9n 2007 binding front brakes

[robroy]

Hi..I am new to this forum.and i have a problem with the front brakes on my polo...They bind ..not all the time usually on a run .not at slower speeds..I have checked calipers {new]..brake pads ..brake hoses .Master cylinder {new]..servo..vac pipe ..When i can feel the brakes are binding i stop the car turn off the engine pump the brakes a couple of times ..and they release.. if anyone can offer a solution i would be very grateful...

[iichel]

Are the fronts or rears sticking? How are the brake pipes (not the hoses, the pipes)?

[robroy]

Hi Thanks for speedy reply..Brake pipes are good all round its only the front brakes that are binding { wheels getting very hot.]..rears stay cool. Its being able to release them that I find puzzling its like the vac pump is producing to much vacuum pulling the brakes on. stopping the car and pumping the brakes releases the vacuum.. brakes come off..

[CarbonChaos]

You could try disconnecting the vac line to the servo to eliminate that,this will obviously give you a hard/ firm pedal and I would only advise this on a short road test type drive but it may help.
Otherwise I would be looking at the caliper sliders make sure they are spot on straight and the callipers move freely
Abs pump valve sticking may be ?

[robroy]

Hi Thanks for reply..Calipers are new and work perfectly in fact the brakes are the best they have ever been..They only seem to bind on a fast run,,so I am leaning towards an ABS problem.The ABS seems to work normally [tested on soft ground]..they do have the issue of hard pedal when pumped with engine off...pedal goes to the floor with engine running,when stationary I will try driving the car with servo pipe disconnected,,

[RUM4MO]

I know that it sometimes turns up some useless hits, but have you tried Googling this, I'm sure that I've read of this exact issue on Skoda Fabia, so you are certainly not the first person to be in this situation - no answer though, I can recall, it is a bit unfortunate that you seemed to have already covered most of the obvious parts!

Edit:- have you actually tried jacking up the rears and spun each wheel to make sure that there is no "wrong" braking effort being applied at either of the rear wheels, obviously the diagonal rear wheel would be the one most likely to "follow" the corresponding front one, just an additional thought while you try to investigate the possible root cause.

[robroy]

Hi..Yes .I have googled it and unfortunately no definitive answer ..I have tried the white knuckle ride of testing with the vac pipe disconnected..no binding I have jacked the car up front wheel off the ground and run it at 60mph for 15 mins..no binding But a short drive on road brakes bind...I am thinking ABS unit ..Is this a DIY job do I need any special tools I.am thinking a second hand unit..breakers..or Ebay.. any advise welcome...

[robroy]

Hi..Yes .I have googled it and unfortunately no definitive answer ..I have tried the white knuckle ride of testing with the vac pipe disconnected..no binding I have jacked the car up front wheel off the ground and run it at 60mph for 15 mins..no binding But a short drive on road brakes bind...I am thinking ABS unit ..Is this a DIY job do I need any special tools I.am thinking a second hand unit..breakers..or Ebay.. any advise welcome...

[RUM4MO]

Do you have VCDS or another scan tool so that you could check the original ABS controller's coding and then the coding of the next one, that is what I would be doing if considering swopping the entire ABS assembly. Remember to only ever fit one that has the same part number.

Edit:- I've never checked to see what functional tests that you can carry out on the ABS controller using VCDS etc, the need or curiosity has not happened yet!

[robroy]

I think I have found the answer to my brake binding problem..To rule out ABS issues I disconnected the sensors at the rear wheels..front wheel disconnect affected the steering...the front brakes where still binding..when binding the brake pedal was biting right at the top with no pedal travel...so I made and inserted a perspex shim between master cylinder and servo...This increased the pedal travel slightly since then no binding and excellent brakes...I hope it works long term we will see..

[CarbonChaos]

Someone may correct me if I’m wrong but I believe there is some adjustment on the servo rod master cylinder side ? This would be a better long term solution maybe ?

Is the the original servo ?

[RUM4MO]

I was not convinced that using Perspex as a spacer is going to work for long.

I think that many years ago, these rods would be adjustable, but now with high volumes and the need to drag down prices, I think that the factory fitted rod will be a fixed length as that will be okay for 99% of cars over their life time. Unorthodox bodging will be required to alter that length.

[robroy]

Hi I agree..The 3mm perspex spacer is not a permanent solution..But it has worked..no more binding brakes..I will now make a metal spacer of 1.5 to 2mm which will reduce the pedal travel but not preload the master cylinder..Its all I can think of to do I hope that reducing the thickness of the spacer will be a permanent fix..Thank you all for your input..