Rear nearside brake (only) locked on!

harveyp6 said:
The problem with removing the diff is that once it's out and you try removing the caliper pivot pin bolts you'll be chasing the diff all over the place because you've got no way of holding it still. Do it all in the car, use diff removal only as the last resort.
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Harveyp6, I do not have a garage and it is 30 degrees celsius; obviously (if it is possible) I would like to dismantle the calipers and replace the drive shaft oil seals and oil catchers in the shade. I have a very sturdy wooden trestle (adapted from an equally sturdy kitchen table) which I use for sawing firewood logs; I was thinking I could mount the diff on that to work on it. What do you think? Is removing the diff to get at the calipers and oil seals overkill?

I do not know whether the grimy crap all over the diff and calipers is all brake fluid or whther some of it is diff oil, so I figure do both while I'm there? The flexible hose between the calipers definately needs replacing - It is dripping with brake fluid - Perhaps Rubythursday had it right at the beginning of this thread when he said that a collapsed brake hose could be the cause of the lock-up (having said that, I did get fluid out of the bleed nipple)? Could be that this hose is leaking and is responsible for all the gunk around there and my attacking the diff is uneccessary?

I was thinking of undoing both of the drives at the disc ends, the prop shaft from the final drive extension, the handbrake cable, the flexible brake pipe and then (supporting the diff, discs and calipers with a jack!) the two bolts holding the diff to the rear mounting bracket?

Again, am I making a relatively simple job more difficult than it need be?

I am very interested in your opinion!

ATB Ray
 
I fully understand the attraction of working stood upright at a bench and in the shade! So lets analyse the job to be done first!

Clearly the calipers need to come off the diff so as to be easily handled as you rebuild them. Plus renewal of all the diff oil seals sounds a good idea - the nose extension seal seems particularely prone to failure. There's most unlikely to be anything wrong with the diff itself. But the supporting pressing at the rear could be cracked, the bushes holding the frame in the base unit are likely to be U/S and you may well need some new rubbers for the mounting at the front of the extension.

So for my money, I'd use the security of the diff bolted to the body to get the calipers off the diff. Then have the diff itself off. Work on the bench for all the repairs. Re-assemble everything on the bench. Finally tighten everything up once re-installed in the car.

Chris
 
chrisyork said:
I fully understand the attraction of working stood upright at a bench and in the shade! So lets analyse the job to be done first!

Clearly the calipers need to come off the diff so as to be easily handled as you rebuild them. Plus renewal of all the diff oil seals sounds a good idea - the nose extension seal seems particularely prone to failure. There's most unlikely to be anything wrong with the diff itself. But the supporting pressing at the rear could be cracked, the bushes holding the frame in the base unit are likely to be U/S and you may well need some new rubbers for the mounting at the front of the extension.

So for my money, I'd use the security of the diff bolted to the body to get the calipers off the diff. Then have the diff itself off. Work on the bench for all the repairs. Re-assemble everything on the bench. Finally tighten everything up once re-installed in the car.

Chris
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Chris,

You make it all sound so simple!

I have read and re-read your suggestions and each time they become even more commonsense; I shall do exactly as you have advised - Thank you very much! :D
 
My first experience of working on the rear calipers was after removing the diff. I'd probably not remove one again to do it but it is more comfortable that way & you can paint it up & make it look pretty.

aaDiffunit-1.jpg
 
The Rovering Member said:
My first experience of working on the rear calipers was after removing the diff. I'd probably not remove one again to do it but it is more comfortable that way
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I'm afraid to say I have to disagree. I can't think of anywhere more comfortable than laying under the back of a P6 doing the rear brakes...... :LOL:
 
To update all my various (but excellent) helpers, once I had (thanks to your advice) removed discs etc so that I could actually see something, I noticed that the handbrake link to the rear nearside disc was jammed on! A 'tap' with an Irish Hammer released it and the siezed disc....Now not sure if the root of the problem lies with the linkage or the piston :?:

In any event, it was obvious now that the brake fluid gush emanated from the flexible hose linking the two calipers. On inspection, even I am not stupid enough to believe that I could undo the flexible hose in situ - You would have to be an alien life form to be able to get any sort of spanner on those banjos and turn them in the space provided (or not provided, more accurately).

I removed the handbrake linkage and both sets of pads and calipers (still linked to each other by the flexible hose) and 'lobbed one of them over the diff....Result - I have both calipers on my workbench in airconditioned splendour :!:

Rear offside appears fine - No brake fluid in the metal cover and the rubber seal in good condition. However, the rear nearside (again perfect rubber seal on cover) was full of fluid and both sets of pads (which look nearly new) are saturated
in fluid, mostly (I think) from the caliper to caliper flexi hose leaking above them.

So, I will need to order new flexible hoses - Is it worth paying £58 to Rover Classics for a set of four Goodrich? Am I being overly cynical when I say I would not be surprised to be performing all this again at the front end? What would you do - Worry about the front pipes when you have to?

Might as well replace all the piston rubbers etc while I have them on the bench - Even though they look okay :?:

Brake pads; from memory, you cannot reuse contaminated pads :?:

ATB Ray
 
Sounds like you're on the right track to sorting the brakes out. Do the seals in both calipers now they're off the car - only disassemble one caliper at a time though.

I went for Goodridge hose when I did my brakes as they're not that much more expensive and they have stainless steel fittings which makes them easier to remove in future if needed - the front hose come in the pack, but you can save them for later. You'll need new pads if the old ones are contaminated and it will finish the job off properly.
 
testrider said:
Sounds like you're on the right track to sorting the brakes out. Do the seals in both calipers now they're off the car - only disassemble one caliper at a time though.

I went for Goodridge hose when I did my brakes as they're not that much more expensive and they have stainless steel fittings which makes them easier to remove in future if needed - the front hose come in the pack, but you can save them for later. You'll need new pads if the old ones are contaminated and it will finish the job off properly.
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Thanks Paul,

I'll do as you suggest.

ATB Ray
 
oddly enough I have seen a siezed rear brake caliper on two P6's in the last month.

Both occured after an unusually hard brake application, and both turned out to be stuck hydraulic pistons.
The pistons were just about returning after a normal brake application, but following a hard application the pistons travelled just a few thou into a more corroded area of bore where they stuck fast.

Just one to bear in mind.
 
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