95 rav4 rear brake problem

buddy25, Sep 17, 8:58pm
there is a proportion valve on the rear brake line abs model .
is this valve serviceable or have to be replaced !
Have failed WOF as brake reading on back brakes very different
lining and hydraulics are all good thx

mugenb20b, Sep 18, 12:36am
Proportioning valves are not servicable, they just get replaced. Don't confuse the proportioning valve with a T piece (if it has one) or brake bias loading valve.thing (you'll see a linkage between the body and valve if there is one). What were the readings!

buddy25, Sep 18, 12:44am
reading 140 l/rear270r/rear
front both 300 It looks like steel block 2feed pipes in 2feed pipes out
on the line about .600mm passed the abs unit i don`t know whats inside it yet

mugenb20b, Sep 18, 12:55am
On the rear axle, have you got drum or disc brakes!

tmenz, Sep 18, 1:04am
Proportioning valves are serviceable. We had a Corolla one, (rejected for WOF because of rear brake imbalance), reconditioned with new valves and springs by 'Just Brakes' in Penrose - approximately $80 as opposed to $500 for a new one.
Apparently they do lots of them for many different makes of cars.

mugenb20b, Sep 18, 1:05am
Really! Well, I learned something new today. Good to know.

buddy25, Sep 18, 1:12am
Drums on the back ,thanks for that info tmenz I will get in touch with them tomorrow, or maybe our local can do the service also

carkitter, Sep 18, 1:51am
For drum rear brakes, I would start with the wheel cylinders first - see if the seals are leaking. If so I'd replace the whole cylinder (both sides) and readjust both rear brakes.
I didn't think a proportioning valve could affect either side of the rear brakes differently! Isn't a proportioning valve for splitting the proportion of front/rear braking force!

Sounds to me like you just need to get someone who knows what they are doing to service your rear brakes properly.

tmenz, Sep 18, 3:34am
The Corolla station wagon that I worked on has dual line brakes so the rear wheels are operated by separate lines from the dual master cylinder. The proportioning valve is a dual unit with a separate valve for each line. If either or both of theses valves deteriorate, then the result is incorrect pressure control and therefore imbalance at the rear wheels.
Dual line brakes are standard on modern cars, so any system with a proportioning valve can be affected.

tmenz, Sep 18, 3:44am

franc123, Sep 18, 6:43am
What were the park brake readings!

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