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Am putting on new front brake rotors (old ones are warped) for my wife's '94 Bonneville. Bolts appear to be Allen or Torx, but are a bit rusty and are needing plenty of wd-40 to see what's needed.

What do I need (and size) to to get them out?

Thanks! Slug

3/8" allen head if I remember right.

Technically, a 3/8" hex. That's all. Don't forget to lube the caliper pins! And also don't forget not to let the caliper hang off the brake hose.

Good luck!

If you don't have a socket style hex that fits, and are reduced to using a simple hex key, you may need to multiply the torque by slipping a large box wrench or a piece of pipe over the arm of the key to break the bolts loose. Sometimes it takes a lot of force to break them loose, so make sure you have cleaned out the hex bolt so that the tool can fully seat. It may also help to turn out the knuckle with the steering wheel so it is easier to apply the force perpendicular to the bolt.

Ok, thanks for all the tips guys!

Seems like our '98 just had hex bolts through the calipers when I did it last.

I thought we had a TechInfo article on this, but maybe I'm just thinking of a detailed post that I couldn't find.

Ok, so off to the parts store to see what I can find .

I popped for the socket style 3/8 inch Allen head as Bill Buttermore favors (see his discussion in this thread). I really don't think a standard type Allen wrench, even with a pipe extender helper, could have done the job on one of the bolts. Thanks again, Bill, for your experienced advice!

We love our old Bonnevilles, but they are getting old. Buy the best tools you can afford for them, if you want to keep them going forever (and they will go forever--believe it!).

I'll update tomorrow on how I come out on this project. The rotor warp seems to bother my wife and daughter, much more than me. But they're the ones who have to drive it.

Maybe we should consider a TechInfo article for disc brakes. There's already enough info in this thread to make it worthwhile. As before, I'm willing to "guinea pig" the work and take pics, if someone wants to put it together and submit. No doubt there's already a post or three on this.

slug

IIRC Archon was making one for the 2000+.

slug wrote:I popped for the socket style 3/8 inch Allen head as Bill Buttermore favors (see his discussion in this thread). I really don't think a standard type Allen wrench, even with a pipe extender helper, could have done the job on one of the bolts. Thanks again, Bill, for your experienced advice!

We love our old Bonnevilles, but they are getting old. Buy the best tools you can afford for them, if you want to keep them going forever (and they will go forever--believe it!).

I'll update tomorrow on how I come out on this project. The rotor warp seems to bother my wife and daughter, much more than me. But they're the ones who have to drive it.

Maybe we should consider a TechInfo article for disc brakes. There's already enough info in this thread to make it worthwhile. As before, I'm willing to "guinea pig" the work and take pics, if someone wants to put it together and submit. No doubt there's already a post or three on this.

slug

If you could take a pic of each general step, I'm sure someone could fill in the blanks. That could be helpful.

This is for the 2000+s, but is basically the same. The only real difference is the caliper pins.

Front Brakes


Raise, and properly support the vehicle.
Remove the wheels.
Using a large C-clamp, compress the pads enough to relieve the pressure of the pads against the rotor.


Remove the two caliper bolts.


Using a screw driver, pry between the caliper bracket and the caliper until it slides off. Support the caliper so that it does not hang from the flex brake hose.


Remove the caliper bracket, and the pads from the bracket.


(If just replacing pads, the bracket and rotor do not need to be removed so those steps can be skipped.)

Clean the mating surface on the caliper bracket, and the steering knuckle where it bolts on. If the new pads did not come with new caliper clips, clean any dirt and grease off them.

If the rotors are original, they may be held on by some clips. These can be cut off, or spun off using some needle nosed pliers. Whether you decide to install them, is up to you.

Remove the rotor. If it is rusted on, spray some penetrating oil around the middle of rotor, then strike the rotor between the studs, with a hammer until the rotor comes off. Use care not to hit the studs, or you’ll damage the threads.

Clean any loose rust from the surface of the hub, with a wire brush.


Put the new rotor back on the hub, lightly grease the caliper clips, then bolt the caliper bracket on to the steering knuckle. Tighten to 137 ft. lbs. (GM recommends using blue thread lock on the bracket bolts.)


Install the brake pads.


Take one of the old pads, and place it on the caliper next to the piston. Using the C-clamp, compress the piston in. Some suggest loosening the bleeder screw while doing this to keep any dirt and old fluid being pushed back into the master cylinder.



Clean the caliper slide pins, and lube with high temperature brake grease.


Install the caliper over the pads. While installing the caliper, push the boots in that are attached to the caliper bracket so that the holes in the boots line up with the holes in the caliper. Install the slide pins, and torque to 63 ft. lbs.

This would also be a good time to bleed the brakes, and flush out the old fluid.

Nice pics and post Dick! I figured either you or Bill B probably had it in mind. (I'll send you pics and verbage related to the '94 style of front brakes if you like sometime. Let me know the sizing and kb you like for pics).

I finished this project about 1:30 AM this morning. The '94 style of pin bolts makes this job a lot harder than the '98 style (see Bill B's discussion in this thread). When the "tucked-in" style of Allen bolt gets corroded, it sort of haunts you all the way through the job. So I had to do a little grinding and a little "massaging" and a little WD-40ing and a little greasing here and there on the pins and sleeves. You just can't get the bolts started into the caliper threads otherwise.

The pin bolts look a little "beat-up" on the slide part. I didn't think to look inside the sleeves or check tolerance. I greased them (but didn't see Archon's post in time about which grease to use) and put them back in.

Should I replace the pins and sleeves? The '94 has about 140k miles on it.

I test-rided the car after the right side fix. Already the "throbbing" was cured. Later this morning I noticed some damage to the right hand rotor: (see bottom part of rotor -- it actually looks worse than the picture. Haven't checked the pad yet. The rotor itself is obviously quite corroded. I didn't even consider it for milling down.)





Naturally, I replaced the left rotor as well.

I didn't do the front brake job myself the last time (about three years ago). It was up on the hoist for new struts and I asked the shop owner to check brakes. He advised new front pads (which I had him do), but he said the rotors were ok at that time. But that's about when I started to feel the "throbbing". And that's also when I started to get "memory steer" due to dry top strut bearings (which took a while to figure out--many thanks to the Pontiac Bonneville Club for help on this!).

My shop owner always makes good on stuff (even out of warranty), but I kind of have to pay attention to what his wrench-guys have done (I'm staying with him on stuff I don't want to do myself because he's personally competent himself, very honest, and has a good heart. Sometimes, though, he just tries a little too hard to save his customers money. Well, I can't fault that very hard!).

(BTW -- I like NAPA standard rotors really well and also their upscale semi-ceramic pads. This combo is used by NAPA employees and works very well for non-spirited to semi-spirited drivers. You "hot-rodders" are on your own!)

Thanks, and yeah...go ahead and send me what you have. I'll send you more info via PM.

I remember the pins from doing work on a '93 SSE. If things aren't too rusty, or dirty, they aren't too bad to get out. If they are - you're in for a tough go of it.

If the pins show damage, often some gouges or slits cut across them, they should be replaced.