Gearbox Identification:

[Voyager]

Me again . . .

I'm working on a Gearbox from a 1992 R100R (chassis & engine manufactured in September 1991). The bike has covered 50K miles.

What is confusing me is that the Gearbox appears to have been cast in 1981. It also had a 'Monolever' rear oil seal which isn't right for the Paralever bike.

Inside, all the gears are late models with the 17.5 degree helical tooth form.

It also has a circlip on the output shaft with a small 'expansion ring' behind it. This is correct according to 'realOEM.COM', but according to other sources (Snowbums/Joergs) boxes made between 1985 and 1994 didn't have circlips.

Also, the Gearbox Serial No. is a bit odd - R0G0300 - stamped upside down on the case just below the air cleaner. It doesn't match anything I've read.

So two questions for the 'Gurus' . .

1. Is this really a year of manufacture date cast into the box ???

On 'Flipfly's' box, this said '90' which appeared to be correct.

2. Is there a site that gives chapter & verse on the origins of individual gearboxes ??

We have that for Engines & Frames, but I can't find the equivalent for gearboxes anywhere.

I know that the late R100Rs were considered to be 'parts bin specials', but did they really come with old gearboxers in order to give them circlips on the output shafts ??

I have all the info I need to re-furbish the box, but I'm curious now


Bob.

 

[(RIP) Proff]

Cast in December 1981.....
Could have been rebuilt or replaced any number of times..

 

[Kenny]

Cast in December 1981.....
Could have been rebuilt or replaced any number of times..

WILL have been rebuilt many times !

 

[Voyager]

WILL have been rebuilt many times !

Well, hopefully not with only 50K on the clock. The bike was laid-up for a number of years as well.

Someone has been in there before but it all looks OK. Very little wear on the gear pinions & selectors but most of the bearings are shot. At least this one had shims

I would like to find out what the original gearbox details were if possible and have been hunting around the Internet without luck.

I suppose the original internals could have been transfered to an old case

More curious than ever now .

Bob.

 

[(RIP) Proff]

In the past, we have whipped a g/box out of a new bike to do a quick repair for a
customer, usually a warranty claim, when the new replacement box came from BMW, it was put in the new bike....

Didn't happen often, but more than once

Kept the customers happy...

 

[DrFarkoff]

I was going to say Bob perhaps they had a motorworks or motobins or various other sources' replacement gearbox hence updated internals in older gearbox?

 

[Voyager]

I guess we'll never know what really happened.

Anyway, a box arrived from Motobins this morning so tomorrow I'll hopefully start the re-assembly - with a 'high fifth' gear .

I'm taking photos as I go but I'm not intending to do ANOTHER Gearbox Refurb thread .

Bob.

 

[Rob Farmer]

I've been oop north for a week so the only communications possible were by carrier pigeon.

That's an early light flywheel gearbox case Bob. Internals could be and probably are a complete mismatch of parts. Check the code inside the end cover as well, often gives an interesting insight into the parts.

All the fun of the fair sorting the old knackers out?