The Big Bad Brake Thread

[Burbman]

Great info here, I did did the C5/GXP upgrade on my '02 GTP. Caution on the rear lines....placement is important! The rear lines are short and since the wheels don't turn I didn't pay that much attention, but the 245 tires are wide enough that they will rub the brake lines if you are not careful. I finished the car on Sat nite, drove to a local car show on Sunday, and when I got home the RR line has a spot where the stainless is gone along with 75% of the rubber. Car now back in the garage waiting for new lines.

 

[CadVetteStang]

I bought the C5 Corvette caliper on 14" C6 rotor hybrid bracket kit for W-body/ N-body cars from Kore3. It is zinc coated and comes with spacers and mounting bolts. Cost is $115 + $14 shipping. Tobin Knighton was my sales/tech rep and he is great to work with.
The kit allows you to install C5 (or C6 base) calipers and JL9 abutment brackets on Grand Prix ( or other W-bodies) and use the 355MM C6 Z06 rotor.
The only hiccup for me was that the kit was originally designed for the N-body cars and has 12MM spindle mounting holes. Kore3 was willing to enlarge the holes to the W-body 14MM size and re-zinc the brackets for $20 more ($10 without re-zinc), but I opted to save the money and do the holes myself on a drill press. Also, Tobin swapped in the 14MM mounting hardware at no extra cost so there will be nothing I have to replace after the bolt hole modification.

I am pretty sure that I have Tobin convinced to produce future production runs with the 14MM holes because of more demand for W-body cars. We even talked about me waiting a few weeks for the next scheduled production run and getting them with the 14MM holes but I opted to buy the in-stock set.

I also did a lot of research and chose to order 14" Mustang Shelby GT500 rotors instead of the C6 Corvette version. They are much cheaper and don't have the retarded cross-drilled holes that only work with Asbestos pads of the 60's. I found them on eBay for $68 in a 2 pack set w/ free shipping.

Cheapest C5 caliper/w bracket set I found was the Power Stop rebuilds from Rock Auto. With core charges included, I was only out about $160 total for the pair after shipping, and they still have the factory raised CORVETTE logo (unlike the AUTOZONE units which were much more expensive and had the lettering ground off).

I also got some shimmed semi metallic pads from Rock Auto for $8.50 + $6 shipping.

This puts me at $375 total so far for the upgrade and all I have left to deal with are the hoses.

I'm actually going to install this on my E-body (not my wife's GP). However, it should all bolt up the same on my 02 Eldorado.
I have a few projects to finish before I get started, but I'll keep you posted.

The last gen Eldorado hoses are actually very long because they have a center bracket. I think I can use the stock ones if I put a spacer under that bracket ( not sure yet). You guys might look at Eldorado hoses and maybe late DTS hoses as swap options. My long side is over 18" and I the DTS long side is 20".

Oh, and Wow! Those 14" rotors are heavy! And those Corvette calipers are light! Was not expecting that much and that little weight.

If you talk to Tobin at Kore3, be sure to mention Cody and his 02 Eldorado.

Thanks,
Cody

 

[handen]

Is there an updated link for doing the rear brake GXP upgrade on an '04+? I need to replace a seized rear caliper on my '07 GT but found somebody selling a full set of GXP calipers and rotors for cheaper than it would cost to buy just the single caliper that I need to replace, but the OP says it's not just a straight swap on the '04+ and the link explaining is dead. I just want to know if it's worth the hassle.

 

[CHI2000GTP]

Overkill's website has a brief mention of the rear GXP brakes. 04+ GP's require more work. Hopefully this gives you an idea of what's involved:

http://www.getoverkilled.ca/wbodytech.html

From the website:

Rear brakes

The only real upgrade is to Grand Prix GXP. The calipers are hard to find, best to order new. These will bolt on to older Grand Prix, Regal, all Impala/Monte carlo but 04-08 Grand Prix will require a swap to spindles that use the parking brake on the inside of the rotor drum on the vehicles previously mentioned. I would consider this update only if doing the Brembos or 12.7" front rotor setup, but wow these plus Brembos infront would stop well.

 

[handen]

Thanks to Archive.org's Wayback Machine™ I was able to travel through space and time to recover the '04+ GXP brake upgrade guide posted by FLIP over at GPONA in 2009, which I will now go through the hassle of reposting below for future posterity (with minor grammatical and contextual edits):

The Complete GXP Brake Installation Guide for '04+ Base/GT/GTP Models

​ Now with working E-brake!

© 2009 FLIP on the now-defunct GPONA.com Forums.


Pt. 1: FRONT
​

Stuff you need to have:

1. Calipers & Caliper brackets
2. Rotors
3. Brake pads
4. Brake hoses

Installation
(Tip: Use Anti-seize on all bolts/lugs when installing.)

1. Remove wheels. (19mm)

2. Remove caliper bracket bolts. (2x15mm)

3. Remove rotors.

4. Clean hub to install the GXP rotors.

5. Install rotors, caliper bracket, and brake pads. Make sure to remember to install the retainer clips on the brackets first.

6. Bolt caliper on. (2x13mm)

7. Install new brake hoses (13mm again) ensuring hose is tight to the caliper (11mm).

8. Bleed brakes. (Bleeder screw is 10mm.)

9. Reinstall wheels and that's it! Note these are 17" OEM wheels from the '05 GTP and '06-'07 GT. It fits!! This may be important information to some! (I.e., me.)

 

[handen]

The Complete GXP Brake Installation Guide for '04+ Base/GT/GTP Models

​ Now with working E-brake!

© 2009 FLIP on the now-defunct GPONA.com Forums.


Pt. 2: REAR

​

Stuff you need to have for an '04+ Grand Prix:

1. Calipers & caliper brackets
2. Rotors
3. Brake hoses
4. Brake pads
5. E-brake cables
6. You can buy ALL the E-brake stuff or get GXP hubs with the E-brake stuff there. Up to you..

Installation
(Tip: Use Anti-seize on all bolts/lugs when installing.)

1. Remove wheels. (19mm)

2. Remove caliper bracket bolts. (2x15mm)

Caliper off:

3. Remove trailing arm bolt. (24mm)

4. Remove adjustable arms. (One long bolt: 21mm)

5. Unplug hub wiring harness.

6. Remove bottom strut bolts. (21mm)

7. Remove hub from car.

You should be looking at this:

8. Install GXP hub & plug wiring harness back in.

9. Install adjustable arms bolt.

10. Install trailing arm bolt.

11. Install rotor, brackets, and pads.

12. Loosen nut for E-brake all the way off. (LEFT SIDE: 16mm plus vice grips)

13. Remove E-BRAKE cable from the clip. (RIGHT SIDE: Screwdriver)

14. Install right side E-brake cable in place then clip it together.

16. Install Left side E-brake cable & bolt it up. Tighten until you can see the springs on the hub starting to move. (DONT OVER TIGHTEN THEM!!)

E-Brake is done!

17. Remove hose bracket from body. (10mm)

18. Remove brake line. (13mm)

19. Install hose and bracket, then install brake line.

20. Bleed brakes. (Bleeder screw is 10mm.)

21. Install wheels and that's it!

Additional information from other posters in that thread:

GM part numbers for rear GXP brake lines:
• 15826462 - Left
• 15826463 - Right


GM part numbers for e-brake lines:
• 15297496 - Right
• 15242626 - LEFT


If you need brake pad retainers or new dust boots for the caliper pins, you can get a complete kit from Raybestos:
• H5682A - Front (4 brackets, 4 boots)
• H5683A - Rear


If you want to do a caliper rebuild you can get the following:


Piston boot + seal:
• CENTRIC Part # 14363032 (rear caliper, order TWO kits to do BOTH calipers)
• CENTRIC Part # 14366014 (front caliper, order TWO kits to do BOTH calipers)

 

[Ridin ON Chrome]

I guess I should update you guys on my big brake experience.

In my attempt to use some GEN 1 CTS-V calipers and the 14" GT500 rotors, they just wouldn't fit behind my wheels with. Need at least 19s in my style and/or spacer.
So since I just bought these wheels with new tires. It was back to the C5 calipers.

Doing research came across the ATS Brembo's which use a 12.7" rotors. Umm what other car used a 12.7" rotor?? That's right the GXP.
Which I already had some, becasue before I found this out, I was just going to do GXP brakes.

So yes the GXP rotors are almost the same exact same dimensions as the ATS Brembo's. GXPs are MM or two bigger and thicker but work fine.

It was still a very close fit and have to run a 3mm spacer to clear the wheel spokes. But they look good. lol