Thoughts On Brake Pad Anti-squeal Spray, Etc.???

[LVDell]

Just replaced my calipers and after I put the pads back into the new ones there is a HORRIBLE squeal coming from the front brakes when I brake (especially at low speeds). What gives? Is there a suggestion to get rid of this horrific sound? The pads have plenty of life in them. Somebody on the Mercedes boards suggested the anti-squeal spray on the pads before install (I am replaceing the pads in my MB) and I thought maybe I should also try this on the P-Car. Thanks for the input!

[HenryV]

Since you have the same rotors and pads, there should be no issue.

Most often, squeals go away with (heavy) usage. Brake hard a couple of times (heat up brakes), the squeal should go away.

But read this link: Brake Noise

It lists 7 conditions to watch out for:

1. Heat cracked or worn "un-true" rotors

2. Rough finish on resurfaced rotors

3. Loose fitting brake pads in the brake calipers

4. Lack of silicone compound on back of brake pad

5. Missing springs or anti-rattle clips that should be on the caliper or pad

6. Improper tightening sequence of lug nuts or caliper hardware

7. Contamination on the brake pad i.e. brake fluid

Any that could apply to you? Especially 6) or 7)? E.g. did you bleed the brakes after installation? Could there be air in the lines? If you didn't use the sensors, did you insert the brake pad in reverse (backing outwards)? Do you brakes feel like before, do they fade? Did you clean the rotors? Anything you remember doing or not doing when re-assembling?

Other idea's

- make sure it is not the sensor (inserted wrong?)

- your brakes may be seizing up. Try an anti seize compound

- apply caliper lube to lubricate the calipers

- attach anti-squeal liners attach to the pads backing plate

Is it just one of the brakes, or do all brakes squeal? That may also give you a hint as to what's going on.

Also, your pistons may not retract fully after you apply brake pressure. That could hint of dirt in the brake line - bleeding them should clean this up.

Call your local Porsche parts store and ask them for advice, they may have other ideas.

I'm sure the solution is a simple one, maybe other people have encountered this problem before.

[LVDell]

Thanks Henry! I think I figured out what I did wrong. A few of the pads didn't remove from the old calipers with the anti-squeal liners attached (still attached to the old caliper pistons). I probably should order some new ones and get em back on then see if the squeal goes away.

By the way, great article link. Thanks!!!

Cheers,

Dell :cheers:

[KarlS]

Dell,

Installing the anti-squeal shims should help. It's also important that if you are reusing the pads to make sure that you install them on the same side of the caliper as they came out of. Also, you didn't mention if you also changed the rotors. If you did, you need to bed the pads with the new rotors.

Karl

PS Don't spray or use any anti-squeal stuff on your pads or rotors. The shop manuals warn against this very explictly.

[LVDell]

Thanks Karl......I ordered the vibration dampners (same as anti-squeal shims?). I didn't change the rotors. The pads went back in the same way they came out.

Thanks,

Dell

[LVDell]

One more thing. The vibration dampners are attached to the pistons not the pads? I am confused then. Since the pads that I re-used had the vibration dampners still attached to them (the pads) will they be fine in the new caliper or do I need to remove all the pads, remove ALL vibration dampners from the pads and install new ones to the pistons?

Thanks for the help and input!

Dell

[KarlS]

The vibration dampers have a sticky side that faces the pads. To install a new set, you insert them into the piston, peel off the paper to expose the sticky surface and then insert the pads. The first time you apply brake pressure, the vibration dampers will get stuck to the pads, which is why you have to pry them off before you can remove the pads.

If you are reusing the vibration dampers, simply leave them in the pistons or reinsert them if they have fallen out. If the sticky surface has lost some of its stick, you may try putting a light coating of high temp glue so they will stick the the pads better.

Karl