This a a basic TH350 tranny question?
Drifting
Joined: Dec 2017
Posts: 1,302
Likes: 226
From: PA
Sorry, that was a typo. I meant to write what the OP actually had, i.e 3.08 to 3.55, but I flipped the numbers in the original. But if you analyze my first post and my follow up you will see that all my writing beyond the line you highlighted and all of it in the follow up post described the gearing needs going from a 3.08 to 3.55. For example, in my second post -
" I'm guessing a 19 as combined with an 8 tooth drive gear it is near perfect for the 3.08 gear ratio and the 8" 70 tires on 15 rims. If it is a 19 tooth then you need to get 22 tooth for the 3.55. It it's 17 tooth you'll need to replace it with a 19 tooth"
I am directing him to go to a higher tooth count driven gear which an any given engine rpm will reduce the number of turns output on the driven gear which is correct as increasing the rear gear ratio will and any given RPM reduce the number of turns output to the rear tires.
Note that I have corrected the typo in the original post and from there there are no changes to the recommendations as originally written as I believe they are correct for what the OP requires.
" I'm guessing a 19 as combined with an 8 tooth drive gear it is near perfect for the 3.08 gear ratio and the 8" 70 tires on 15 rims. If it is a 19 tooth then you need to get 22 tooth for the 3.55. It it's 17 tooth you'll need to replace it with a 19 tooth"
I am directing him to go to a higher tooth count driven gear which an any given engine rpm will reduce the number of turns output on the driven gear which is correct as increasing the rear gear ratio will and any given RPM reduce the number of turns output to the rear tires.
Note that I have corrected the typo in the original post and from there there are no changes to the recommendations as originally written as I believe they are correct for what the OP requires.
Last edited by vince vette 2; Apr 8, 2018 at 08:34 AM.
Thread Starter
Advanced
Joined: Oct 2015
Posts: 99
Likes: 1
From: Morristown/ Knoxville area Tennessee
Whats the difference between the "drive gear" and the "driven gear"? what are you referring to when you reference " 8 tooth" drive gear?
Last edited by flyguy767; Apr 8, 2018 at 08:39 AM. Reason: Add something
Safety Car
Joined: Oct 2007
Posts: 4,203
Likes: 1,074
From: South Florida
The trans manufacturer
wants you to drive the car, to warm the trans fluid to approx 140-165*F,
and also hit every gear, R, D, 1,2,3,4,5,6,7,8, all the gears. Get fluid into them all.
Then, back in park, on a level surface, trans fluid 160*F~ or so, you check the level.
wants you to drive the car, to warm the trans fluid to approx 140-165*F,
and also hit every gear, R, D, 1,2,3,4,5,6,7,8, all the gears. Get fluid into them all.
Then, back in park, on a level surface, trans fluid 160*F~ or so, you check the level.
Drifting
Joined: Dec 2017
Posts: 1,302
Likes: 226
From: PA
The drive gear mounts around the output shaft. It requires removal of the tail shaft housing to access it. It will turn once for every one turn of driveshaft. it is more difficult to change.
The driven gear connects to your speedometer cable. It "meshes" with the drive gear. As the transmission output shaft turns the drive gear "drives" the driven gear to turn the speedometer cable.
The driven gear is relatively easy to remove. It requires first the uncoupling the speedometer cable which is simple to do other than the fact that there is limited room to get your hand and any tools in there. I have a scar on my thumb from 4 stitches I got 35 years ago when my adjustable pliers slipped off the cable coupling and my thumb slid against an exhaust heat shield. After the cable is detached then there is a small bolt you need to LOOSEN, don't remove it, and a toggle you then flip out of the way. Then you grab the end of the "bullet" (you'll understand the name when you see it) which is the part the cable was connected to. The driven gear should come out with it (move slowly). Then it's an easy swap.
The driven gear is what you want to replace assuming there is one with a proper number of teeth available for the drive gear you have. Per my earlier posts I think this it highly likely.
The driven gear connects to your speedometer cable. It "meshes" with the drive gear. As the transmission output shaft turns the drive gear "drives" the driven gear to turn the speedometer cable.
The driven gear is relatively easy to remove. It requires first the uncoupling the speedometer cable which is simple to do other than the fact that there is limited room to get your hand and any tools in there. I have a scar on my thumb from 4 stitches I got 35 years ago when my adjustable pliers slipped off the cable coupling and my thumb slid against an exhaust heat shield. After the cable is detached then there is a small bolt you need to LOOSEN, don't remove it, and a toggle you then flip out of the way. Then you grab the end of the "bullet" (you'll understand the name when you see it) which is the part the cable was connected to. The driven gear should come out with it (move slowly). Then it's an easy swap.
The driven gear is what you want to replace assuming there is one with a proper number of teeth available for the drive gear you have. Per my earlier posts I think this it highly likely.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
OK, so I check the tranny fluid level in my TH350 after it has been sitting for a month or more and the engine is OFF and completely cold. The fluid reads very high on the dip stick. I start the engine and let it run for 30 minutes and get to engine operating temp of around 155-160 deg.(checked with laser temp gauge) after the thermostat has opened and it doesn't register on the dip stick. I cycle it through the gears as it is running and still no change. Is this the correct reading? Is it actually low on fluid and I probably have a leaky gasket? It only drips after its been driven and parked I'll notice some drippy's on the floor. Should I ignor the completely cold reading and only use the hot reading? I know it sounds stupid, but the reason I ask is because I have a little tranny fluid loss under the car and was wondering if it is blowing out cause it is over full.
doesn't read?
leak?
i guess the tranny dipstick tube is leaking at the case.
you didn't say if you add any fluid.
as stated over and over, check fluid with engine running.
if the tube is leaking at case, you could see what you do.
engine off tran fluid level rises and leaks at tube.
running will show about quart low.
