32 replies to this topic

[01smartc]

Hi all, just bled my brake on the race car.

The car is on axle stands, if i put the brakes hard on... i can still just about turn the wheels with my hands... is this ok, they are really tight but should i be able to move them at all?

Cant drive it as engine not fitted yet

Chris

[il-barba]

would help to say what brakes you have and if you have a servo or not.

but i do not think you should be able to move them by hand. maybe if they are driven and bed in they will be better (i am assuming you have new brakes)

[icklemini]

the front should be locked on - certainly shouldnt be able to move them with your hands if the brake pedal is hard down...

the rears: well depends if you have done anything with the brake bias....

Edited by icklemini, 18 January 2009 - 08:20 PM.

[01smartc]

The brakes are a custom set up with seperate front and rear cylinders with the rear biased off about 80% ... no servo.

Its strange when my grandad presses the pedal i can just about turn the wheels.. however if i press the brake pedal then he cant turn them at all.

Is it just that he's not pressing hard enough or that i'm hercules turning the wheel lol

Edited by 01smartc, 18 January 2009 - 11:02 PM.

[icklemini]

i wouldnt worry too much about it - get it finished and see how it drives/stops...

[MikeStewart]

Sounds like it wouldnt even pass an MOT at the moment, try the same test on another car - if it has a servo the engine has to be running - and compare results.

[Dan]

A servo does absolutely nothing to improve the braking effort.

[lorry]

The brakes are a custom set up with seperate front and rear cylinders with the rear biased off about 80% ... no servo.

Its strange when my grandad presses the pedal i can just about turn the wheels.. however if i press the brake pedal then he cant turn them at all.

Is it just that he's not pressing hard enough or that i'm hercules turning the wheel lol

What size master cylinder have you used, do you still have the same pedal box? I presume it is the same on both front wheels?

[MikeStewart]

A servo does absolutely nothing to improve the braking effort.

Yes however you wont get full braking with the servo empty, try stopping a car when the servo doesnt work - its no fun.

To get through the MOT you need better than 50% braking efficiency which is half the weight of the car across all four wheels. So I would be expecting something like 100Kg force at each of the wheels, it will be enough to lock the wheel so you cant turn it by hand.

[01smartc]

Ok ... some news!

I can drive the car and its as bad as I thought... the car struggles to stop. Ive got a line lock which i cna lock the rear brakes off! With the rear locked off i struggle to stop the car with the front brakes. Ive got KAD 4 pots so I should be able to lock up easily!

When the rear is not locked off the back wheels lock up easily before the front!

Somethings not right with the front set up! The brake pedal is hard and im not stopping at all!

Chris

[Dan]

What size masters have you used?

[01smartc]

0.7" front

0.625" rear

[Ethel]

I'd swap those over. You could whip the pads out one at a time and make sure the system can push all the pistons satisfactorily.

[2lrminivan]

have you got the calipers up the correct way with bleed nipples at the top

[01smartc]

Checked pistons, they all work fine... but dont travel very far.

Why would you swap them over?

KAD calipers have bleed nipples top and bottom so dont think you cn get it wrong?