MOT time - and failure... NOW PASSED!

V

V8P6B

Member
Well the old girl has broken her 3 year reputation of clean passes with a failure this year. Rear brakes... :( I don't know what's wrong with them yet, but the calipers were jr wadhams exchange ones 3 years ago, so I'm hoping I just need to have a look at the adjusters.. I'll keep you posted...
 
Re: MOT time - and failure...

What a B#**er!
Could be worn down pads or adjusters not working properly??
Hopefully not partial piston seizure!
What sort of mileage have you done since they were fitted?
What did the MOT say about the operation of footbrake,handbrake,balance etc?
As you need to know if its 1 or both sides on footbrake,or just 1 handbrake not working!
 
Re: MOT time - and failure...

Hard luck Tony , :( If that was all though , then not too bad . :D Nothing worse than a list as long as your arm of niggling faults .
 
Re: MOT time - and failure...

Hi Pilkie, The car has done about 6500 - 7000 miles since the calipers were put on, so I'm probably guilty of not using the car enough, (2500 miles/year). I recall that when fitted, the handbrake was good enough on both sides to torque the rear driveshaft flange bolts! The problem now is a 55% imbalance from one side to the other, on both handbrake and footbrake, so as it seems to relate to both, this could suggest an adjuster problem, and not a seized piston, well, not a hydraulic one anyway. But we shall see... I guess I'll be getting intimate with the underside of the rear of the car again tomorrow..
 
Re: MOT time - and failure...

You could have 1 side working well and the other hardly at all!
its all done on % average from both,so you could have a near perfect 1 side and nowt the other giving the imbalance!
You need to know from your MOT guy if its both badly down on performance or which side aint working properly!
If the n/s isnt working then it could also be a collapsed link flexi hose!
Happy grovelling under it tomorrow!
 
Re: MOT time - and failure...

Pilkie said:
If the n/s isnt working then it could also be a collapsed link flexi hose!
Click to expand...

No it couldn't because it's down on the handbrake as well.
 
Re: MOT time - and failure...

I'll ask my friendly MOT tester tomorrow which side was down. Doesn't give too much info on the failure notice. If its really bad on one side, I may be able to tell which is which by jacking the car up one side at a time before getting under it.
 
Re: MOT time - and failure...

You should be able to see which one it is causing the problem just by looking at them.
 
Re: MOT time - and failure...

Pilkie said:
But only if you know what to look for! :wink:
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Go on then, what am I looking for? One pad adjuster piston further out than the other? The discs are beautifully shiny and clean on both sides of both discs, so both sides are doing something. I guess I'm looking for difference in pad wear across the 2 sides. Also worth checking then swivel pins I guess. Anything else? :?:
 
Re: MOT time - and failure...

V8P6B said:
Pilkie said:
But only if you know what to look for! :wink:
Click to expand...

Go on then, what am I looking for?
Click to expand...

The angle of the handbrake quadrants when the handbrake is pulled on. On the side that isn't working the quadrant will be spun round a lot further than the other side.
 
Re: MOT time - and failure...

Does the caliper feel loose on the swivel pin when handbrake is on?
Apart from seeing "looking at" worn pads,discs,fluid leaks,and how it all operates,it will mean getting yer hands dirty.
Have you spoke to Mr MOT yet?
Could be just air in the system and it needs a bleed.
Remove disc and pads and see if the piston operates when handbrake or footbrake are pressed,dont worry it wont pop out,the bit you can see is not hydraulic its lever operated from the small internal piston.
 
Re: MOT time - and failure...

Right, I've had a "look". Calipers are moveable by hand with the handbrake off, but both tight when its on. one handbrake quadrant may be very slightly further round than the other, but its such a small difference it's hard to tell. Pad wear is even on both sides.The calipers themselves are as clean & new looking as the day they were fitted, (I know that doesn't mean anything). I'm going to try bleeding the brakes first, as there may be air in the system. I previously did a "quick swap" on a failed brake light switch, which may have allowed a bit of air in. I've also had to change the hose that goes from the reservoir down to the master cylinder, as it was weeping. Once I've bled them if its no better, I'll pop the driveshafts off, remove the pads and make sure the adjusters are working properly. I did read somewhere that you can put the car on ramps, and drop the diff with the driveshafts in place to get better access to the calipers, but I don't know how stable the rear end would be doing that.
 
Re: MOT time - and failure...

V8P6B said:
I'm going to try bleeding the brakes first, as there may be air in the system.
Click to expand...

That would affect both calipers, not just one, and certainly wouldn't have any bearing on the handbrake not working, so I'd say don't waste your time bleeding it. You may have to bleed it after you've fixed it, so wait until then.


V8P6B said:
I'll pop the driveshafts off, remove the pads and make sure the adjusters are working properly.
Click to expand...

That's where I'd start.


V8P6B said:
I did read somewhere that you can put the car on ramps, and drop the diff with the driveshafts in place to get better access to the calipers, but I don't know how stable the rear end would be doing that.
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Another waste of time and effort, which would make the job more difficult, not easier. There's plenty of room to do everything you'll ever need to once the driveshafts are dropped and the discs are off.
 
Re: MOT time - and failure...

Cheers Harvey That makes sense. I reckon it'll be easier to bleed the brakes (if I need to) once the discs are off too. Where's a good place to support the car under the rear? I've got it on ramps at the moment, just to give it a visual. Can I put axle stands somewhere like the ends of the rear crossmember that the trailing arms go into? Or under the rear springs somewhere? Obviously NOT the dedion tube... Doesn't seem to be many good places to put them.
 
Re: MOT time - and failure...

V8P6B said:
Where's a good place to support the car under the rear? Can I put axle stands somewhere like the ends of the rear crossmember that the trailing arms go into?
Click to expand...

That's probably about the best bet. Chock the front wheels as well.


V8P6B said:
Doesn't seem to be many good places to put them.
Click to expand...

I'd agree with that.
 
Re: MOT time - and failure...

Right, Saturday morning job, Driveshafts off, rear discs & pads removed, Everything seems free. Pads had plenty of meat left on them, and were evenly worn (i.e. the same both sides). Adjusters didn't appear to be seized, in fact I wound them back in with my fingers. The handbrake was good enough for me to undo the driveshaft bolts, and they were F****in tight, so that was encouraging. After removing the discs & pads, I got 'er indoors to operate the handbrake and footbrake to see what was happening. The handbrake operated the non hydraulic piston correctly on both sides, and they adjusted out with successive pumps of the brake. I wound them back in easily by hand on both sides. The pivot pins were free on both sides. Before I put the discs back in, I bled the brakes, just to make sure there was no air in them, I figured it was easier to get to, and I used a vacuum bleeder. I refitted the inner pads, then the discs, and built it all back up. Operated the handbrake, and nothing at all on both sides, wheels span freely with the handbrake on. I figured that as I'd wound the pistons back in on both sides, they should adjust up automatically. After operating the handbrake many times, (I could hear the adjusters clicking while doing this), the handbrake came back up on both sides, so I know the adjusters are working ok. The handbrake again was good enough to hold the disc while torquing the bolts up, so should be good enough for the test. Everything seems ok, but I will adjust the handbrake cable, as the lever comes up a long way before the handbrake operates. It's back in for its retest Monday, so hopefully it will pass ok this time. Fingers crossed... :?
 
Re: MOT time - and failure...

Well, the good luck never worked. Rear N/S brake still not working properly :( :( I couldn't see anything wrong when it was stripped down, the piston was moving in & out correctly when the brake pedal was pressed, and when the handbrake was pulled. I know the adjusters are working ok, cos when I reassembled it all, there was no handbrake at all until I'd pulled it on & off a lot of times, and both sides adjusted up ok. The swivel pins are clean & free on both sides. So, unless the link pipe is a problem, (its only 3 years old & looks like new), then I guess the caliper's gonna have to come off for further investigation. There were no signs of fluid leaking out anywhere, and it is working, but not enough. So piston seized? Link pipe? The O/S brake is fine. Its so annoying... :evil:
 
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