Thread: Rear Brake Upgrade Junkyard GXP Upgrade Compatibility Question

Maybe I am just a moron and missing the information, but I have searched the forum and read the sticky threads on brakes and cannot figure this out!

I am thinking about upgrading my rear brakes on my 2002 grand prix gt, and have seen the kits etc. out there but don't feel that they're really worth the price (plus my budget is limited)

As GXPs in junkyards are a rare and very quickly picked over item, grabbing their brakes are not going to happen.

However, while browsing rockauto, I noticed that the calipers and brackets were identical between the base GT and GXP brakes. Now I know that rockauto isn't always correct, so I figured that I would see if anyone knew what the real difference is?

I know that the 04+ GT rear rotors are different as far as the e-brake and have smaller diameters so they obviously won't work, but if the rotors and brackets are the same, does this mean that I can grab some base GT rear calipers and brackets, bolt them right up, and buy a set of GXP rear rotors and pads?

Turns out these calipers are on quite a few buick, pontiac, and chevy cars so if that's true, upgrading the rears just became a lot cheaper and simpler.

Just a thought. Hopefully someone with GXP brakes can set me straight!

You're right Blueguy that they don't do a whole lot, and I will definitely be upgrading my front calipers.

However, I just got a pair of reman calipers as a gift off a 04+ GT. From what I can tell, its the exact same caliper with the exact same steering knuckle and mounting with the same hub. It looks like the difference is that the GXP uses the inner parking brake shoe (as the 97-03 use) along with the stock 04+ calipers. The only part numbers that are different are the brake hardware, pads, and rotors themselves (which I need to replace anyhow). Since I do not have two to compare, this is just speculation, but it appears that they "compensated" for the thicker rotors by making the pads thinner to begin with, and by changing the height and mounting of the pad, they were able to increase the rotor diameter.

My question is whether the part numbers are actually different for these, whether they are interchangeable, and whether the mounting (and/or brackets are different).

Basically, could I upgrade to "GXP" rear brakes for the same price as a normal full brake job rather than spending $500+ at zzp... and someone wanting to upgrade their rears would only have to purchase the "regular" 04+ calipers (junkyard, wholesale etc.) and pads and stuff and save a ton.

I'm assuming someone has figured this out already and just hasn't bothered to post it since it seems obvious, plus as you stated, it's not really necessary or that beneficial to most. Plus, who would have thought to try this since you can't simply swap this on regular 04+ because of the e-brake.

Just in case anyone stumbles across this post, I'll answer my own question. Turns out the rotor, caliper, and bracket are different, but RockAuto and other sites list them because they say that the other fits those without "special ride handling." Now, I'm not 100% on this, but I've never heard of any GXP that doesn't have these rear brakes, but you have to know what you're looking for.

Here's the correct caliper for upgrading your caliper:
https://www.rockauto.com/en/moreinfo...432258&jsn=444

And here's the base GT caliper and bracket:
https://www.rockauto.com/en/moreinfo...432258&jsn=456

Interestingly enough, the GXP caliper is actually cheaper than the stock (probably because the stock contains the parking mechanism internal rather than using the internal pads like GXPs and 97-03s).

Basically, If you're replacing your brake rotors, pads, and calipers, there's no reason not to go with these (unless of course you own a 04+)!

So in closing, sorry about the noob thread. Hopefully someone finds this information helpful, or at least amusing!