Write-Up: GXP Brake Caliper + Rotor Conversion

So, I replaced my LF hub last night, and decided to see if these Grand Prix GXP calipers and brackets fit the Riv. They DO!!! No fabrication, no tapping or drilling, they bolt right on!


The stock wheels wouldn't clear them (obviously), but my 17's fit perfect. Notice the difference in rotor size lol.


The brake hoses have the exact same connection to the caliper, and are damn close to the exact location of the stockers. I think I just might buy some rotors and pads and mount these bad boys up. The stock Riviera bracket bolts fit perfectly.....seriously. I'm geeked.

What year are those from? And I take it these wouldn't bolt right up to a 95/96?

They're from any Grand Prix GXP (the V8 version). They went from 2005 to 2009.

From the dealer they're about $250 a piece for the calipers. About $50 per bracket. I haven't looked at the rotors yet. I have pads too. I just need to figure out which rotors will work. Don't go buying or finding anything yet. Let me be the Guinea Pig. So far, they appear to be absolutely direct bolt-ons.

I've also found that some Impalas have dual piston calipers as well. Not nearly as fancy as the GXP's, but dual piston nonetheless. I think they just might work also...even with stock rotors. I did a brake job on a 2008 Impala the other day and was like "hmmmm". I'll figure it out for us. No more modifying Camaro brakes to fit.....that's my goal

Hey Scott--- I think the sub for the GXP brakes would have been ATE or Bendix -- on the Riv it was ATE I think-- and I bet the GXP rotors slide right on and the GXP mounting brackets fit on the Riv spindles. 

FYI there were also some Olds 98s around 1997-1999 that had front brakes as dual pot calipers on 16" wheels.  Kinda wonder if those might fit directly.

Albertj

Those WERE the GXP brackets and calipers I have both sides with pads at the shop. I just now decided to see if they fit. They're damn near perfect, right down to the brake hose fitting and location.
Hell, if those Impala dual calipers bolt right on, it'd be a good, inexpensive upgrade IMO.

I think, and don't quote me on this, that the Olds caliper mountings were different. I don't think we'll have any on the shelf for me to play with. I WILL test those Impala ones though. I'm also going to grab a GXP rotor and see if it fits right in. It's obvious that the bolt spacings and thread pitches are identical, but I'm not sure if the ears are extended on the GXP knuckle to allow for a larger rotor.

the point is, isn't the GXP using the same bolt circle?  Don't the hubs match (center hole)?

There has been some discussion re: Monte/Impala caliper upgrades. You can read more about it here:

https://rivperformance.editboard.com/t8685-possible-06-monte-impala-brake-upgrade

@albert (because I can't quote) Yes, they have the exact same bolt pattern and center.

@AA I didn't realize someone did it. Cool shit. Less work I have to do lol

What I'm not clear on, are the GXP calipers basically the same as the Impala/Monte's?

Well, by looking at them, the GXP calipers are longer in length, and the pistons are also thicker and spaced farther apart then Impala calipers. I assume this is so they can use longer brake pads and bigger rotors. I'll see if I can get pictures of the two next to each other.

That would be great. If you don't mind, I'll split this thread to form a GXP caliper upgrade Write-Up, assuming someone will do the mod. If they turn out to be the same as impala/monte calipers, we'll just merge into that thread.

I'll be doing the mod as long as I can convince my shop foreman to let me have the parts lol. Calipers, brackets, and pads are just sitting in the back room in the boxes. Nobody knows where they came from....

Now THIS sounds awesome

FYI, different size rotors are required for GXP caliper fitment. The rotor outside dia is 12.71 (323mm). Overall height is 2.04". Not sure the disk ring thickness. This rotor was used in the following vehicles:

BUICK PARK AVENUE (2003 - 2005)
CADILLAC DEVILLE (2000 - 2005)
CADILLAC SEVILLE (1998 - 2004)
PONTIAC BONNEVILLE (2004 - 2005)

Rotor part #s:

AC Delco: 1770915 (GM#89047762)
AC Delco DuraStop HD 18A1755 (GM#19157306, 19175346)
RAYBESTOS: 580264R
RAYBESTOS HD: 580264
POWER STOP Drilled/Slotted: AR82107XPR
WAGNER: BD126187
Centric 125 Series: 125.62084
Centric 125 Series (cryo treat): 125.62084CRY
Centric Drilled/Slotted: 12762084L/12762084R
StopTech Sport Slotted: 126.62084SL/126.62084SR
StopTech Sport Slotted (cryo treat):126.62084CSL/126.62084CSR
StopTech Sport Drilled: 128.62084L/128.62084R
StopTech Sport Drilled (cryo treat): 128.62084CL/128.62084CR

Interesting note from RockAuto re: AC Delco:

FRONT 1ST DESIGN; FOR VEHICLES WITH VIN PRIOR TO 1G2HZ54Y45U129028, MUST ONLY USE TOGETHER WITH 18045380 PAD KIT-FOR 2ND DESIGN SEE 88964116; w/ANTILOCK DISC BRK(JL9); w/o BONNEVILLE GXP(WA2)

FRONT 2ND DESIGN; FOR VEHICLES WITH VIN 1G2HZ54Y45U129028 & LATER, MUST ONLY USE TOGETHER WITH 19152666 PAD KIT-FOR 1ST DES SEE 19202731; w/FRT & RR DISC ANTILOCK BRK(JL9); w/o BONNEVILLE GXP(WA2)

Available pad compounds for GXP front calipers:

Akebono ProACT Ceramic (ACT1019)
Hawk Performance Ceramic (HB467Z.540)
Hawk HPS Street Ferro-Carbon (HB467F.540)

Right. I haven't gotten that far yet lol. You can tell by the picture that the stockers are WAY too small.

So, we don't have any Impala calipers in stock. The Chevy dealer across the street doesn't even have one. The closest supplier that has one is 40 miles away....lol wtf. I talked to the NAPA we deal with down the street. I'm going to go there tomorrow or something and use one of theirs for measurements and pics.

I just put in new rotors and pads and I am finding that I shouldve went to fbods or these. They take more abuse and dont get as hot as fast, right? I have to take adderall or drink 2 liters of coffee before I drive if I wanna right lane chill. Otherwise, it's WOT from every stop. I need help.

charlieRobinson wrote:

I just put in new rotors and pads and I am finding that I shouldve went to fbods or these. They take more abuse and dont get as hot as fast, right? I have to take adderall or drink 2 liters of coffee before I drive if I wanna right lane chill. Otherwise, it's WOT from every stop. I need help.

No, they still get hot, they're just able to take the heat and dissipate it faster. Yes, the stock Riv brakes, when beat on a lil bit, start fading and the rotors warp. I've gone through at least 4 sets of rotors and had to reface each set twice.

*** Not trying to bash the GXP brake mod, just stating a few facts *** I will be making some comparison to F-Body, since I think some (myself included) are wondering which option is the best way to go.

There's more to 'warping' rotors than size and weight of the rotors. According to StopTech, most times when people think rotors are warped really aren't. What happens is the pads get too hot and coat the rotor face with an uneven layer of pad compound (called uneven deposition or imprinting), causing pulsing known as judder. I think warp does happen eventually, but this is how it starts.

A good high temperature performance pad won't 'warp' rotors like a cheaper or mid-grade pad when driven hard and hot, because it doesn't smear the compound as much. When cool, a high-temp performance pad scrubs the rotor surface, keeping them nice and strait. StopTech has actually used race pads (Hawk Blue) to turn 'warped' rotor surfaces back to true, on the car, eliminating judder completely. A few of us have put thousands of miles on stock Riviera rotors with F-Body calipers and good pads with no issues.

Agreed, OEM Riviera calipers are not adequate for serious driving, mainly because there aren't many good pad compounds to choose from. The 12" rotors are not the weak point, though. It's the small caliper and pad that hold you back.

GXP's rotors are a bit bigger, which is going to help some with heat management. GXP's larger calipers and pad surface are much better for heat over OEM, which is going to help a bunch to fight fade and judder. However one limiting factor for GXP brakes is pad compound availability. You can't get as many serious pad options for GXP because the pad makers don't stock them. No track-ready pads are available. Best I've found are Hawk HPS and EBC Yellowstuff, good for street only. Upgrading from OEM to GXP will offer a big improvement, but if you plan to see benefit over F-Bodies, invest in one of the two mentioned compounds.

For most daily driving, I think GXP and F-Body will feel much the same, as they are similar in size and material. When you really get on them, GXP may show a slight advantage over F-Body if equipped with the same pads. But I would stick to F-Bodies for track duty or very repeated high speed stops, since you will have the option to upgrade to a variety of high-temp racing compounds.

ZZP offers a kit complete with drilled Brembo rotors for anyone interested. Actually not a bad deal for what you get, but I'd upgrade from the included pads if you want to push them really hard:

http://shop.zzperformance.com/store/p/667-12-7-inch-GXP-Dual-Piston-Brake-Kit.aspx

AA wrote:

What happens is the pads get too hot and coat the rotor face with an uneven layer of pad compound (called uneven deposition or imprinting), causing pulsing known as judder.

You want me to take a picture of this? I see it all the time. It's actually visible on the rotor.

Sure, I'd like to see. I have seen pad imprints from a hot pad coming to a stop before, but not a severely FUBARed one. Here's my rotor after a few hard stops. The compound is deposited on the rotor face, has a grey cast to it. It must be evenly applied, because there's no judder.

This is all academic for 95/96 owners unless they swap out their hubs/knuckles, true?

Can you include the write-up link in this thread for that critical step to swap out to 97 and up knuckles on a 95/96?  I did a quick search but didn't find it.  Thanks.

There is some info here in the F-Body thread:

https://rivperformance.editboard.com/t2310p15-write-up-f-body-brake-mod#2006

AA, here is a picture of a rotor with "judder". I still had to reface them, but they weren't warped at all. They were a bit thinner towards the edges than the center, but that's normal considering there's more clamping force towards the edge of the rotor, and they wear that way. Notice all the schmuck built up...

Are the 95/96 knuckles so unique from every other GM product that no other dual-piston caliper will fit from another model?

I understand that this and the F body mod isn't a bolt-on for 95/96, but wondered if there was an alternative for the 95/96 that didn't require new knuckles/struts/springs from a 97+

Al

Im with al. What would work for us black sheep lol