brake bias

[doogydawg]

this is a double post as I wasnt sure if it should go in the kitcar section, so could a mod please delete whichever is needed, cheers.

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 firstas there is no wieght in the front. 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. drawing.jpg

[GreenV8S]

The Tilton valve should go in the line to the rear brakes. But that valve will only correct for weight transfer effects under heavy braking. You also need to set the static brake balance correctly so that the balance is correct under light braking. So set the static balance first (by getting the right mechanical/hydraulic advantage to the front/rear wheels), then use the Tilton valve to compensate for the weight transfer.

[Avocet]

They do a very basic test for this in the SVA scheme. The front and rear wheels are, in turn, put on brake rollers (like in an MOT station) and the same 5 pdeal efforts are applied to both axles. They then take an estimate of the Centre of Gravity height and stuff the results into a little spreadsheet that decides whether the front wheels will lock before the rears under each set of pedal efforts. The efforts are supposed to range from light to near lock-up. The "pass" criteria is that the front wheels MUST ALWAYS lock up before the rears. This is just so that the car doesn't tend to spin when you brake and lock the rears up. As GreenV8S says, you need to try various stops in various conditions (ideally not on a public road!) whilst messing about with the bias valve to make sure you can't lock the rears.

[lotisi]

If you have a single circuit master cylinder you can do a direct replacement with a dual circuit one from a later beetle or even better a Transporter one, in addition you can fit T3 wheel cylinders on the rear which definitely help in a buggy.

[Cathar]

Here's your pic:

As stated above, your fronts should always lock first, so for now I'd leave everything alone until you know more about the vehicle and cars in genereal; a messed up brake balance is _not_ fun at all...

[mat205125]

I think that the problem with the brake bias in your picture could be primarily a result of using different sized wheels and tyres on each corner of the car.

You are 100% right, however, in your valve positioning for this set up.

The best way to control brake bias would be with the fitment of an adjustable pedal box that separates the front and rear circuits, with adjustment given by the lever bar acting on the cylinders (usually on a thread and controlled by a rotating knob)