The MGF Register Forums

Hi All

Just over 100 miles ago, i replace the back disc and shoe on my MGF. As i knew it would not pass the mot. However it gone in for it mot and fail on it brakes.

The normal brakes are fine, and passed. It actualy failed on the hand brake. The near side is applying only 36kg, of stopping force and the off side is appy the about 136kg, of stopping force. Well i though it would we simple to fix today, but i recon i am not near in solving the problem. I know the system mean to self adjust to take up wear is this a issue.

I've take the near side brake caplier apart and read greased. i have tighten up cables a litte under the hand brake.

Any idea what else could be causing this?

look forward to your response.

The procedure for replacing the rear brake pads carries a CAUTION that you must seat the pads by the footbrake before applying the handbrake in order to set the auto adjust.
Alternatively you may have a typical seized rear caliper.
Geoff F.

I have re seat the near side wheel, only. Should i actually do both at at the same time.

With the auto adjust should i also give some slack at the hand brake side before applying the hand break.

I would disconnect the handbrake cable on both sides and if you have time put the wheels back on and take the car for a run pressing the foot brake a lot then reconnect the brake cable. This may help but I suspect you are going to need a new caliper.

Chris Tideswell wrote:I would disconnect the handbrake cable on both sides and if you have time put the wheels back on and take the car for a run pressing the foot brake a lot then reconnect the brake cable. This may help but I suspect you are going to need a new caliper.

Chris, I've got the same prob. Sticky caliper. There are repairs kits around on the net at a fraction of the cost of a new caliper. You know if they are any good, or just delaying the inevitable? I always used new rubbers on the old shoe brakes.

I looked into a rebuild kit but all you get are new seals, and as far as I can tell there is nothing wrong with the seals as the problem is more mechanical. I have one of my old calipers and I plan at some time to strip it down to see if the problem can be fixed, it maybe that they just need striping and cleaning. If you have the time it maybe worth a go reconditioning one of the calipers but be ready to buy a new one if it doesn't work.

A brand new rear caliper from Xpart is £105 (each inc VAT).

Chris Tideswell wrote:I looked into a rebuild kit but all you get are new seals, and as far as I can tell there is nothing wrong with the seals as the problem is more mechanical. I have one of my old calipers and I plan at some time to strip it down to see if the problem can be fixed, it maybe that they just need striping and cleaning. If you have the time it maybe worth a go reconditioning one of the calipers but be ready to buy a new one if it doesn't work.

A brand new rear caliper from Xpart is £105 (each inc VAT).

"more mechanical' Can you explain? I know the cost of new, hence my query.

There is two parts to rear calipers, the hydraulics and the mechanical part that operates the hand brake. What happens is when the hand brake is released is the mechanism should disengage the piston, but over time this doesn’t happen meaning that the piston is still pushing against the pad leading to the brakes binding.

When I fitted the new caliper last month I took some time to try and understand how to set the handbrake up properly (not just twiddling the adjuster nut) but it's difficult to explain without a picture.

Hi Chris, do you have links to setting up handbrake "properly"?

I'm struggling a bit as I think I inadvertently did something "out of order" during or before changing rear brakes (I was trouble shooting binding issue before knew about handbrake adjustment rules) and I want to "reset" the cable system before adjusting... essentially is there a default position for the adjuster bolt or cable slack / distance to bolt? If not, what if someone does the things they shouldn't, for example adjusts before pumping brakes, or pumps before finished adj, or pulls lever before finished adj, and so on..
how do I start everything from scratch?? This info I can't seem to find...

Issue is my rear nearside brakes were binding a lot and it seems sticky but still rotates and releases (not as smooth as offside), and was full of crud (other side fine), and I've managed to free up binding by taking the caliper off and reattaching (I think I pumped brakes after and no binding) but if I move handbrake mech on caliper or adj it binds again

For now just looking for clear adjustment guidance if you have it

Many thanks
Marc

As Chris says, it's difficult to work out what is happening as it's all enclosed

Just a couple of points: Disconnect the cable via the clevis pin, and try and work the caliper lever by hand. It will probably need some extra help using a bit of tubing over the lever, or Mole grips. If it seems difficult to move, use brute force to get the movement you want to see. There is a roller bearing that corrodes over time, and probably loses any lubricant that was there when new. If you can move the lever to and fro with grinding noises, then the rollers have rusted up - but might well loosen up if you continue the exercise the arm. Don't forget that part of the caliper is open to the atmosphere, no hydraulic fluid/ action near this part of the mech. Water can and does get in over time causing rusting up of the roller bearing. There is no harm in crunching up the mess inside as it's already compromised, and can't get any worse.
If you are brave/adventurous enough you might be able to get some sort of lube/fluid past the rubber seal. If you accidentanly push the seal inside the caliper housing!!!!, all is not lost as you can use a suitably sized chunky "O" ring between the caliper body and the operating arm. (don't ask me how I know, but all has been fine for years now).
You want to get to the point where the lever can rotate ok, and snap back under the rotary spring smartly with no assistance.
If this is achievable, exercise the piston/seals by winding the piston back and pushing out using the foot brake several times.
If all seems ok, push the piston up against the disc, and then adjust the handbrake cable mech at the lever end. trial and error here as you don't want any pretension on the hand brake cable. A bit of slack to make sure all is working as it should (sort of), and then adjust properly after a bit of use.
As Chris has intimated, new calipers have needle roller bearings (or should have). Re-con ones seem to use hard nylon as a bearing as the roller bearing has a hole for a piston rod which acts on the bottom of the piston assy, and which is probably unobtainable.
Over the years, I squirt a bit of WD40 over the lever spring seal, and cover with some grease. 20 years on, the levers snap back as intended.
Sorry for the long ramble - fiddling about years ago seems to have made the calipers still ok.

If you do nee rear calipers 'Bitz have a sale on new ones for £ 85 a side but you could probably find tested 2nd hand ones for a fair bit less.