Comet Gearbox Crunching

[Steve Burden]

Thanks for the quick reply vibrac. Any idea what this plain ring steel is that was against the pressure plate. I cant see it on any drawings? Thanks Steve

 

[vibrac]

This is just to show all plates are the same of the two types perhaps it was just added rather than spending a few pounds on the lost friction spacing

 

[nkt267]

Short or weak clutch springs will make the clutch slip. John

 

[chankly bore]

Have this morning spent a little time on the new edition. Taken the primary case off after a trip to Halfords to buy some imperial hex keys. Does not matter how big my tool collection gets always need another. Stripped the clutch down for clean and inspection. Still not received my workshop manual yet so was just looking to see if anything jumped out at me. First of all the springs measure 30.35mm to 31.48mm. After printing some info from the technical pages on here I understand they should be 38.10mm min so this could be first problem found. Also after looking at the online drawing of the Burman clutch my steels don't seem to match this description. On taking off the clutch drum cover after removing the springs the first steel was a non splined steel. Next was a normal looking splined steel then 2 x clutch plates together with no steel in-between. I have done enough clutches in the past to know this is not correct is it? also i'm not sure what the first non-splined steel is doing is this acting as a shim?. The clutch plates don,t seen to have any meat on them measuring 2.99mm to 3.01mm. I would post a pic of the steels in the order I took them off. I took a picture just don't know how to upload. Any comments would be most welcomed. Not having the previous owner with us any more I cant ask the relevant questions as to why. Thanks Steve

A lot of your information seems incorrect. There should be six plain and five friction plates. The best plan is; 1.5 mm. plain nearest gearbox, then alternate friction and thin (1mm.) plain plates and 2mm. plain plate outermost. The clutch drum must be 1 1/2" deep to accommodate this. Springs should be 1 3/4" free length. There shouldn't be an adjuster in the centre of the alloy pressure plate. If you don't have the right drum, go for a new later type, fitted to some late Comets and machines such as Matchless with the GB52 gearbox. This will require new friction plates. You may also have the wrong centre. Check the mainshaft for runout and the condition of the splines. Do it up to gorilla strength after fitting the right locking tab. The Spares Co. has everything you need. Further information? just ask. Cheers, F5AB/2A/7945 since 1970 with an original clutch, plus Comet on Steroids (with a Newby clutch)

 

[Chris.R]

I have been looking at my 1954 Comet clutch which has not been used in the 30 years the bike stood in a museum she is nearly ready for the road but needs the clutch sorting, I have a new cable, if I need inserts how many are there, I recon 144 they look to be metaled inserts impregnated with copper elements? of course I have yet to fit cable and adjust to find out if I need to do anything else to my Comet.

 

[Martyn Goodwin]

New inserts???? The friction 'pads' are bonded. What makes you think they need replacing? Anyway if the friction plates are toast simply purchase new friction plates from the spares co. - there are 5 required.

On reassembly do NOT be tempted to use motor oil or ATF fluid in the primary drive case. The prefered oil to use (given whats available today) is MOTUL TransOil 10-30

 

[Peter Holmes]

Aren't bonded friction plates a fairly recent innovation, probably only available for the last 30 odd years or so, the originals Burman plates would have been inserts, as did the original twin pilot clutch plate.

 

[Martyn Goodwin]

Chris,
here is an extract from the Alternative Spares List, thats available from the Spares Co. For a Comet owner it is an invaluable resource. Identifies all of the clutch bits n the assembly sequence.

 

[brian gains]

the clutch drum isn't notched fouling friction plate tangs?, clutch centre not loose? clutch basket outer ring not fractured at junction with base/back plate?

 

[Chris.R]

Chris,
here is an extract from the Alternative Spares List, thats available from the Spares Co. For a Comet owner it is an invaluable resource. Identifies all of the clutch bits n the assembly sequence.
View attachment 35276View attachment 35277

Thanks Martyn I was only asking in case of a problem as the next step is to look at the clutch which has not been used in anger for 30 years.