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Brake bias adjuster needed?
trialsman - 23/5/20 at 02:05 AM

OK let me explain what I have and what the problem is. My Locost used a 1979 Escort MK2 estate as a donor. I just upgraded my front brake calipers to Wilwood 4 pots. I have the standard drum brakes in the rear and the standard single master cylinder with separate lines going to the RT front and LF front brakes and a single line going to both rear brakes. These brakes are a LOT better than the original ones I had and I love them. But I am having trouble when applying hard braking. The RF front caliper will lock up especially when cornering while braking. The car does not seem to pull to either side on hard braking. Rear drums will lock up under panic stops. Do I need a bias adjuster? How do you plumb it in to the lines. Any recommendations of what brand? Thanks and stay safe by social distancing in your se7en, Russ

AdamR20 - 23/5/20 at 06:57 AM

Assuming your car is left hand drive, locking the front right is perfectly normal as it will have less weight on it than the left. You could sort this with corner weighting, but then you'd have an imbalance between under and over steer on left hand right hand bends.

Bias valves usually set front to rear bias, rather than left to right.

The 4 pot calipers you have will technically be the same or less power than the original M16 brakes, which is likely why you feel like you have a touch of locking at the rear.

I say feel, because these things are notoriously hard to sense. If the front right locks, then it is unlikely the rears will too.

trialsman - 23/5/20 at 12:44 PM

It's right hand drive.

jps - 24/5/20 at 08:13 AM

Originally posted by trialsman
The RF front caliper will lock up especially when cornering while braking.

Is this just when turning right, i.e. is the front right wheel becoming unweighted - hence easier to lock it?

Jervo - 24/5/20 at 08:27 AM

If you get the car on stands and have an assistant push the brake pedal whilst you are turning each wheel-preferably with a torque wrench, you should be able to check the relative brake torques for each wheel.

Make sure the assistant is pressing the pedal consistently and holding that load!

Typically, on single seaters I used to run we would have held the pedal to achieve say 120lbft on the front and then measure the rears- around 80lbft.

In your case check across axles are similar (within 10%).

I tend to agree however that this sounds like a classic imbalance in corner weights.
Worth checking your wheel / tyre circumferences across axles in case thatís causing it.

trialsman - 24/5/20 at 02:50 PM

Occurs on straight line and RH (drivers side) turns. But only sometimes. Thanks for the hints. Russ