Rear wheel hub and speedo gearbox.

crawsue · Post by **crawsue** » Fri Aug 27, 2010 2:57 pm

After my recent thrilling rear wheel lock-up ,I am forced to renew my speedo gearbox.I ordered the one listed in the club spares scheme...no.900520...which states "similar to 024448".It arrived this morning but while my original gearbox drove the cable from the top this replacement drives from the bottom.Before I fit, can anyone confirm their compatibility? Casing numbers differ slightly,my original is no.Bg 5331/247 ratio 2/1...the replacement is no. BG5330/0287 ratio 2/1.If this is not the correct replacement can anyone suggest if the only other one listed in the spares scheme is suitable? It is no.900631 "lightweight and Norton wheel models".my 'bike is a bog standard G 80 1959. Also ,I have been studying "Biscuit's" excellent cutaway picture of the rear-hub assembly,and ordered without checking a new circlip as numbered by Biscuit as 017219.When it arrived it is described as "Circlip Front Hub" ,on studying the parts list I see that the correct parts number is 010740...can anyone comment if they are compatible? Thanks in advance.

Stuoyb · Post by **Stuoyb** » Fri Aug 27, 2010 3:32 pm

I too suffered a rear wheel lock up on my 1959 G12 last year.
I ordered the 900520, it fitted and has worked OK for the last 1000+ miles.

crawsue · Post by **crawsue** » Fri Aug 27, 2010 3:55 pm

Cheers for that,can you confirm that your original gearbox was driven from the top and the replacement from the bottom? C.

Stuoyb · Post by **Stuoyb** » Fri Aug 27, 2010 4:13 pm

Yes, exactly as you described.

crawsue · Post by **crawsue** » Fri Aug 27, 2010 4:19 pm

Thanks. Eamonn,if you are monitoring this post ,I have now confirmed with Jim Gunn that the circlip part number that "Biscuit" quoted is wrong,the rear hub circlip number is 010740...the one quoted 017219 is for the front hub.It may help circumvent some future grief if you can change it on the photograph.Regards CR

Eamonn · Post by **Eamonn** » Sat Aug 28, 2010 9:26 am

The photo and its details (click here to view) have now been updated accordingly.

Don Madden · Post by **Don Madden** » Sat Aug 28, 2010 6:17 pm

I had noticed the differing location of the cable mount of the gearbox, too. I have Hartley's "Matchless", both of Bacon's books on AMC, & both of Mick Walkers books on the marques as well as many other books. I reviewed the pictures of bikes at the factory to determine which was correct for the various models & years. I could find no clear pattern, some having the cable on top, others on the bottom. For me, it makes not difference but do not know why there is no consistantcy. The AMC bikes did use the more durable iron body with the squarish edges painted black, not the cast zinc with rounded edges painted silver that wear out immediately. I have gone through many of the zinc ones on other brands but never wore out the case of the iron ones.

I have found most of the old gearboxes are siezed from hardened grease that must be cleaned out before using.

Cheers, Don.