sidecar paul
Life time member
Number of posts : 1589
keefk1100lt wrote:Just about any K series 'box should fit. Internal gear ratios are:-
K75 - Gearbox Ratios 4.50 / 2.96 / 2.30 / 1.88 / 1.67 : 1
K100 - Gearbox Ratios 4.50 / 2.96 / 2.30 / 1.88 / 1.61 : 1
K1100 - Gearbox Ratios 4.50 / 2.96 / 2.30 / 1.88 / 1.61 : 1
The 75 seems to have a slightly longer first gear but otherwise they're the same. Externally, AFAIK, they're identical.
I don't know where this figure of 1.61:1 comes from.
All the BMW literature gives the top gear as 1.67:1 across the K range.
I believe the gearbox internals are common to all K's, the only differences being the paralever lug and some models had painted boxes.
Even the K1 has the same ratios according to my BMW sales blurb.
Paul.
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'84 K100RS (0014643) (owned since '85), 86 K100RS (0018891) with Martello sidecar (built as an outfit in '88),
'51 Vincent (since '67),'72 Montesa Cota (from new), '87 Honda RS125R NF4 (bought 2015)
....No CARS never ever!