Front Caliper Rebuild

#1
I went for a drive in Rover the other day and noticed it was a bit sluggish on the get go and wanted to slow down quicker than normal. Did a couple of checks on the road i.e. release the brakes put in neutral on a grade, and no movement. As I suspected the brakes were locking on.
That ended that trip so return home and raise the front, I have rebuilt the rear brakes previously so didn't start looking there, and check the wheels for rotation. Sure enough not much wheely turny happening without some effort.
Off with the calipers, the seals were brittle and cracked on both and the pistons were corroded and very hard to remove. I've ordered new pistons from Mark Gray and I already have the seal kits.
The outer dust seals on the left side these were relatively intact but there was heavy rust buildup on the pistons within the seal. Almost like the seals had no effect on keeping the piston clean and free of moisture.

When I rebuild the calipers and fit the new pistons (I'm going to use steel again) and seals I'm thinking there should be some grease coated on the pistons under the outer dust seal. This will keep out any moisture which may get past the seal.

Now to my question.What grease should I use? I have proper brake rubber grease for assembly, is this OK. Or should I look at a copper or nickel based grease? Also how will the grease perform when the brakes get how, will it spill out of the seals and contaminate the pads? I'm only looking to put on a thin smear of grease on the pistons, not too much.

Anyone with experience with this?

Many thanks,
Craig
1972 P6B 3500 V8 NZ Assembled
 

SydneyRoverP6B

Well-Known Member
Staff member
#2
Hi Craig,

The dust seals do work reasonably well, but only whilst they remain supple.

I would strongly advise against using any form of grease, for the reasons that you mentioned, melting and contamination.

The recommended replacement period for brake seals and the flexible brake lines is every 3 years, within the time frame that they will still be supple, but almost no one, myself included, will replace them so frequently.

Ron.
 
#3
Both Bendix and Castrol make a specific brake grease which is designed not to damage the rubber components and provide high temperature protection. The bendix grease is blue, the Castrol grease red. both are silicon based I understand. generally you can't get them in small amounts as they are a trade product. You can get one time use packets but I don't believe they are of the same quality as the trade stuff. Make sure you specify Brake Grease not ordinary rubber grease.
 
#4
Thank you both for the replies. I'll look for specific brake grease and lightly smear this on the insides of the rubber and exposed pistons.
Also looks like I should plan some preventative maintenance on the calipers in a couple of years time.

Craig
 

clive P62

Active Member
#5
Hi guys.
This is what i use on my brake rebuilds.
I put a small amount of grease in the dust gaiter as well to keep out moisture .
Clive. 20161107_190146.jpg
 
#7
hello Clive,
I have a 3500, just purchased as a 20 Year in a garage, post (some hopes)
I bought it unseen, distance the problem.
The brakes are seized solid, at the front so far.
I have the callipers off the car, I put 100lb air pressure on both, but only got the larger piston to move on one of them.
Which brings me to a previous post, maybe you refurbish these callipers as a buisness? The pistons would probably come out with the correct tooling,
I you can do this, would you email me
bloftus26@gmail.com
thank you
Brian
 

Penguin

Active Member
#8
you can often free stuck pistons by giving the caliper body a firm tap with a hammer whilst pressurizing the caliper
 
#13
grease gun, worked well, how do I get the bloody grease out of the callipers. brake system out of order, so no good putting the callipers back on the car.
Any-one got an old master cylinder for sale or loan, may be able to set up on the bench
regards
Brian
 
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