Anyone know the best/easiest way to determine the rearend ratio of our cars? Also were there diff. ratio's available and what might they be.

Where Are You From? Ohio

Do You own a car built by Durant? 1930 Durant sedan

Jim.... The correct way to know the ratio of your rearend is to count the number of teeth on the ring gear and divide that by the number of teeth on the pinion gear. So for example, Let's say you have... 35 teeth on the ring and 10 teeth on the pinion, your ratio would be 3.5 to 1.
In the case that your rearend isn't dissassembled, turn the tire 1 complete revolution and count how many times your drive shaft turns. Same example, if your drive shaft turns 3 1/2 time with a complete tirn of the rear tire... again, 3.5 to 1 ratio.
Sorry to say I don't have any real idea about the ratio's of the Durant cars? Hope this helps.

Where Are You From? Ohio

Do You own a car built by Durant? Flint

Thanks Jim, I did rotate the drive shaft, it rotates 2 1/2 turns to one rev. of the wheel. So, 2.5 to 1 ratio I suppose. Curious as to what ratio's are on other member's cars.

Where Are You From? Ohio

Do You own a car built by Durant? 1930 Durant sedan

Jim,
A 2.5 ratio seams awfully high for our old cars...Don't forget that their are differential gears that have I'm thinking a 2 to 1 ratio, if you were to stop one wheel the other would turn twice as fast..If you had both wheels jacked up when turning the driveline it is difficult to have both axles/wheels turning at exactly the same speed....See what you would come up with by jacking up just one wheel and turn your drive line until that wheel turns exactly two turns and then cut it in half...An example, if the drive line turns 8 times to make the wheel turn 2 times you would have a 4 to 1 ratio...If I am wrong would someone please correct me.

Bill

Where Are You From? Leavenworth, WA / Yuma, AZ

Do You own a car built by Durant? 1923 A-22 Touring, 1929 Durant model 40 Coupe

Where Are You From? Hyattsville Md

Do You own a car built by Durant? Yes

Jim,

Yes, That would be correct.

Bill

Where Are You From? Leavenworth, WA / Yuma, AZ

Do You own a car built by Durant? 1923 A-22 Touring, 1929 Durant model 40 Coupe

I believe that my car has a 4.1/1 ratio typical of the 4cyl cars ... BUT the 6cyl --I have heard, has a 3.9/1 ratio. The 3.9 should, I think, propel the 4 cyl at a speed more suitable to todays road speeds.

Where Are You From? Ontario

Do You own a car built by Durant? 1930 Durant

Thanks to all who replied....the saga continues...I did have both wheels off the ground when I made my initial test. I will try as has been suggested...only raising one wheel off the ground and rotating driveshaft and counting wheel revolution....stay tuned....results are forthcoming.

Where Are You From? Ohio

Do You own a car built by Durant? 1930 Durant sedan

It's my opinion that if you drive these old cars anywhere near today's speeds, you are being suicidal. I would think 45 mph is a decent top speed for that era. Poor brakes, wooden wheels, sloppy steering, no shocks, fragile tires...!

Do You own a car built by Durant? yes

WOW.... glad you guys jumped in there and got me corrected! Guess I was thinking about checking the ratios on my Dodge with a ring and pinion gear set?
Guess I never have been much of a rearend guy!

Jim, I took a look in my '27 Flint parts book and they list 2 different beveled ring gears... the first with 43 teeth and another with 46 teeth. I don't believe they ever made a 4 cylinder Flint, so that wouldn't explain the different gears. Also curious is the fact that the rear end had 2 different tracking widths of 57 1/2" or 59 1/2" depending wether it had mechanical or hydrylic brakes?
Not sure if a Durant parts book would show different gears or not?

Where Are You From? Ohio

Do You own a car built by Durant? Flint

Jim,
You may have gotten the directions backwards in your first try. Do as said and "Turn one rear wheel" then count the "turns" of the Driveshaft (make a chalk mark on both wheel and drive shaft for reference). The driveshaft should turn between Four and a Half to Five (or more) turns. This will equal a 4.5 to 5.1 or greater Rear end Ratio. These are pretty standard for our era cars.
Lance C.

Where Are You From? Niceville Florida

Do You own a car built by Durant? 25 Locomobile JR-8 Brougham, 25 Loco JR-8 Sedan, 26 Loco JR-8 Roadster project, 30 Durant 610 Deluxe Sedan

Ok, here is latest info....I raised only one wheel,(rr)and rotated driveshaft 2 1/2 turns, wheel rotated one rev. I then rotated driveshaft not quite 5 turns, and the wheel rotated 2 revs. Just for curiosity, I did the same test with the left rear wheel...results are the same. I referred to my 1930 Durant owners manual, no information on gear ratios. I looked up info in a Durant parts manual, it lists possibility of two diff. ratios. (1) 47T ring gear with 10T pinion. listed for the models 614 and 618. (2) 44T ring gear with a 10T pinion. listed for models E,407-611-614-618-670

So, if I take the 47T ring gear and divide it by the 10T pinion, I get a 4.7/1 ratio, which is closest to my experiment of turning driveshaft and counting wheel turns. So at this point, I have to assume my Durant has this ratio. The only way I will know for sure is to take the thing apart and count the teeth, which I am not ready to do now.

Thanks again for all the help. The curiosity issue for me is settled in my mind.

Where Are You From? Ohio

Do You own a car built by Durant? 1930 Durant sedan 614