1991 1.9 GTi hand brake/foot brake balance issues

[brianthemagical 1]

So I've been having issues with rear brake balance for a number of years (and MOT's) and I can't fathom what it may be.

 

The RH rear brake, both foot and hand, are significantly lower power than the LH.

 

I think I've fixed the foot brake with new compensators. The LH was broken, meaning that it had no upper limit and made the RH look low when the compensator hit its limit. This is TBC when I can next get it to a garage.

 

I've changed the calipers (both sides), pads, discs, cables. Bled all 4 calipers. But the handbrake on the RH is sill too low.

 

I've adjusted the handbrake as much as I dare, the balance bar pulls more cable on the RH.

Looking at the caliper with the hand brake on, the caliper arm has pulled significantly further on the RH than the LH (agreeing with balance bar).

 

I'm at a loss as to what to try next. Or what is actually happening. I'm at the point of buying another pair of calipers, brake lines and a master cylinder and hoping the fairies fix it.

 

Any suggestions, from basic first principles to convoluted and crazy very much appreciated.

Thanks

Edited March 15, 2020 by brianthemagical
Addition of pictures

[jackherer 543]

Have you got the correct handbrake cables on each side? There are different part numbers for the left and right sides.

[welshpug 1,621]

start by slackening the cable right off, pump the brake pedal a dozen times or so to allow the piston to self adjust then try again, you shouldn't have much tension on the cables at all.

 

too much tension in the cables stops the mechanism from adjusting which will give a longer travel and allow the handbrake mechanism to bottom out.

[wicked 103 3 Cars]

What WP says; slacken the cables completely and do some firm stops to let the calipers adjust. 

 

Next to that; you LH caliper doesn't look like a 205 caliper to me. The handbrake lever and dust cap look like 306/xsara to me. 

Maybe there is a small diff that could explain the unbalance in adjustment if it still present after auto-adjusting the calipers.

[welshpug 1,621]

caliper on the left is a newer Bosch design, there are still 30mm piston versions of these, though I agree its still worth peeling the dust cover back and confirming.

[wicked 103 3 Cars]

yes, most are 30mm, but judging from the current angle on the RH handbrake lever, I think it will be fine after auto adjusting with slackened cables. 

[brianthemagical 1]

On 3/15/2020 at 3:19 PM, jackherer said:

Have you got the correct handbrake cables on each side? There are different part numbers for the left and right sides.

Yes. I've even tried crossing them over to see if that helps. Cables are relatively new. And I have another set waiting just in case.

 

13 hours ago, welshpug said:

start by slackening the cable right off, pump the brake pedal a dozen times or so to allow the piston to self adjust then try again, you shouldn't have much tension on the cables at all.

 

too much tension in the cables stops the mechanism from adjusting which will give a longer travel and allow the handbrake mechanism to bottom out.

The cables are/have been slack. Although it's possible to push the caliper arm further back (i.e. less braking) by hand. So although the cable is slack, the arm isn't as slack as it could go. If that makes sense. Could this indicate air in the caliper? Or that it's not self adjusting correctly?

I might try and push the arm as far back as it'll go, and then have a helper pump the pedal.

 

Just to clarify, in the pictures the hand brake is on (very hard!) highlighting the difference in travel between each side.

 

I had the dust cover off the mechanism and they look similar. I'll have a better look and compare to the pair that have been removed.

 

I'll give the auto adjustment a go over the weekend, and hopefully confirm with the MOT station that the foot brake is functioning correctly.

 

Thanks for all the help, much appreciated.

[brianthemagical 1]

So, an update.

 

Yesterday I did as advised. Disconnected the HB cable for the RHS (low effort side) and pulled the caliper arm back to zero travel.

Pumped the brakes and tried again.

Fixed!!!!

Worked as expected, couldn't turn the wheel with the HB on.

 

Went for a drive, when I was back home I thought I'd try and creep forward with the HB on to see what it felt like and for future reference. Wasn't promising.

 

Had the wheels off the ground this morning, tried again with a breaker bar on the wheel nuts.

LHS still as expected. RHS I can move by hand. So back to square one.

 

So the question is, why dose adjusting the calipers work, and then stop working?

What is changing when I drive the car?

 

I'll try auto adjusting again, then not touch the car and see if it de-adjusts without interference.

 

Thanks again for the help so far.

 

Edit;

Tried again to 'fix' it as recommended above; disconnect HB cable, pump foot brake, all's good. Only this time, it's not all good. The HB is still low effort, I can turn the wheel by hand.

Edited March 21, 2020 by brianthemagical
More info!

[brianthemagical 1]

I've had another look over this morning to see if I can make any more progress.

 

Had a little play and managed to 'fix' them again using the advice above (disconnect handbrake cable, pump brakes. Using mole grips to move the lever arm on the caliper).

From what I can tell, this fixes them for one application of the hand brake, then the second application there's long travel on the lever and no braking force.

 

Is this telling me there's something wrong with the adjustment/compensation mechanism?

 

The problem caliper is a little looser on the sliders, so I swapped them left to right and the problem caliper is still a little loose.

Maybe the caliper is binding on the slider?

 

I'm not sure what my next steps are.

 

Maybe another new caliper to see if the sliders are tighter and there's less looseness.

 

Take the caliper apart and see if I can work out how the adjuster/compensation works.

[wicked 103 3 Cars]

Since your LH caliper is already replaced (new model) I would replace the RH caliper as well for the same type. Can be found on a lot peugeot/citroen models. 

 

Edited March 28, 2020 by wicked

[brianthemagical 1]

On 3/28/2020 at 1:15 PM, wicked said:

Since your LH caliper is already replaced (new model) I would replace the RH caliper as well for the same type. Can be found on a lot peugeot/citroen models. 

 

I think the calipers are the same. The only difference is the lever arm, which I assume is due to what was available when they were reconn'ed. The RH caliper is also a new recon part. 

 

Well, I think I've fixed it. Took the handbrake mechanism off the caliper, had a play with turning the worm screw parts. Put it all back together and it's fixed!

 

I still can't really work out what it is that would have fixed it, but i'm not complaining.

 

Thanks again for the help.