Caliper Seal Kit

[AGM]

Hi all,

I'm after sourcing a caliper seal kit for our 80 series.

Where's the best place for me to look?

Thanks in advance!

Alex

 

[Shayne]

http://www.biggred.co.uk/

 

[flint]

Another place is http://brakeparts.co.uk/#!/ and go to the online store.
If not already done, it might be worth checking that the pistons and bores are serviceable before ordering though.

 

[AGM]

Thanks!

Flint - what's the best way to check that please?

Alex

 

[BRE Fabrications LTD]

I would recommend replacing all
of the Pistons while you are servicing the calipers. I regret not replacing mine the first time around and ended up having to rebuild all of the calipers again earlier this year because of it.

They aren't too bad price wise from Big red. Their service was really good too.

 

[flint]

First thing is to see if the pistons move freely. Assuming that the calipers are off, you can check this by putting a piece of something, wood works, about the same thickness as the disc between the opposing pistons (this stops them flying out) and gently pressing the brake pedal, or if disconnected attach a foot pump or similar air supply to the inlet on the caliper. If the pistons don’t move or you can see that they are rusty, there’s a fair chance that they might need replacing, and or the bores might need honing as well. If in doubt, and to avoid a fair bit of messing about, then a rebuilt caliper could well be a better bet. If the fluid hasn’t been changed for a long time and looks murky, it’s probably absorbed quite a bit of water from the atmosphere which can rust the pistons in even if the outer seals look ok.
Edit, make the piece of wood a bit thicker than the disc !

 

[Michael Montgomery]

First thing is to see if the pistons move freely. Assuming that the calipers are off, you can check this by putting a piece of something, wood works, about the same thickness as the disc between the opposing pistons (this stops them flying out) and gently pressing the brake pedal, or if disconnected attach a foot pump or similar air supply to the inlet on the caliper. If the pistons don’t move or you can see that they are rusty, there’s a fair chance that they might need replacing, and or the bores might need honing as well. If in doubt, and to avoid a fair bit of messing about, then a rebuilt caliper could well be a better bet. If the fluid hasn’t been changed for a long time and looks murky, it’s probably absorbed quite a bit of water from the atmosphere which can rust the pistons in even if the outer seals look ok.
Edit, make the piece of wood a bit thicker than the disc !

Flints right ....if your gonna repair do it once, do it right thats what I did with mine not long ago. The companies recommended look good. I used http://www.biggred.co.uk. Ordered fronts & rears. Looked as good as stock.

 

[Gary820]

Another vote for big red.
Rebuilt my fronts and will be doing the rears next. For the price of the kits fit pistons and it's done then.
Full front kit to do both calipers was £70 from their e bay shop

 

[Chris]

One point though about the bores and honing them. The piston doesn't actually touch the bores. The seal is the rubber seal in the groove. Just drop a piston into the bore without a seal and you'll see what I mean. There's no metal to metal contact. It's the piston that moves in and out against the o ring. Doesn't matter what the bore is like really. It's the pistons that need to be in good fettle.

 

[flint]

It’s the effect on the seal of rubbing on a corroded surface that’s worth avoiding.

 

[Chris]

Absolutely, but that's on the piston Flint, not the bore. The bore touches nothing at all. The seal is in the bore and the piston moves in the seal. The seal doesn't move in the bore. Hence the bore can be fairly rough. Nice to have it shiny but it serves no purpose to have it like that.

 

[flint]

Yes, you’re quite right Chris, probably just being a bit pernickety. As long as the groove in the bore is undamaged and holding the seal properly, it shouldn't be a problem. I have replaced pistons before which had score marks from rubbing on corrosion damage in the bore, but that was probably down to the ageing and failing of the seals not holding the piston true, or bad seating on the pads allowing the piston to tilt. As the clearance between piston and bore is not huge, maybe 7 thou ish, it doesn’t take much for them to touch. I agree that it’s not neccesary to be a mirror finish, but honing does take off any corrosion.

 

[flint]

Perhaps I should add that I tend to be a bit careful about brakes after having been hit by a 2cv about 30 years ago. It came from a side road on a common in Kent and I saw that he wasn’t going to be able to stop and neither was I. I tried to speed up hoping to miss him, but he hit me just in front of the back axle and bounced off the back wheel. If I’d T boned him, he wouldn’t have walked away. The front of the 2cv was not a pretty sight. The driver was pretty shaken, but not injured and admitted he’d just been working on the brakes………Lucky really as I was in a large truck, only slight damage and I was able to wend my way to Vienna.

 

[Chris]

Sure. Understood. What I have found though in the 80 pots is that water tends to collect, I guess it pools in one spot and you do get corrosion. I think that's why it's important to give the brakes on these old cars a fairly regular pump through to freshen up the fluid in the ends of the lines, especially if you off road them.

I use a bit of wire wool to shine them up a bit. You're right about not wanting flakes to get jammed into the seal.

 

[flint]

Thanks Chris, I meant to say that I was being pernickety, not you. When I got my 95, which is much the same setup, one of the first things I did was to take the calipers off and have a good look as the brake fluid looked as though it hadn’t been changed for quite a while. Sure enough, on the offside front only one piston wasn’t sticking and on the other side, two were seized. It had not long passed its MOT, so unless it was an iffy one, I presume that the brakes were still up to scratch enough as far as that went. The rears were ok, not long changed by the looks of them. When I finally got the pistons out, which took the best part of 90 psi and much tapping to shift the worst, they were in quite a state, the bores were a mess and the inner seals virtually non existent. The outer seals didn’t look too bad, so it was mainly moisture in the fluid that had caused the damage as far as I could tell. I hadn’t paid much for the car (the owner was convinced the engine was on its way out, it was just a £5 bearing for the alternator needed, I did tell him !), so I treated it to a nice pair of refurbished calipers. Regular fluid change would probably have avoided the damage and is a cheap insurance.

 

[Chris]

and getting the pistons out can be a hell of a task actually. Pumping them out is one thing. An airline sometimes works, but before now I have had to weld a piece of steel across the piston and wind them out with a bolt. The one thing you can't do to get them out is try to turn them. The seal will grip like a boa constrictor as it moves and you've no chance.

 

[Roger]

and getting the pistons out can be a hell of a task actually. Pumping them out is one thing. An airline sometimes works, but before now I have had to weld a piece of steel across the piston and wind them out with a bolt. The one thing you can't do to get them out is try to turn them. The seal will grip like a boa constrictor as it moves and you've no chance.

One option I stumbled upon out of desperation is to use a grease gun - in the box of plenty I had a grease nipple with the same threads as the union bolt - it must be a common size as I think this grease nipple was a spare from my unimog ownership days.

I had one caliper that was rock solid on 2 pistons, tried it all, air, heat, gripping and twisting, brute force and ignorance - the hydraulic action of the grease took it out with no issues - I guess I used half a tube of grease doing so but it was worth the £1.50 it cost!

 

[Chris]

That's very clever.

 

[flint]

Good tip ! I had a petrol ex nato mog for a while, did lots of sterling work round the place (it’s a bit hilly here) especially when all the poor old elms had to come down. Fine machine, didn’t like the cost of fuel or spares too much though.