't see anything. TIA...

Midnight 85

On my '85 I had to drill the holes up inside those cavities where the spacer blocks go. I used the x brace as a template to drill them. I can't remember what size I drilled them to but I think it was 9/16. You will need to find a thing called a nutsert. It goes in the hole you drilled then you need a special tool that will set them in the holes, just like a pop rivet would work. Actually you can do it with a 3/8 coarse thread bolt, nut & flat washer. Just put the nutsert in the hole then thread the bolt into it with the washer & nut already on the bolt. Then you can set the nutsert by holding the bolt with a wrench while turning the nut & washer against the nutsert. This is not as easy as the tool so maybe you can find one you can borrow. Nutserts are available on ebay the last I checked. I might have some left but I'd have to check on that.

Shock96

It seems that the rear will need to be drilled and tapped. You could drill and add an insert like a timecert.

92ragtop

BTW, there are also two pairs of studs (5/16? or so)that stick down from the floor pan for the rear sections of the brace. If they're not there, you'll have to come up with something for them as well. Tip: your parking brake cable goes beind the spacers at the back, so that it doesn't hang out the side.

While you're getting all that figured out, give some thought to boxing the X-brace with 4" flat stock for even more rigidity. Doing that made quite a difference on my vert. (Even my wife noticed the change.)

Here is a pic of mine:
Note the notches for the floor pan studs.

corvetteronw

I attended a C4 class at Bloomington Gold that was taught by Chris Petris.
This very same question was asked by a 93 coupe owner whose car was up on a lift and being used as a demonstrator. Chris showed us where the front of the brace could be bolted in using the existing tapped holes that are in all 86 to 96 Corvettes. He then said to mark the holes where the brace would be in the rear and to use self-tapping bolts to attach it.
Some of you are probably tired of me pointing this out but if you go to the www.vette2vette website you can find the frame braces that he has for sale. These were designed by Gordon Killebrew and work great on my 91.
I was just at his shop earlier today as I am writing a magazine article about his business. I did see a stock C4 frame brace there in his inventory. I don't know how much he is asking for it though.

Shock96

Does anyone have a pick of the vette2vette solution installed?

c4cruiser

Coupes didn't get the X-brace so there were no holes in the rear of the frame. You will have to drill the holes and install some nutserts.

As mentioned, the convertibles used 4 studs in the floor pan to provide the extra stiffness to reduce flexing of the vert body. To be able to get the OEM stiffness from the brace, you will need to drill holes in the floorpan and install bolts or studs. You will need to remove the seats, carpeting and insulation. Make sure you completely seal the hole around the new studs or bolts to prevent water from entering.

Also be aware that the convertible ride height was about 1" higher than the coupe in order to allow for ground clearance for the X-brace. The brace will clear the factory exhaust.

Joe C

thanks fo the idea! took my X-brace to a local welder/fabricator to get a price for boxing in the members per your attached photo. ready for this (drum roll please) - $50 . couldn't pass that up - should get it back later this week, or first part of next week... one thing i'm having him do is to add a series of plug welds, length wise, down the center of each member, about every 6-8" or so... don't know if that will help, but i figure it can't hurt.

92ragtop

$50?!! Give the guy a 12-pack as a bonus! I spent $20 just for the metal.

Spray it with a can of rubberized undercoating to finish it off nice.