Hi All, 

 

First of all Happy New Year to all members. 
 

And now to the problem. On MOT has been pointed  to me the following: 

Offside Rear Service brake binding but not excessively. 
 

With thoughts that I will give it proper cleaning I figured out that the rear O/S break caliper piston won’t return after pressing break pedal or hand break apply and stays pressing the break pads which causes stiffer wheel rotation. 

 

I manage quite easily to rewind the break piston fully back but after assembly pads and caliper back together and couple break pedal pressing the wheel won’t rotate easily and behave like siezed piston. 
 

Any ideas what to lube or clean before I will rebuild or replace break caliper? 
 

Could it be caused by trapped air? 
 

Thanks for thoughts. 

 

 

How loose/tight were the pads when refitted? Did you clean off all the rust that might be on the carrier bracket surfaces that the pads sit between?

 

Compare the angles of the brake actuating levers on each side in both the on and off positions and you will see the problem.

I have cleaned all pads surfaces on carrier and lube pads before fitting back. The actuating levers are in same position on both side. 
 

I tried to inject a little break lube I have had from previous calliper refurb under piston seal which seems to helped when pushing piston back with tool but once I press the pedal it apply breaking force on the pads but won’t release fully back. 
 

But I’m still able to rotate with break disc with hand but much harder than use to..

 

I found on web that helped to someone inject a little bit of fresh break fluid under piston seal but I’m not sure with that regarding breaking fluid impact on rubber seal?

Most probably the handbrake mechanism sticking on that side. With the h/b lever down/off, try pushing up on the actuator arm on the caliper. If it moves, it's sticking. Establish whether it is the caliper or cable by disconnecting the cable and operating the arm manually to see if it still has a sticky point when released.

So I ended up with a new break caliper purchase and it's even worse than with the original one. 😃

 

The angle on break leveler is same on both side, so I exclude its hand break mechanism.

 

What does not make sense to me is the fact it that if I I tighten a new break caliper to the break carrier as it should, I'm not able to rotate disc manually, it's completely stuck. But if I undo a screw holding break caliper to the carrier just a little bit, it's free the disc and I can manually rotate it more easily. 

 

Any idea please? 

 

I have cleaned break carrier for a dust and rust, fitted a new break pad spacing plates and lube those guide bold...

Just out of curiosity have you checked the flexy pips for stifness or corrosion 1 might be corroding more than the other on the inside which could be slowing the return of brake fluid to stop releasing the brake.

just a theory.

How do I do that? Just by squeezing pipes and comparing to each other the pressure needed to for compression? 

For those who changed calliper in past, am I missing any step if I just fitted a new calliper and than with opened bleeding valve pump the pedal until fluid was coming out of bleeding valve? 

Basically i new ones am sure are soft and suttle old ones go hard and stiff  #pardon the punch .

as for your last post you did clamp the flexy pipe before removal of old unit 

17 hours ago, Nosnx said:

So I ended up with a new break caliper purchase and it's even worse than with the original one. 😃

 

The angle on break leveler is same on both side, so I exclude its hand break mechanism.

 

What does not make sense to me is the fact it that if I I tighten a new break caliper to the break carrier as it should, I'm not able to rotate disc manually, it's completely stuck. But if I undo a screw holding break caliper to the carrier just a little bit, it's free the disc and I can manually rotate it more easily. 

 

Any idea please? 

 

I have cleaned break carrier for a dust and rust, fitted a new break pad spacing plates and lube those guide bold...

 

If you have just tried to free the caliper piston by retracting it once and then refitting it, there will probably be a line of crud inside the caliper

 

When you refitted and tried the brakes again (using the same pads), the piston seals will just hit this line of crud again, and you are back to square one.

 

If this is the only way you can clean the caliper / piston then this is how I did mine, and been fine for ages. (although fronts). should work with rears, just a little more fiddly.

 

Remove caliper but leave fluid line connected, Take note of piston position inside caliper ie how far in / out it is. Call it its resting position

wind piston fully back then push piston out using foot pedal it needs to be pushed out gently but past its resting position

Ideally it wants to go as far as possible but without popping it out, and ideally in and out a couple of times.

I undid reservoir cap whilst winding back but must remember to close it whilst pressing brake pedal

 

However if your 'new' caliper was actually sourced from a good source then using this new one makes the above info irrelevant and I would suspect either your handbrake needs adjusting, but in my opinion, more likely you need to check your fluid and bleed your brakes properly.

 

Good luck

 

7 hours ago, Tilt said:

 

If you have just tried to free the caliper piston by retracting it once and then refitting it, there will probably be a line of crud inside the caliper

 

When you refitted and tried the brakes again (using the same pads), the piston seals will just hit this line of crud again, and you are back to square one.

 

If this is the only way you can clean the caliper / piston then this is how I did mine, and been fine for ages. (although fronts). should work with rears, just a little more fiddly.

 

Remove caliper but leave fluid line connected, Take note of piston position inside caliper ie how far in / out it is. Call it its resting position

wind piston fully back then push piston out using foot pedal it needs to be pushed out gently but past its resting position

Ideally it wants to go as far as possible but without popping it out, and ideally in and out a couple of times.

I undid reservoir cap whilst winding back but must remember to close it whilst pressing brake pedal

 

However if your 'new' caliper was actually sourced from a good source then using this new one makes the above info irrelevant and I would suspect either your handbrake needs adjusting, but in my opinion, more likely you need to check your fluid and bleed your brakes properly.

 

Good luck

 

Thanks for input.

 

I have first refurbished the original calliper but i did not help at all. Assumed calliper is damaged behind point of repair I ordered a new, original from TRW, painted red and fitted. The result you know. Wheel is sticking even more than with old calliper.  
 

I was doing one man break bleeding way with one way valve on the pipe to avoid air getting into system but when I was pressing pedal, I left reservoir opened, still keeping eye on break fluid level. 
 

Could it have impact on it? 

Not at all unless the fluid went way low 

On 17/03/2020 at 19:37, Nosnx said:

What does not make sense to me is the fact it that if I I tighten a new break caliper to the break carrier as it should, I'm not able to rotate disc manually, it's completely stuck. But if I undo a screw holding break caliper to the carrier just a little bit, it's free the disc and I can manually rotate it more easily. 

 

 

Was this before or after you tried to bleed the brakes (ie before you pressed the brake pedal or tried the handbrake).

 

Did the disc spin freely the first time you fitted said new caliper? so before connecting brake line???

 

Is this car off the road??? for a few months???

After break bleeding. I may make mistake after calliper fitting in the process of getting fluid into break caliper?

 

Once I fitted calliper, I opened the valve and start pressing break pedal until the break fluid didn’t start coming out from bleeding valve. Than I closed bleeding valve, fill up the reservoir, open the bleeding valve again and start pumping break pedal. Once fill up approx 100ml, I closed the valve and check reservoir...Fill  up the break fluid and repeated the process above...

 

Also I have noticed, once I fitted calliper to the break carrier, before bleeding I was trying slide it and it did not move smoothly on those slides like previous one, so it might get sticking on those break pads plates as they are a new too. 

I will have a loook over the weekend as I’m busy with work now.

 

Yes, the car was much less driven and parked in garage from November as I have a company car now...
 

 

So, I did a further investigation of my break caliper problem and I found that in compare with left side, the break caliper is much tougher to move*green arrow* on those carrier sliders *yellow arrow* once tightened.  I have cleared and lubricate those sliders, but it didn't help so I guess, need replacement. Question is if the break caliper should be replaced too? 

 

Edited 22 March, 20206 yr by Nosnx

Have you tried the slider pins individually in the carrier/flushed the holes with WD-40 or similar and cleaned with a cotton bud?

 

Could be burned/dried old grease deposits inside or bent pins from a previous spanner monkey.

@MicMac Yes, bent pins is the only thing that makes sense to me at this point, though how someone would bend them accidentally, No idea.

 

Cleaning and lubricating the sliders and rubbers should be a given really when replacing a caliper.

 

@Nosnx As an aside, what grease did you use. And I thought you already had a new caliper? Which caliper is in your photo?

 

A reasonably simple job seems to have become quite complicated. 

I would say either start again, rewind piston fully and after re-installation, inc pads, see if the disc will turn BEFORE pressing brake pedal.

or...............I will leave this for later. Hope you can sort it

The grease I’m using is from Textar. 
 

The break caliper on the picture is the refurbished/old one. Swapped it back to check if the new one isn’t faulty but old is sticking in same way as a the new one now after I assembled everything together. 
 

49 minutes ago, Tilt said:

rewind piston fully and after re-installation, inc pads, see if the disc will turn BEFORE pressing brake pedal.

I did that many times. The disc is moving freely with fitted caliper and rewinded piston fully in. What is sticking is caliper on those sliders if tightened and once the piston is pumped into position to break it’s stuck completely. Must by bend pins, it’s only logical explanation to me...what isn’t is how I bend them 😃

 

Hopefully the set of a new ones will sort it, otherwise I’m looking on faulty break line or break cylinder 🤔? 

Edited 22 March, 20206 yr by Nosnx

Here's another angle, have you tried cleaning pins/holes thoroughly, checked they move freely and reassemble without any grease?

 

Perhaps the grease is causing things to hydraulically lock, if so only apply a thin smear and work the pin by hand to distribute the grease.  Make sure the rubber bellows are clean also and do not lube where it seals to allow expansion.

 

Do this before connecting the handbrake cable to eliminate that cause.

Edited 22 March, 20206 yr by MicMac

Its the piston sticking from what you describe, I had one where the handbrake lever would not return fully and the handbrake compensator was askew, balancing the cables meant the caliper dragged, a piston seal had been fitted the wrong way round, they look symmetrical but they are not, fitted the correct way around means that the piston can retract slightly, the wrong way will cause brake drag.

Sounds like you've found your fault, but if not I suspect it may be an internally collapsed brake pipe, allowing the fluid through to get the brake on, but when you come of the break the reverse movement of fluid collapses the pipe internally......problem is, there are usually no signs of problems on the outside of the pipe. So if new pins doesnt work, id suggest a new flexi pipe/pipes.

@J.R. He has tried a new caliper bud........

 

"Stuck completely" suggests to me, either bent pins or brake fluid locked off somehow............collapsed pipe or other fault in the system.

 

@Nosnx How did you clamp the flexi pipe when you dismantled the caliper (a few times)???

                 Was the reservoir always good with fluid when you bled it?

                 What age is the car?

 

 

 @Tilt 2008, always kept serviced regularly, break fluid included.

 

I clamped flex pipes with those plastic clamps from halford, did not like the idea of clamping hoses but wanted to minimise get air in system as much as I could so I made 💯 sure the right level of break fluid...

 

The pins and proper bleeding is next step....

Edited 23 March, 20206 yr by Nosnx