Will my stock 15" GT wheels allow a 12" corvette brake rotor conversion? I have searched and some internet pages say it will fit stock wheels and some say you need 17" wheels. Which is it? I need rotors and pads anyway for my '88 Fiero and thought this would be a great upgrade if the GT wheels clear the 12" rotors.

You will need a bigger wheel. The 11.25" LaBaron rotor barely fits inside a stock 15" and even then only if your balance weights are on the outside of the wheel. HT Motorsports recommends 17" or larger.

If you use the rear wheels only it will fit, but the front wheels on the '88 will not fit over the calipers since the inside edge that drops into the center comes too close. OleJoeDad and I tried it on my '88 GT with a 12 inch Corvette conversion. However, it only clears by about 1/4 inch or less with the rear wheels.

To summerize:
I can run 12" corvette rotors and my stock calipers on the front and rear of my '88 Fiero if I use 4 rear 15" GT wheels all around?

[This message has been edited by sportcoupe (edited 12-26-2010).]

The smallest wheels I could get to fit on my 88 with the 12" Corvette rotors (with stock 88 calipers) was 16". And even then I had to get really creative when it came to getting the brake hose to not touch the inside of the wheel. I never tried the rear 88 wheels on my fronts, so I can't speak for its fitment. One thing was for sure, the spare didn't fit at all. I'll try to get a picture later of how my 16" wheels fit. The clearance issues usually come in where the hose attaches to the caliper, there is this tall square block on the caliper, and it is usually the limiting factor.

I don't know if I would do it or not, but the rear '88 wheels have the clearance for the calipers, but just barely. As to how well it would work in the back with the E-brake I don't know. The brake lines would be extremely close too. So I would really suggest that you go to 16" or larger wheels even if it is technically possible to run the rear '88 wheels. If you put the rear '88 wheels on the front they will stick out a ways from the wheel wells too.

I forgot that the backspacing of stock wheels was different front to rear. Thanks.

Since I'm keeping my stock 15" GT wheels looks like I just buy factory '88 rotors and pads. All my rotors need replacing and I thought I'd upgrade if possible. Oh well.

quote Originally posted by sportcoupe: FieroAddiction says that the 12" corvette brakes with fit behind a stock GT 15" wheels. This statement is in the 3rd picture down of the following link: http://www.fieroaddiction.com/brakes.html

The 88 calipers on a 12" rotor are very, very close to rubbing. As you design the caliper brackets to accomodate the larger rotor, there is some freedom with the design. If you bias the caliper placement so it is as close to the rotor as possible, then you can make them fit a stock 15" fiero wheel (FieroAddiction route), but give up some braking benefit. If you bias the caliper so the brake pad is at the outer edge of the rotor to maximize braking benefit (similar to the WCF design), then they will rub on the 15" wheel...

The short answer is some do, some don't and the ones that used to advertise they fit the stock 15" wheels are not longer being manufactured.

quote Originally posted by fieroguru: The short answer is some do, some don't and the ones that used to advertise they fit the stock 15" wheels are not longer being manufactured.

Is there a dimensioned diagram available for the FA brackets that fit stock 15" wheel? I can make my own if I have the measurements.

quote Originally posted by sportcoupe: Is there a dimensioned diagram available for the FA brackets that fit stock 15" wheel? I can make my own if I have the measurements.

Not that I am aware of. Someone who had a set would need to check the offset distance (FieroAddiction's latest style just offset the holes sideways vs. rotating while offsetting).

From my own research:
The stock 88 rotor measured 10.432" and vette one was 12.007". To keep the rotor pads in the same relative position the new hole distance should be 0.7875". The stock caliper distance has the edge of the brake pad inset from the edge of the rotor, so you can go out further if you would like. I pushed the pad out flush with the edge of the vette rotor and came up with 0.947". I never measured how close you could bring the caliper in before it rubs (all my fieros run 16's).

I assume FieroAddictions brackets have an offset slightly less than the .7875" that would give the calipers the same clearance to the rotors as stock.

thanks guru