9 replies to this topic

[ryanill]

Model:mayfair
Year:1984

problem: hi im having trouble with my clutch in regards to the amount the pedal travels and of cource that leads to more travel on the slave.

i suspect the problem to the mix and match pedal box the mini came with as i hav a break pedal witch is the later type this the hexaginal kinda shaped pedal witch is correct as the older type was stoped in 1976 but my clutch is the old square type pedal as pre 1976. i first had trouble with the clutch not dis engaging witch i presume was as the older clutch pedal was a different profile it had less travel and when the clutch was next to the break the clutch pedals travel upon release stoped a good 2 intched befor the break did.so i took the clutch pedal out and using oxiasetalen i reprofiled the clutch pedal to sute the break. now my problem is that the clutch travels way to far and is dis engaging the clutch far to much so that when i go for a quick gear change there is so mutch travel on the way back the clutch is still out and i accelerate witch is slipping the clutch momentarily. what i need to know is when the pedals where redesinged in 1976 did they change the didtance between the point it pivots and the point they attatch to the master cyclinder. and would a correct period clutch pedal solve my problem as the only way i casn stop it at the moment is to manufacture an clutch pedal stop ro stop me over traveling the pedal but this will cause the pedals to be at different postions and have diferent amount of travel.

so for such a long post but any help would be mucg appreshiated

ryan

[Ethel]

I'm pretty sure the clutch master cylinder has always been 3/4" inch bore. The later (hexagonal) pedals do have an altered lever ratio to increase braking effort (hence the brake pedal sits higher because it also travels further to move the master cylinder piston the same distance). Since the master cylinders are in the same place on the body the only way to do this was to move the axle of the pedals closer, and since the clutch has the same axle it had to move too.

None of this should effect clutch operation too much as it can still only push the clutch arm from the return stop to the throw out stop. The best fix would be to shorten the pedal between its axle and the master cylinder pushrod so the pushrod is being pushed straight up the bore.


Sidenote: Metro clutch masters are 5/8" bore,

[GraemeC]

I'm

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I'm irritated by Firefox forcing me to use the quick edit button to edit posts

[ryanill]

hi ethal is it just the break pedal that modified on the new pedal or was the leverage point modified on the clutch to ?
ryan

[Ethel]

It was changed for the benefit of the brakes, but as they are on the same axle the clutch had to change too. I think the figures might be in one of the Vizard books but it can't be a lot. It just happens I've got my (little pedal) box out at the m so I could measure that.

hi ethal is it just the break pedal that modified on the new pedal or was the leverage point modified on the clutch to ?
ryan

[ryanill]

thanks ethel if you could measure the pivot pionts that would be usful.
i will also hav a look for the info on the net aswell thanks agine
ryan

[ryanill]

hi all just a little add on to my progress from last night.

i desided to do an experiment......

i dipped the clutch and released untill i was just on the bite witch was quite a way up off the floor. i then diped the clutch a fraction to release the clutch plates and got my glamerouse assistant to measure the gap between the pedal arm and the floor pan that it would stop up against. the measument was 40 mm rom the first bent in the pedal as you come down from the pedal bax to the floor see diagram..
 diagram.bmp   477.76K   2 downloads

now with this measurment i have made a temporary pedal stop. once this was fone i went out for a test drive. witch seems to have soldved the problem 90% but how even there is still a small amount or resistance on the return of the pedal. if i relese the clutch quickly for a swift gear change the clutch id still slightly slipping. the is a brand new master and slave on the clutch and it all been bled. is there any other cause for this slow returnas wen you reles the pedal you can phisicaly see the diference between the relese on the pedal and the slow return of the clutch.
ryan

[Ethel]

Have you got a return spring on the clutch arm?

55mm from centre of the pedal shaft to the centre of the clevis pin on both pre 76 pedals, in case anyone has a set of post 76 pedals to measure for the benefit of Mini kind.

[ryanill]

yes the return spring is brand new. was such a struggel to get on i would have thought there was no way the clutch could lag on relese.

the only part of the hydraulic system that i hav not replaced is the small flexibel hose from the copper pipe to the slave cylinder. could this be casusing troubel if it has perished in side ?

ryan

[Ethel]

It could, a simple test would be to compare the return time with and without the help of the bleed screw. you could check the clutch arm and plunger are nice and free as well.

yes the return spring is brand new. was such a struggel to get on i would have thought there was no way the clutch could lag on relese.

the only part of the hydraulic system that i hav not replaced is the small flexibel hose from the copper pipe to the slave cylinder. could this be casusing troubel if it has perished in side ?

ryan