Brake piston stuck

Hi,

Tried to change my pads today on my 90 but ran into a few problems.

The pads were very hard in place, i did eventually get them out but I couldn't move the pistons back at all to put the new pads in place. With the pads removed a pressed the brake pedal a few times to move the pistons out a bit so I could give them a clean hoping they would go back into place.

1 of the pistons came out all of the way while the other 3 only came out very little, now the one that came out all the way wont go back in at all. No matter how hard I push it , nothing happens.

Any help would be great

Thanks

you need a proper tool to push it back in now unless you completely remove it and use a bench mounted vice.

id buy a pair of calipers

I'd buy new calipers too.

As above, a new patten caliper is about 40-50 ish. I messed about with one of mine for ages, and even did for the disk in the process, then just got a new caliper and it remains good till this day.

if the piston is ok you will need to take the dust cover off and seal as they tend to swell, check behind the seal for " furring " and clean, replace with new seal and dust cover put a little bit of brake fluid on the piston and push it back in by hand should go in but if not then a "g" clamp in the centre of the piston and back of the caliper will help but keep it square and it should go in quite easy !!

LukeMcneil said:

Hi,

Tried to change my pads today on my 90 but ran into a few problems.

The pads were very hard in place, i did eventually get them out but I couldn't move the pistons back at all to put the new pads in place. With the pads removed a pressed the brake pedal a few times to move the pistons out a bit so I could give them a clean hoping they would go back into place.

1 of the pistons came out all of the way while the other 3 only came out very little, now the one that came out all the way wont go back in at all. No matter how hard I push it , nothing happens.

Any help would be great

Thanks

Click to expand...

I'm assuming you have clamped the flexi pipe & loosened the bleed nipple before trying to put it back it otherwise no g clamp or brake tool will push it back in

jamesmartin said:

id buy a pair of calipers

Click to expand...

jamesmartin said:

id buy a pair of calipers

Click to expand...

Thanks for the helps guys Going to get a new caliper now, hopefully all goes back together okay

New pair! If one is gone the other is often close behind

Dunno - my calipers piston wasnt retracting. I just did the one. That was some years ago now, and ive had no issue with the other (original) one.

bankz5152 said:

New pair! If one is gone the other is often close behind

Click to expand...

Always good advice if funds allow.

LukeMcneil said:

Thanks for the helps guys Going to get a new caliper now, hopefully all goes back together okay

Click to expand...

you should have 2 new calipers,to ensure braking is even on the axle,i wouldnt fit just one

New bolts too.
And use the correct socket to remove the old ones or they can round off leaving you in a world of ball ache.
It's been a while since I removed calipers but it's a multipoint bolt head iirc and they are usually tight.
I ''think' I used a 1/2" or 9/16" multipoint socket which was a very close , maybe too close a fit(I had to tap it on to the bolt head) but it never failed to undo them.
Again (iirc) metric multipoint sockets slipped under pressure but the splines on the head were very rusty.
If everything really goes Pete tong you'll need new brake pipes/hoses too..
If you can have the vehicle off the road for a while you could rebuild your old ones with new seals and stainless steel pistons. I've done that to all 4 of my calipers as have others, it's not hard if you split the calipers, I sandblast them first but it's not necessary.

^^ what @Flossie said in his last paragraph.
I would not comsider buying new calipers as you will only
Have the same problem again. Get a set of stainless pistons, a set of genuine (must be genuine) pistons seals and retaining rings, and a set of gallery seals.
Split the caliper, remove the old gallery seal, use compressed air to “remove”, or fire into the ceiling, the old pistons, remove the old retaining rings and seals, rub down and paint, and in true Haynes fashon refitting is the reverse of removal!
If you do go for a rebuild with stainless make sure the retaining rings and seals are genuine as I have found the pattern ones do not fit as well and the retaining rings are very easy to damage so buy more than one set. To fit the retaining rings the radius arm washer is the perfect size to use as a drift and do not be gentle. One sharp central tap with a hammer to seat it is far more effective and less likely to damage it than gentle taps around the outside.

dag019 said:

^^ what @Flossie said in his last paragraph.
I would not comsider buying new calipers as you will only
Have the same problem again. Get a set of stainless pistons, a set of genuine (must be genuine) pistons seals and retaining rings, and a set of gallery seals.
Split the caliper, remove the old gallery seal, use compressed air to “remove”, or fire into the ceiling, the old pistons, remove the old retaining rings and seals, rub down and paint, and in true Haynes fashon refitting is the reverse of removal!
If you do go for a rebuild with stainless make sure the retaining rings and seals are genuine as I have found the pattern ones do not fit as well and the retaining rings are very easy to damage so buy more than one set. To fit the retaining rings the radius arm washer is the perfect size to use as a drift and do not be gentle. One sharp central tap with a hammer to seat it is far more effective and less likely to damage it than gentle taps around the outside.

Click to expand...

I've never had a problem with britpart seals and rings tbh.
My method is to clean the recess that the ring and wiper seal sits in thoughly, scrape it shiney clean!
I then fit the piston seal then the piston then slide the lubed wiper seal and ring assembled together down the piston and locate into the recess as far as possible with your fingers. I have a piece of tube which is slightly narrower than the recess and slightly wider than the piston, a sharp tap on the end of the pipe seats the ring perfectly.
I would also , if I did the job again, pop the pistons nearly out whilst still on the vehicle, once off and on the bench it makes life easier if you have a stubborn piston. I've had 4 out of the 10 pistons that air wouldn't shift no matter how much I tried and I ended up MIG welding a bar to the piston so I could use a vice on it to draw it out.
If time was an issue, an option could be new calipers but replace the pistons with stainless ones, that should be easy to do with no need to split them.

jamesmartin said:

you should have 2 new calipers,to ensure braking is even on the axle,i wouldnt fit just one

Click to expand...

Thanks for the reply guys. Ordered 2 new calipers so should be fully functional soon.

A few quick questions, what siZe flare spanner do I need for the brake pipe attached to the caliper? I thought ti was a 10mm but it doesn't seem big enough.

And interms of when fitted, I plan on clamping the brake lines on either side when replacing, should I bleed all of the breaks or only the front ones

Thanks in adavance

11mm,if you clamp the flexi you should only need bleed that caliper

Keep your eye on the brake pipe whilst turning the nut, they can bind together and your pipe ends up twisting= scrap.

if y ou want to keep same calaperswith out fitting stanless steel pistons et the best way is to block 3 pistons get wife to push brake while you watch piston don't let it come out to far lub with brake fluid keep working it back words and forwords until it frees up