Unbalanced rear brakes

Hi!

Im having problems with my mk1 cabriolet DX, rear brakes does not pass the annual technical inspection due to an incorrect balance between rear wheels braking (R/L). the handbrake works correctly and both wheels brake equally so it is a hydraulic problem or in the braking distribution.The first time the brakes are bled, they seem to brake correctly, but after a while they decompensate again and the fluid takes in air. It has been bled many times and the problem continues. Does anyone know what may be happening? Could it be the rear brake regulator?

Thanks a lot!

Bad rear wheel cylinder if they are leaking and you have to bleed them or that your MC/ is toast.

But there is no leak of brake fluid anywhere. If it were the MC, would only the rear wheel of the passenger fail?

Thanks a lot!

You could have a proportional valve that is wonky.

Older cabriolets with the weight controlled proportional valve on the rear axle beam has been known to have issues.

If you have to re-bleed, then you have a leak somewhere.

If you have ruled out the MC, and the rear Wheel Cylinders, then you are left with brake lines, or the rear "compensator/proportional" valves.

Briano1234 said

You could have a proportional valve that is wonky.

Older cabriolets with the weight controlled proportional valve on the rear axle beam has been known to have issues.

If you have to re-bleed, then you have a leak somewhere.

If you have ruled out the MC, and the rear Wheel Cylinders, then you are left with brake lines, or the rear "compensator/proportional" valves.

Really not too difficult to sort surely  in my opinion

Sent from my SM-G960F using Tapatalk

Have you had the drums off to have a look see?

Just had to fix mine after it failed the UKs MOT, no fluid obviously peeing out but enough leaking out of slave cylinder to contaminate shoes and mean no breaking.

The opposite side of the cylinder was seized. These were installed new about 20 years/40,000 miles ago.

The other side of the car looked OK but under the cylinder dust cover was full of fluid.

Over the years I've done 4 or 5 Golf/Jetta rear brakes and its always becasue of seized and/or leaking cylinders and never worn out shoes.

drums can be a nightmare, check the adjusting slider is grabbing and that you can set them equally by hand before adding real brake force. as above get a set of new cylinders and  measure the liners and internal of drum, see if since been bad they need changing,  did this job 2 months ago, was a mare took 4 attempts to get within the MOT spec.  Now have a full set up drums, liners, and cylinders sat in a box "just in case " for next cabbys MOT.

Kenneth Cartwright said

drums can be a nightmare, check the adjusting slider is grabbing and that you can set them equally by hand before adding real brake force. as above get a set of new cylinders and  measure the liners and internal of drum, see if since been bad they need changing,  did this job 2 months ago, was a mare took 4 attempts to get within the MOT spec.  Now have a full set up drums, liners, and cylinders sat in a box "just in case " for next cabbys MOT.

How much for the full set

Sent from my SM-G960F using Tapatalk

Okey, new MC fitted, new brake cilinders, new brake hoses and fluid.

Problem persists, the right rear wheel brakes less than the other. my cabrio gli is from 1989 so it has the mk2 MC with the two rear brake adjusters in the MC. This has to be the problem, we have cleaned them with ultrasound but no luck either. I have realized that the regulators are not what they should be (533612151) but that they actually have mk3 ones (1H0 698 401). the first ones are very difficult to find so I will buy the second ones again as it seems that it can work with them.



Thanks!

Is the condition of the adjuster mechanism inside the drums / shoes good, I've had an issue many years ago where one shoe adjuster didn't grip under braking force and ultimately lost brake power, symptoms very similar to a failed master cylinder, but 2 fast pumps of the pedal and brakes were perfect.

I don't think it's the same problem. They are revised and the handbrake works perfectly.

Thanks!

i have a few valves lying around mate

Have you had the drums off and had a look to see if anythings obviously amiss in there?

It seems that they are very difficult to buy, in the end I bought the mk3 ones. If I need to, I will contact you, thank you very much!

Early-1800 said

Have you had the drums off and had a look to see if anythings obviously amiss in there?

Yes, everything is new except the regulators, we have seen that one has a bent thread. The first braking works well but the next day it doesn't anymore, it seems to catch air bubbles

Are both the rear wheel cylinders the same?

There is 2 types of wheel cylinder, the bigger 17mm one for cars with a rear brake system regulator and smaller 14mm cylinders  for cars with out a regulator.

mark1gls said

Are both the rear wheel cylinders the same?

There is 2 types of wheel cylinder, the bigger 17mm one for cars with a rear brake system regulator and smaller 14mm cylinders  for cars with out a regulator.

 yes, 17,5 mm ATE. One side works perfectly every time.  it is the other that little by little brakes less and coincides with the bent regulator.

Thanks!

Finally the problem was in the pressure regulator. I have put the Golf MK3 ones thank you very much to all!!!