AMC Gearbox /clutch problem

[gotoole]

gearbox shaft dimensions.jpg

i wonder if anyone, who has easy access to a clutch or AMC gearbox. could help me with measurements on the output side of the gearbox.

I am refitting the clutch onto the gearbox which has had new bearings etc. fitted. The clutch inner fits onto the main shaft of the gearbox but goes on too far touching the end of the sleeve gear ( the output gear holding the sprocket.) When the clutch centre nut is tightened it locks the clutch mainshaft and sleeve gear/output shaft . As far as i can see , there should be a small, about 1/16" gap between the rear of the clutch inner and the sleeve gear.

I can only assume that the mainshaft is not extending enough from the gearbox, or that the sleeve gear/output shaft is extending too much , narrowing the space for the clutch inner. I have measured the distance between the end of the splines on the main shaft and the output shaft at 0.767" (19.45mm) while the corresponding distance on the clutch inner is 0.850" (21.61mm).

I have attached a photograph which will hopefully explain the measurements i am talking about. The measurement in red is the problem as it needs to be longer to accommadate the clutch.

However I have no idea what the actual measurements should be and I would be very grateful if anyone with access to a gearbox of clutch could make those measurement and compare for me.


All these parts fitted correctly bwfore refurbishment .

Thanks
ger

[dave16mct]

I'm sure someone posted with this problem recently. He did sort it so do a search.
Dave.

[Mick D]

Hi

Check your clutch centre - the splines should be stopped preventing the centre from sliding along the main shaft too far. Owners tend to overtighten the clutch centre nut thinking it will prevent loss of torque, however this action combined with normal use causes the spline stop to wear away and allow the cenrte to slide further along the main shaft and exhibit the symptoms you have.

Clutch Spline Stop.png

Not saying this will be the cause of your problem but it's the first thing to check - new centres are available.

Regards Mick

[gotoole]

Thanks for replies
Yes, Mick , first think i checked but the stops "look" okay. The difference is quite big, over 2mm - so i feel there is something wrong inside the box.

Thanks Dave, I will search again. - problem is AMC gearbox brings ups over 600 hits

[Mick D]

Hi

I have 19.74mm for the 'red' dimension.

Regards Mick

[gotoole]

Hi

I have 19.74mm for the 'red' dimension.

Regards Mick

Thanks Mick, so not too much different to my measurement. to the "stop".
I measured 21,6mm depth inside the clutch centre So perhaps the clutch centre is more worn than I thought.

[gotoole]

Sorry for reviving this thread again, but i have identified the problem as wear in the clutch spider allowing the clutch to push up too far on the mainshaft and bind up the gearbox. I now have a replacement spider and rubbers etc and want to rebuilt the centre. but it looks more daunting than i originally thought.

i wonder if any one can point me in the direction of instructions, or videos , in how best to go about this. i have removed the three screws and the top plate but I have not yet removed the spider or the rubbers

Appreciate any help
thanks
Gerard

[jack clegg]

Lever the old rubbers out. Something sharp & pointed stabbed into the middle of the wide rubbers first. Make sure you get the wide rubbers on the correct side on reassembly. Insert spider into centre whilst on the mainshaft. Insert wide rubbers first. Then using the clutch centre holding tool, compress the wide rubbers to enable room to insert the short rubbers. Can be tricky. Spider sometimes rides out when compressing rubbers.

[gotoole]

Thanks John
Sounds straight forward - hopefully I can manage it
Should rubbers be lubricated in any way?

[Mick D]

Should rubbers be lubricated in any way?

Hi

I used red rubber grease last time I did the job, worked well, if you don't have any then vaseline will work too, don't be tempted to use detergent.

I'd suggest you run a fine file over the edges that the rubbers have to pass in order to remove any sharpness and machining burrs.

Regards Mick