944 turbo rear brake dampening discs

[craiginuk]

I've finally traced a rattle from rear left of car to brake pads rattling. Pretty sure i don't have dampening discs fitted. PET says I need 4 off 928.352.096.10 and 4 off 928.352.096.11. Are these discs there to stop squeal or would they also help to stop pads moving/rattling over bumps?

Rattling noise over bumps stops if I gently appl brakes. Makes sense as it has only been doing it since indy cleaned up fronts and rears for plate lift.

 

[924nutter]

I have changed the pads, front and rear, on my Tcab; the dampening plates are self adhesive and are a push fit into the recesses in the pistons. You then remove the backing paper and fit the new pad, so that in use you have a pad glued to the damper fixed to the piston so I would think that over bumps and Fruggiing great pot holes, this would help stop the pad rattling. On top of the cost of the plate lift rectification the cost would not have been insignificant (I think about £112@ £14 per plate IIRC) but less that unbolting all the calipers and retro fitting the plates that you didn't fit when you had the calipers off in the first place. Factor in the risk of breaking one of the pad wear sensors or the wires then this like scoring forty in datrs by going double 19 double one!

 

[craiginuk]

Hadn't realised i,d have to remove the calipers to get the damping plates in. Thought i could just take the pads out and slot the damping plates in. Damn, as always my 20 min job is turning into a 2 hour one and that's probably just per caliper!

The plates are even cheaper, £5.28 from Bert..

 

[924nutter]

I used genuine Porsche parts, so, great that you made a saving. I would say 30 mins per corner, as you have easy fitting pads with no plate lift

 

[bmnelsc]

ORIGINAL: craiginuk

Hadn't realised i,d have to remove the calipers to get the damping plates in. Thought i could just take the pads out and slot the damping plates in. Damn, as always my 20 min job is turning into a 2 hour one and that's probably just per caliper!

The plates are even cheaper, £5.28 from Bert..

I think these can be done without removing the calipers (with fiddling and small fingers) as these should be changed along with pads... I appreciate there are no standards for the size of mechanics hands but needle-nose pliers and a screwdriver can get into pretty small places with patience

 

[924nutter]

Unfortunately we are not just talking about a shim here. There is a circular clip about 10mm deep that locates in the annular recess in each piston, two per plate as described in my first reply and there is never going to be enough clearance to get them out with the caliper in situ, and any way why would you try? The caliper is only attached by two lateral bolts and you can hang the caliper on the spring if you fashion a hook from a trusty coathanger. Having had the plate lift rectified the pads would slide out easily and it would probably be quicker anyway, even if the method you suggest was feasible in the first place and I am prepared to be enlightened but I'm pretty sure that you can't get the dampening-plates out in situ because of the hefty expanding spring and cast lugs on the caliper. The pad would have to be worn to nothing to give enough push-back clearance to wiggle the plate out but then you need to take the caliper off to change the pad anyway. I personally think it would take longer to leave the caliper on, after all the longest part of the job is jacking the car up, and taking the wheel off.

 

[tref]

Correct me if I'm wrong, but you don't need to take the calliper off to change the brake pads, so taking the pad out would leave you a pads thickness (more than 10mm I'd say) to get the damper in.

 

[craiginuk]

ORIGINAL: tref

Correct me if I'm wrong, but you don't need to take the calliper off to change the brake pads, so taking the pad out would leave you a pads thickness (more than 10mm I'd say) to get the damper in.

Yep that is what I was thinking. I'll order the dampers and then see how it goes when it comes to fiting them. Some time back I had the calipers off to get the discs/drums off to check handbrake. I hadn't realized then that there is a flexi hidden away on end ow what looks like a solid brake line. Last time I undid the brake line and had to bleed brakes. So this time, even if caliper has to come of worst case, I can leave the pipe on.

Thanks
Craig

 

[scam75]

I doubt very much that the shims/dampers being missing would cause the rattling. I have my rears shim free and have no noise at all. I do have the shims on the front as I got a lot of squeal without them, rears however have always been silent without shims.

The pistons will take up the slack in a damper free situation I would think. Your rattle is most likely your brake backing plate or something to do with your handbrake set-up.

Stuart

 

[craiginuk]

Thanks Stuart,

Only bit that confuses me is the noise goes away totally when I apply brakes. Handbrake would not be affected by applying brakes. I was thinking the pads might be moving vertically in the calipers some how.

What do you mean by backing plate? Is that the wire cross that holds pads in?

 

[scam75]

The big metal dust shield behind the disc. But it's not that if it goes away when you brake. What you say probably rules out the handbrake too! I just can't see how the lack of shims is the issue. Maybe you have a loose caliper? Check the 2 bolts round the back that secure your rear calipers.

When you release the foot brake the pads no longer hold the disc but they don't move away from it. Try pushing a caliper piston back with your fingers and you'll see what I mean! A seriuosly warped disc however may exaggerate what you say but you'd have brake shudder through the pedal if that was the case.

Stuart

 

[Diver944]

I've never removed the calliper to fit those shims. Simply pull out the pads, push the pistons right back into the calliper housing then clip the shims into the pistons. Replace the pads then press the brake pedal to allow the sticky surface to contact the back of the pad.

 

[924nutter]

Well I must have missed something, or more likely forgotten, then and it's great to see that collectively we can all learn something new. On my car when I saw them they did look like the caliper from my 928 s4 I put my hand up and say that I did make an assumption that these would be the same, so sorry to mislead you.

 

[craiginuk]

Thanks all, this is one of the reasons this forum works so well. Where else can you get so much help in such a short space of time. I've put up a few questions regarding my daily driver on a BMW forum and all I got was tumbleweed. Thanks for the input.

I'm still not 100% they will cure the rattle but have ordered some from OPC, £5.74 each so worth a punt snd I guess Mr Porsche put them in there for a reason.

 

[924nutter]

That might be Mr Brembo

 

[craiginuk]

Finally got round to fitting these. Annoying rattle gone!

 

[Eldavo]

Any more info on these?

I don't think I have these fitted and I get brake squeal from the front. I have a flat pad with two metal discs on that fits between the pad and the piston but it sounds like these are something different and would stop the annoying squeal.

Pics?

 

[Hilux]

ORIGINAL: Eldavo

Any more info on these?

I don't think I have these fitted and I get brake squeal from the front. I have a flat pad with two metal discs on that fits between the pad and the piston but it sounds like these are something different and would stop the annoying squeal.

Pics?

Looking at your cars spec I assume its a regular track day car and probably on aftermarket pads? Some of these can squeal terribly.


I have always tended to throw squeal shims over the hedge and instead swear by coppergrease between piston and pads and on pad shoulders also ensuring the pads are loose in the caliper by a bit of judicious grinding and never had issues with it.