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Brake refurb project
http://forums.tipec.net/viewtopic.php?f=27&t=21888		 Page 1 of 1
Author:  stratfordshark [ Tue Sep 20, 2016 12:22 am ]
Post subject:  Brake refurb project
Finally got my S4 back on the road this weekend after finishing a lengthy brake refurb project which has kept it in garage since shortly after Beaulieu (I can only work on her weekends, and was delayed by torn CV boot too). Project included:

New discs and pads all round (Pagid)
New flexible hoses all round
Replacing one hard line with seized Union
Repainting all calipers
Replacing all decals
Replace all steel pad guide plates
Replace all piston seals and dust boots (16 of each!)
Replace all bleed valves
System flush and bleed
PSD flush and bleed (not related to braking performance, but convenient to do at the time)

Virtually wrote off summer driving season, but the results in terms of pedal feel and stopping power are fantastic - must be just how it felt out of the factory. I am a bit of a fusspot as the brakes felt fine before, but the difference is astonishing. I think the biggest factor is tackling all the plate lift, and the new seals (they do more than seal - the action is to pull the pistons back on releasing brakes). If you fancy doing similar project I strongly recommend it, and I expect all 928s with original brake system parts are of an age to benefit as all will have plate lift to some degree, and rubber parts (hoses, seals) will be aged.

(Photo with rebuilt caliper mounted taken before installing pad sensor and pad retainer spring)

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Author:  Waylander [ Tue Sep 20, 2016 9:25 am ]
Post subject:  Re: Brake refurb project
new plates added to your bill quite a bit, they can be cleaned and straightened easily.

nice job though and it does make a huge difference, and I don't think my Mrs would allow that on the kitchen table :lol:
Author:  stratfordshark [ Tue Sep 20, 2016 11:27 am ]
Post subject:  Re: Brake refurb project
Hi Waylander

Thanks for kind words!

On the second and more important point, my wife was not best pleased! What I hadn't realised was that when I was pressing pistons back in by hand into the caliper bores, I was making some lovely ink marks on the tablecloth with parts of caliper pressing on the newspaper i had carefully laid out to keep things clean.

On the plates, I picked up all the front plates for a song on eBay a while back, and had them stashed in my parts store. They were less than £10 each brand new sealed Brembo items for all four for front, compared with usual £30 each. But as you say the original plates once cleaned up would have been in lovely condition. My problem was using a very heavy handed technique to get the original plates out involving grinding/chiselling off the machine screw heads, then punching out the plates. This was effective, but bent the old plates beyond being able to re-use. As I had new ones I was not fussed about grinding the heads completely off, so some of the plates were bent almost 90 degrees before they came off! After that I could get out the remains of the screws with torch for heat, and cutting slot in them. Even then one screw in each caliper would not come out this way, so I had to weld nut onto them which worked very well (and the heat of the welding broke any remaining corrosion). You are right about expense as new rear plates were around £30 each for all four (daft price for piece of steel and couple of screws). the seals and boots are very cheap though - rear ones £25 for the axle.

If I was doing it again I would not bother trying to attack the screw heads, and weld nut on from the start as they come out so easily this way. I didn't try that first as this was my first go at MIG welding, so wanted to try more familiar techniques first. The dome head machine screws were mostly in very poor condition - just blobs of rust/corrosion really. I tried just chasing them round with chisel, but this was complete failure as getting good angle on them is very difficult, and the heads anyway were in such poor condition that they would just distort under blows from cold chisel. Those caliper plates are the biggest bugbear of brake refurb (together with freeing off brake line unions), as the combination of materials and location is great recipe for corrosion, and access is awkward without splitting the calipers.
Author:  Prophead [ Wed Sep 21, 2016 8:26 am ]
Post subject:  Re: Brake refurb project
very nice job!

Where did you source the rebuild components from? I have 4 pot brembos on the front of my 924 track car (think they came from a 944 S2) and will be rebuild them over the off season.
Author:  Waylander [ Wed Sep 21, 2016 12:53 pm ]
Post subject:  Re: Brake refurb project
thats the hardest part, getting those crap screws out.

the parts for the calipers can be bought from

http://www.modeperformance.co.uk/

they are Brembo dealers, the last couple of sets I have done were with new seals, bleed nipples and dust covers, came to about £120 per axle.
Author:  stratfordshark [ Wed Sep 21, 2016 1:21 pm ]
Post subject:  Re: Brake refurb project
Prophead wrote:
very nice job!

Where did you source the rebuild components from? I have 4 pot brembos on the front of my 924 track car (think they came from a 944 S2) and will be rebuild them over the off season.


Various sources as the bits I needed sometimes not in stock with any particular supplier.

Addiction Motorsports in East Ham good for Brembo original parts (I got bleeders from them).

Seals and dust boots were from Bigg Red in Worcester (excellent prices and service) and a German compnay nb-parts (find on eBay under that name). Bigg Red service is excellent - most stuff arrives next day. Both are using aftermarket rubber, but I had zero problems with it (some people have reported problems with aftermarket seals as the tolerances are very tight, and they've not been able to squeeze the pistons back in). Getting the right parts is a combination of knowing the sizes, and can help to know other Porsches using same sizes (e.g. I think Cayenne also uses the 28/30mm sizes used in rear S4 calipers, so can be easier to look for listings of these parts as Cayenne rear kit or similar).

Bigg Redd good for gathering all the parts into single kit. For example the front axle kit I needed is same as 996 Turbo (36/44mm). I can't remember if Bigg Red even listed a 928 kit, but I just ordered the 996 one which comes nicely packed with all seals needed, dust boots, and new bleeder caps, together with sachet of red brake grease which is much better to work with than brake fluid for lubricating the seals and pistons.

I think the Brembo rubber parts are at least double price of alternative. The alternative 36/44 front kit from Bigg Red was £55 for whole axle which I thought very reasonable. Smaller rears less than half that price.

In all my searches I hadn't found that company Mode Performance used by Waylander. I will make note of them for future too - all Brembo original parts.

You need to check which calipers your track car has, as the design of the Brembos used by Porsche changed around 1989 from having scraper rings round the dust boots, to a newer design which Brembo have continued to use to date, so it's pretty easy to get those more modern parts (my S4 is MY1991 so has those newer parts). The older calipers were the ones with raised lettering for Porsche, not just a flat decal/stencil so that's one way to check before even removing the pads to examine the dust boots. The caliper plates were assembled from 3 or 4 different sources including 9-apart and one-man bands on eBay. Your OPC can supply repair kits for the calipers once you've identified which calipers are on your 924, but they put on a big mark up onto the Brembo mark-up!

If you're not repainting calipers (I imagine you keep things functional on a track car!), then changing seals and boots is a pretty fast and enjoyable job. Just make sure not to scratch the piston bores when you're fishing out the square cut piston seals. I used metal pick so had to concentrate, but you could just use a cocktail stick and run zero risk! Once you're in swing of it you can rebuild a caliper in minutes really - the most time-consuming part is clamping different pistons as you use compressed air to push out whichever you're working on.

The difference with the rebuilt calipers is night and day in braking feel and power, and that's before the new pads and discs are properly bedded in.

If you don't have time to DIY then Addiction and Bigg Red both offer rebuild service. I also hear good things about a company called Godspeed based in Wales, but no personal experience or connection with any of these. I did look at rebuilding cost first, but the more I looked into what's involved, the more fun it looked doing it myself though any of these companies would have done a much better job of the painting than I could (they would media blast and powder coat I think).
Author:  Prophead [ Wed Sep 21, 2016 1:51 pm ]
Post subject:  Re: Brake refurb project
Thanks for the detailed reply. My calipers have the raised lettering, typical.
Author:  51rider [ Sun Apr 30, 2017 8:14 pm ]
Post subject:  Re: Brake refurb project
stratfordshark wrote:
Prophead wrote:


If you don't have time to DIY then Addiction and Bigg Red both offer rebuild service.


Bigg Red would not touch my 944 s2 calipers for a refurb when I made a telephone enquiry the other day. Simply referred me straight to Pro Calipers who are the trading name for addiction motorsport.
Author:  stratfordshark [ Sun Apr 30, 2017 9:22 pm ]
Post subject:  Re: Brake refurb project
How odd - I thought returbing brembos was part of Bigg Red's stock in trade!

Oh well Addiction should help I think they quoted me when I was first looking at refurb options, but I decided more fun and cheaper to DIY!
Author:  51rider [ Sun Apr 30, 2017 9:30 pm ]
Post subject:  Re: Brake refurb project
stratfordshark wrote:
How odd - I thought returbing brembos was part of Bigg Red's stock in trade!

Oh well Addiction should help I think they quoted me when I was first looking at refurb options, but I decided more fun and cheaper to DIY!



I was very surprised too. I'm going to start my own thread so as not to clog this up.
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