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-   -   th350 gear ratio check (https://classracer.com/classforum/showthread.php?t=82453)

richie 2 07-03-2022 09:52 AM
th350 gear ratio check
 
any way of determining 1st, 2nd ratios with an assembed unit? tks

Charles Stewart 07-04-2022 09:57 AM
Re: th350 gear ratio check
 
No answer after 275 visit ???
I may be completely wrong with that and I never played with an auto transmission but I will try a tentative solution here.
The standard gear set for a TH 350 is: 2.52, 1.52, 1 to 1 or 2.75, 1.52, 1 to 1. That means if you put your trans in first gear and turn the input shaft 2 and a half rotation (2.52), the output shaft should turn one rotation and so on (1.52 and 1 of rotation for the input shaft, for the second and third gear, should give you one rotation for your output shaft).
You can make a tool with an old trans yoke and work on the output shaft side. Make 1 turn from your output shaft and count the rotation of the input shaft.
I repeat, I may be totally wrong but it’s the way I see it.

Kevin Panzino 07-04-2022 11:06 AM
Re: th350 gear ratio check
 
Quote:
Originally Posted by Charles Stewart (Post 663829)
No answer after 275 visit ???
I may be completely wrong with that and I never played with an auto transmission but I will try a tentative solution here.
The standard gear set for a TH 350 is: 2.52, 1.52, 1 to 1 or 2.75, 1.52, 1 to 1. That means if you put your trans in first gear and turn the input shaft 2 and a half rotation (2.52), the output shaft should turn one rotation and so on (1.52 and 1 of rotation for the input shaft, for the second and third gear, should give you one rotation for your output shaft).
You can make a tool with an old trans yoke and work on the output shaft side. Make 1 turn from your output shaft and count the rotation of the input shaft.
I repeat, I may be totally wrong but it’s the way I see it.

Yes, but you would have to apply/release the various clutches. You could use compressed air in the proper test ports to do so.

Rory McNeil 07-05-2022 10:37 PM
Re: th350 gear ratio check
 
Quote:
Originally Posted by Charles Stewart (Post 663829)
No answer after 275 visit ???
I may be completely wrong with that and I never played with an auto transmission but I will try a tentative solution here.
The standard gear set for a TH 350 is: 2.52, 1.52, 1 to 1 or 2.75, 1.52, 1 to 1. That means if you put your trans in first gear and turn the input shaft 2 and a half rotation (2.52), the output shaft should turn one rotation and so on (1.52 and 1 of rotation for the input shaft, for the second and third gear, should give you one rotation for your output shaft).
You can make a tool with an old trans yoke and work on the output shaft side. Make 1 turn from your output shaft and count the rotation of the input shaft.
I repeat, I may be totally wrong but it’s the way I see it.
Although that method works with a manual transmission, it won`t work with an automatic. You can turn the tailshaft until your hand falls off, but it won`t rotate the input shaft.

Mark Yacavone 07-05-2022 11:44 PM
Re: th350 gear ratio check
 
You should be able to do this with air pressure. The rear most port ,behind the servo is main pressure.
Screw in an 1/8 pipe nipple and plumb an air hose to it..Give it all you got.
Put it in manual low, and it should put the fwd. and lo/rev clutches on.
Put a vise grip on the input and a yoke in the rear. 2 and 1/2 turns should be easy to count.
If it doesn't work , the seals could be bad or maybe a reverse valve body..Try the 3rd position .
Don't worry about 2nd if it shows 2.52 low.

Charles Stewart 07-07-2022 08:51 AM
Re: th350 gear ratio check
 
Thank gentlemen for sharing and expanding my knowledge because I am here to learn. :)
Keep on,


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