12" Rear Disc Brake Mod

Installing a larger and lighter 2 piston caliper is a bigger job than one might think.you also have to install a proportioning valve to maintain bias and an emergency  spot caliper. it could work. lose some weight and get a better feeling braking system.

Good point. For our Lemons racer we bought a proportioning valve and planned to fine-tune the system that way. Then we realized we could do the same thing by changing just the pads to a different compound. We tried two different pads on the front and nailed it on our 2nd try! The front and rear wheels lock up at exactly the same time on dry track, fronts lock just before the rears in wet.

Here's a good read for anyone wondering why I'm not a fan of bigger rear brakes on a Riv:

http://www.stoptech.com/technical-support/technical-white-papers/rear-brake-upgrades

oldsman105 wrote:

For those of you wanting to do a brake upgrade here is a minor one.


Bonneville GXP brake brakets part # 18026216 Order 2.
and GXP Rear rotors (11.7" compared to stock 11")
and Pads of your choosing.



The rear brakes are the same on a Riviera.

Anyone ever confirm/do this? My rear rotors and pads are about due, so if all it takes are new brackets I'm game. I found a guy who replaced them with STS (yes, more STS lovin') brackets to get the 11.7" rotors.

http://www.pontiacbonnevilleclub.com/forum/topic39170.html

Also, anyone who has access to a parts counter (*coughAbaddoncough*), can you compare a Grand Prix rear hub to one off a Rivi? 97-03(?) GP's had the e-brake in the hub where we have it in the caliper. If the rear hub bolts on we have access to more than just the above mentioned upgrade.

Upon further inspection, the caliper brackets will work and there are a decent bit of vehicles you can pull them from. I'll be the guinea pig since my rear brakes need done anyways, so I wouldn't advise anyone else to do this until then.

Where to get the bracket from (MEASURE FOR 11.7" ROTOR FIRST, MAKE SURE E-BRAKE IS ON THE CALIPER AND NOT IN THE HUB/BEARING)

03-05 Park Avenue Ultra
00-05 DeVille
98-04 SeVille SLS
98-03 SeVille STS

Be careful pushing braking limits with the increased rear bias. I would use a lower friction pad (cheaper metallic like Duralast) to offset the extra leverage increased rotor diameter. That way you'll see the benefits from a larger pad/rotor combo (mainly added life and some added decel from higher speeds), without lift-off oversteer braking into a gradual corner.

Don't forget, cars that have the same front setup as us (97+) have the upgraded rear setup. That and the new rotor isn't much larger (.7"). Since I'm already running 1" larger rotors in the front (96 used 10.x", 97+ used 11.x") and F-body calipers things should be good. I grabbed the brackets today off a 2000 DeVille and will get around to putting them on sometime this year or early next.

If I'm not mistaken, the Parking Brake assembly is attached to the backing plate on the GP's, not the Hub. The Hub actually has nothing to do with the PB itself. You'd have to install the backing plate and all the necessary hardware from the donor car in order for the PB to work, IF the brake cable has the same end on it.

Or, screw the parking brake.....

Abaddon wrote:

Or, screw the parking brake.....

Hmm..... 30* incline on the driveway...... Neighbors parked directly across the street..... Nahhhhhh...

Ha. My P-brake cable has been rusted solid for a couple years now. The last time I used it, the rear brakes stayed applied.

Your driveway is that steep??!!

Abaddon wrote:

Your driveway is that steep??!!

Yep. 2 of my cousins even have driveways that are nearly 45*.

What the??!!! That's 12" up for every 12" forward. That's impossible. A Land Rover or a Hummer can't even traverse a grade that steep.....

Abaddon wrote:

What the??!!! That's 12" up for every 12" forward. That's impossible. A Land Rover or a Hummer can't even traverse a grade that steep.....

I might be a bit off, but they're damn steep. Ever see the driveways in Pittsburgh?

matt270avian wrote:

oldsman105 wrote:

For those of you wanting to do a brake upgrade here is a minor one.


Bonneville GXP brake brakets part # 18026216 Order 2.
and GXP Rear rotors (11.7" compared to stock 11")
and Pads of your choosing.



The rear brakes are the same on a Riviera.

Anyone ever confirm/do this? My rear rotors and pads are about due, so if all it takes are new brackets I'm game. I found a guy who replaced them with STS (yes, more STS lovin') brackets to get the 11.7" rotors.

http://www.pontiacbonnevilleclub.com/forum/topic39170.html

Also, anyone who has access to a parts counter (*coughAbaddoncough*), can you compare a Grand Prix rear hub to one off a Rivi? 97-03(?) GP's had the e-brake in the hub where we have it in the caliper. If the rear hub bolts on we have access to more than just the above mentioned upgrade.

I can confirm this as both those are me. That is my second bonneville in the link . I found the STS brackets are the same as GXP brackets.

I figure I'll post a "write up" even though this barely deserves it.

Get rotors and caliper brackets off of an '00 DeVille. There are other cars that share the larger rotors, but for simplicity just go with a DeVille. You will almost always find one in a junkyard. You can also buy brake pads for the DeVille too, they're the same pads as 95-99 Rivis. It just makes life a lot easier to buy everything (97+ front and 95-99 rear) for a DeVille.

The only mod you have to do is to flatten out the dust shield. That's it. Just grab a pair of pliers and have at it. The metal bends fairly easily and you should have one flattened out in less than a minute.



After that it's literally just a rear rotor and pad job. Put on the new rotor, then the new caliper bracket and make sure it all clears. The hardest part of this job is rotating the caliper piston back in.

I noticed a slight improvement under hard braking, but nothing night and day. It's a little more squirrely when you really get on them, but day-to-day it feels about the same. I didn't officially measure the before and after stopping distances but it is noticeable.

I don't seem to see many devilles in the boneyards near me but if i do i'm definitely doin this although I think AA's probably right on with the bias issue. I wonder if those cars have different proportioning valves and stuff as rivs. Oh is there any issue with getting the factory spare on the back with these brakes?

turtleman wrote:

I don't seem to see many devilles in the boneyards near me but if i do i'm definitely doin this although I think AA's probably right on with the bias issue. I wonder if those cars have different proportioning valves and stuff as rivs. Oh is there any issue with getting the factory spare on the back with these brakes?

I haven't tried the spare yet. I'll go out in a bit and try it for you. There definitely is more rear bias with this mod, but it's nothing that's really that hard to control.

Rock Auto lists the 03-05 Park Avenue, 00-05 DeVille, 98-04 SeVille and 04-05 Bonneville as having the same caliper bracket and rear rotor (11.7").

Stock spare does NOT fit. If it was a 15.5" or 16" it would. It's that close. I also have a '96 spare, so the 97+ might be bigger. You could probably grab a spare out of a DeVille for a couple bucks and be fine, which might also solve the problem of any of our spares not fitting over the F-body calipers.

so any of those cars you listed should have an appropriate spare then although I guess there's no guarantee that those spares have to fit f body brakes huh

turtleman wrote:

so any of those cars you listed should have an appropriate spare then although I guess there's no guarantee that those spares have to fit f body brakes huh

Pretty much. How well does a stock rim fit in the spare tire area? That would be a good alternative....

I've used the OEM spare over F-Body calipers on front wheels with no issues.

AA wrote:

I've used the OEM spare over F-Body calipers on front wheels with no issues.

Really? Mine wouldn't fit...... Maybe 97+ has a different spare?

The spare is 16", same diameter rim as OEM wheel. It has to be, otherwise TC freaks out because it thinks one wheel is spinning faster than the others.

AA wrote:

The spare is 16", same diameter rim as OEM wheel. It has to be, otherwise TC freaks out because it thinks one wheel is spinning faster than the others.

Mine's a 15". Weird.

Nada Guides confirms the spare tire for '98 is: T125/70R16

http://www.nadaguides.com/Cars/1998/Buick/Riviera-V6/Coupe-2D/Specs

Couldn't find specs for '97 & earlier.