Tue, 04/24/2007 - 12:31
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This weekend I acquired a 1960 R69 with an "S" stamped transmission and a rear drive indicating 32/11 as the gears. I should also add the drive casing is nonvented.
It is very possible the rear drive was replaced sometime in the past. I haven't been able to identify the availability of those gears in a BMW much less an R69.
I've inquired at the archives but was curious to see if anyone here might know where/when thise gears might have been used. I even wondered if the person stamping the casings grabbed a "2" instead of a "5" by mistake. I haven't taken the drive unit apart to count the teeth on the ring gear but may do that sometime later.
- 529 reads
Tue, 04/24/2007 - 17:10
#2
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Rear drive - 32/11
...or is the 2 and upside down 5? Sorry...couldn't help it.
Seriously, my Motorcycles From Munich 1923 to 1969 shows an 11/32 for a 1956-60 R60 solo machine.
Best regards,
Bruce
Tue, 04/24/2007 - 17:10
#3
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Rear drive - 32/11
...or is the 2 and upside down 5? Sorry...couldn't help it.
Seriously, my Motorcycles From Munich 1923 to 1969 shows an 11/32 for a 1956-60 R60 solo machine.
Best regards,
Bruce
Tue, 04/24/2007 - 17:50
#4
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Rear drive - 32/11
Thanks for the help. Based upon your reply and that of others off the list I do believe the drive is from a same-year R60.
I took the bike out for a nice ride today. It's sunny, high 80's and just a super day for a ride. The bike runs and rides extremely well. I've decided to just drive it for now. It has great patina.
Tue, 04/24/2007 - 18:13
#5
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Rear drive - 32/11
I remembered that the July 2005 issues of BMW VMCA News had an article on gear ratios for various bikes. Indeed, it shows a solo R60 with a rear drive of 32/11 along with a speedo ID of 1.12. The R50/2, R60/2, and R69S got the 25/8 with some of the later R69S and R69US got the 27/8. My '69 R69S has a 27/8 rear drive.
I guess the 32/11 drive will give you a better top end range, but wouldn't the bike suffer a bit on initial acceleration and low end torque? Those are pretty tall gears relative to the other gearing at the time. I always tend to get that stuff backwards, though...
Kurt in S.A.
Tue, 04/24/2007 - 19:54
#6
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Rear drive - 32/11
Yes, they are tall gears. I've been riding the bike around town but haven't been on the highway yet as I need to replace the rear seal. I had an R50 with sidecar gearing so the long legs on this one feels pretty nice. Kinda like overdrive
Larry
Mon, 05/28/2007 - 09:18
#7
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Rear drive - 32/11
Hi, the correct rear drive for your 1960 R69 is a 35/11 which gives a ratio of 3.18:1 compared to the 32/11 of the R60 which you have and gives 2.91:1. A post-1960 25/8 gives 3.13:1 and was introduced to reduce the number of teeth and therefore beef them up a bit.
I would leave it as it is, my Dads R69 has had a 32/11 in for about 40 years, I've ridden it many times and it makes for a lovely long-legged tourer, my own R69S (before I put the chair on and went to 26/6) had a 27/8 and I really had to rev the nuts off it and I only ever used to get about 45mpg and those are English gallons. The R69 is a very different bike to the R69S and has a lot more bottom end pull especially if you use the manual retard, although they will motor along, it was a 69 that still holds the 24 hour record, Dad has the back wheel off that one.
If you do want to find a 35/11 it was also fitted on the R50 (not 50/2).
Enjoy your bike!
Tue, 05/29/2007 - 23:06
#8
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Rear drive - 32/11
Yes, the taller gears are exactly what I want. I'm setting this bike up with an Avonaire fairing for long distance riding. Our speed limit here is 75 mph so I can make good use of the long legs
A 32/11 doesn't sound right for a R69 (R69S??). There's some information on this website about rear end gearing on various models.
http://home.jps.net/~snowbum/ringgears,etc.htm
Kurt in S.A.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2