rear caliper overhaul

quattro

Administrator
Staff member
#1
I have never even had the rear calipers off a P6 before, but as I have the diff out it seems a shame not to replace the seals and give them a good check over.

The manual states that you need to grease a whole list of parts with special brake grease - anyone know if this is still available and does it come with the rebuild kit?

Do the drags pins and cover nuts come with the rebuild kit? or is it not necessary to replace them?

Is it as fiddly as it looks and will my FFS (Fat Finger Syndrome) be helpful ? :?

I'll see if I can take some pics of the event

Richard
 
#2
Yes it is that fiddly! You can either admire the mechanism as a work of Swiss watch standard craftsmanship or wonder at the sheer stupidity of expecting anything that intricate to work under the rear end of a motor car! I have some helpful photos taken round at Pilkie's I'll email you tomorrow. (they're still in the camera at the moment)

Chris
 

Tor

Active Member
#3
Hi Richard,

I've never seen an OEM rebuild kit, but the aftermarket ones I've used came without pins, grease and cover nuts. The latter don't take a lot of torque to provide a seal and unless rusted away can be reused, otherwise you'll be able to fit slim replacement nuts of a regular type.

Personally I didn't find it all that difficult, and a petite set of fingers isn't what's needed really. Getting the sprung, self-tightener ratchet mechanism together so that it works is the clever bit to me. Given time and patience, I'd probably take a few minutes to study it before dismantling.

I also kept finding a "mystery" O-ring left out after everything was assembled, which sits behind the plastic cover through which the handbrake quadrant goes...

Tor
 

SydneyRoverP6B

Well-Known Member
Staff member
#4
Hello Richard,

The OEM Girling kits do come with a raft of parts along with the seal kit, but these days they are as rare as the proverbial hen's teeth.

The drag pins only need replacing if they are bent, otherwise they can be reused. The special grease is water resistant with a high melting point specification, so something like Castrol EPL2 is perfectly acceptable.

The hydraulic pistons, one in each caliper are tiny, and in normal operation their range of movement is very slight indeed, but nevertheless the bores need to be in perfect condition without any pitting whatsoever. Stainless steel resleeving if not already done is the permanent fix.

They are quite fiddly, but the good news is once done they won't really need touching for close to another 100,000 miles.!!

Ron.
 
#5
Isn't the special grease the red Girling grease ?
When I did mine I didn't take the handbrake mechanism out , just enough to change the hydraulic seals
 

SydneyRoverP6B

Well-Known Member
Staff member
#6
DaveHerns wrote,...
Isn't the special grease the red Girling grease ?
When I did mine I didn't take the handbrake mechanism out , just enough to change the hydraulic seals
Hello Dave,

I was taking the view that it was for the mechanical mechanism rather than red rubber grease for the hydraulic seals, so you may well be right. I use mauve Girling rubber grease which is not gluggy like some of the red rubber greases which can cause problems if used in certain applications.

Ron.
 

testrider

Active Member
#7
I rebuilt my rear calipers a couple of years ago and I thought the most difficult part was taking them off and refitting them back on to the car. The actual rebuild was fairly straight forward and took about an hour each side and the bled easily in about 5 minutes too. With the diff already off the car Quattro, you missed the hard bit out.
 

quattro

Administrator
Staff member
#8
testrider said:
Quattro, you missed the hard bit out.
I took the diff out - that was a hard bit :shock:

:D

Anyhoo, that diff is a bit heavy isn't it?

What's that piece of paper all about? Do I need to replace that with a new one, or just be careful with the one I have?

I don't have a suitable size allen key so work has stopped for the time being - will have to get one. (3/16?)

Piccys when I have finished

Richard
 

testrider

Active Member
#9
Hi Richard, I've no idea what the paper was for other than perhaps to absorbe moisture. My caliper housings were full of fluid so I just dried the paper as best I could and put it back in.

I found it easier to bleed the system with the discs removed as this gives better access to the bleed screw, so leave them off the diff when you put it back on.
 

quattro

Administrator
Staff member
#10
The first one, that I removed yesterday, has a small amount of thick black liquid in it which doesn't look like it should be there.

The pads look fine, almost new, so I might just put them back in 8)

I have some braded hoses which were supplied with the car, which is good because one of Sparky's broke when I bent it.

Shouldn't take too long

Richard
 

harveyp6

Well-Known Member
#12
The paper used to come with the genuine Girling caliper kits, which were for a pair of calipers, also contained a new pistons, and all the plastic seals that don't come in the kits you get nowadays. Cue: Back when i were a lad....... :)
 

Demetris

Well-Known Member
#13
quattro said:
Anyhoo, that diff is a bit heavy isn't it?
Tell me about it, i have been under the car hugging the diff and the gearbox (not at the same time :shock: ). At least the diff fits and bolts into place much more easier.


quattro said:
What's that piece of paper all about? Do I need to replace that with a new one, or just be careful with the one I have?
When i rebuilt the rear brakes about 3 years ago, i just cut some strips of ordinary inkjet printer paper and smeared some ordinary grease (high melting point ones probably won't be any good) on them.
It's not the real thing but i reckon they will work better than 40 year old original strips.
 
#14
quattro said:
testrider said:
Quattro, you missed the hard bit out.
I took the diff out - that was a hard bit :shock:

:D

Anyhoo, that diff is a bit heavy isn't it? ...


... I don't have a suitable size allen key so work has stopped for the time being - will have to get one. (3/16?)


Richard
The diff is quite heavy, I just managed to get it out on a trolley jack.

I didn't need an allen key to dismantle mine, as the pivot pin was seized enough to get the cap nut with the 'o' ring off without it turning, after which I tapped the pin out with a hammer and drift, which was scary, as the pivot pins were completely corroded in... :shock: I suspect I'll need one when it all goes back together though, so would appreciate it if you let me know what size allen key to buy, mine are all metric..
 

harveyp6

Well-Known Member
#15
V8P6B said:
I didn't need an allen key to dismantle mine, as the pivot pin was seized enough to get the cap nut with the 'o' ring off without it turning, after which I tapped the pin out with a hammer and drift, which was scary, as the pivot pins were completely corroded in... :shock: I suspect I'll need one when it all goes back together though, so would appreciate it if you let me know what size allen key to buy, mine are all metric..
I've never used an allen key, in fact if it ever came about that I needed one having gone out to do the job, I'd be in trouble as it's not something that I would have taken. When you put it back, if the nut is free on the thread on the end of the pivot pin, (which it will be) then if you push the pin inwards with your thumb it locks it enough to do the nut up no problem, and so far the same thing has always happened taking them off as well.
 

quattro

Administrator
Staff member
#16
I needed the allen key to remove the location plate screw which had an allen head on it. Tight little bugger too.

5mm allen key fitted that :)

Richard
 
#18
Classics Monthly did a step by step P6 rear caliper rebuild with Red Hat Rovers a little while ago - Ill look later and see if I can find which issue it was in
 

Dave3066

Well-Known Member
#19
alfesti said:
Classics Monthly did a step by step P6 rear caliper rebuild with Red Hat Rovers a little while ago - Ill look later and see if I can find which issue it was in

July 2008

I have that article scanned if anyone wants it PM me :D

Dave
 

quattro

Administrator
Staff member
#20
I took a whole load of pics on the second caliper, and here they are.

The caliper, still on the diff from the rear.

And from the front

Hand brake cable has already been disconnected and diff is off the car, which obviously makes it a lot easier. I have removed the drag pins here and the pad retaining plates, note the position of the anti rattle spring here. There is a different shaped one on the other side as can be seen here still with the pad retaining plate.

I then removed the split pin and clevis pin connecting the hand brake lever assembly to the cam lever in the caliper. Note the position of the felt washers – take some pics. I then removed the two bolts on the diff and removed the whole hand brake mechanism, it could be just moved to one side, but I am cleaning it all up and painting it so I removed it completely.

I then removed the stop pin, to allow the cam to rotate slightly and enable me to get a socket on the spring loaded nut cover for the hinge assembly. Don’t allow the cam to come out as yet though, it may even be a good idea to put the stop pin back in after removing the nut ( I was just careful).

I then removed this bearing, which looks like the head of a bolt, then tapped out the shaft to release the caliper.

Got it in the vice, then removed these nuts, noting where the brake pipe bracket fits, (Spring retaining clip on the other caliper).

Removed the rubber washers and discarded them (if you have them in your rebuild kit) and carefully removed the paper and put somewhere safe.

Took a photo from every angle to aid in rebuilding




I took the nuts off and gently levered the spring upwards slightly, then pulling the piston down from below, I popped the strut/lever assembly out, which sounds a lot more difficult than it is. This is what it looks like out

I then carefully levered the spring upwards until it came apart from the S spring then removed it.

The S Spring can then be lifted away as can the main beam.

This pic is a bit blurry, but this bit is then removed. This bit does not appear in my Rover manual or my 1977 parts manual for some reason? Perhaps they are later calipers?

The knurled head can now be unscrewed from the cup assembly and withdrawn.

Then pushed the cup assembly downwards and removed from below. I then undid the allen bolt here (this is the one I couldn’t find an allen key to fit) and lifted the plate away, noting the washer (Piston stop)

Now I turned the hand brake cam and lifted the hand brake pin upwards so that I could get hold of it and remove it from the caliper body.

This bit of nylon is then removed along with the rubber o-ring behind it. This nylon is not in the parts manual either?

Then using an air gun in the brake pipe hole, I popped the piston out. I don’t know what to do if you haven’t got an air line, that might be fun.

I haven’t done much more but have found that the cup assembly is pitted badly so needs replacing.

Also the cover on this side is rusty, so I rubbed them both down and painted them with some enamel I had left over from the shocks.

More when I get time.
 
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