Final Drive

[comet]

Rob, you'r beating a dead horse. There is no way that you can pull aprox. 900 lbs. at todays highway speeds with the kind of horsepower your R69 is producing..................Comet

[tricyclerob]

Comet, The rig actually does quite well. Runs along at 60 without much fuss and is just as comfortable at 65. As Allan mentions, it does slow, and a downshift to 3rd is required on hills. Depending on the hill a downshift is not enough causing the bike to slow to 40-45, which is why I'm looking at a lower ratio. On level, or slight incline it's not an issue.
I don't plan on riding the interstate. I have other bikes, including my K75RT, if I feel a need for interstate travel.
As far as "beating a dead horse", I guess it depends on what one is satisfied with.
The slightly relaxed pace is one of the reasons I ride vintage. My R69 is a rider with a few 1000 mi trips to it's credit. rj

[EuroIron]

you mean you can't change them on the calculator?

if that rig is working with the final drive currently in it

putting a wide ratio unit in place may be just what the Dr ordered for a dual purpose rig that can do solo or hack duties with virtually no fuss

so what if for solo duty you start out in second gear?


Rob -

Try using Anton's graphical calculator to get an idea of RPMs, etc., for different final drives. http://www.largiader.com/articles/gearing/

Not sure if it's got all the ratios you're interested it; plus you can't really change the tranny ratios. Follow some of the links on his site...maybe you can use the math on Snowbum's site and create your own best combination.

Kurt in S.A.

[schrader7032]

you mean you can't change them on the calculator?


On Anton's website, the tranny ratios are fixed for the display. Certainly, one can use a calculator and/or spreadsheet and do some additional computations.

Kurt in S.A.

[Allan.Atherton]

... one can use a calculator and/or spreadsheet and do some additional computations. I have an interactive Excel spreadsheet that relates all the gear ratios and tire sizes to speed and rpm. It was started by Wayne Van Orden and I polished it up and added gears to it.

It has been priceless in understanding sidecar gearing. But I find not many people have Excel, fewer can use Excel, and almost nobody seems appreciative of the spreadsheet. I suspect they mess it up and can't get it back, and don't mention it. Best to make a few copies to practice on.

[schrader7032]

I have an interactive Excel spreadsheet that relates all the gear ratios and tire sizes to speed and rpm. It was started by Wayne Van Orden and I polished it up and added gears to it.

It has been priceless in understanding sidecar gearing. But I find not many people have Excel, fewer can use Excel, and almost nobody seems appreciative of the spreadsheet. I suspect they mess it up and can't get it back, and don't mention it. Best to make a few copies to practice on.

I have my own and am certainly comfortable with Excel. I doesn't have all the bells and whistles, but given the variables involved, I can compute speed and RPM. I can manually change any gear ratios or final drive ratios and see the results. It certainly helps to see what can happen...

Kurt in S.A.

[comet]

Rob, The formula for RPM is MPH divided by 60, times 5280, divide that by rear tire circumfrence, multiply that by fourth gear ratio times rear drive ratio and you will have your RPM. Dont trust your speedometer use the mile markers on the highway and divide 3600 by the time it takes you to travel one mile (in seconds) to get your speed. 65 MPH was 5500 RPM with my R69S, running a 26:6 rear drive and I believe a 400X18 tire. pulling a Ural, In my opinion max RPM if you want any longevity out of that engine. And by the way, when running at that speed reach down and put your hand on a valve cover, hotter than L isn't it. Not good, you're beating a dead horse Comet

[vonkas]

I haven't read the wole threade you might already have your answer - here's mine: No it wont fit and none of the internals will transfer either. That's a definite. I know because I tried!

Jim


I guess this could be a dumb question, but .. Does anyone know if a later mdl. final drive, [/5 or?] would fit on a /2? Actually on a R69? They look identical, except for having a shock mount stud, instead of a bolt.

[Allan.Atherton]

... 65 MPH was 5500 RPM... running a 26:6 rear drive and I believe a 400X18 tire...
The spreadsheet confirms that it was a 4.00 tire:
82.625 Tire Circumference
4.333 Final Drive Ratio
5500 Engine RPM
64.49 4th Gear MPH

[VBMWMO]

I guess this could be a dumb question, but .. Does anyone know if a later mdl. final drive, [/5 or?] would fit on a /2? Actually on a R69? They look identical, except for having a shock mount stud, instead of a bolt.
I'm looking for a lower ratio for sidecar use, and have been watching E-bay, etc for a while, and have not seen any for /2, in the lower ratios.
I had a 26/6 which I tried for a bit but it seemed way too low for general use.
Thanks, rj