BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down    Lower first gear on Fri Jun 05, 2015 8:26 am

floyd

avatar
Life time member
Life time member
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.


__________________________________________________
1984 K100 Adventure Bike
    

2Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 4:05 am

K75cster

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


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

3Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 4:38 am

floyd

avatar
Life time member
Life time member
@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.


__________________________________________________
1984 K100 Adventure Bike
    

4Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 4:45 am

charlie99

avatar
VIP
VIP
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 ?


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

5Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 4:59 am

floyd

avatar
Life time member
Life time member
@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 Wink

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 Mad


__________________________________________________
1984 K100 Adventure Bike
    

6Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 5:03 am

charlie99

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

giggles


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

7Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 5:13 am

floyd

avatar
Life time member
Life time member
@charlie99 wrote:um 40 to 240 in 5th gear ...nope they don't like to crawl

giggles

Thats flying, not crawling!


__________________________________________________
1984 K100 Adventure Bike
    

8Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 5:20 am

floyd

avatar
Life time member
Life time member
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


__________________________________________________
1984 K100 Adventure Bike
    

9Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 7:08 am

Holister

avatar
Life time member
Life time member
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


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

10Back to top Go down    Re: Lower first gear on Mon Jun 08, 2015 10:13 am

floyd

avatar
Life time member
Life time member
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 Laughing

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


__________________________________________________
1984 K100 Adventure Bike
    

11Back to top Go down    Re: Lower first gear on Tue Jun 09, 2015 4:11 am

RicK G

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


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum