Parking Brake Problems
 

Hey everyone, have a curious problem that is intermittent and not reproducible on the 3 in my sig, it just happens when it happens. Problem is my parking brake works normally, the handle stops at the 4th click with normal force and the brake holds normally then it could be the next time I use it (if on paper routes could be the next minute) the handle will go almost to the very extent of its travel OR at the extent of its travel and the brake will not hold well on an incline. Attached are two pictures taken within 5 mins of each other, the first shows the brake when the handle goes right to the top, the right brake as you can see is NOT working, the next pic the handle worked fine and as you can see the right brake worked.

My dealership told me there is a ratcheting cam type system in the rear calipers that push the pistons (showed me a new caliper) but I am not 100% convinced this could be the problem, it does make sense but I want to be sure before I spend over $300 on new calipers for the rear. The dealership could not reproduce the problem to verify it though, they are just guessing.

Any other ideas on what it could be or any support for the dealers theory?

P.S.
I am uploading videos to YouTube showing the handle movement if anyone would care to view that also.

There is a ratcheting system in the rear calipers. When you replace the rear brakes (and compress the pistons) you have to pump the parking brake lever about 20 times to get them back into position.

Have you replaced the brakes in the rear? If so was it recently? If not have you checked to see their status? In some years of the 3 the rear brakes actually wore more quickly than the front, and the inner pad tended to wear much faster. I don't know that being worn a normal amount would cause this issue...... certainly shouldn't cause an issue with the brake lever itself.

Brakes are original but need to be replaced, they did pass inspection but just barely. I have kept an eye on them and they are getting thin, fronts need to be replaced as well (rotors included).

Lets play hypothetical: Lets say the pads are worn down, this means the ratchet system has to rotate as the pads wear to keep the parking brake in spec, this means that if I get new pads the ratchet might be turned back to a point where its not "worn" on the teeth (if that is my problem) and work properly again until I hit that point in the ratchet.

Does that make sense? Would it be better to just get new pads and see if that fixes this (at least until they wear down again)?

Yeah I cant quite picture how the handle travels all the way to the extent of its travel either, I can imagine that the arm that pushes the ratchet in the caliper slips and the cable just pulls it fully but I haven't seen the guts of the caliper to be sure that is what happens.

Well if the pads are at the end of their life you'll need to replace them anyway. Might as well do those and see if it makes a difference, and if not see if the calipers need replacing. You may be able to find replacements off of a junked car. IIRC the Mz5 uses the same caliper in the rear (just a longer bracket for bigger rotors) so that would increase your donor pool.

Cool thanks for that bit of info!!! I am going to the junkyard tomorrow if it doesnt rain and look for some 3s and 5s. If I replace the calipers I will tear them apart and see exactly what happened and post pics on here :D

MazdaTirol and icspots:

You may want to look at the ratcheting mechanism and see if a little lubrication makes it work consistently again. I have fixed somewhere around 100 bicycles and many of them have "rapidfire" shifters which use a ratcheting cam mechanism. If they don't work it is because the lube has dried up and that keep the tongue from dropping behind the teeth of the cam. A shot of WD 40 makes them work again flawlessly. (I made a few easy bucks that way).
If this picture is correct then the ratcheting mechanism is inside the housing above the bleeders. I would try to put some WD 40 in there and make it work.
http://www.eskimo.com/%7Ehwang/image...e5Brakes01.JPG

I did not read every word of this thread, so, sorry if I am somewhat off.

Your spot on, even have the exact caliper that I was shown, is that a bolt on top that can be removed to get some oil inside as well?

"Your spot on, even have the exact caliper that I was shown, is that a bolt on top that can be removed to get some oil inside as well?"

Honestly I don't know. I am the guy who would try opening the bolt to see what's behind. My guess is that this bolt hods the whole sub-assembly on the back of the piston.
But first I would apply a penetrating oil (WD 40) externally and move the lever by hand or with a prying tool.

I think Tanprotege is also trying to say at least loosen the bolt and spray some penetrating oil there before re-tightening, as well as other places.

Yes, noggin. But I have to make sure people understand that I have not taken that piece apart myself, meaning I could be wrong.

I am also not sure if there is a 'ratcheting" mechanism in there. I think the ratchet is built into the handle. What I expect in this housing is something more like a rack and pinion. The pinion would be at the inner end of the shaft and the rack would be a push rod that pushes against the caliper piston. Maybe the teeth don't always engage.
MazdaTirol: if you take it apart please take a picture and show us.