G'day , I Have been speaking to a few people who have told me I should run rear break bias as it would make my car suit conditions better !!! I have a 1980 datsun stanza, I use for autocross . I am currently looking into setting up a hydraulic hand break and a rear brake bias set, up I understand how the hand break works but not to sure about brake bias set ups ! Any help would be great Cheers .......

You play with brake bias to change the balance between front and rear brakes. Put simply, using the handbrake is effectively 100% rear brake bias - by adjusting the foot pedal bias more to the rear (ie get the rears working more than the fronts) you can achieve a similar (but not as drastic) result as reefing on the handbrake. The rear end will want to break away under heavy braking.

Depends on your driving style, how it brakes at the moment, etc as to whether it will be a useful thing to do.

The idea isn't so much to improve braking (although it can if you have way too much front bias currently), but rather to change how it handles under brakes. Getting the back end a bit loose under brakes is the idea behind heaps of rear bias on dirt.

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

1. If you are off road, the world is your oyster.
2. If you are on road the brake bias adjustment device MUST be out of reach of the driver, i.e. located in the engine bay.

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Regards, Graeme
Just trying to help...
http://nissanman.shutterfly.com/
graemes@internode.on.net

For dirt as Dave said. However for the tarmac a different story. Too much rear bias and you'll spin out into a wall. Ask LAG510. Basically for the road and track you want your fronts to lock up before your rears. Dirt would be different but if you're getting a hydro handbrake then you don't really need to bias to the rear IMO.

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1928 Model A CC Pickup

i have no idea how anyone has time to use a handbrake in racing situations. Ive got a hydra set-up in my D/C car and have only used it in prac laps

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Driving takes three abilities: Accelerating, braking, and turning.
More power only helps acceleration.
Lower weight helps all three.

what sort of a brake bias are you setting up? a proportioning valve fitted to the rear brake lines or a pedal box with two independent master cylinders?

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Team AFRICA doing it because we love it not because we can afford it!

Not quite true. HAnd brake is more for the slow tight stuff where you want the car to turn into hairpins etc, whereas rear brake bias keeps the rear end moving around under braking at higher speeds. You don't want it to start swapping ends under brakes, but you do want it unsettled under brakes (on gravel). This makes it much easier to turn in to corners, and easier to deal with the unknown (eg. going sideways into a corner helps you scrub off speed if the corner tightens etc)

Also, on gravel the grip levels are lower, so you will have less weight transfer under brakes. That's why you need a bit mroe rear bias just to balance the brakes out, let alone getting more braking at the back.

Using the handbrake (steering stick) while racing is something that takes time and practice. Mostly I don't bother if I can get a decent pendulum happening, specially if the bias is right so you can get the tail wagging under brakes at will (controllably, not snapping out and trying to overtake you). It's really only the slow speed stuff coming into a tight hairpin where I use the handbrake to bring the back around.

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They have drifting in forests now?
What will they think of next?

Quick question - how would you go about moving the bias to the rear without fitting a pedal box ?

I've run a proportioning valve in the rear line, but that was to reduce rear bias for the tar. I don't see how its possible to increase rear bias using a proportioning valve in the rear line ? Is it OK to put it in the front brake lines ? Never seen it done that way, is it a good idea ? Or even possible ?

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

Good question, Dave

HAving never set one of these up before (my cars have all had them fitted when I bought them) I believe you need to pull out the factory proportioning valve, which then allows the rear to run full (or increased) line pressure. Then you use a bias adjuster to wind the pressure back down.

Also, people play around with master / wheel cylinder / caliper sizes to fiddle with the balance, then tune the balance with an adjustable proportioning valve.

IMO the best solution is a proper pedal box, but the bias valves seem to work well enough.

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They have drifting in forests now?
What will they think of next?

Thanks heaps guys .....

heres assuming you still have drum brake rear end want more rear fit next size up wheel cylinder

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Jason
1600 Historic Touring Car

^^^ way to go.

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A little knowledge is a dangerous thing.
www.datsport.com

"R.I.P. Baz. 29 April 2022. Thank you for all your contributions to the Datsun community over the years. You will be missed." - OZDAT

Any idea what wheel cylinder it would be ? Different car or just a bigger one of Datsun ?

240z from memory. Memory ain't great though

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1928 Model A CC Pickup