Darien

The front brakes are squeeling again Not only while applying pressure, but even driving down the road. I jacked the front end up, and both wheels are a little hard to spin, maybe 1-2 pounds of pressure.

What would cause this??

Gretch

Brake pads wearing evenly, inside and out? dampers installed between pistons and pads? last time the system was bled?

Bill Ball

Caliper rebuild kit - basically new seals and boots. You will do a flush at the same time.

hacker-pschorr

The S4 calipers on my 79 are wearing unevenly as well. I fear my calipers are so dirty from sitting for many years covered in brake dust they need a rebuild. Problem is, the kits are only offered with the piston, around $40 - $50 per piston = 4 each caliper. So now I'm considering another set of calipers instead.

hacker-pschorr

See my post above - unless you have a source for kits without the pistons, you could get used calipers for about the same price and save yourself a boat load of labor.

Darien

I just pulled the pads and they are uneven I haven't bled it ever..

Bill Ball

Hacker, yes, that's odd. I only see kits through 86 on the Big3 websites. They are cheap and just boots and seals, but there are no listings beyond 86MY. I guess I bought the individual seals and boots somehow. I just asked Susan at DEVEK for stuff to rebuild the calipers on my 89. I did not get pistons. It was not expensive, certainly far less then rebuilt calipers. I'll go through my receipts when I get home for PNs. Couldn't have been more than $10-15 per wheel.

Darien, the rebuild is pretty easy unless the piston is really stuck bad.

Paul D

Last year I rebuilt the calipers from an 86.5 before I installed them on my car. I bought the pressure seals through StopTech. I could not find anyone that sold the scraper ring style dust boots so I reused the old ones. I beleive these scraper ring style dust boots are unique to the 86.5 4 piston calipers on the 928. The diameters for the pressure seals are 42mm and 36mm for the fronts, and 30mm and 28mm for the rears. They charged me $7.95 for each seal (16 of them) plus shipping ($131.45 for the peace of mind).

hacker-pschorr

How long ago was that? The seals used to be available without the piston, I think that is the issue; they are not sold separately anymore.

Darien

Could the pistons just be dirty? Any way to clean them??

Paul D

First line of defense would be to completely bleed the brakes and the clutch circuit while you are at it.. At a minimum it should be bled every 2 years. When you say the pads are worn unevenly are you saying that the inside pad is worn more or less than the outside pad? If so it might also be time for new pads too. If new fluid and new pads don't help it might be time for a rebuild. When I rebuilt my calipers there was some 'crud' in the piston bores and on the back side of the pistons that probably would not come out with regular bleeding. It was easily wiped out with a soft rag after disassembly.

928drvr86.5

86.5 through early 87 Brembos differ from late 87 onward Brembos. I went round and round with StopTech and Brembo trying to find a new piston for one of my rear calipers about a year ago. in mid 87 Brembo changed the design of the piston and dust boot. New pistons for the 86.5 - early 87 are not available.

Bill Ball

Darien: Yes they could be encrusted and clean up with a little solvent and scotchbrite. Steel pistons in aluminum do that. I have seen it with my motorcycles where there is no boot and moisture gets to the piston/caliper junction. The crust buildup is on the outside of the piston and can cause it to seize.

hacker-pschorr

The Brembo's on my 79 came from an eary 87S4 (build date is late 86) - so kits without the pistons are available for these?

My front calipers were so bad, my power bleeder could not push fluid through them (last bleed was at least 6 years prior). I needed a helper to push on the brake pedal with the power bleeder attached. After two bottles super blue fluid, I gave up, installed the pads (this was last year, ran two DE's with the car). Now I plan to pull the calipers, see what spraying some brake clean through them does, if I cannot find rebuild kits.

hacker-pschorr

My mechanic has noticed Wilwood calipers have no dust boot, at least the ones he has installed (on cars, not motorcycles).