Is there actually a repair set for the brake force distributor?

[eriknetherlands]

I have my brake force distributor out of the car, dismantled, refreshed etc. Normally i'd take the opportunity to replace the 2 black rubber seals on the piston, but RealOEM does not provide a number for the kit, identified on the parts drawing as RS 8; RS for Reparatur Satz #8.

are these seals actually available?

 

[Cornishman]

I don't think so, I could not find one.
Regards
CB

 

[aearch]

take it apart and size the seal -then you can match it at the parts store
ive done that on many occasions

 

[deQuincey]

the o-ring is no problem, just remember to ask for EPDM
the second seal is not that easy, i would not touch it, you can break it and there is not an easy way to replace it, at least i know of no source

 

[bavbob]

I have always feared to fiddle with this. Exactly how can you test "in-vivo" that the thing is working the way it is supposed to?

 

[Belgiumbarry]

try hard braking on a wet road ... rear wheels should never lock before the front ones.

 

[eriknetherlands]

As no repair set is appearently available, i'll just keep in mind the testing procedure (thanks Barry) and if it fails I can always try to use the hint of DeQuincey to replace the generic O-ring (choosing EPDM). So assembled the whole thing and put it away for later install.

 

[bavbob]

deQ, is this thing nothing more than a resistor in series? Are there two ways it can fail, always open or always closed? Sorry, just turned 60, asking a lot of questions about a lot of things these days.

 

[Belgiumbarry]

this diagram shows the working of the brake pressure reducer.
B is the pressure you make with the pedal , the same as in the front calipers
A is the reduced pressure in the rear calipers

the harder you brake the more weight transfer to the front wheels , so they can take more brake pressure ( more tire friction ) and the rears less and less

in fact a pre historic ABS system.... so the rear wheels don't lock first and the car would go sideways.

 

[Belgiumbarry]

nice demonstration of rear wheel locking on purpose ... to turn a car
The grey stick next the gear stick is the same as the brake pedal but only acting on the rear wheels and without pressure reducer ....

 

[bavbob]

Quite interesting, I thought this was the way it worked, always a gradient between the front and rear pressure, I did not predict the gradient changes with pressure, thought constant.. Thanks!