NEW CALIPER NOT WORKING

L

lunarboy

New Member
I have just finished overhauling the brakes (1970 3500 auto) and put 2 recon calipers and associated pipework etc on the rear. bled the system then took it for MOT. Brakes didn't feel fab and at MOT station they advised that handbrake has too much travel and that the off side rear caliper doesn't work at all !! the garage re bled the system getting fluid out of nipple and firm pedal but no movement from the new caliper (the near side is working fine as are the fronts). When i got the calipers, i took the calipers out of their packets and piped them up using the old calipers as a template- what am i missing :cry: :cry: Do recon calipers fail and how does the handbrake adjust - I thought it would auto adjust? :?
 
If you stick a big screw driver in how much does the pad / piston retract ? - more than a say 1/4 inch is probably full piston travel which could be why both the foot brake and hand brake don't work

One side of my car is hopeless for self adjusting, if I push the piston back in and then pull the hand brake on it will some times self adjust. Some time not, when I end up unscrewing the piston one turn by hand ( take the pads out 1st )
 
I've got the same problem with my new project. I found the pads at the back were not touching the discs & the handbrake is no use at all!

I've been advised that it is a sticking piston, so have dismantled the calipers & am putting new kits in. This is presumably where you are now, so I'm sorry I can't help. i will just have to see when I get them rebuilt. :(
 
thanks - I bought fresh reconditioned units as i thought i would remove any doubts - time is a little scarce just now so it was the expensive but easy way out - or so I thought :wink:
 
If you had operated the levers on the calipers manually before you fitted them you would have seen that they weren't working and saved yourself the bother of fitting them. Operating the handbrake lever by hand would have shown whether the piston was gradually moving out or not, but it is possible that you haven't adjusted them up correctly when you fitted them and they are in fact working OK. They are a self adjusting caliper, but they need to be set up properly in the first place so that they continue working.

Having said that I've had recon calipers people have bought that were u/s, but by checking first I always found out before fitting.
 
If the brake caliper has just been rebuilt and the piston adjusting mechanism is fully retracted, when you then press the foot brake the piston will move out of the caliper to its limit. When you then press the brake peddle a 2nd time the piston won't move any further but the pads aren't touching the disc. Which is why the brakes don't work - the piston movement is fairly small so the correct adjustment is important.

So push the piston back in and operate the handbrake to see if they then self adjust - it is pulling on the hand brake that moves a lever against a serrated wheel on the piston ( under the dome cover ) that screws the piston out and therefore reduces the amount of hydraulic or handbrake movement.

I suspect the serrated teeth on the self adjuster don't always bite against the lever.
 
got a guy with 40 years experience to check it out and it is u/s - now back off car and piston seized solid !! Now back in post :( never had anything professionally recon before that failed - we live and learn. in terms of setting up the handbrake - what needs set up if the caliper is built properly why would it not self adjust? I don't see anything in the manual :?

Cheers
 
There is a few things that can stop the self adjustment.

I have seen the retaining pin clogged up with dirt and paint. The inner pad should slide along if it sticks the caliper thinks that it is fully adjusted and wont move any further out.

Was it definitely the piston that was seized. The bit that pushes against the pad for some reason is called a "cup" this can get cross threaded. There is a small piston that is operated from the brake cable lever this can fall out and wont then operate the mechanism.

Was the brake working hydraulically at all? Did you strip it down?

They take a bit of thought to get your head round. You can give me a call or email if you need a hand.

Colin
 
If the caliper isn't set up correctly initially, (or it fails to self adjust) then eventually you'll lose both the hand and the footbrake because there is so little travel on both of them that the pad never gets in contact with the disc before the handbrake tappet runs out of travel, or the hydraulic piston hits it's stop.
 
Thanks guys, these were "brand new" reconditioned calipers that were not cheap! I fully expected them to be able to be bolted in place and when rebuilt with all new fittings, pads etc to function properly. The reconditioning company (not the supplier) has accepted that the caliper piston is seized and the caliper had been returned - 1 in 6 fail i am advised. The joke here is that I could have re built the originals on the bench but didn't have the time :) Thanks arthuy also - i should have paid your petrol to come through and teach me about the world of replacement parts for Rovers before putting it all back together :wink: I can't face the suspension just now :) Anyway, its all about learning 8) look forward to getting her back on the road soon.
 
lunarboy said:
The reconditioning company (not the supplier) has accepted that the caliper piston is seized and the caliper had been returned - 1 in 6 fail i am advised.
Click to expand...

I don't know what to say to that, other than it's about time someone who knows how to do them took on the job.
1 in 6 fail! That's some track record! :roll:
 
Phil Robson said:
I've got the same problem with my new project. I found the pads at the back were not touching the discs & the handbrake is no use at all!

I've been advised that it is a sticking piston, so have dismantled the calipers & am putting new kits in. This is presumably where you are now, so I'm sorry I can't help. i will just have to see when I get them rebuilt. :(
Click to expand...
Having now rebuilt both rear calipers & servo I now have some brake force at the rear & a working handbrake, however certainly not up to P6 standards. The new project failed its MOT yesterday on the lack of rear pressure (20 somethings each rather than 120 ish I was told, likewise for the handbrake - so a long way short!).

The only odd thing I've noticed is a sort of mechanical squeezing noise coming from the servo when I apply the foot brake (similar to a power - steering noise). Could it just be that the rears are not bled properly?

I've run out of ideas having 'clicked' the pads out as far as they'll go. The fronts are fine. I have no fluid loss at all. Any ideas? :?
 
The servo does make a noise as it works so that may be the noise you're hearing, and as it's a single line system if the loss of efficiency at the rear was caused by the servo, then I'd think you would get reduced readings on the front as well.

My first thought would be that you haven't got the rears set up quite as well as you think you have. Bleeding will have no effect on improving the handbrake readings, even if there was no fluid in the system at all the handbrake should still work at its maximum efficiency, after all what good would it be if the handbrake didn't work if you lost all the brake fluid.......
 
harveyp6 said:
Bleeding will have no effect on improving the handbrake readings, even if there was no fluid in the system at all the handbrake should still work at its maximum efficiency, after all what good would it be if the handbrake didn't work if you lost all the brake fluid.......
Click to expand...
:oops: ..yes, of course!

I'll have take the pads out again & have a look at the movement of the cups.. :(
 
You need to set the calipers up with the disc out, or at the very least the outer pads out, otherwise you never get the pads close enough to the disc at rest, and there's far too much lost movement before the pads make contact with the disc. The handbrake quadrants also need to be right back on their stops, and all the setting up is best done with all the handbrake linkage disconnected and moved out of the way. I always try to resist the use of the word "adjusting"* as there isn't any adjusting up to do once it's all correctly set up initially, the adjustment should be done by the calipers themselves.

* I bet I've done it loads of times though, it's just so easy to say "adjust them up"............ :LOL:
 
I've now had the handbrake linkage off & pads out again. The handbrake quadrants are on their stops & the 'clicking' of the ratchet sounds fine.
However, I have noticed one thing: the pads are not making contact with the discs across their full surface - around 1/2 is the best. The pads were those on the car when I got it recently, but being 'chunky' I didn't replace them, despite refurbishing everything else! :oops:
The shiny part of the discs (especially the inner faces) is not very well marked by the pads, so I hope this is the problem. I'm going to put a new set in tomorrow & see how it goes (stops! :D )

Has anyone else had this experience?
 
harveyp6 said:
lunarboy said:
The reconditioning company (not the supplier) has accepted that the caliper piston is seized and the caliper had been returned - 1 in 6 fail i am advised.
Click to expand...

I don't know what to say to that, other than it's about time someone who knows how to do them took on the job.
1 in 6 fail! That's some track record! :roll:
Click to expand...

You may well be right there - We've bought several from Wins in the last year - one we bought for our upcoming 3500 auto was broken inside, we had to get an instant replacement. All sorted now. So we have probable had about nine good ones to one failure.

Generally I do find Wins to be the best supplier, regardless of this. And prices have been fairly consistent for a while now.
 
Phil Robson said:
However, I have noticed one thing: the pads are not making contact with the discs across their full surface - around 1/2 is the best. The pads were those on the car when I got it recently, but being 'chunky' I didn't replace them, despite refurbishing everything else! :oops:
The shiny part of the discs (especially the inner faces) is not very well marked by the pads, so I hope this is the problem. I'm going to put a new set in tomorrow & see how it goes (stops! :D )

Has anyone else had this experience?
Click to expand...

I assume that the slippers that hold the inner pads are fitted the correct way around? The register that locates on to the mills pin that is on the caliper is offset, and fitting them the wrong way moves the pad too far up the disc. Also that the caliper pivots are free. I always clean the discs with emery whenever they come off, whether for new pads to be fitted or any other reason, and then reset the calipers.
 
You must log in or register to reply here.
Back
Top