8 replies to this topic

[Mini bullet]

hi all,

i have a mini Spi but i have a bout a inch of travel in the brake pedal.

i have changed to following:

Discs
Calipers and pads - to mini spares 4 pots
Flexi hose - to Goodridge braided
rear shoes
rear drum cylinders
rear drums - to super fins
servo - brand new
slave cylinder

pretty much every thing apart from the copper hoses.
oh and i have bled the system to death!!!

we (andy and i) have also done to bleeding the correct way for a LHD mini as mine is a import.

when the brake bit they are solid and will lock up under heavy braking. the prodlem is the excive travel of the pedal. if you pump the pedal the bit point is raised for the next use but then returns to the original level (bout an inch again).

i have tried to be as honest as i can with the discription of this but it has completly confuddled us. if any one has any ideas im all ears.


Richard

[Monstrous]

Have you adjusted the rear brakes?

[TrialsLife]

The inch of travel I couldn't see being a problem as such. As long as the brakes are working. More of your preference.

As long as they modulate (not just on and off, you can slowly increase the braking power) and lock up with at lest 60% of the braking power to the front (which it should be anyway) it should be fine.

The one thing I can think that could be causing the extra travel is the fact that you may now have more braking fluid in your system, which means there is now more to be comressed. For example, two cars fitted with the exact same brakes but one has longer brake hoses. The one with the longer brake hoses would have a spongier feel to the brake as the fluid can be compressed more.

You've installed 4 pot calipers which as far as I know have a larger capacity of fluid and if you have installed different drum cylinders compared to what was on there before that could change things.


One last thing that has popped into my head, are you noticing this when the car engine is running or not? Servo brakes sometimes need "pumping" when the engine is off to create the usual feeling in it.

[ginigwunkle]

if the pedal pumps up then theres air in the system.......

are the calipers the ones with 3 bleed nipples?

i take it by 'we (andy and i) have also done to bleeding the correct way for a LHD mini as mine is a import' you bled the brakes:

rear passenger, rear driver, front passenger front driver side...

[AngeloEvs]

A common fault is maladjustment of the rear brakes (including the handbrake adjustment) and no matter how well you bleed the brakes if the rear pistons have to move a great distance you will have excessive pedal play. A quick test is to apply the handbrake and then test the foot pedal and compare the travel with hand brake applied. A better test to isolate whether the excess play is due to the rear or front brakes is to clamp the rear hoses with mole grips or G-clamps but make sure you cover the hoses with some form of protection to avoid damaging them. This will prevent the brake fluid from entering the rear pistons. If the brakes feel much better then your problem is rear shoe/handbrake adjustment or air in the rear braking circuit. The brake bias valve could also be faulty and this prevents proper bleeding of the system. If, while doing these checks the brakes still need pumping then the problem is with the front brakes, if you have a servo, try bleeding the brakes with engine running.

Edited by AngeloEvs, 17 March 2008 - 01:02 AM.

[Mini bullet]

Thanks everyone,

yes we bled in the correct order (haynes book listing) we also used a eziebleed thingy magig with a air flow from a spare wheel (if this makes any sense im suprised!).

the brake travels about an inch and it dosnt feel like there is anything moving then just stops. im compering this with my dads Tpi cooper (R reg) with his its got like 10mm of travel, then your face hits the screen!!! this is a completly standard Rover system, so i cant see why its diffrent to mine when ive upgrade it all.

we will be changing the discs again at the end of the month as ive got a set of tar-ox 40 groove discs and mini sport 7.9" calipers to go on, so well have the fun of bleeding it all again! well try bleeding with engine running.

Edited by Mini bullet, 17 March 2008 - 05:48 PM.

[jayare]

Do NOT use any type of clamps on braided brake hoses as suggested above or you'll ruin them.

Make sure there's no play in the front wheel bearings as if there is, the discs will push the pistons back into the callipers further, meaning you have to push the pistons further out on initial application to get the pads onto the disc.

One other thing to check is all the clevis pins that connect the brake pedal to the master cylinder (via the bell-crank thingy) and that the hole in the pedal itself is still round - because of the leverage ratios, 1mm of wear in total between all the pivots means you'll have about 10mm extra travel at the pedal to take up all the play before anything happens at the master cylinder.

JR

[Mini bullet]

Didnt clamped the braided pipes! thanks though.

the split pin at the master cylinder has been replaced with an R clip, refitting that was a BasT*ard enough let alone a split pin, took both of us a torch and what seemed like ten pairs of hands!

mmmm food for thought there though, ill have a look when globle warming kicks in again over Maldon!

[Mini bullet]

Oh forgot to say, got my 7.9 calipers today!

happy me!