Rear Brakes Binding

[oligoon]

The MOT man told me that the rear brakes are binding a bit on my 02 Leon Tdi - so i took the wheel off to make sure th sliding caliper hadn't stuck.

However it appeared that the handbrake actuator lever was stopping the pads coming off totally as it was resting on its end stop.

is there any adjustment that can be made on this?

is there anything else to look for?

 

[ninjabadger]

i know what this is i had same thing striped brakes right down still did it changed left hand brake cable no more trouble

 

[oligoon]

ta for reply,

however the cable is slack enough in the little actuator arm that the bobble on the end can be slipped out of its holder on the end of the arm. it seems to move freely enough too.

i did bend the end stop a bit so that the lever had more ability to take the brakes off, however it did not seem to really want to.

is there a drawing somewhere of how these brakes work? or have haynes produced one of their "super" manuals for the mk 1 leon yet?

 

[ninjabadger]

what are your pads like try spraying round the lever with wd 40 and tap the arm back and forward with a hammer

 

[Muttley]

oligoon wrote

however the cable is slack enough in the little actuator arm that the bobble on the end can be slipped out of its holder on the end of the arm. it seems to move freely enough too.

Too loose then.

Jack up the rear (chock the front so that it doesn't roll away ) Handbrake full off, spin each rear wheel. Do they spin freely or do they bind?

Apply the footbrake. Does each of the wheels stop?

Apply the handbrake. Same question.

All cars with rear disks have a weakness in the handbrake mechanism, except those that use a separate brake system (pads or a drum) just for the handbrake. The handbrake is mechanical and acts directly on the rear caliper pistons. The rod is threaded and rotating the piston moves it up or down the thread, for adjustment. There is a little slack in the actuating rod (enough to let the pads knock off the discs, like the front brakes do), but once this is taken up the piston is forced to rotate up the rod to make contact with the disc.

Water and dirt get into the caliper where the actuating rod goes in and this can eventually jam the mechanism. This could be what you have, with the handbrake lever in the caliper jammed part- or full-on, not allowing the pads to retract and clear the disc.

i did bend the end stop a bit so that the lever had more ability to take the brakes off, however it did not seem to really want to.

You don't want to do that The lever at the caliper end should be just off the stops when the handbrake cable adjustment at the drivers end is correct.

is there a drawing somewhere of how these brakes work? or have haynes produced one of their "super" manuals for the mk 1 leon yet?

I've never found one.

 

[oligoon]

wow, nice reply ta very much - i can now understand how they work - cunning so that the application of the foot brake actually adjusts the hand brake for you.

like you say its probably down to grot on the threaded rod - presumably this is similar to a normal thread pitch of say 1.5mm. presumably without taking the whole thing apart its difficult to clean up?

i did try the rotate test (after both handbrake and foot brake application - it made no difference) - the nearside would go about half a turn before stopping on a hand spin, the offside maybe more. neither were very free.

 

[Muttley]

oligoon wrote

wow, nice reply ta very much - i can now understand how they work - cunning so that the application of the foot brake actually adjusts the hand brake for you.

It has to - the camming action of the pivot inside the caliper does not have a very large throw, so the thing has to self-adjust to keep working.

I did spend a lot of time underneath my old Mk.2 Golf GTI cursing the Girling calipers that had locked up after about 90K miles.

like you say its probably down to grot on the threaded rod - presumably this is similar to a normal thread pitch of say 1.5mm. presumably without taking the whole thing apart its difficult to clean up?

I've actually never been inside the caliper to find out, but it is reported as a "coarse" thread - it is there for adjustment rather than fastening, so it is expected not to bind up, unlike a nut and bolt.

i did try the rotate test (after both handbrake and foot brake application - it made no difference) - the nearside would go about half a turn before stopping on a hand spin, the offside maybe more. neither were very free.

You still have hand and footbrake operation, so things aren't bad yet. Do the handbrake levers on the calipers move very far when the handbrake is applied? You could try liberal application of WD-40 or the like to see if you can free the mechanism. If that works, try greasing the relevant parts, expecially where the lever pivot goes into the caliper.


The best description I've found is this one, albeit for an older car

http://www.eveshamsquash.co.uk/audi/parkingbrake.html

There's an exploded diagram of a Ford caliper here, but on its own it doesn't help you very much

http://www.fordscorpio.co.uk/images/rearcalipers.gif

 

[oligoon]

thanks again for the reply. that article is nice i will print it out and keep.