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sva fail (leighton) 2nd time
andy188 - 15/5/09 at 05:26 PM

sva fai, again,
rear brake inbalance, had adjused rear brakes, let 1 off adjusted up other side, had improvement today but still failed all ok otherwise, any ideas, thanks


splitrivet - 15/5/09 at 06:05 PM

Sorry to hear that, would it not be worth finding a local friendly MOT station who would let you use thier brake rollers for a fee, thats what I did.
Cheers,
Bob


andy188 - 15/5/09 at 06:20 PM

thanks, have allready sorted the local mot garage (week today am, sva test pm) need to know offf ideas of what could be wrong, have a week to fix. thanks again.


mad-butcher - 15/5/09 at 06:25 PM

Disc or drum
what parts are new
what parts are S/H
Fail on handbrake or hydraulic system
If handbrake is it std one piece cable or modified (if so how)
tony

[Edited on 15/5/09 by mad-butcher]


mr henderson - 15/5/09 at 06:43 PM

It would help if you would provide a much more complete description of the problem.


bitsilly - 15/5/09 at 06:58 PM

Drive very slowly with the handbrake on. Then drive with brake on for a while to help them bed in.
Trailer the car to a trackday or a big car park to do so. Or jack up the rear wheels.
Presuming you have hydraulic brakes then the brake pressure must be equal in both calipers, which possibly means one has much better initial unbedded in contact - so get bedding!
If it's not that, then have a look at your discs wear pattern afterwards to see if they give any hints.
Good luck.

ps did the examiner offer any help/advice/solutions?


andy188 - 15/5/09 at 07:22 PM

hi, thanks for all your input etc,
drum brakes on rear, handbrake good, hydraulics fail,
right cylinder replaced during build , old shoes all round, handbrake cable shortended on left side, left side not pulling up as well as right, results from test as below
brake force axel 2 ns (p1) 12, (p2) 15, (p3) 14, (p4) 29, (p5) 44.
brake force axel 2 os (p1)18, (p2) 20, (p3) 24, (p4) 47, (p5) 68.. hope these help, thanks, andy


adithorp - 15/5/09 at 07:35 PM

First off, adjustment (within reason) of the brakes has little effect on braking power. It just reduces the pedal travel.

If you've changed a cylinder, have you checked the pistons are the same size as the other side? Measure the diameter to check. If the diameter is larger then that'd give higher presure. Don't just go off part numbers; things get boxed wrong or the other one might be smaller than it should be. Is the the other one sticking? That'll give low readings that side. Was there any fluid contamination on the shoes? If so change them.

adrian


mad-butcher - 15/5/09 at 08:22 PM

Did you mix the drums up when cleaning sometimes this can have an adverse effect on braking because of the wear ridges on shoes and drums, I for one don't like automatic adjusters, I adjust the shoes until they just start to rub then back the adjuster off 1 turn, then pump the pedal a couple of times to bring pistons out.

tony


FEZ1025 - 15/5/09 at 11:22 PM

Have you got some air in the system on one side.

Alan...


snapper - 16/5/09 at 06:50 AM

Replace cylinder that you did not replace first time, if in doubt buy 2 identical and replace both, replace shoes, make sure the correct contact points have a very small thin layer of copper grease to ease the sliding of the shoes on the backplate.

If you get access to a brake test roller you could check then swap cylinders to see if the bias swaps with the cylinder, if it does its the cylinder.


andy188 - 18/5/09 at 08:33 PM

hi, thanks for all the advise, changed cylinders, new shoes, bleed up, feels better, will bed in over next couple of days, will let you know how we get on friday. andy