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Discussion Starter #1
Help please

My rear brake effort is very low

Long story my van went for its mot and failed on low brake pads one side on front and poor rear foot brake and handbrake force, I changed front pads, adjusted handbrake mechanism (as found linkage was slack with lever arms on the stops on the calipers) and suspect rear load sensing valve leaking(I had lubed this and excersised it the night before the mot it was dry before lubing it) anyway changed front pads, changed rear load sensing valve as thought perhaps actually seizing or poss internal problem with it and bled rear brakes.

Went back for re mot front brakes excellent, handbrake excellent as well but rear foot brake force low and tester thought load sensing valve leaking from body by lever arm and with foot on brake pedal when starting engine pedal travels long way down so new load sensing valve fitted and adjuster wound in 4 revolutions to increase fluid pressure to rears, brake system fully bled with gunson pressure bleed kit brakes checked on mot rollers and rear brakes still same poor foot pedal force handbrake.

Info:- T4 1.9TD 800 special swb 2001 panel van completely standard apart from stainless steel exhaust

Brake pedal solid with engine off with foot pressure applied pedal travels approx 2 inches I have measured full pedal travel with bleed nipple open and its approx 1 inch further travel than pedal travel with engine running.

Any ideas welcome please thanks in advance
 

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is the van lowered? if so maybe the rear loadsensing bias valve thinggy needs adjusting?

otherwise, the rear calipers on post '96 t4's can cause issues (pistons, sliders & even stuck pads) and it's worth checking for criped brake-pipes (metal & rubber)

Rich.
 

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There are (I think) 5 different sets of spring for the valve, dependent upon the main springs fitted to the van.

It's also been known for people to put a few bags of sand/cement or concrete blocks/paving stones in the back to give some load.

With no weight in the back, the rear brakes "shouldn't" be doing much anyway...otherwise you find it passing your driving position in either a clockwise or anti when you have to brake hard in wet conditions :eek:

Mine was set up (after lowering) by a VW Van dealer (had to be done by them due to Norwegian Law!) at a cost of 250 quid!
Since then it has passed the tests every time, but there is always a "note" that the rear discs have a coating of rust....probably 'cos they hardly ever come on! I:

I've started driving to the test centre with the hand brake on to clean them LOL:
 

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Discussion Starter #4
Standard height all round I know its not messed with as I know the previous owner its done just over 100k, last year it just got through on brake test this year it failed its got a golf engine plus two gearboxes in it as well as wheels, steel golf 2 front subframe etc a couple of hundred kgs still failed.
 

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Discussion Starter #5
Can anyone tell me is the braking system split diagonal or front to rear I have a non ABS system and the master cylinder is 4 port type
 

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Not split diagonal.

2 pipes to the front, 2 to the rear VIA the balance valve. (VIA the valve!!!!)
If you don't have that set correctly, you're p*ssing in the wind to adjust rear brakes.

Also; have you stripped the rear calipers down and lubricated the sliders?
 

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Brake pedal solid with engine off with foot pressure applied pedal travels approx 2 inches I have measured full pedal travel with bleed nipple open and its approx 1 inch further travel than pedal travel with engine running.



That don’t sound right, with no vac pedal should be solid with little travel, earthier there’s still air in the system or the master cylinders suspect, are the rear clipper pistons free, pads stuck, if it’s been driving around empty normally they size up, disconnect the loads sense valve is it stuck if not tie full open should lock the wheels up very easily.

By very easily I mean easy, on heavy van with ABS there is no load sense valve (at least not on our German market van) and on our heavy camper the ABS chatters away frequently controlling the rear brakes.
 

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Discussion Starter #8
Thanks for the info re brake line split I guess that could explain the poor rear foot brake force, but really good front brake force.

Well today I replaced the master cylinder bled the system and the brake pedal is the same as mentioned before :*

I haven't taken the rear brakes apart yet but surely if the handbrake is operating correctly (on mot test handbrake force really good, way better than the foot brake).

Oh well I guess re bleed them tomorrow and look at rear calipers then

Thank you all for your replies.
 
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