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Refurbishing Metro 4 Pot Callipers


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#1 JonnyAlpha

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Posted 11 January 2019 - 01:23 PM

I have salvaged a set of 4 Pot Callipers and want to tidy them up before selling them on.

 

Do the calliper units come apart to remove and refurb the cylinders, i.e. fit new seals and cylinders if needed? 

Or should I just Citric Acid dip them, clean them up, and sell them on?

 

Pics to follow.



#2 nicklouse

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Posted 11 January 2019 - 01:32 PM

you can but I would replace the seal that goes between the caliper halves.

 

I just used compressed air to pop out the pistons and a pad spreader to refit the seals.



#3 alex-95

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Posted 11 January 2019 - 04:25 PM

I personally wouldn't recondition them with new seals etc to sell on just in case something did happen which could cause the brakes to fail, if the person that bought reconditions them then its their fault. 

 

Not saying you'd do a bad job either :lol:


Edited by alex-95, 11 January 2019 - 04:26 PM.


#4 Wiggy

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Posted 11 January 2019 - 04:25 PM

I use a grease gun to pop the pistons out, as I don't have a compressor.

#5 Moke Spider

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Posted 11 January 2019 - 06:42 PM

Before you do anything with them, make sure all the Bleed Nipples are in tact, there's 3 on each Caliper. Often they seize and are snapped off in the body.

 

They other thing to watch out for are which type of Metro Caliper are they? There was 4 that I know of, there's types A & B and those for Solid or Vented Discs in each type, with some of the Vented ones using spacer blocks and some not.

 

In these, the Type A's were made by AP and are the more desirable, with parts for them still available. The type B's, off hand, I can't recall who the manufacturer was, but parts for these are difficult to get, and even the Pads can be obscure to find. As a result, the types B's are much less desirable and often people won't buy them.



#6 Carlos W

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Posted 11 January 2019 - 06:49 PM

New pistons and seals are available from minispares, but they’re not cheap.

You’re unlikely to make much money refurbishing them.

I ended up splitting mine then welding a bolt to the piston to remove it.

#7 JonnyAlpha

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Posted 11 January 2019 - 06:52 PM

I personally wouldn't recondition them with new seals etc to sell on just in case something did happen which could cause the brakes to fail, if the person that bought reconditions them then its their fault. 

 

Not saying you'd do a bad job either :lol:

 

That's a fair point. I think what I will do is strip and clean them and leave the rest to the seller.

 

you can but I would replace the seal that goes between the caliper halves.

 

I just used compressed air to pop out the pistons and a pad spreader to refit the seals.

 

Damm - just sold my compressor!!!

 

I use a grease gun to pop the pistons out, as I don't have a compressor.

 

And fill em up with Grease?



#8 Wiggy

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Posted 12 January 2019 - 12:41 AM

Yeah, it's no big deal to wipe out. I then use a tyre inflator with an airbed nozzle on to blow out the grease from the bits you can't get to.

#9 Icey

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Posted 12 January 2019 - 01:24 AM

It’s about £100 in parts to rebuild a set and they aren’t worth a whole lot more than that.

If you aren’t using them yourself then give them a bit of a clean and just sell on as spares/repairs. It’s not really worth the bother.

If you do rebuild them, personally I’d never use the grease gun method. You’ll never get all the grease out of the internal channels. Either find a way of gripping them (I had some modified circlip pliers) or find a compressor to borrow.

Word of caution to anyone using compressed air to remove pistons - be careful! There is more energy stored in that compressed air than you realise, if you get a body part in the way of a piston when it releases it’ll do you a mischief. Hold the calliper in a vice, secure the airline and retreat to a safe distance!

#10 nicklouse

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Posted 12 January 2019 - 12:42 PM


Word of caution to anyone using compressed air to remove pistons - be careful! There is more energy stored in that compressed air than you realise, if you get a body part in the way of a piston when it releases it’ll do you a mischief. Hold the caliper in a vice, secure the airline and retreat to a safe distance!

very very true. in fact i would go as far as saying you should not use compressed air to remove the pistons but only to get them moved out so you can extract them. As the metro is dual circuit you only need to deal with two pistons at a time unlike the other single line 4 pots. did mine last year http://www.theminifo...-out/?p=3538626



#11 JonnyAlpha

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Posted 12 January 2019 - 06:11 PM



It’s about £100 in parts to rebuild a set and they aren’t worth a whole lot more than that.

If you aren’t using them yourself then give them a bit of a clean and just sell on as spares/repairs. It’s not really worth the bother.

If you do rebuild them, personally I’d never use the grease gun method. You’ll never get all the grease out of the internal channels. Either find a way of gripping them (I had some modified circlip pliers) or find a compressor to borrow.

Word of caution to anyone using compressed air to remove pistons - be careful! There is more energy stored in that compressed air than you realise, if you get a body part in the way of a piston when it releases it’ll do you a mischief. Hold the calliper in a vice, secure the airline and retreat to a safe distance!


I had been pricing up parts and the Pistons are quite pricey. I think I strip them down, clean them up and ship them on. May get £50 a Calliper?



Word of caution to anyone using compressed air to remove pistons - be careful! There is more energy stored in that compressed air than you realise, if you get a body part in the way of a piston when it releases it’ll do you a mischief. Hold the caliper in a vice, secure the airline and retreat to a safe distance!


very very true. in fact i would go as far as saying you should not use compressed air to remove the pistons but only to get them moved out so you can extract them. As the metro is dual circuit you only need to deal with two pistons at a time unlike the other single line 4 pots. did mine last year http://www.theminifo...-out/?p=3538626


Just looked at your link nicklouse - what a fab garage (well the monitor that is), always had a PC in my garage for reference but a large screen on the wall is great. Where did you get the digital Haynes Manual?

Edited by JonnyAlpha, 12 January 2019 - 06:12 PM.





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