Porsche 996 Caliper Refurb

[Dpicariello]

Evening everyone,

In an effort to cure the dreaded droning of my 996's during motorway driving I have resorted to a complete caliper rebuild.

I have removed the pistons and they look absolutely fine, infact they are perfect. One piston was a bit tricky to remove (using compressed air) but wasn't seized.
The main seals are fine but my dust seals had swollen horribly (see below).

I have used copper grease and plastilube (not at the same time) in the past to try and cure the vibrations but one of them has reacted with the seals and caused them to swell.





They had continued to function fine but they are going to be replaced.
If anyone is able to check their dust seals then please do as although it's not a major issue it could cause problems.

I have given the calipers a really good clean and touched up a few chips and scratches so they look pretty good now.







I could re-use the old main seals but seeing as I have taken them all apart then it would be best practice to replace them. I have tried a few places, mainly Porsche suppliers and it's gonna be >£100 for seals which is a bit eye watering.

Has anyone else managed to get the seals for a better price? I am after seals for calipers 996 351 426 and 996 351 425 (36mm and 40mm piston sizes).

I have the Brembo and Porsche part numbers for the dust seals:

36mm - Brembo: 20 4872 44, Porsche: 951 351 917 00
40mm - Brembo: 20 4872 46, Porsche: 951 351 917 01

If I have to bite the bullet and pay the full price then so be it, i just thought I'd check with people on here first.

Thanks very much

Dan

[twoqu]

http://www.s2forum.com/forum/showpost.php?p=484251&postcount=14

Seal kits are per caliper. They contain 2 seals of the same diameter.

[Le S2 Audi]

As far as I know you can not get these from anywhere else other than the dealers...

I can find oud out what is my price tomorrow from the dealers and let you know... But I doubt I can get the 20% discount...

Drop me a PM..

[Fat Audi 80]

Re: Droning. I have discussed this with one or two forum members, and would like to suggest a possible cause:

Dan, can you measure accurately the distance between disc inside edge and the caliper body and then the outside edge and the caliper body? What I am getting at is, is the caliper positioned centrally over the disc so that the pads on either side have the same distance to travel? (This probably needs to be done hot and cold) I am wondering that because the caliper is a non floating design, if there is slight offset from to either side of the disc, could this cause one of the pads to remain in contact everso slightly?

This problem must be a result of the way we mount them, as I can't imagine all Porsches do it??

Just a thought.

Cheers,

Steve.

[GazzaG60]

steve. my 6 pots are not exactly centre IIRC. i dont get droning. i dont get any noises at all from them. oh excecpt when cleaning the crud off the discs when its been stood. porsche discs rust.

[bernsaudi]

The only thing I have ever managed to do to get rid of the noise is to put new bearings on and clean calipers, lasts for about 6 months..

[Jamo]

You can buy the seals at design911 or type911, i'm sure if you phoned jasmine motorsport they could also supply

[Dpicariello]

You can buy the seals at design911 or type911, i'm sure if you phoned jasmine motorsport they could also supply

I'll try those places, thanks Jamo.

@Steve, yes I'll measure them once they're all built back up. I've got another potential solution as well as I think it's definitely a dragging pad. There's some evidence that the top of one of the pads has worn more and as such could be the cause. i'll keep this updated as I learn more.

Thanks

Dan

[Colesy]

I cured this problem with new calipers. I didn't change anything else whatsoever.

I'd tried all the suggestions but couldn't stop the motorway droning before this.

So my belief it it's something that a caliper refurb should fix, possibly pistons that aren't seized but are slightly sticky, can't be sure though.

[Rusty]

The only thing I have ever managed to do to get rid of the noise is to put new bearings on and clean calipers, lasts for about 6 months..

Ditto. Also, worn pads can be better than brand new.

Steve has hit the nail on the head here. Alignment. Both offset and angular. It might be possible to apply pressure vi the brake pedal when fixing the calipers in place, make sure that the disc is firmly secured with 2 off whell bolts. Check after securing the caliper in place and before torquing / beasting it into place

[GazzaG60]

the caliper needs to be square thats for sure. trhe slight offset from centre should be ok and take by the piston.

this puzzles me though. my mate says he gets some niose from his 997c2s big 4's whereas my 6's are quiet.

i know the solution must be to buy gt2 6 pots

[Dpicariello]

Bit of an update....

Calipers are now rebuilt by AP Racing with new main seals and new dust seals. Everything has been pressure tested and all is good.

One of the pistons was a bit sticky when we removed it so that could have been the source of the vibration in that it may have not been retracting fully.

I got the seals from www.modeperformance.co.uk. Pricey but they got them to me within 24 hours and were very helpful.

I'll be refitting them on Friday so will report back as to whether I throw my toys out of the pram.

[andy10v]

I have used copper grease and plastilube (not at the same time) in the past to try and cure the vibrations but one of them has reacted with the seals and caused them to swell.

What grease is safe to use near the seals?

[s2_wot]

Just a thought and I could be way off, is it not normal to trim down the 4 little pins that the pads sit on with these brakes, doesn't look like it's been done in the 1st pictures.

[Robatron]

Dan, did AP racing completely rebuild them?

I'm looking to have my calipers rebuilt but so far the only company I've found is a company called Bigg Red.