Anyone know if the Bonneville GXP front calipers and rotors work for the 2nd Gen? Same chassis, same knuckle? same bolt pattern, etc? i already have the Grand Prix GXP brakes on my '03. i'm looking to upgrade my '01 and don't really want to go back to the GXP setup because of the brake lines.
*note Brake lines started rubbing on my wheels and had to bend them back. running a 20 X 8.5 inch wheel.
The Bonneville runs the same chassis as the Aurora. In the Grand Prix does not. The calipers are similar but I believe the Bonneville calipers are slightly bigger. Also, the Grand Prix calipers are aluminum
Post by AuroraGirlFromMars on Sept 21, 2019 18:06:02 GMT -6
Aluminum calipers sound nice. Are the pistons also aluminum? If I wanted to go up wheel size I would do that just because rust kills everything up here. And aluminum doesnt rust, just corrodes slightly.
I'm not sure about the Pistons. I can tell you that they are significantly lighter than the stock brakes and there are two Pistons compared to one. The only thing that is a pain in the ass are the brake lines. You have to run the ones from the Grand Prix and you have to sort of finagle them so they fit right. I'm talking about how they're angled. The bolt up just fine.
Last Edit: Sept 22, 2019 22:58:03 GMT -6 by AmunRoo
Reviving this thread with a question: I did the GXP caliper swap way back when, always wondered if anyone also did the master cylinder replacement to restore the original pedal feel? I mean, going with the GXP bigger bore calipers must have increased the pedal travel somehow. Can't recall what the pedal travel was originally, but I'd expect the master cylinder bore to be larger on a GXP master cylinder compared to an Aurora master cylinder...
Found out that the Aurora has a 1-inch bore master cylinder, and there's a 1.34" bore master cylinder which exists for J55 brake equipped GM cars of the same vintage, Buick Lucerne & Cadillac Deville. Looks kinda interesting...
Last Edit: Jul 20, 2020 16:03:35 GMT -6 by gdouaire
To answer my own question: even between similar GM cars such as the Buick Lucerne, Cadillac STS or Pontiac Bonneville, and while master cylinders on these cars that have the outlets on left side, they have a wide variety of thread sizes. The Aurora is the only one with 14x1.5mm threads, while the STS has 12x1.5mm, Bonneville 10x1mm, the Deville 12x1mm, and the Lucerne, 13x1.5mm. Not every car has the 1.34" big bore master cylinder, because the Heavy Duty J55 brake option was not available on all models.
Closest Call: the J55 2006 Lucerne with 13x1.5mm threads. But you'd have to change the brake lines from the master cylinder to the ABS BPMV.
And that's assuming the spacing between the bolts to mount the master cylinder on the brake booster are all the same.
Post by AuroraGirlFromMars on Jul 25, 2020 7:07:35 GMT -6
I say ultra because ultra had different brakes esp in the rear. the 97 to 98 park avenue had a suspension change over to aluminum like the aurora, so that may have something to do with it. Any cadillacs?