Possible rear brake issue

[Graham Sewell]

Having had my meticulously repaired by an authorised agent, last night I found that the inside of my nearside rear wheel was coated in black 'oily' substance. For the moment I am assuming brake fluid is the cause as a new brake cylinder (live axle) was required to pass the MOT during the rebuild. Also, the goop (for want of a better technical term) did not smell like axle oil (hypoid) or petrol.

 

Also, for cross reference, it could be cleaned easily off the wheel using white spirit. Also, the pedal pressure was still firm last weekend when I was driving so it is not a complete failure.

 

Not having had much time for troubleshooting due to weather conditions last night, I will obviously need to investigate the root cause of the problem. I am hoping that it is just a case that a union between the brake pipe and cylinder needs a quick tighten, but what else do I need to check to ensure safety - I really need to get the car sorted for the bank holiday so that gives me 2 weekends.

 

I am guessing that as a minimum, that I will need to take the drum off to check for contamination of the shoes/drums and that I will need to bleed the brakes.

 

I am sorry if this is a little vague, but I don't normally touch brakes as I leave safety issues to the 'professionals' who, so far, have had two issues with work done on my brakes in as many months - so I would like to learn to do it properly.

 

 

Low tech luddite - xflow and proud!

 

Edited by - Graham Sewell on 8 Aug 2002 10:43:48

[Paul Ranson]

My experience of leaking slave cylinders is visible brake fluid running onto the wheel/tyre/floor rather than spread around the wheel.

 

If it were leaking under pressure then I would expect that to be detectable in the pedal.

 

Brake fluid is clearish rather than black.

 

I would suspect wheel bearing or CV grease, except that it's a live axle...

 

Don't take the drum off and then press the pedal! The union to the slave cylinder and the bleed nipple are both accessible from the back plate without removing the drum. I would check those for tightness. And that the pipework is intact. When you remove the drum the slave cylinder ends will have dust covers. If peeling these back reveals fluid then you probably have a leaking seal.

 

(I once carefully rebuilt a slave cylinder only to find on reassembly that the threads for the bleed were stripped....)

 

Paul

[Tonycaterham]

Graham,

 

I have the same problem i.e a fine black film around inside of rear wheel.

 

The problem is a (very) slight oil leak from the (live) rear axle which will get fixed sometime as it is very slight and does not find its way onto inside of the rear brake drum!

 

You could possible diagnose your problem by removing rear wheel and brake hub and see if there is an oil trail from the halfshaft. If it is brake fluid then could be attacking paint on rear backplate which may help identify cause. Car should not normally leak when standing unless the diff has been overfilled. Alternatively clean off the rear wheel/rear backplate in the garage get in the car and pump brake peddle dozen on so times then look for evidence of brake fluid. If none take car for a spin and then if slight oil film on rear wheel then definitely halfshaft seal leaking.

 

Hope this helps

 

Tony

[Graham Sewell]

Tony7

 

Any idea what the best way to fix such a leak would be - never having really looked at the rear axle. I was hoping that it wasn't the brakes, but the dirty is more than just a thin film (unless most of the crap is dust that is attracted to the oil).

 

It would be good news in some ways if the brakes are not the fault as it would restore some faith in the authorised agent. It just sems like a coincidence that the cylinder was replaced 300 miles ago.

 

Low tech luddite - xflow and proud!

[Tonycaterham]

Graham,

 

This is dependent upon which type of axle you have either Ford or Ital.

 

I have the ford axle but most of foillowing should apply to the Ital axle as well.

After removing the brake drum you will see the halfshaft is held in place at the outer end by a flange which is held on by four bolts acceable via a hole(s) in end of the halfshaft which holds the wheels studs. First thing is to see if any are loose and tighten. If tightened and still leaks then could try removing plate and using gasket sealant round face and re-tighten. If that does not work then will have to remove halfshaft and renew oil seal which will probably involve renewing bearing at same time.

Unless you are comfortable removing halfshaft with a halfshaft puller or home made equivalent best left to local garage as bearing will require use of press to remove and fit a new one.

 

Regards

 

Tony