25 replies to this topic

[bmcecosse]

The original question was about SEIZED pistons - grease gun is the way. Unseized pistons are no problem at all.

[daemonchild]

Kez is right, compressed air is dangerous. There is a very real danger of the piston coming out a very high rate of knots.

Something like this should only be considered as a very last resort, there are far better methods, as detailed above

I can't see 100 psi air moving the pistons - it needs good hard pumping with the grease gun! I would say the 'danger' with 100 psi air is very low - but it wouldn't shiuft the caliper pistons I have had to tackle! The grease gun is perfectly safe - and it works - just takes a little time to clean everything up afterwards.

If you have got unseized or partially seized pistons compressed air will move them.

Not all compressors are 100psi, i run mine at 150psi and trust me when the pistons come out they have a lot of force behind them.

I wouldn't only advise people with a lot of exprience to takle getting the pistons out with an air line.

I can imagine they would FLY out!
You'd want some solid wood correctly positioned to act like a bullet catcher??
(Not that I'm planning this!)

[Saxo-Fiesta-Mini]

escort cosworth and seirra cossworth around 91 did a single piston caliper which was a float type caliper and is a common upgrade on fiestas u clearly dont know fords very well

http://www.fiestatur...64/?hilit=cossy brake upgrade#p1729264

so there u go Mr know it all

the same design carried over onto the mondeo 2.5 v6 mk1 and is the same as the cougar v6 minus a slight edit on the casting

Edited by Saxo-Fiesta-Mini, 26 June 2009 - 10:02 AM.

[bigmotherwhale]

get minispares stainless caliper pistons they wont corrrode

[Saxo-Fiesta-Mini]

Even calver in this months mini mag agrees with using an air compressor to remove the pistons.
i agree to use something to catch the caliper and to use care and be very careful.

[Cooperman]

I must admit to using comp air to get the pistons out easily. However, I do use a block of wood which is the right width to stop the pistons from flying out under 6+ bar pressure. If one side is then stuck, I use a big G-clamp to clamp the freer piston before blowing the sticky one out further. It just takes a bit of care.
I do recommend the stainless steel ones and I always split the calipers before easing the new pistons and seals in.
The biggest problem can be getting the outer dust seals back in, which needs to be done before joining the two halves back together with a new rubber O-ring. I tap the dust seals in using a large socket of just the right diameter and adding a bit of rubber-grease to help.
It is usually wise to fit new bleed screws too.
Make sure you have a big can of brake-cleaner to thoroughly clean everything before re-assembly. Blow everything with an air-line as well.
Good luck with the job

[gonzoavfc]

thanks mate, thats a big help will let you know how it goes

[guywithvan]

i used the grease gun method last week as i dont have access to a air line,worked a treat and would recommend it to other people,grease gun was from halfords just remove the tip and screw straight on.

[bmcecosse]

If the pistons are 'stuck' there is no way an air line will move them ! The fact that 'calver' recommends it - should tell you enough anyway! Grease gun is the way - it never fails - and no dangerous high pressure air flying around. Note the official advice is to NOT split the calipers - the bolts are supposedly 'one use' only, and the little seals are not always easy to get new.

[Nightrain]

A have always split the calipers, then you can grip the seized in a vice and work it loose. Only calipers I haven't been able to get the seals for are the early vented metro calipers with the spacer.

[GraemeC]

I always split the calipers too, makes dis-assembly and assembly so much easier.

The square section o rings (for the normal Mini calipers) are readily available from MiniSpares, as are the bolts to hold the calipers together.
The main reason the bolts are one use only is due to the arrangement they use to prevent them coming loose - a small nylon section within the thread. However if they are cleaned, thread locked and torqued I see no issue.

Edited by GraemeC, 06 July 2009 - 08:21 AM.