Rear brake pressure-regulating valve adjustment

Failed MOT , too much rear brake:(, it want to be a drifter:D

Need pics of "lever" at rear brake pressure-regulating valve from stock suspension at ride height and from suspension at full droop with stock shocks? Want to see where the lever should be, so I can make extension to the bracket. Stock adjustment is not enough and haynes guide is some what cryptic...
 
Too much rear bias? I wasn't aware that front/rear bias was part of the MOT regs for brake testing?

I understood there were criteria for brake imbalance between both front wheels and both rear wheels but not front/rear spit.

What does the MOT failure sheet reference, as I'd like to see the referenced MOT section...
 
pollyp that link gives just an error page?

Mine looks like this at suspension full drop without the tool there
(picture borrowed from http://www.micra.org.uk/threads/rea...lve-after-lowering-for-facelift-models.50178/
dscf4014-jpg.19960

There is not enough adjustment so rod is not pulling the lever
And at ride height the rod stick out even more

Is that rod threaded fully?
 
Here in Finland there is little driving test in MOT and rear locked before front...

Braking forces at brake dyno was almost the same between front and back.
Last years MOT front braking forces was better so then there was not a problem and I think inspector did not do heavy braking then, and now I took car to different MOT station. A mistake.:mad:
 
pollyp that link gives just an error page?

Mine looks like this at suspension full drop without the tool there
(picture borrowed from http://www.micra.org.uk/threads/rea...lve-after-lowering-for-facelift-models.50178/
dscf4014-jpg.19960

There is not enough adjustment so rod is not pulling the lever
And at ride height the rod stick out even more

Is that rod threaded fully?

found u have to be a club member and logged in to see stuff in the diy guides section but here we go:

1043wl.jpg


when resting at stock height the little nut at the end of the spring rod pulls the bias arm away from the internal valve plunger and so with minimal loading on the valve, the brake fluid can flow in & out freely

brakebiasstockheight.jpg
when the rear is lowered below stock the nut no longer pulls the arm back at rest and instead allows the main spring to push up against the bias arm which then applies force against the valve plunger causing a constant restriction.​
when braking, the applied brake pressure from the master cylinder can overcome this restriction, rear brakes would respond a little slower than the fronts​
brakebiasloweredunadjus.jpg
but when releasing the brake pedal the fluid can't return back easily, retaining the pressure and so the rear brakes bind causing premature wear, overheating disc & pads and poor economy​
brakebiasloweredunadjus.jpg
so what you need to do is lower the nut till it pulls the bias arm back out, just enough to relieve pressure off the bias valve​
brakebiasloweredadjuste.jpg

if the rod doesn't have enough threads, i just used a ziptie to pull the bias arm off the valve slightly when the susp is level
 
Do you know what your brake force readings were?

If I remember correctly, we had around 270kgs on each front wheel and around 70kgs on each rear wheel, which was pretty low.
 
Forces was without bracket
front 1,8 kN 1,7kN
rear 1,5 kN 1,8kN
Ebrake 1,2 kN 1,2kN

and now
front 1,8 kN 2,0 kN
rear 0,7 kN 0,8 kN


Year ago forces was at different MOT station
front 2,2 kN 2,1 kN
rear 1,9 kN 1,8 kN
Ebrake 1,2 kN 1,2 kN


I think that under 1 kN is too low for rear because now it just "plows" front locked(not enough weight transfer to front because of coilovers) and feels that car is not stopping properly?:mad: But its cleared MOT so its safe...o_O

And I have 1.6 N14 front brakes and stock master cylinder if that matter
 
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