MOT Failed on rear parkingh brakes

[oskiee6]

Hi all,

Its been a long time since I have been on the forum. Just come back from MOT. It failed on a few things which I think I can resovle however my concern is near side/offside parking brake recording little or no effort. What will the problem be . The calipers ? the bake cable ?

How much do calipers cost and where can I get them ?

[xyy81t]

generally a brake caliper overhaul sorts this issue - take them off strip them down, clean replace seals if necessary and put back together. how high does the lever come up? if more than 3 clicks it will need adjusting which might help a bit

[oskiee6]

Lever comes up quite a bit. Do you think I need need cables?

[xyy81t]

not unless they are rotten, you could squirt some oil between the outer sheath and cable to free them up a bit if they are stiff

[stevepx]

mine just needed the cables adjusted so i had 3 clicks on the parking brake the as xyy says strip down the calipers give them a good clean and you should be ok.

[Ralf S.]

There's a few areas to check...

1) Rear brake compensator. Is your spring under tension or loose? Adjusting the compensator (£free) will improve the operation of the handbrake.

2) Cables. The rear cables could be sticking and/or stretched. New ones might help but at £20 a side, I'd leave that until one of the last resorts. Once they're off the caliper, you should be able to easily slide the core in and out of the sheath... put some oil and then grease in there and work it in. If they feel "tight" (bent or kinked outer .. or the inner core liner is damaged.. ) get new ones.

3) Pads worn out. New pads give the handbrake mechanism less work to do. If your pads are down to the last 2-3mm.. get some new ones.

4) Calipers seized or sticking. This is the most likely. You can get overhaul kits if the seals are damaged but a strip-down and clean is the only way to recover them. If the pistons are scored or look beyond help, or if the nipple is broken off and you can't face overhauling them, you can get replacement, reconditioned Budweg calipers from Brakes, brake discs, brake pads, brake calipers - Brakes International Shop .. all new internals and a shiny freshly re-anodised but previously second-hand body.. on an exchange basis.

They're about £100 each (once you get the rebate) for the alu' calipers.. so probably a last resort.. but they're essentially "brand new" calipers.


Ralf S.

[groovylee]

as said above really, take the calipers off and give them a good wire brushing, lube the brake cables, and adjust the handle bit, it is under the handfbrake gaiter

[xyy81t]

Originally Posted by Ralf S.

There's a few areas to check...

1) Rear brake compensator. Is your spring under tension or loose? Adjusting the compensator (£free) will improve the operation of the handbrake.

Ralf S.

how does the compensator affect the handbrake? i thought the handbrake acted on the calipers mechanically? as the compensator works through the hydraulic system i didn't think this has any effect on the handbrake operation.

[Ralf S.]

I'm not sure.. but I got quite a bit better readings on my handbrake when I adjusted the compensator.

I don't know if the act of adjusting it just reduced some free-play or slop in there, rather than the compensator otherwise having an involvement in anything when you put the handbrake on.


Ralf S.

[Dave Brand]

Originally Posted by Ralf S.

3) Pads worn out. New pads give the handbrake mechanism less work to do. If your pads are down to the last 2-3mm.. get some new ones.

Pad wear has no effect on handbrake performance. The friction level of the pads is the same throughout their working life.

[Ralf S.]

Yeah but.. new pads means the piston is further back inside the caliper body. It's closer to the handbrake self-adjuster mechanism so you seem to get a better thrust on it.

I was whole days trying to get Tarquini (155v6) through his last MOT.. trying different things and then measuring the difference in hand-brake pressure. New cables actually made the least difference.. compensator and new pads were #1 and #2.. even though logically I can't explain it. I just put it down to "random weirdness"

Ralf S.