DIY Fix On Rear Brakes - By Bennie Hurter (aka
Many guys struggle with
the brakes on their Hiluxes especially the SFA models. Many times
the problem is to do with the rear brakes.
One of the major problems
is that the mechanism in the rear drums is dirty or rusted due to
a lot of mud and water driving. This article does not cover the
servicing of these drums but goes beyond to another problem that
guys experience which actually has a fairly simple fix, if only
people knew about it.
Guys tend to service
and adjust the rear brakes in an attempt to get the brakes to work
better but many times they forget an important piece of the puzzle:
the LSP & BV :? :wink: :wink:
This article covers the
working and adjustment of the Load Sensing Proportioning and Bypass
Valve. The aim of this valve is to adjust the pressure which is
applied to the rear brakes in relation to the amount of weight that
is loaded onto the vehicle.
If you look at the set-up
of this valve it reminds you of a ball float of a toilet’s
reservoir and it works similarly.
As the weight on the
vehicle increases, the suspension is pushed in and the body/chassis
move closer to the rear axle. This movement is sensed by the LSP&BV
also known as the Load Sensing Valve and it increases the pressure
which is applied to the rear brakes accordingly.
On a new vehicle, this
valve works fairly well, but on older vehicles with sagging suspension
or on vehicles with suspension lifts and modifications, the suspension
geometry falls outside the normal working parameters of this valve.
Then it needs to be adjusted or modified to work.
Manual shows a fairly complicated way of setting this valve using
fancy pressure gauges that must be attached to the front and rear
brakes and pressures must be measured and this valve be adjusted
to get the pressure ratio to within specifications.
here to download the pdf file
However, most of us do not have the time or equipment to do it that
way so we must do it the “Trial and Error” or “Hit
and Miss” way by adjusting shackle no 2 and then driving the
vehicle to test the effect.
After lifting my rear
suspension by replacing rear leaf blades and lengthening the shackles,
I realised that my rear brakes were not working anymore.
I tried adjusting
this valve but could not get it to work again so I decided to lengthen
the Shackle no 2 with about the same amount of suspension lift I
gained. In the photograph below I extended the shckle by welding
piece of round bar into it.
way to extend the shackle is by using a "long nut" .
See the next two photographs:
below shows Frik and his son's modification:
saw that you could also move the valve itself to help with the adjustment,
but I doubt that it would have been enough.
After this lengthening
exercise, I could then adjust the length of Shackle no 2 until my
wheels were braking but not locking up too quickly on Gravel or