Author Topic: How to identify Final Drive Ratio...?  (Read 973 times)

Offline radguzzi

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How to identify Final Drive Ratio...?
« on: October 26, 2021, 12:40:51 PM »

I have a surplus Tonti Final Drive unit that I would like to sell and need to be able to identify what the ratio is.  How does one go about doing that...?  From the outside...

The only marks on the castings are Part Numbers so I am guessing that is not going to be a help.  The only other number is a number "11" stamped into the bearing hub.

I would venture a guess that it is the more common 8/33 however, I honestly do not know.

Any ideas folks...?

Thanks,
Rob









 

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Offline Bob Wegman

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Re: How to identify Final Drive Ratio...?
« Reply #1 on: October 26, 2021, 12:55:01 PM »
How about rotating the pinion and counting the revolutions needed to rotate the wheel hub gear a complete revolution.
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Offline mtiberio

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Re: How to identify Final Drive Ratio...?
« Reply #2 on: October 26, 2021, 02:10:22 PM »
How about rotating the pinion and counting the revolutions needed to rotate the wheel hub gear a complete revolution.

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Online Antietam Classic Cycle

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Re: How to identify Final Drive Ratio...?
« Reply #3 on: October 26, 2021, 02:33:06 PM »
Or pull the pinion carrier out of the case and count the number of teeth on the pinion gear. You'll want to inspect the teeth for damage anyway (and take photos for any prospective buyers).
Charlie

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Re: How to identify Final Drive Ratio...?
« Reply #3 on: October 26, 2021, 02:33:06 PM »

Offline Petrus Rocks

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Re: How to identify Final Drive Ratio...?
« Reply #4 on: October 26, 2021, 03:36:10 PM »
What Charlie said.  It's off a V11, correct?

Offline radguzzi

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Re: How to identify Final Drive Ratio...?
« Reply #5 on: October 26, 2021, 05:07:44 PM »
Or pull the pinion carrier out of the case and count the number of teeth on the pinion gear. You'll want to inspect the teeth for damage anyway (and take photos for any prospective buyers).

Ok, I count nine (9)teeth... There is an inscription on the end of the pinion "392"  What is all this telling me Charlie...?

I do not see any indication of abnormal wear on the gear teeth.

Thanks,
Rob












What Charlie said.  It's off a V11, correct?


I don't believe so, I'm thinking an 80's vintage LeMans, CX or SP... just a guess though.

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« Last Edit: October 26, 2021, 06:06:27 PM by radguzzi »
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Offline guzzisteve

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Re: How to identify Final Drive Ratio...?
« Reply #6 on: October 26, 2021, 06:07:58 PM »
That's a Convert rear drive. Small splines & 9/34 teeth.
« Last Edit: October 26, 2021, 06:09:26 PM by guzzisteve »
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Online TOMB

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Re: How to identify Final Drive Ratio...?
« Reply #7 on: October 26, 2021, 07:06:57 PM »
If the pinion has 20 teeth on the front part of the shaft 9 teeth ib the pinion  and 34 teeth on the ring its  for a convert

Pinion 9 teeth

Ring 34 teeth

Final ratio is 3.777

The 392 #on the pinion  will match the same # on the ring so you know that the ring and pinion are a match set

It's a high ratio final drive but the torque converter and the internal gears in the transmission make it work.

TOMB
« Last Edit: October 26, 2021, 07:13:26 PM by TOMB »
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Re: How to identify Final Drive Ratio...?
« Reply #8 on: October 26, 2021, 07:21:05 PM »
Spare rear drive for your Convert!
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Offline radguzzi

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Re: How to identify Final Drive Ratio...?
« Reply #9 on: October 26, 2021, 08:10:34 PM »
That's a Convert rear drive. Small splines & 9/34 teeth.


If the pinion has 20 teeth on the front part of the shaft 9 teeth ib the pinion  and 34 teeth on the ring its  for a convert

Pinion 9 teeth

Ring 34 teeth

Final ratio is 3.777

The 392 #on the pinion  will match the same # on the ring so you know that the ring and pinion are a match set

It's a high ratio final drive but the torque converter and the internal gears in the transmission make it work.

TOMB

It is indeed the numbers that you both mention. 

I may just reconsider and keep it for my own Convert.  Ya never know when you might need a final drive... hope not but if it left, guess what would happen..! ?!

Great information, you guys are great, thanks.

Current:
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Online TOMB

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Re: How to identify Final Drive Ratio...?
« Reply #10 on: October 28, 2021, 08:17:54 AM »
Just a follow-up it was also a special differential ring and pinion for the Cal 11 convert that had six teeth on the pinion 20 teeth on the spline the coupler from the spline to the drive shaft was a 20 on one end to 10 on the other I don't remember what the ring  teeth count but it was a special gear set just for the convert Cal 11 probably would work on it earlier convert if anybody has any other information please add it

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1972 Eldorado new to me so "0" miles so far
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1980 CX100 50 MILES
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1976 HONDA CB400F 27 MILES AND BUILDING SOLD

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