StratfordShark

I thought I was on home stretch on this brake project - repainted all the callipers and they look nice (I masked the pistons, so they don't look so lovely in the photo), so I was about to replace all the seals and dust boots.

Started with rear callipers first, and pushed one of the 28mm pistons with compressed air. It came out all the way and left dust boot behind. On one of my front callipers the boot just pulled out nicely from its groove, but this one seems stuck fast in the groove. The centre of the boot just tore away when I tugged it, and picking away at the remains just makes tears in what's left, and nothing is pulling out of the groove to give me a start cleaning the entire groove.

Any suggestions please for how to proceed? If all the boots take this long the project is never going to end! I thought this would be the easiest part but it's funny how projects turn round and bite you...

StratfordShark

All sorted now. I dug out rubber in a section of the groove, so exposing the metal ring of the boot. With rubber around it removed I could lever it with pick so it pulled out rest of the boot remains.

The other 28mm boot just popped out with the piston.

Should finish this caliper and its sister rear tomorrow.

FredR

Adrian,

If you had difficulty removing the boot then it probably confirms the need to replace it so nothing lost

Rgds

Fred

StratfordShark

I think you're absolutely right Fred. With new seal and boot, that piston now works very smoothly and easily when I puff some air in. Silver lining etc!

FredR

Indeed! When I had recent problems with my rear suspension I inspected the calipers carefully, could not see any obvious issues to kept them as was but I know it is only a matter of time before I must do the same so when our cooler season arrives in November I will probably do this job before something fails.

Of course my 928 is some 5 years younger than yours and does not get the hammering from slosh and grit your system probably does but then heat tends to takes it's toll on rubber parts over hear and this difficult to know when to replace pre-emptively.

Still if parts like this last 25 years then I reckon they owe you nothing and have done very well indeed.

It is a never ending quest or so it seems- my front suspension is the current issue and still struggling to find the cause of the annoying [mystery] squeak when I go over speed bumps! It sure annoys the hell out of me but I hate replacing things out of frustration not knowing what the cause of the problem is.

Rgds

Fred

StratfordShark

Have you checked the anti-roll bar bushes? Very cheap and easy to change parts, but if they are not lubricated they may be source of squeak.

The thing with the brakes is they operated fine with good feel before I began all this work, but what I'm finding (sticking pistons, side plate corrosion and seized pads) must have compromised the system. I think it may be analogous to the advice new buyers are given about the engine - it's such a fine unit that it can seem impressive even when not on song (timing off, knock sensors retarding ignition for example. Ditto 4 X 4 pot fixed Brembos is powerful braking, so the system can lose a lot of performance before it's obvious, at least in normal driving.

PS my MY91 S4 is now sulking after having a few extra years put on her age

FredR

The sway bar was the first thing eliminated. Checked by running with the end disconnected. Everything was cleaned and greased.

Rgds

Fred