Speedo for R60/2 with sidecar

[Skylinechili]

I'm currently reassembling my father's old R60/2 and haven't been able to locate the original speedometer. From doing some reading, appears it isn't as simple as just grabbing a used one size fits all speedo...

Bike info:
1967 R60/2 with a Steib S500
Transmission is marked "S"

Any help with the correct speedometer information would be greatly appreciated!

[jwonder]

What is the rear ratio? It is stamped on the final drive in the rear. A number /number. Then we can tell you the ratio of speedo that matches that rear.

[Skylinechili]

Looks like a 25/8

[Flx48]

Hi Sky-
The S on the trans simply means it was built as a Sport trans, not a sidecar or early years trans.
That said, all Earles fork bike trans had the same output ratio, so for the purpose of what speedo to use, the trans is irrelevant.

What you would want to know, to have an accurate speedo, is what rearend ratio you have.
You can can check the tooth count stamped on rear at the driveshaft mount, find the quotient, and that's your ratio.
But you may want to double check the ratio, 55 years (how's my math?) is a long time and it's possible, though perhaps not probable, that the gearset was changed at some point.

I posted this in an answer last year, as a method of confirming the rearend ratio-

"...the most common method is by feel through the driveshaft rubber boot.
For the rearend, place the bike on the centerstand, so the wheel may be rotated.
Palpate the head of one of the four bolts that connect the driveshaft to the trans output flange under the rubber boot, and simultaneously note the wheel position.
The goal is to rotate the wheel one complete revolution, while counting the number of driveshaft revolutions.
In the case of 25/8 gears, the driveshaft will rotate 3.13 revolutions to turn the wheel 1 complete revolution; so that's 3 complete revolutions of the driveshaft plus about an 1/8 of a turn.
For 27/8 gears, (US models) that's 3.38 revolutions, or 3 complete revolutions plus a little more than a quarter turn.
27/7 gears (3.86) would be 3 revolutions plus around 7/8 of a turn.
And 26/6 gears (4.33) would be 4 revolutions plus a little more than a quarter turn."

If your rear isn't installed at this point, all the easier to confirm which gearset you've got; put a magic marker mark on a tooth at input and output, turn and count.

Best-
George

[jwonder]

For a 25/8 you need a W=0.75 for KPH or a 1,2 for MPH.

Salis lists them here https://www.bmwclassicmotorcycles.com/ ... ruments-4/

Spike buck has them here https://vintagebeemerparts.com/new-vin ... 0-000-090/ without the BMW logo though.

If you need other places to get them let us know.

[Skylinechili]

Great, thanks for the information.

[vechorik1373]

BUT, a 25/8 (25 teeth ring gear, 8 teeth pinion gear) final drive is a solo geared rear end.

There are two side car gear sets. 27/7 and 26/6. The 26/6 is a stump puller for the Alps. The engine will SCREAM at 55 mph. For hilly terrain, the 27/7 is my favorite choice with a side car. You usually do not have to down shift, to climb a big hill, with the side car attached.
Unless all your riding is on flat land, you will find that with the 25/8 final drive, you will be downshifting to 3rd,to climb hills.

Just so you will know. And, yes, if you put a 27/7 in, your current speedometer will be very inaccurate.
Side car speedos are available new, but not in MPH only KPH.

[weh8127]

I went thru the Speedo error thing last year on this site when I started to hunt for a 27/7 drive for my R 60/2 rig. My solution is the HUD Speedo app for your phone free, and a $6 handle bar mount for your phone. With it you can use a sharpie to mark your bezel for 25mph, 40mph and 55mph which should be fine.