Several clutch issues.

[rcbowman]

Long time no see, everyone.

So the clutch died the other day. I have not taken it apart yet, but through the hatch in the bell housing I can see, when I wiggle the fork holding the release bearing, that the cup that holds the release bearing now fits over the thrust plate on the clutch cover. That is to say, the graphite doughnut has not just worn down, it has disappeared. I expect to find bits of it down in the bell housing.

Anyone seen that happen before?

And no, before you ask, I don't ride the clutch or hold it down at stop lights. When I saw the design of the thing when I first pulled the gearbox, I got very careful about that. (I also put in a new release bearing at that point.) I have reason to suspect other things were out of adjustment, though...

But more to the point, I'm wondering about replacing it with a real ball-race bearing. I see one listed over at East Sussex Minors. I have seen on other threads here contradictory information about whether it's a simple replacement or only works with certain clutch covers. It's kinda expensive, though, so I don't want to do it without some expert advice.

The other matter: since I really hate pulling the gearbox, I may be replacing the clutch while I'm about it, so any recommendations or disrecommendations on the manufacturer would be welcome. I am leery of the manufacturer I got my current one from, because of this weird failure - though I recognize this failure doesn't have much to do with the clutch itself.

I note that the Borg&Beck model pictured over at ESM actually looks like the 1098 clutch in the manuals; mine doesn't - it has modern-looking fingers, but still has that thrust plate for the graphite bearing to ride on... a curious hybrid.

Any experienced opinions would be welcome. Thanks in advance.

p.s. one more thing: I'm wondering more and more about the people who previously owned my car, and exactly how many things they put together wrong. Does anyone know how much difference it makes if the release bearing fork is the wrong type? In the photos, 948 is curved, 1098 is straight, and this'll make a slight difference in the adjustment range. Is it a problem if you have the wrong one?

p.p.s. While we're at it, a real subtlety for you trivia buffs: on the clutch relay 'shaft with lever', what is the difference between the 948 model (com114) and the 1098 model (com115)? Is there a greater angle between the two levers on the later model? I'm suspicious I may have the earlier model on my car, and this may be pushing the adjustment range off as well. Thanks again.

[bmcecosse]

You could just get a lump of graphite machined and fitted into the old housing! Or - just get an engineering shop to fit a standard thrust type bearing (adapted from another car) into your thrust bearing housing. I only suggest because you are at a distance from the UK suppliers.

[Willie]

When I first stripped my Minor I found that it had an 'early' type of clutch fork and that incredibly the aluminium housing had been butchered and re
welded in an attempt to reposition it for the 1098 clutch. Bad idea. I think
that the 948 fork is slightly shorter than the 1098 (but not certain) so it is vital to fit the correct type. My factory workshop manual does not show pictures of these levers so it is difficult to identify the differences.

[rayofleamington]

From what I can gather having worked with the 1098, 948 and 803 gearboxes is that they all have different forks! There are also different bolt patterns to mount the front plate (the plate that has the pivot on it).
It is however possible to bodge different combinations to fit together (not recommended).

The 803 has a different lever ratio (pivot position) giving less pedal effort but also gives less clutch operating stroke.
The 1098 clutch cover is much bigger. The 948 and 1098 have a different offset in the release bearing - probably because of the much bigger clutch cover on the 1098.

Therefore to be sure of parts fitting properly it's best to use a matching set of parts.

As mentioned, other combinations are possible (eg 1098 clutch on a 948 engine with 803 pivot plate and lever on a 1098 gearbox! That took some drilling and filing...)

To use a 'ball race' release bearing, it is best practise to ensure that the release bearing is concentric to the clutch. If it is not concentric then it will wear out rapidly. Bear in mind that the Minor release system does NOT put the release bearing concentric to the clutch (it moves on an arc!). Therefore with the standard release lever and a roller realease bearing I would expect more problems not less.
If you can convert to a concentric release bearing (often used when people do a Type-9 conversion) then a roller bearing is the best choice (but can still be noisy )

[Axolotl]

p.p.s. While we're at it, a real subtlety for you trivia buffs: on the clutch relay 'shaft with lever', what is the difference between the 948 model (com114) and the 1098 model (com115)? Is there a greater angle between the two levers on the later model? I'm suspicious I may have the earlier model on my car, and this may be pushing the adjustment range off as well. Thanks again.

This may be relevant, from the workshop manual:-

"Cars from 198690 onward are fitted with modified clutch operating rods which are 5/16" diameter compared to 1/4" diameter of the earlier type. The increase in diameter also necessitates the use of modified pedal and relay shafts and when replacement parts are supplied for cars prior to No. 198690 they will be of the modified type and the remaining parts of the clutch operating mechanism will also be supplied."

It could be that ESM now supply both 1/4" and 5/16" shafts, rather than requiring you to replace all the parts together.

Also, at some stage, the pedals were re-aligned, with the clutch pedal and shaft being moved from inside the longitudinal member to outside it with a spacer going inside. That may also be the difference.

There's supposed to be a separate master cylinder cover-plate instead of the original sigle gearbox cover over all on cars with this arrangement of pedals.

Maybe one of you number buffs can say where in the series that shaft change occurred. It doesn't seem to be engine-size specific.

[rayofleamington]

Also, at some stage, the pedals were re-aligned, with the clutch pedal and shaft being moved from inside the longitudinal member to outside it with a spacer going inside. That may also be the difference.

As far as I can tell, the 'twin pedals inside the chassis leg' continued up to the end of SII and the 'clutch pedal outtside the leg' started with the Minor 1000 in 56

[rcbowman]

Thanks for the replies. Still looking for advice on designs and manufacturers of the clutch, though.

I think
that the 948 fork is slightly shorter than the 1098 (but not certain) so it is vital to fit the correct type. My factory workshop manual does not show pictures of these levers so it is difficult to identify the differences.

Nor mine. They seem to be allergic to picturing that particular part in any of the diagrams, both in the manuals and in the parts catalogues. However, ESM now has photos of the two, which is useful.

From what I can gather having worked with the 1098, 948 and 803 gearboxes is that they all have different forks! There are also different bolt patterns to mount the front plate (the plate that has the pivot on it).
It is however possible to bodge different combinations to fit together (not recommended).

I wasn't about to try fitting a clutch made for something else. I already ran into the problem when first fitting a new clutch (having before that time assumed I had the original engine and gearbox).

Still, there are different makers, some with the original pattern, some with a different form. Any recommendations?

The 803 has a different lever ratio (pivot position) giving less pedal effort but also gives less clutch operating stroke.
The 1098 clutch cover is much bigger. The 948 and 1098 have a different offset in the release bearing - probably because of the much bigger clutch cover on the 1098.

Hmm. This is interesting. I'm trying to figure out the details of my strange clutch adjustment, and this may be part of it.

Therefore to be sure of parts fitting properly it's best to use a matching set of parts.

I did buy a set last time, but I'm not entirely sure I believe in the manufacturer.

To use a 'ball race' release bearing, it is best practise to ensure that the release bearing is concentric to the clutch. If it is not concentric then it will wear out rapidly. Bear in mind that the Minor release system does NOT put the release bearing concentric to the clutch (it moves on an arc!).

Egad.

Why on earth... oh, right. Because it's not fitted on the column at all, so even if you have it contacting concentrically, as it pushes (and as it wears) it'll move off-center.

Therefore with the standard release lever and a roller realease bearing I would expect more problems not less.

At least this finally explains to me why they used the stupid graphite doughnut rather than a real bearing. I'd always wondered.

If you can convert to a concentric release bearing (often used when people do a Type-9 conversion) then a roller bearing is the best choice (but can still be noisy )

Sorry, 'Type-9'? What's that?

I'm not about to try any fancy conversion requiring precision machining. Not on important mechanical parts. I'm a metalworker, but not equipped (temperamentally or equipment-wise) for precision work. Especially since, if I screw up, the replacement parts have to come across the ocean. There isn't a nice, easy conversion kit for the 1098 ribcase to concentricize the bearing, is there?

[rcbowman]

The rods I've seen are all 5/16". My chassis number is in the 700000s, so it's not an issue.

Also, at some stage, the pedals were re-aligned, with the clutch pedal and shaft being moved from inside the longitudinal member to outside it with a spacer going inside. That may also be the difference.

As far as I can tell, the 'twin pedals inside the chassis leg' continued up to the end of SII and the 'clutch pedal outtside the leg' started with the Minor 1000 in 56

This is a left-hand drive car, so the pedal is outside the frame and has a heavy rod running through it to the inside. Er, or maybe you were talking about LHDs. In any case, that part at least is working, and not apparently an issue, and I'm just wondering about the rest of the linkage.

[rayofleamington]

Sorry, 'Type-9'? What's that?

It's a Ford RWD manual gearbox fitted on huge numbers of cars in the 80's and 90's

This is a left-hand drive car, so the pedal is outside the frame and has a heavy rod running through it to the inside. Er, or maybe you were talking about LHDs. In any case, that part at least is working, and not apparently an issue, and I'm just wondering about the rest of the linkage.

Ah - yes LHD and RHD are not the same thing when it comes to the clutch/brake pedal shaft arrangement. Sorry for forgetting you weren't in the UK! For the UK/RHD cars the pedal arrangement was changed in 56.

[bmcecosse]

No - not aware of any concentric conversion. But if you are a metal worker - you must know other metal workers - surely one of them could muster up a lump of graphite into the old housing ? I don't think you need to change too much here - the clutch was working/not slipping - yes ? So it's just a new grahite release bearing you need.

[rcbowman]

closer:

(the stuff in the corner is fragments of the graphite explosion)
...


Pretty dramatic. No wonder it suddenly didn't work anymore.

[bmcecosse]

Errrr - yes - it does look a little worn. Not much hope of putting new graphite in there then. I think you will just need to order a new one !! Or make one up from scratch. Graphite release bearings were very common in the 40/50 s - you may well find something from another (American) car that you can adapt to suit - although I appreciate that most are automatics - and not stick shift!

[rcbowman]

Oh, I'd already ordered and received the new bearing before taking it apart. ESM's nice about shipping overseas, and it's surprisingly quick. Probably quicker, easier, and cheaper than finding someone who has blocks of machinable graphite and a machine shop...