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Now the truth comes out Thu Jul 11, 2013 2:40 pm
Rick G
admin
After getting some questions as to where the info came from about the K100 and K75 gearboxes having different top gear ratios I did some investigating with the parts book/s
I first got the info on the motobrick site and I questioned it then and was shown copies of the original sales brochures that BMW printed for the North American market and most likely the rest of the world as well.
It stated the K100 as having a top gear ratio of 1.61 - 1 and the K75 was 1.67 - 1. This can not be correct as the part numbers for all the 8v engines K100 or K75 are as follows Drive gear on the input shaft is 23211 451 039 and has 18 teeth that is common all the way through to the end of production of the 5 speed getrag gearbox which was 3/1997.
The driven gear on the output shaft part number is 23211 451 075 and is a 30 tooth gear and is the same right through the production of gear boxes for the 8 valve engines.
However there is a difference in the gearboxes for the 16 valve engines K1 K100 RS 16V and all K1100, the driven gear is part number 23211 461 900 and it is a 29 tooth gear.
So actually the difference is between the 8v and 16v engines not the 3 and 4 cylinder engines.
The ratios are correct but the 8v engines have a 5th gear ratio of 1.67 - 1 and the 16v engines have a 5th gear ratio of 1.61 - 1.
This info has come from real OEM which we all seem to accept as a reliable source for this type of info.
I first got the info on the motobrick site and I questioned it then and was shown copies of the original sales brochures that BMW printed for the North American market and most likely the rest of the world as well.
It stated the K100 as having a top gear ratio of 1.61 - 1 and the K75 was 1.67 - 1. This can not be correct as the part numbers for all the 8v engines K100 or K75 are as follows Drive gear on the input shaft is 23211 451 039 and has 18 teeth that is common all the way through to the end of production of the 5 speed getrag gearbox which was 3/1997.
The driven gear on the output shaft part number is 23211 451 075 and is a 30 tooth gear and is the same right through the production of gear boxes for the 8 valve engines.
However there is a difference in the gearboxes for the 16 valve engines K1 K100 RS 16V and all K1100, the driven gear is part number 23211 461 900 and it is a 29 tooth gear.
So actually the difference is between the 8v and 16v engines not the 3 and 4 cylinder engines.
The ratios are correct but the 8v engines have a 5th gear ratio of 1.67 - 1 and the 16v engines have a 5th gear ratio of 1.61 - 1.
This info has come from real OEM which we all seem to accept as a reliable source for this type of info.
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"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived." Dalai Lama
Bikes 1999 K1100 LT with a Big Block 1200
