vw transporter failed D.O.E on weak rear brakes

cabbott

my transporter failed the D.O.E the other day on weak rear brakes, plus a few other things. i opened the rear brakes and they are perfect as i only changed them a couple of years ago for the previous owner and they passed the test soon after. at first i thought it would be the load sensing valve on the rear ciezed, but this is moving when the brake pedal is pressed, maybe it needs adjusting, anyone got any ideas on this one.

i wonder did they just fail me to get me back for another €42. he didnt fail two bulging brake hoses and a track rodend with some play.

crosstownk

cabbott wrote: »

i only changed them a couple of years ago

A couple of years ago!!! Maybe something has given up the ghost since........

What were the results that led to the fail?

Darragh29

cabbott wrote: »

my transporter failed the D.O.E the other day on weak rear brakes, plus a few other things. i opened the rear brakes and they are perfect as i only changed them a couple of years ago for the previous owner and they passed the test soon after. at first i thought it would be the load sensing valve on the rear ciezed, but this is moving when the brake pedal is pressed, maybe it needs adjusting, anyone got any ideas on this one.

i wonder did they just fail me to get me back for another €42. he didnt fail two bulging brake hoses and a track rodend with some play.

Can you post the test data up here?

cabbott

here's the results...front left 287, front right 300, rear left 67, rear right 72, handbrake left 224, handbrake right 205. i opened the brakes tonight they look brand new but well bedded in though and no ciezed cylinders as i said they appear perfect, two years is not a long time considering the van has done little milage in this time.

Darragh29

cabbott wrote: »

here's the results...front left 287, front right 300, rear left 67, rear right 72, handbrake left 224, handbrake right 205. i opened the brakes tonight they look brand new but well bedded in though and no ciezed cylinders as i said they appear perfect, two years is not a long time considering the van has done little milage in this time.

Your rear axle hydraulic circuit is causing a problem, you have very little braking force at the rear axle when using the brake pedal... Are you sure the wheel cylinders are not seized???

Those results are so low that if you jacked up the vehicle and threw the drum back on and got someone to press down the brake pedal, you would still be able to turn the road wheels on both sides. You have effectively no braking at all on the back axle when braking with the pedal. Try adjusting the wear adjusters and see if they tighten up at all...

If that doesn't improve the situation and you are 200% sure that the wheel cylinders are not seized, then the problem is the brake balance valve.

cabbott

absolutely certain theres no siezed cylinders, ive suspected the load sensing valve from the start. but the only time ive seen problems like this is when the valve was siezed, but its not. i may just try some adjustment on it and see what happens, a new one is €140 + vat.

Darragh29

cabbott wrote: »

absolutely certain theres no siezed cylinders, ive suspected the load sensing valve from the start. but the only time ive seen problems like this is when the valve was siezed, but its not. i may just try some adjustment on it and see what happens, a new one is €140 + vat.

It's defo not your brake linings or the mating surface on the drums anyway because your handbrake data is sound. If you are 100% sure your cylinders are not seized, it must be the load sensing valve from my reasoning. I haven't had this particular problem on a VW Transporter before so maybe someone else on here could confirm this diagnosis for you...

cabbott

i compaired the position of my load sensing valve today with another transporter in work, both vans were empty, the rod connected to the valve which sits on two adjustable rubber stops was sitting about 6mm off of these stops on my van without the brake pedal pressed and the wheels on the ground. on the other van it was sitting on the stops, when i pressed the brake pedal fully on the other van the rod lifted about 6mm off the stops, so i adjusted the tension on the 2 springs to set mine up to behave in the same way, ill run her through the test and see what happens, id say itll be ok, ill keep ye all posted.

cabbott

went back for thr retest today and passed. dont know what the results are but she sat down well on the rollers, a pass is a pass i suppose.:):)