Hi, got a problem with the near side brake caliper on my mk2 uno turbo. When the handbrake is up the near side rear wheel is turnable. However the offside brake is solid??

Only changed the that caliper about 2 years ago with a lockheed recon, and now is seems to be failing. I have taken the caliper apart and the seals and piston seem to be moving freely.

Checked the hand brake cable to the caliper and seems to have enough tension. I have also tightened the hand brake cable, which did make any difference.

What else can I try to get it working?

Hmmm. I've never had problems with the rear-wheel calipers. Have you tried slackening off the cable all the way at the handbrake lever? Can you see the cable moving the lever on the caliper? If not, then perhaps you have a seized cable.

Now that I think about it, I have had this problem after all with a Lancia Thema (similar rear-disc setup). It was after I wound the pistons in for a pad change, the self-adjusting mechanism just would not self-adjust. The problem was a partially-seized cable, meaning that the caliper lever would not go fully-off. I reckon if you slacken the cable off, pry the caliper lever 'off', and then apply the footbrake a few dozen times, that should allow the self-adjuster to adjust.

-Alex

Hi Alex

Thanks for the reply.

>> Have you tried slackening off the cable all the way at the handbrake lever?

Previously the handbrake lever would go up about 4 clicks, now i have over tightened to about 2 clicks and which hasn't improved things.

As I understand, too much play on a handbrake lever is a MOT failure. Anything more than 4 clicks could be considered as a MOT failure.

>> Can you see the cable moving the lever on the caliper?

The cable does move the caliper lever fractionally when the handbrake lever moves up and down. However the movement is very slight, compared to the offside caliper that works fine.

I traced the short handbrake cable from the caliper to a pulley system, and checked for play. When the handbrake lever is pulled up the pulley moves approximately 1.5cm to the right, which intern pulls the nearside caplier lever. Not sure it this movement is sufficient.

The pulley was covered in muck, I cleaned off with a wire brush, sprayed the pulley wheel and pivot with WD40. I then applied normal grease to the pulley wheel, cable and pivot. Moved the pulley left to right for the lube to work through and identified amount of play.
I did notice that when the pulley is fully levered to the right, using a long screwdriver, the caliper doesn't lock the wheel tight. This makes me think the caliper is at fault. Not sure exactly how the internal workings of this caliper, and how to identify problem.

For your guidance, with the claiper away from the brake disc, I noticed that when the level is pushed down several times to piston moves up. Eventually it will reach a maximum height, which seems more than sufficient to lock pads to disc. I had to turn the piston clockwise to lower back into normal position. Not sure if is normal behaviour.


>> The problem was a partially-seized cable, meaning that the caliper lever would not go >> fully-off. I reckon if you slacken the cable off, pry the caliper lever 'off', and then apply >> the footbrake a few dozen times, that should allow the self-adjuster to adjust.

Will try the above, but unsure what you mean by "pry the caliper lever 'off'"? How do I do this?

Thanks

Mario

maybe then screw mechanism inside the caliper that activates the handbrake is stuffed or stripped. remove the caliper and take out the piston, then actuate the lever on the caliper and check if the screw moves up or down, if it does'nt you better invest in a new caliper.

M@nticore said:

maybe then screw mechanism inside the caliper that activates the handbrake is stuffed or stripped. remove the caliper and take out the piston, then actuate the lever on the caliper and check if the screw moves up or down, if it does'nt you better invest in a new caliper.

Click to expand...

Hi M@nticore

Thanks for the post

When I removed the piston, I pushed the lever on the caliper right down. The screw moved about 1cm up. Not sure is the right amount of travel?

Didn't seem enough, but thought if the screw is moving up, then it should be working.

that is more than enought movement, remember when your pad gets pushed against the disc it only needs about 2-3mm to lock the disc with the pads.
Check your cables, as the one might be stuck.

Hmmmmm... sounds like you have most of the checks done...

Gun_Metal_Grey said:

Previously the handbrake lever would go up about 4 clicks, now i have over tightened to about 2 clicks and which hasn't improved things.

As I understand, too much play on a handbrake lever is a MOT failure. Anything more than 4 clicks could be considered as a MOT failure.

Click to expand...

I think you should have at least four clicks travel for the adjusters to work properly (as described in my previous post). I would be very surprised if you failed the MOT based solely on 'number of clicks'. In fact, I'm sure you won't. Some cars have a finer ratchet than others (the one in the Uno is not very fine...) so it would be impractical to set a 'four-click limit'. As you say, too much play in the handbrake is the fail (e.g. if the lever came up more than 2/3rds of the possible travel with nothing happening).

You will find that if the adjusters do their job correctly, the handbrake will end up with less travel than what you might need in the first place to get them working. You can always tighten it up again later if you're not convinced

Here is the 'official' word from the handbook:
"Follow this procedure to adjust handbrake lever travel:
- Pull the lever up three or four "clicks".
- Loosen tensioning locknut A; turn nut B until cable C is taut, then tighten the locknut.
- Ensure car does not move when the handbrake is engaged."

I personally would beg to differ - I always adjust the tension with the nuts, etc. unloaded (lever fully off). I don't know how you would otherwise decide how 'taut' to make the cable! But you can gather from the above instructions that at least three or four clicks would be the result (probably more, if the cable was not left particularly 'taut').

For your guidance, with the claiper away from the brake disc, I noticed that when the level is pushed down several times to piston moves up. Eventually it will reach a maximum height, which seems more than sufficient to lock pads to disc. I had to turn the piston clockwise to lower back into normal position. Not sure if is normal behaviour.

Click to expand...

This sounds good. That is the action of the self-adjuster that you are seeing. My concern is still that this self-adjustment (that you have seen by operating the lever) is not occuring when the cable is connected, because the cable is not slack enough to allow the lever to go fully-off (or, the cable is partially seized and therefore not allowing the lever to go fully-off).

Will try the above, but unsure what you mean by "pry the caliper lever 'off'"? How do I do this?

Click to expand...

Right, I meant that the lever should be fully-clockwise (against its stop, as you look at the caliper underside) and therefore in the handbrake 'off' position. I think also that you should disconnect the cable (I know that it's a nuisance, but that will enable you to check it for seizure*)

I still think that the problems are most likely to lie in the cable or the tension... and less likely to be in the caliper itself.

-Alex

(* - spelling? "i before e, except after c, and except in 'weird' and 'seize'..."?

Well, I found these interesting pages:
http://www.motuk.co.uk/manual_310.htm
http://www.motuk.co.uk/manual_370.htm

Pretty complicated, but absolutely no mention of the number of clicks present at the lever? The only requirement is that once fully applied, the lever "must not be at the end of its working travel". I think you will find, in the case of the Uno, this is approximately ten clicks or more (the lever would be pointing straight up!)

Thanks,
-Alex



-Alex

alexGS said:

Well, I found these interesting pages:
http://www.motuk.co.uk/manual_310.htm
http://www.motuk.co.uk/manual_370.htm

Pretty complicated, but absolutely no mention of the number of clicks present at the lever? The only requirement is that once fully applied, the lever "must not be at the end of its working travel". I think you will find, in the case of the Uno, this is approximately ten clicks or more (the lever would be pointing straight up!)

-Alex

Click to expand...

Hi Alex

Thanks for the info and the MOT link is quite good...gives you the load down on what exactly a MOT inspector checks for!

I think we managed to sort the handbrake problem;

We identified that the handbrake cable at the rear wasn't balanced; right side had too much resistance. So we inspected the pulley system [see photo]again, and added extra lube and wedged a long screw driver into the pulley and moved it side to side several times. Also hit the bastard a few times with a hammer. This freed up the pivot.



We then looked at the caliper lever, that has the cable hooked into it [see photo] again lube was added to moving parts, including the cable. I pryed a long screw in between the lever and the caliper body, moving the lever up and down several times. This was done to both sides.



We moved the handbrake lever up and down.

As I was parking up the car, the foot brake has become very spongy, and car will not stop!! Gonna take a look this weekend, maybe I have to bleed the rear brakes.

Good stuff - photos are good too!
I like the bit of our language in there: "hit the bastard a few times with a hammer". I thought that was a Southern Hemisphere thing

Not sure why the brakes would now have become spongy, but you can never bleed the brakes too many times!

Let us know when it passes?

Thanks,
-Alex