Servo rebuild and brake bleed

R

restojon

New Member
Hi all,
I'm about to replace my brake servo seals, (kit now in post). I had the mysteriously vanishing brake fluid problem, but what I needed to pick your collective brains about was this. I am working outside with jacks and axle stands and once the servo is refitted I'll need to bleed the brakes, and while this is no problem on the front calipers I'm having real trouble getting to the rear bleed nipple(s). I can just get a ring spanner on but can't turn it and definately not with a bleed hose on, am I putting off the inevitable by not lowering the axle? or is there anything that anybody could suggest?
Any help would be very appreciated as my motivation is only just holding out under the threat of working in the snow :LOL:
Cheers,
Jon.
 
You shouldn't need to lower the diff, but trying to get at the bleed nipple with the car on the ground will be awkward, but not impossible. You need a good quality 7/16" AF mini-ring, slide yourself under the car, reach though between the diff and disc, crack the nipple open to be sure it's free, then nip up, and then fit the bleed hose (making sure any dustcap is off the nipple) then slide the spanner up the bleed hose and it will guide it straight on. Best done on a day when it's not snowing.......
 
Hi,

I've just put my 'new' car's diff back up (I lowered it to strip & service the rear brakes) & it looks like I've put the fexible brake hoses the wrong way round on the off side caliper. The caliper-to-body (with wire protection) hose is in the bottom hole & it can't reach the body fitting easily. The bridging hose is in the top hole which seemed logical when I put them together :roll:

Can anyone confirm that I've got them mixed up, please? :?
 
Hello Phil,

The brakes will function just the same regardless of the orientation of the hoses, but as you have noticed, the reach of the wired hose is slightly compromised. The correct way is the other way around,...wired hose on the top, joining hose on the bottom.

Ron
 
Hi Phil,
If nobody's got there before me, when I get under my car (doing it outside in snow) I'll have a look and let you know. It would seem that something is in the wrong place though from what you've said. I can understand why you wouldn't want to have to lower it all again though.
It may help if you add to your post the exact type of P6 you have and the series etc, they do use different calipers on different models, just a thought.
Good luck with it.
 
Thanks for the help gents. I suppose I'll just have to change them round :( . The difficulty is undoing the bridge pipe as it will need unscrewing at the near side aswell in order to unscrew it out of the RH caliper. Might try without dropping the diff again - when I start swearing I'll know I can't avoid it!

It's an early 'S' by the way. Nice car, but a lot to put right.....
 
restojon said:
I can just get a ring spanner on but can't turn it and definately not with a bleed hose on, am I putting off the inevitable by not lowering the axle? or is there anything that anybody could suggest?
Click to expand...

I had a similar problem with my P6 a few years ago where I was trying to remove the door hinge pins.

The only spanner I had which fitted was too long to be able to get it on the hinge, and turn it, so I cut it in half. It sounds a bit drastic but I still have the spanner(s) and use it for all sorts of tight spots.

Just a thought

Richard
 
HI,

I have done the rear brake bleeding with the diff in situ and with it lowered. After trying it lowered I'm going to say, lower the diff. It's only three bolts holding the diff carrier in place. There should be enough flex in the bushes to allow the diff to drop on a jack. Once down there its so much easier to access the nipple and get a good flow. But that's just my luck doing it single handed. One warning, make sure that the hose to the body is not stressed by the diff weight at any time. I normally losen the nuts securing to the body bracket to be sure.

Cheers,

Steven
 
Thanks for the advice, I'll give both of those a go. I've got a few doubles in the spanner drawer, if the diff drop is that easy then I'll get it down (without wrenching the brake hose out of the car)
Have angle grinder.... will travel. :D
Thanks guys.
 
So, the latest instalment of the brake saga goes something like this. I recently pulled my servo to investigate the mysterious disappearing brake fluid problem and when I stripped it found no problem, however a weep from the master cylinder had caused some leakage down the bulkhead and I ordered a seal kit and set to it. When I removed the master cylinder I found a crack had developed in the master cylinder mounts and it fell in two when I removed it so after much begging and borrowing sourced a S/H master cylinder and I stripped cleaned and fitted my seal kit to this and was on my way (after much fiddling with the little white nylon non return insert). Now since this has happened I've also had to replace my clutch master cylinder seals, and my clutch slave cylinder has begun to leak again, (I've only recently replaced this less than 6 mths ago!! Grrr) but we still have a clutch so we shall come to this after I resolve my more immediate problem which is this, I'm now losing brake fluid quicker than ever, it's dropping half an inch in less than 5 miles, I've looked around the calipers and cannot see any signs of leakage, I've checked all the lines that I can find again no problem, I've checked the air valve in the servo which was exhausting fluid from the little air filter so I've flipped the seal around and it doesn't seem to be leaking now, but I will recheck this to make sure. The brakes are not pulling to either side, and on the first pedal stroke produce adequate stopping power but on the second stroke you can really feel the assistance of the servo. You can hear the servo pressurising whilst the engine is running and the brake pedal is pressed and if you start the car with foot on the pedal the pedal lowers as the engine fires up. I'm using DOT4 fluid and the car is a 71 2000SC with the large plastic reservoir, is there anybody out there that can give me any pointers? I use the car everyday for work (but not today obviously :x ) and would like to try and get it rolling again as soon as I can and any help would be very much appreciated. Thanks.
 
The normal answer to that sort of question is that it is leaking from the rear calipers and filling up the cavity with the handbrake mechanism in it. But that rate of leakage ought to make it obvious! So for large amounts of fluid going walkabout and not appearing on the floor it has to be going via the servo into the engine. Are you sure it isn't?

Chris
 
Thanks for your reply. I've just had the servo apart and I cant see any signs of leakage into the large canister part of it. Should I be looking elsewhere in the servo? There has been a bit of white exhaust recently but I put it down to the cold weather and moisture in the exhaust as it doesn't smell like oil burning and it's mostly on warm up. I've just pulled the master cylinder too and there is the slightest film of fluid on the brake pushrod and dust seal but I'm thinking that's probably ok? I can feel my hair getting thinner by the minute with this one! :D
 
I think I may have found my problem, it would appear that the rubber hose from the reservoir to the inlet brake line (to master cylinder) has shrunk in the cold and has allowed to the fluid to escape through the gaps, there were no jubilee clips on this pipe (there is now!!) but it doesn't end there, also the seal in the reservoir lid has shrunk too allowing fluid to escape through the lid even when tightened up as if a gorilla had wound it down, AND the brake fluid level sensor is leaking through the lid too, I warmed it up and it seems to have stopped, have done 40 miles of testing and no fluid loss, brakes feel fine so I'm hoping that we've cracked it.
Where I live we've had the cold particularly bad, and I live on a north facing ridge just to make it better, (I've still got ice here from the end of December!!!) and everything that is made of rubber has copped it, all of my fork seals in my bikes have sprung leaks, the clutch slave and master cylinder seals have given up on the series 2 and my brand new clutch slave cylinder on the series 1 has begun to leak too, not only that all the door seals have tried to stick to the door shuts, but we oiled them just in time and all were ok bar one.
So, all told rubber and cold don't mix, I think I might give it a hot water bottle for the cold nights, and I hope that this is the end of the saga.
Thanks to everyone for the help and advice.
 
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