Any gurus out there know...?

Out of the plethora of gearboxes BMW have made....will any of them offer a lower first gear that will go into a K100 gearbox?

Would like to have more ability to craaaaawl along without working the dry clutch so much.

If you haven't used the 3.2:1 F/D from a K75, then that would be the 1st port of call.

K75cster wrote:If you haven't used the 3.2:1 F/D from a K75, then that would be the 1st port of call.

Cheers mate,

Soooo....This FD would have a lower rotational speed for a given engine rpm - correct?

Thanks for that one...obvious port of call as you say.

I have a feeling that all the ratios in the gearbox are all the same Floyd

the diff is the clue

unless you can do some magic in one of the similar r series boxes for first gear ....look for any monolever series for investigation is my guess ....twb and some others like the us based r series  mob might have some additional information ...swap gear sets for first ?

charlie99 wrote:I have a feeling that all the ratios in the gearbox are all the same Floyd

the diff is the clue

unless you can do some magic in one of the similar r series boxes for first gear ....look for any monolever series for investigation is my guess ....twb and some others like the us based r series  mob might have some additional information ...swap gear sets for first ?

Thanks Charlie....Was hoping TWB would chime in with a part number hehe. 

The 75 fd seems like a good idea...but will obviously effect the ratios across the board, rather than just 1st....that may be a good thing tho....my k loves to sit at 130-140kmh...just seems like thats where it wants to be....which gets me in trouble

I was a postie for a while, and the training they gave me was some of the best motorcycle riding instruction ive ever had. Anyways....we had to craaaaaaawl along so slow. The test was something like we had to ride 10m in 30secs without putting our feet down. and had to do turns on the spot at full lock for a while. Was good fun...

Anyways, the K dont like to crawl

um 40 to 240 in 5th gear ...nope they don't like to crawl

giggles

charlie99 wrote:um 40 to 240 in 5th gear ...nope they don't like to crawl

giggles

Thats flying, not crawling!

This graph compares the road speed of the RS, RT and 75 FD's on a K100 gearbox

The lines, from top to bottom, are RS, RT and 75

If you do the calculation for 3000rpm as an example there's 3.5kph difference

Your K100RS
@3k rpm in 1st gear @4.50:1
FD ratio @2.81:1
Tyre circumfrence = 2m
Road speed = 28.6kph

Your K100 with K75 FD
@3k rpm in 1st gear @4.50:1
FD ratio @3.20:1
Tyre circumfrence = 2m
Road speed = 25.1kph

Kaptain Holister wrote:If you do the calculation for 3000rpm as an example there's 3.5kph difference

Your K100RS
@3k rpm in 1st gear @4.50:1
FD ratio @2.81:1
Tyre circumfrence = 2m
Road speed = 28.6kph

Your K100 with K75 FD
@3k rpm in 1st gear @4.50:1
FD ratio @3.20:1
Tyre circumfrence = 2m
Road speed = 25.1kph

Thanks for some perspective Kapn Holister....

Having said that...when my current LT (swapped out from the knackered RS when I still had a spares cache...oh the days) packs it in, so to speak, I shall likely swap it out for a disc brake K75 unit....Time to investigate how many splines these units have....as Im also considering a driveshaft and swing arm lengthening and spline numbers are an obvious issue there.

fun stuff 

I wanna ride this beast to meet that Irish Eccentric mob we read so much about! 

All the K75s had a 20 spline drive whether it was drum or disc rear brake.