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final drives

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Daniel Shea
Posts: 1
New Member
Topic starter

I have an R75/6 1974, my late fathers old bike he bought brand new back in the day. I'll soon be rebuilding it. I'm certain it has the American final drive, for quicker acceleration with lower top speed. As I understand it there is a European final drive that would lower engine rpm at highway cruising speeds, I'd like to get one. What I'd like to know is the available ratios and perhaps advice on a good place to find them.
Thank you,

Posted : 04/28/2019 10:10
Richard W
Posts: 2546

• Look in your shop manual. Most good shop manuals will list all the ratios and what they were used on. Then check your ratio (stamped into the case) against the manual.

• Buy a working, assembled final drive, not the parts. The parts will take special tools and shims that most shops won't have.

• Use vendors shown in Airmail if you can.

Hope this helps.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

Posted : 04/28/2019 10:48
Ken Cruise
Posts: 6
Active Member

Hi Daniel!
I did the same thing, but read tons ahead of time. I installed a 2:91 ratio on my old R60/6 (33rd year with this bike). I had a rebuilt R75/6 engine so I was a little afraid I'd fond the gearing too high for climbing mountains in the passes. Instead I find the bike more relaxing than it used to be with the old 37:11 drive (less fuss and vibration at highway speeds). That being said, if you have the 32:10 it is not worth the bother and expense, as that ratio is close enough that there would be little difference. I have to gear down sometimes, but with a 5 speed it's OK. I am no longer looking for a sixth gear like I used to (maybe I'm just getting older!).


Ken Cruise

Posted : 05/03/2019 19:36


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