Poor handbrake - Why?

[Aiketgate]

I recently replaced the rear callipers on the MGF.
Being an inquisitive type, I decided to strip the old callipers down, to try to discover the problem with the handbrake mechanism.

Let me say right away:- For me, this was an exercise of curiosity only.
I do not know how long this method will keep the handbrake working properly.

A WARNING

Don’t mess with your brakes unless you know what you are doing.

Having said all that, this is what I did.
The calliper showing the handbrake mechanism



PART A – STRIPPING, FREEING AND REBUILDING.

1/. Firstly, I disengaged the spring using a pair of long-nosed pliers. The spring can now be removed and at this point, attempt to rotate the mechanism. The lever should move freely against the pressure of an internal spring.

Ha! The mechanism was actually stiff, almost to the point of seizure!

Nb. Please note that any movement of the lever will move the calliper piston out from the cylinder. Using the long-nosed pliers, screw the piston back in (clockwise).
(in this picture the piston boot has been removed)

2/. Remove the 17mm nut and spring washer, and you will see that the lever has a rectangular locating hole that fits onto the shaft.
This is merely a push-fit, honestly! Some WD40 and a small persuader enabled me to loosen and remove the lever.

3/. Now you can see the shaft seal, beneath which should be some high temperature grease to lubricate the shaft, allowing easy rotation.
This grease degrades over time and usage, and causes the seizing problems. By carefully easing the centre of the seal aside, I was able to insert the feed tube of a can of WD40, and used it to flush the solid remnants of the old grease out.

4/. Now I temporarily refitted the lever, and repeatedly manipulated it until the mechanism became free.
Again, you need to remember to screw the piston back in as you rotate the lever back and forth.

5/. The lever should now rotate easily.
The internal spring should return the lever from this position(a)


to this position(b).


6/. I then refilled the seal by spraying-in plenty of white lithium grease, which is a solid high temperature grease, and rotated the lever to spread the grease further into the problem joint.

7/. I then rebuilt the mechanism by reversing the steps 1 and 2.


I REPEAT:-Don’t mess with your brakes unless you know what you are doing. However, if you want to refit the calliper and use it, it’s up to you. If so, follow part B.

Part B - REFITTING AND HANDBRAKE ADJUSTMENT


1/. Remove the sliding mechanism(in the concertina sleeves) on the carrier. Clean and re-grease with high temperature grease. Refit to carrier.

2/. To refit the calliper to the car, first refit the carrier to the hub(2x17mm bolts). This enables you to refit the brake pads onto the disc.

3/. Trial fit the calliper unit over the disc and pads, if necessary screw the piston in(clockwise) or out(anti-clockwise) until the calliper is a close fit(1-2mm clearance total.)

4/. You can then re-bolt the calliper to the carrier(2x12mm bolts), and re-connect the brake pipe. Now re-bolt the handbrake arm to the calliper(2x12mm bolts).

5/. Repeat 1-4 for the other calliper.

6/. Make sure that the handbrake cables are free and adjust them (under the centre console) until you can attach both back to the calliper handbrake levers. WITHOUT MOVING THE HANDBRAKE LEVERS. In other words, pull the cable to the lever, do not pull the lever to the cable.

7/. Adjust the cables again until the handbrake levers just begin to move. Your handbrake is now adjusted.

8/. Bleed the brake system. Test the brakes and handbrake are operating properly before road testing.

David

[Broon]

Thats fantastic mate. I have been meaning to tackle the rears, especially handbrake for a few years now, as its always a good candidate for an MOT fail.

I will use this guide in the spring/summer

[designad]

Excellent How To...thanks!

[jonathanharding]

Excellent advice - thanks.
I need to service my rear brakes as my F pulls momentarily to the right when braking from speed in the wet.

Questions
1. can the caliper piston actually come out of the caliper housing at any time?

2. Can this service be completly without removing the caliper from the flex brake pipe, if the caliper is supported / tied up?

[Petevick]

that could well be a very cost saving post

[Aiketgate]

Originally Posted by jonathanharding

Excellent advice - thanks.
I need to service my rear brakes as my F pulls momentarily to the right when braking from speed in the wet.

Questions
1. can the caliper piston actually come out of the caliper housing at any time?

2. Can this service be completly without removing the caliper from the flex brake pipe, if the caliper is supported / tied up?

Jonathon,
1/. Yes, if you keep manipulating the handbrake lever, and don't screw the piston back in, eventually it will come out of the cylinder, but the boot will stop it actually falling out.

2/. You could attempt to do this with the calliper still attached to the flexi-pipe, but IMO it would make the job a lot harder!
I suppose the way to do it would be to remove the spring, 17mm nut and spring washer, and the lever itself before removing the calliper from the
carrier. Otherwise I don't think you'd be able to exert enough force to get them off while the calliper dangled from the flexi-pipe.
However, the job is so much easier with the calliper 'on the bench' and it doesn't take long to remove the flexi-pipe - and to re-bleed the system afterwards(especially if you seal the fluid reservoir with cling film and tie up the freed flexi-pipe as high as you can). You are only refilling the calliper with fluid, and TBH, I would always do it by totally removing the calliper.

Anyway, sorry for the long answer, when I could have just said - It's possible, but not as easy!

David

[jonathanharding]

Thanks David - great info and advice
Jon

[Chris T]

Nice one Aiketgate!

[MGFNorway]

Great post! have to do this myself.

[Dr Dave]

Good work!

[MGFmad]

Thanks for doing this work and posting a write up I have just scraped a pass during my last 2 MOT's, even though my pads are set as close to the disc as possible. I have always planned to do the very work you have shown to see if anything can be improved.

This has provided the answer as the lever is not returning fully on my calipers. Now I know there is a cure.

Excellent.

[Aiketgate]

Thanks for all the kind words.

I thought I might strike a nerve with this thread, having read so many posts about poor handbrake function.

I have to say that when I compared the new calliper to the old, it was quickly obvious where the problem was.

Plus, I think that a lot of handbrakes are not adjusted properly, I know mine was way overtight, trying to compensate for the lack of movement in the handbrake levers, I guess.

David

[Tim.]

Good experiment David

[Dr Dave]

Originally Posted by Aiketgate

Plus, I think that a lot of handbrakes are not adjusted properly, I know mine was way overtight, trying to compensate for the lack of movement in the handbrake levers, I guess.

Indeed, I see it all the time. The caliper lever should be resting against it's stop with the handbrake lever in the off position.

[Petevick]

now added to my web site.

[Aiketgate]

Originally Posted by Petevick

now added to my web site.

OMG! Fame, at last!

[Station]

My car has failed on the handbrake (parking brake not adequate yadda yadda yadda).
I'm just wondering if the cable is stretched or the handbrake calipers mechanism is seized? I will have to check it out in moment.

[cjmillsnun]

Originally Posted by Station

My car has failed on the handbrake (parking brake not adequate yadda yadda yadda).
I'm just wondering if the cable is stretched or the handbrake calipers mechanism is seized? I will have to check it out in moment.

Most likely the calipers have siezed. It is a common problem on the F and TF

[Aiketgate]

Originally Posted by cjmillsnun

Most likely the calipers have siezed. It is a common problem on the F and TF

Yep, Callipers! Almost certainly.
You can get recon. callipers for £60-70, or try the above marvellous piece of ad-hoc engineering prowess, made possible by the incredible talent of ME, ME, that's right ME!

David

[Tim.]

Originally Posted by Aiketgate

... , or try the above bodge

Think you're being a little unfair to yourself David.
If properly done; cleaned thoroughly and assembled nicely, its a proper job imo.