binding brakes Mk1 VRS . Braking issues

[Tonypan]

Rear Brakes..

Hi all

So rear passenger side inner Brake pad became jammed and to the stage it was metal to metal . 

Replaced discs and pads both rears . 

Replaced caliper on left rear , Replaced handbrake cable .

Still have this issue of after a short period of driving the brakes start to binding and start to bring the car to a stop when free wheeling. 

Jacked up rear in this binding state and found both rear wheels where difficult to turn. 

Open the rear bleed nipple on master cylinder and right right rear became free to rotate. The rear left not as free as right .

Any experience of this fault condition anyone on this forum would be appreciated.  Thank you 

[krisp1]

The fact that opening bleed nipple freed off the binding, I suggest changing the flexible brake hoses to both calipers. The inside of the hose can degrade and create a one way valve causing the binding.

Also ensure both brakes are free to slide on its pins and the edges of the pads are lubricated to prevent jamming and the brake sticking on.

 

[J.R.]

8 hours ago, krisp1 said:

The fact that opening bleed nipple freed off the binding, I suggest changing the flexible brake hoses to both calipers. The inside of the hose can degrade and create a one way valve causing the binding

 

He released the bleed nipple on the master cylinder which released both seized rear brakes so the chances of it being what you say, both hoses with simultaneous internal blockages is as close to zero as you could get.

 

Check the handbrake cable compensator, it should be at 90° to the tension rod and the rear cables should be evenly adjusted and level with each other (bad description) if it isnt then the problem is with the handbrake/self adjuster mechanism on the cable that is further forward.

 

I think you may have 2 faults, perhaps one being a new caliper thats not 100%.

 

It will be a master cylinder fault, the pushrod being too long can cause this but only if someone has been messing around with it.

 

It also sounds like the NSR  caliper handbrake lever or the self adjuster is partially seized.

[Silver Bullet]

I had a similar problem,  bought 2 new rear calipers + b/pads, offside bled ok working fine, when I came to do the n/s (using pressure bleeding from the master cylinder)

nothing, no fluid came out. Garage thought the ABS block had packed up or had a bad airlock. I bled the ABS using VAG-COM process still nothing.

My final attempt was to replace all of the nearside brake line with Cunifer +  flexable hoses from the ABS to the wheel cyinder. Bled it SUCCESS !!!.

I think this hose is the culprit, and as was said earlier had collapsed and was acting as a one way valve. When I took it off bits of the inner wall came out :-

 

The offside one does not seem to have such a severe  bend, but I do plan to replace it as well. Also I would suggest fitting return springs to the hand brake mechanism (see below)

[Tonypan]

Thanks Silver Bullet, 

Have ordered rear hoses both sides . A point of note . I jacked the car up on all wheels .

Tested master cylinder by pumping brakes with engine off . Kept foot on brake and started engine the pedal dropped an inch or so. Thus providing master cylinder OK . I read somewhere that was a litmus test to see master cylinder OK.

However because I was only checking rears . I thought let me just check fronts as car was in air . Found nearside front locking up ager just one or two presses on pedal. Repeated,  baked from MC and wheel was free to turn . One press on pedal the wheel locked up.

So I have rebuilt front caliper , yet to fit .

In summary going to replace both rear hoses and refit nearside caliper and report back. 

Thank you so much 

[Tonypan]

Sorry for typos. 

Baked = bleed 

Ager = after 

 

[Tonypan]

On 10/03/2024 at 19:43, Silver Bullet said:

I had a similar problem,  bought 2 new rear calipers + b/pads, offside bled ok working fine, when I came to do the n/s (using pressure bleeding from the master cylinder)

nothing, no fluid came out. Garage thought the ABS block had packed up or had a bad airlock. I bled the ABS using VAG-COM process still nothing.

My final attempt was to replace all of the nearside brake line with Cunifer +  flexable hoses from the ABS to the wheel cyinder. Bled it SUCCESS !!!.

I think this hose is the culprit, and as was said earlier had collapsed and was acting as a one way valve. When I took it off bits of the inner wall came out :-

 

The offside one does not seem to have such a severe  bend, but I do plan to replace it as well. Also I would suggest fitting return springs to the hand brake mechanism (see below)

 

[Tonypan]

Hi Steve,

The car is still in the air .

I refurbished the master cylinder. 

Replaced the ABS . Couldn't get any fluid from one inlets pipes in ABS unit. 

Removed Master cylinder to double check my rebuild work. 

I found that the reservoir was still not seating fully home . On the bench I found that when correctly fitted the brake fluid reservoir is fully  seated with little to no wobble. Plan of action 

Refitted master cylinder . Apply sufficient force to fully seat reservoir. 

Then see if  getting fluid out of both inlets in ABS unit .