1.4 ZX FRONT BRAKE IMBALANCE

[citronut]

a customers L reg ZX 1.4 petrol failed the MOT on imbalance on the front brakes,

the N/S was/is about a 100 less than the O/S when both applied together,

before i took it back for the first re/test i removed all the front pads, pistons went back very easy, and the calliper slides are very free with no sideways movement, discs are very clean and shinny with no bands of rust on the inner or outter edges, so the pads are useing the full disc surface,

re/copper sliped every thing and bunged it back to gether

on representting the car it still had nearly the same imbalance,

i took it away and fitted a new flexi hose to the N/S, and gave the pads a good sandding with coures production paper amd both sides of the disc a sanding with a flap wheel to ruff the surface up,


on the third visit to the MOT station we put it on the rollers bedfore loging it on to the system,

still nearly the same so i went off again after discussing it with the guys at the MOT station,
i then fitted the old flexi from the N/S onto the O/S just in case there was any restriction, as there was very slight drag on the O/S wheel which did not show up on the rollers,

i also copper sliped the calliper slides even though they were clean and free to move,

on route to the MOT station i felt the car was rolling a lot freer

on returnnig to the station we stuck it back on the rollers, to find the O/S brake went up to nearly 300 and the N/S still only managed about 200,


when indipendantly tested they both go about 300,

it dose appear the O/S one comes in very slightly before the N/s,


any thought would be greatfully recived


regards malcolm

ps.
this cars prvious MOT runs out tommorow

[uncle buck]

If my memory serves me correctly the car will have solid discs, and the pads will be held in place with metal "L" strips. (Bendix system)
I seem to remember this set up being very problematic & the outer pad often jambed & somehow stopped the caliper sliding, this was evident as the inner pad (next to the piston) was quite often worn right down while the the outer was still next to new.
I seem to recall filing a little off of the metal horn of the pads so at to make them not such a tight fit helped cure this problem.

Just had a look at the Haynes Manual & it says that the pads have to be fitted a certain way so check that they are correct...

From the Haynes manual....

"looking at the pads from the front of the vehicle, the innermost pad groove must be higher than the outer pad groove"



HTH.

Cheers.

[citronut]

ok thanks uncle buck

i will check that once i get to the workshop, even though all the pads seem to be free moveing in the callipers,

these pads are handed for each side, not like the BX pads which are all 4 the same shape,

and one way round they wont fit into the calliper/s

regards malcolm

[uncle buck]

Did you cure the problem today, I'm interested to know what is / was causing it?



Cheers.

[citronut]

well first thing i did today was jack the front off the ground, rotated N/S wheel and it spun free, rotated O/S and it had slight drag,

all the pads were in corectly

so i took the pads out piston went back very easy, but i found the slides to be tight to move,

with the calliper of the car i could see no fault even after poping the slides out, nice and clean,

re/fitted the calliper at the corect torque and it was tight on the slides,
bought new calliper fitted, took the car the MOT station on the rollers it was a little better and only just scrapped tthrough the MOT,

silly thing is every time i have driven this car and tried stamping on the brakes, they have not even twitched

regards malcolm

[uncle buck]

The main thing is it satisfied the MOT requirements

I bet you're glad to see the back of it...I used to hate jobs like this...I like a challenge but sometimes things just make no sense.



Cheers.