Anton28

Hello everyone. This is my first official post! I'm looking forward to contributing to the community! I just purchased a 1991 Trans Am GTA and staring my mods.

I've spent hours research and still can't find a definite answer. What brakes can fit behind a 17" GTA wheel on 3rd gen? LS1? C5? C6? I don't think a four-piston CTS-V or similar caliper will work, will it?

Thank you in advance, everyone!

LsxMatt

iTrader: (4)

An ls1 brake will fit. I believe it will actually fit a 16” gta as well with a small spacer. I’m not sure about 4 piston brembos. I crammed a set under my old 17” c5 wheels with some grinding, but they would still rub the wheel when going over bumps so I upgraded to an 18” real fast.

Anton28

Thanks for the info. Good to know that the LS1 brakes will fit. Wondering if slightly larger c5/c6 calipers will. I waiting for HAWKS to reply.

Anton28

I just spoke with Hawks'. I'm told I can run a 13" rotor and a c5/c6 caliper should be fine. I will continue my investigation and report back.

LAFireboyd

iTrader: (3)

With regards to Hawk's quoting 13", C5/C6 Standard front brakes are 12.8", so consider that a nominal 13". I believe a couple of people here on TGO are running the Standard 12.8" with 17" wheels: one with the new 17" IROC repro; the other with a 17" ROH wheel.

As for calipers, C6 calipers are the best of the 2-piston calipers: LS=good; C5=better; C6=best(aka Z51, Heavy Duty). NOS C6 calipers are still available in red, yellow, black, dark grey metallic and matte dark grey(blackish). But if you prefer a different script than "CORVETTE," then the same HD calipers were used on Cadillac's XLR and XLR-V, with "XLR" still available in NOS matte grey, and "V1" still available in NOS gloss black. Or for no script, to leave plain or have custom decals made, the 05-06 Pontiac GTO also used the same HD calipers, available remanufactured.

Big Brake Upgrade offers C5/C6 partial and complete conversions for the front, and a C5/C6 rear conversion for the 9-bolt axle(w/ or w/o parking brake). Conversions support multiple options: C5/C6 Standard 12.8" front/12" rear; C6 Z51(HD) 13.4" front/13" rear; C6 Z06 14" front/13.4" rear.

QwkTrip

iTrader: (22)

An aftermarket 17" wheel will almost always clear LS1, C5, C6 brakes. There would have to be some odd "style" feature resulting in a small barrel diameter for it not to work (like the Firehawk replica wheels).

Anton28

I just came across this thread. The guy used 13" C6 kit and its rubbing on the 17" GTA Wheels.

https://www.thirdgen.org/forums/brak...-17-gta-w.html

84 1LE

iTrader: (9)

Thats mine and its not and doesnt rub.The "vette" logo looked like it would, so i ground it off.Since its not a vette i didnt want it on there anyway . Ive yet to see any issues with these, but they are 12.8, not exactly 13".

LAFireboyd

iTrader: (3)

I see. Pretty tight. But in that linked thread, the calipers do clear, but, true, it's close. I don't have GTA wheels, but from what I've read, their flat face can present minor clearance issues with bigger brakes.

Car's not a 'Vette, so go with the plain face remanufactured calipers for the 05-06 Pontiac GTO; same calipers, but no raised cast graphics, then customize them with decals. Remans are like new, but raw, although I think Power Stop offers remanufactured calipers powder coated red or black. Being remans, they'll come with pad abutments brackets, but you can't use those because they're specifically for GTO fitment. It's those brackets that make the difference for fitment from car-to-car, not the calipers. So you'll still have to get abutment brackets for C6 Standard brakes. But C6 used two different brackets, so be sure to get the correct one: one for Standard(JL9, I believe), and one for Z51/HD(J55). You can find them on ebay, raw, or already powder coated red or black, raw/NOS from Kore3, probably from other sources, too. Then if a spacer is still necessary, at least it will be a very thin one.

Or if you don't mind the $$$ for 4-piston Wilwood calipers, contact Scott at bigbrakeupgrade.com I believe Wilwood offers some narrow calipers for the C6, which allow for 13" brakes in tight-fitting wheels, and Scott can tell you about them. He's great, always willing to help people workout such situations.

IROCThe5.7L

Your calipers hit your wheel weights?

84 1LE

iTrader: (9)

Boyd, yes i read the same, even the 16" versions have the same problem/

Iroc, those were stick on weights, so no biggie.

Anton28

I ended up getting the following done with Scott at BigBrakeUpgrade.com

1. LS Spindle and hub conversion
2. LS 12" rotor
3. C6/GTO caliper w/no logo
4. Stainless steel brake lines

I will be instaling sometime next week and will post pics.

The car arrives this weekend along with the 17" GTA wheels, UMI Weight jack kit, and Koni Yellow Shocks. I'm super excited to start on the mods!

cradled

How did it go? I am contemplating jumping down this rabbit hole as well.

George Klass

Bumping this thread to share my experience. Just did a complete suspension and brake swap. For the front brakes went C5 calipers and rotors, Powerstop Z26 pads and BBU hubs + brackets.

At the same time Konis, UMI tubular arms, UMI strut mounts and UMI weight jacks.

Without the supplied spacer from Hawks the wheels don't work. They touch the calipers, cannot move. With the spacer on they have the tiniest amount of clearance. A bit disappointing because at a minimum need a spacer for the rear now to make it look flush all around. We've got the weight jacks height set a bit on the high side due to worried about the wheels rubbing the fender.

84 1LE

iTrader: (9)

Sounds like you're in the same boat as me. Also stick on weights need to be closer towards the back. Too close to the face and calipers will knock them off. Also using hawk spacers...had to, but no other issues to this day.

Thirdgen89GTA

iTrader: (5)

Unless you are auto crossing or road racing, a LS1 brake will upgrade you to capable and consistent performance. If you can get better for the same price or similar go for it.

I have the C5 brake kit on my front's, and a 4th gen LS1 axle out back. And they fit with plenty of room under my 17" SS wheels.

George Klass

Price between both was negligible. Even if I went with LS1 would still be the same situation. These wheels are ***** when it comes to brake upgrades. I think the only setup requiring no spacer would have been 1LE.

IROCThe5.7L

I apologize if I didn't read closely enough. With the Hawks 17" rims you still need the supplied spacers? I needed the spacers with the stock brakes. After the C6 brake upgrade it pushed my wheels out enough where I no longer needed the spacers. The stick on wheel weights are close the caliper but they do not hit. I thought for sure they would. I guess there's some differences between the GTA and IROC wheels...

George Klass

Yeah, had to use the spacers. Without them the wheel was on the caliper