speedo gear box

hndnbus72 · Post by **hndnbus72** » Wed Jun 22, 2011 2:06 am

I have recently had to rebuild my rear hub on my 1956 Matchless G80S.
I have yet to install the speedo gearbox as this is what I believe was the cause of the failure and destruction of the rear hub. I have followed the procedure found on line here. I noted that the past owner had added extra shims etc which I am sure did not help. Now to my question, when I install the gearbox and cable how tight should the jamb nut be and also the axle nut? I assume the axle nut should be fairly tight but I am worried the jamb nut was to tight in the first place and started part of the problem. Any help would be appreciated. The bike runs great without the gearbox as I have done some short test runs till the cable arrives.
Regards
John Hanson

wilko · Post by **wilko** » Wed Jun 22, 2011 11:29 pm

There must be a spacer on the inside for the nut to tighten against, or you will just crush the body of the drive thinking it's tight!

Rob Harknett · Post by **Rob Harknett** » Thu Jun 23, 2011 12:30 am

Just be sure, when the wheel is all tightened up by the spindle not. you then and only then can rreally tighten up the speedo drive nut. Make it real tight, or, it may come loose and turn winding up the cable till it snaps or you get thrown off the bike. Of course, if you ever want to get the speedo drive off, you first undo that lock nut before loosening the spindle nut. Having seen what a loose speedo drive nut has done to others, I regulary check mines tight as can be.

Merlin · Post by **Merlin** » Thu Jun 23, 2011 1:00 am

Very true been there done that,I am now paranoiak about that bloody nut.

zwarts · Post by **zwarts** » Thu Jun 23, 2011 10:02 am

I am sorry to throw a spanner in the works on this one but I see no reason why the speedo gearbox retaining nut (part no.021593) needs to be much more than finger tight. If the hub bearings, seals and spacers are correctly assembled and the speedo gearbox is in good order, then this nut somply keeps the gearbox driving dogs in engagement with the slots in the bearing adjuster ring (part no.021583). I set mine up with the cable in position and then just 'nip' the nut lightly with a spanner. In many years/miles of AMC riding this has always been more than adequate. If you consider what the nut does, and the consequences of the speedo gearbox seizing, it is pointless overtightening this nut. Consider what the gearbox is made of!
Bob.

Malleon · Post by **Malleon** » Fri Jun 24, 2011 12:30 am

Mazak??

ianselva · Post by **ianselva** » Fri Jun 24, 2011 11:33 am

quote:
I am sorry to throw a spanner in the works on this one but I see no reason why the speedo gearbox retaining nut (part no.021593) needs to be much more than finger tight. If the hub bearings, seals and spacers are correctly assembled and the speedo gearbox is in good order, then this nut somply keeps the gearbox driving dogs in engagement with the slots in the bearing adjuster ring (part no.021583). I set mine up with the cable in position and then just 'nip' the nut lightly with a spanner. In many years/miles of AMC riding this has always been more than adequate. If you consider what the nut does, and the consequences of the speedo gearbox seizing, it is pointless overtightening this nut. Consider what the gearbox is made of!
Bob.
That was the logic I used when re-assembling my rear wheel after the usual gearbox seizing /bearing undoing saga. In fact I even thought about cutting the cable threads down so it became an easy release item if it did seize and just pulled the cable off spun round.

Merlin · Post by **Merlin** » Fri Jun 24, 2011 12:14 pm

The crimp on the end of my cable is loose so that's what happened the next time the nut came loose,the cable just pulled free pushed back nut tightened simple.