By joining you will help ensure that we can continue to provide this service
JOIN HERE!
Final drive gear ratio
- wa1nca
- Posts: 1231
- Joined: Thu Sep 27, 2012 5:15 pm
- Location: Ashfield Ma
- Has thanked: 11 times
- Been thanked: 18 times
Final drive gear ratio
25/8 final drive gear ratio is 3.12
gear ratio almost the same
What is the difference
Does one have a better top end or low end better than the other
Tommy
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA
Re: Final drive gear ratio
Dave
- Flx48
- Posts: 262
- Joined: Sun Oct 25, 2020 3:11 pm
- Location: NW CT
- Has thanked: 2 times
- Been thanked: 7 times
Re: Final drive gear ratio
I'd always gone with the ASSumption that the 11/35 gears basically were used in the '50s models, while the 8/25 was with the '60s bikes.
This conclusion only from looking at the instruction and shop manuals of the day, and my cursory observations of different bikes through the years.
I figured it was probably a cost cutting measure, to simply have to cut thirteen less teeth for basically the same ratio.
(no doubt there's someone out there that can sense the difference of a 0.05 ratio in use, but it's not me)
Using the same speedo also makes sense; again would a different speedo ratio be warranted for 0.05?
Seems one could have that much of a difference by virtue of their tire choice.
Best-
George
- vechorik1373
- Posts: 268
- Joined: Fri Oct 27, 2006 3:00 am
- Been thanked: 22 times
Re: Final drive gear ratio
Technical Adviser, Former owner, Bench Mark Works
662 312 2838 cell 9 am to 4pm CST PLEASE!
-
- Posts: 149
- Joined: Fri Oct 27, 2006 3:00 am
- Has thanked: 2 times
- Been thanked: 9 times
Re: Final drive gear ratio
Chuck S
-
- Posts: 91
- Joined: Fri Nov 02, 2012 8:18 am
- Has thanked: 1 time
Re: Final drive gear ratio
Westwood, MA USA
-
- Posts: 149
- Joined: Fri Oct 27, 2006 3:00 am
- Has thanked: 2 times
- Been thanked: 9 times
Re: Final drive gear ratio
Anecdotally, I went back and looked at pics of bikes I've owned over the years. I owned a 1958 R50 with a non-vented 37/11 rear drive, a VERY original 1961 Dover White R69S that had a vented rear drive housing (I don't have any info on what ratio it had at this point), and a very original 1962 R50S with a vented rear drive housing and 25/7 rear drive.
Does anyone have any parts books dated in between mine? I'd be curious to know when the 25/8 ratio was actually introduced and when the vented housing went into production and became standard.
Chuck S
- schrader7032
- Posts: 9050
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
- Has thanked: 3 times
- Been thanked: 34 times
Re: Final drive gear ratio
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
-
- Posts: 149
- Joined: Fri Oct 27, 2006 3:00 am
- Has thanked: 2 times
- Been thanked: 9 times
Re: Final drive gear ratio
The November 1963 Parts book shows both the 37/11 (for the earlier models) and 25/8 (for later models) ratios available. It also shows what I believe is the vented case part number (ending in 306) listed but the exploded parts drawing still shows the unvented case and the actual vent, cap and screw that hold it in place are not shown in the parts list....
Looks like 8/25 was the standard solo ratio by February 1965. The 37/11 ratio is no longer listed here. What I believe is the vented case part number (ending in 306) is listed but the exploded parts drawing still shows the unvented case and the actual vent, cap and screw that hold it in place are not shown in the parts list....
Does anybody care about this stuff or am I just talking to myself... ?
Chuck S