brake bias

[doogydawg]

sorry if this is in the wrong section
I have a vw based beach buggy I:E engine in the back, it also has the fuel tank in the back, so all the wieght is at the back of the buggy, now buggies are known for the front wheels locking up first. the buggy I have bought, has a tilton bias wheel under the drivers seat, I have followed the brake pipes from the master cylinder, now the bias wheel is installed in the rear brake pipes, would this help stop the fronts from locking up first ?? it also looks like it is a single brake circut,as the drawing is as it is on the buggy.
I have a small rough drawing of the setup, its on a neal hydraulic pedal setup.
bit confused to say the least.....Im new to all this car stuff LOL
cheers for any feed back.
heres a link to the drawing
blue box is the brake fluid tank up front.
purple is the brake sensor
green is the bias wheel
www.wwwafalsureclipsecouk.eclipse.co.uk/brake drawing.jpg

[Mikey G]

I am unable to open the picture but i think you have the flow restrictor type of bias valve, what this does is adjust the pressure to the rear brakes. Fully open you are looking at maybe 60/40 front/rear but closing it will reduce the pressure to the rear causing less braking in them. This will only worsen your locking up of the front.

May i suggest looking at yor rear brakes first to make sure they are working properly before making too many adjustments.
To set the valve up just go to a nice stretch of tarmac and open the valve fully, try to lock the rear brakes before the front then gradually close the valve until you can feel a fairly even balance in the way the brakes work.
Being rear engined you are going to need more braking to the rear than most cars but you will still get a shift in weight to the front resulting in more force needed at the front than the rear under hard braking.

Hope this helps.

[doogydawg]

cheers matey for the reply.
sorry didnt thank you before..had this flu thats going around...no its not man flu...proper flu....
was chatting with the guys at tilton via e-mail..basicly, the person who did the buggy before I bought it, should have fitted the bias to the front wheels to help them stop locking up.as there is no weight at the fron of the buggy and its all at the back.
so just need to swap it around.
cheers for the info.
steve.

[GreenV8S]

doogydawg said:

should have fitted the bias to the front wheels to help them stop locking up.as there is no weight at the fron of the buggy and its all at the back.

that sounds scarily wrong.

[MR2Mike]

Note that the front wheels should always lock before the rears anyway, having the rears lock first will cause you brown trouser moments at best.

I guess what you are saying is that even with the bias valve set to allow full pressure to the rear brakes, that the bias is still too far to the front? I would personaly be somewhat reluctant to move the bias valve to the front brakes, would it be possible to get rear slave cylinders with a larger diameter (assuming drums at back)?

[GreenV8S]

You need a bias valve in the line to the rear brakes to move the brake balance forwards under heavy braking to match the weight transfer. Putting a bias valve in the front brake circuit would have the reverse effect which is just plain wrong.

It may be possible to use a 'bias' valve in the front circuit backed right off so that it just worked as a fixed 1:3 or 1:4 attenuator, but that is not using it for its intended purpose it is just bodging your way round the fact that the static brake balance is wrong. You would still need a proper bias valve in the rear circuit to compensate for the weight transfer.