Splines

[Fritz58]

Probably another daft question, but here goes: My “new” to me 1994 registered R1100GS came with no final drive. The one I have has 16 splines which I think is correct for a 1997+ bike. However the drive shaft has 20 splines, correct for 1994. Presumably the 17 spline drive shaft is better? Is changing that out the best option? Or change the input bevel? Thanks!

 

[Ian J Hartley]

I’m not sure I understand your question. As far as I am aware 16Tooth spline is the gear box end and 20tooth spline is the final drive end. So the 17tooth spline is a mystery to me perhaps others can clarify.

This explains driveshafts in detail.

/https://largiader.com/articles/driveshaft/

 

[Fritz58]

I’m not sure I understand your question. As far as I am aware 16Tooth spline is the gear box end and 20tooth spline is the final drive end. So the 17tooth spline is a mystery to me perhaps others can clarify.

This explains driveshafts in detail.

/https://largiader.com/articles/driveshaft/

Yes I already read the article - thanks! That’s how I worked out what I had. 16 splines need to fit into 16 grooves, so I assumed 17 splines around them. But I’ve probably just confused you and myself. I am just looking for a second opinion /advice on what to change - I’m thinking it should be the drive shaft as presumably 16 is an improvement on 20 which is why they changed?

 

[Ian J Hartley]

Nope, I’m still none the wiser.

I’m assuming your R1100GS has a 5 speed Gearbox with an output shaft with a 16 tooth spline. Which is standard.

I’m really not understanding the final drive having 16 Tooth spline. Unless it has the small end of the drive shaft still attached, which would account for you counting 16 Tooth splines.

Drive shafts which are 20 tooth at both ends are for the 6 speed later gearboxes.

 

[Fritz58]

OK. Currently on the bike which is a ‘94 is the shaft from your left hand two points, but the “female” sliding joint has 20 splines. However the male sliding joint has 16 splines. So I am looking for advice on the best component to change so the splines can align. The main shaft with the female or the final drive with the male. Hope that is clearer?

 

[Ian J Hartley]

I think iI now understand.

Sounds like the bike you got without a final drive didn’t have a complete drive shaft, just the half fitted to the gearbox output shaft.

The final drive you have has the missing half of the drive shaft, but will not connect to your remaining drive shaft because of the splines difference.

Trying to match the two might be difficult. Later model drive shafts are as I indicated in my earlier post. You might get some success trying Motorworks or James Sherlock to see if they have an earlier final drive shaft end which will match.
Failing that then maybe getting a complete shaft for the R1100GS might be the easiest route, at least you would know it would fit.

If I understand correctly you have this:-

 

[Fritz58]

I think iI now understand.

Sounds like the bike you got without a final drive didn’t have a complete drive shaft, just the half fitted to the gearbox output shaft.

The final drive you have has the missing half of the drive shaft, but will not connect to your remaining drive shaft because of the splines difference.

Trying to match the two might be difficult. Later model drive shafts are as I indicated in my earlier post. You might get some success trying Motorworks or James Sherlock to see if they have an earlier final drive shaft end which will match.
Failing that then maybe getting a complete shaft for the R1100GS might be the easiest route, at least you would know it would fit.

If I understand correctly you have this:-View attachment 482319

Yes! Just that. I think my question is which spline configuration is the best? 16 or 20 ? Was there an engineering reason why they changed or was it purely financial! I managed to find a 20 spline male end but it would be useful to know for future reference!