9 replies to this topic

[scott_65_cooper_s]

I'll try and keep this as brief as possible. Had my MOT on my Mk1 today, got an advisory on the brake pedal travel. Symptoms as follows, first press of pedal goes virtually to the floor, lift off and reapply and it's a good firm pedal and brakes work well.

The car's just had a full restoration and the spec is as follows:
- All new lines
- New remote servo
- New cooper s reservoir
- New rear cylinders
- New rear shoes
- Goodridge hose set
- New pistons & seals in the calipers
- New disks & pads on the front.

The system has been bled 3 times, twice by myself and once by the garage. So my question is, what else do I do?

One thing I have noted is that there were two different pedals for the Mk1, the first being 21A1426 for std cars and 21A1065 for cooper S. As I robbed an 850 deluxe for bits in my restoration, I assume I have 21A1426, could this "wrong" pedal be the source of my problems? If so where the f*** am I going to get a 21A1065 from as they are now obsolete. If my problem is pedal related, would a later pedal box on my mk1 reservoirs work?

Or Could it be the calipers.....

Really hoping someone can point me in the right direction.

Cheers

Scott

[pdaykin]

The pedal won't make any difference - it was slightly thicker and the pad is at different angle for head/toe

Check the master cylinder or possibly the hub/bearings for movement

Edited by pdaykin, 24 May 2013 - 09:19 PM.

[scott_65_cooper_s]

Hmmm... so the plot thickens. Master cylinder, along with hub bearings are all new, checked on Weds before mot and no play in wheel bearings. Cheers for the response though.

[sledgehammer]

I'm surprised it passed with that amount of pedal travel

 

pull up hand brake - does that improve it ?

 

to find the problem I would use a clamp on the flex pipe of each wheel to eliminate it

 

then by pass the servo if the above don't work

 

you mention 'New cooper s reservoir' - do you mean new master cyl ?

 

also check when bleeding - that the pedal returns all the way up - they can stick a fraction from the top

Edited by sledgehammer, 24 May 2013 - 09:29 PM.

[scott_65_cooper_s]

I'll have to check the handbrake on/off tomorrow, and yes I meant a new master cylinder. The cooper s one being larger.

[Captain Mainwaring]

Once you've eliminated wheel bearing slop - you've got shoe adjustment left.

Suggest you park up - get a firm pedal by pumping twice as you have been, leave the car for 10 mins and see if you have to do the same thing again. Don't move the car. If you can then this points to rear shoe adjustment (assuming the MoT tester didn't warn about excessive wheel bearing play).

 

How on earth the tester allowed an advisory only for brakes you need to pump up to stop is beyond me.

[Gr4h4m]

Adjust the rears up.

[scott_65_cooper_s]

Unfortunately I can't get out to have a look until tomorrow, but with a couple you saying adjust the rears, I suddenly had a thought. I have a manual bias valve replacing the one normally undef the subframe at the rear. I thought I had set it to nearly closed, so it is bias towards the front, however I may have misunderstood and have it fully open. The garage adjusted up the rear brakes and handbrake, so I'm now thinking I've created my own problem.

Will check & feedback.

[sledgehammer]

If the bais valve was nearly closed - then that would have caused resistance to flow - so air may still be in the back pipe work

 

wind it open & re bleed the backs

 

then set how it should be

 

still suprised it passed with a low pedal

 

also try a triple pump - hold down - then release the bleed - always works for me

Edited by sledgehammer, 25 May 2013 - 02:13 PM.

[scott_65_cooper_s]

Well, been out and done about 30 miles today. As I thought, I'd left the bias valve open after I bled the rears. Readjustment and bedding everything in, pedal feels much better & overall much more confidence inspiring.

Thanks all for your advice.