A Turbo 375? Really? [Archive] - Chevy Nova Forum

: A Turbo 375? Really?


waverous
12th-April-2010, 11:19 PM
My TH400 needs a yoke and I have been looking for one around town and on Ebay. The yoke everybody is trying to sell me has spline shaft diameter of 1.875 - which is too big. I have been told I need an older, obsolete yoke with a spline shaft diameter of 1.68. OK, I try searching for the smaller shaft and I run across a guy who says I can use a TH350 shaft cause I in fact have a TH375. :eek: OK, I'll bite - was there ever a TH375?.

62 NovaWagon
12th-April-2010, 11:24 PM
Yes there was, a TH375 is just a weak TH400 but they can be upgraded to 400 status with 400 parts, no big deal!..

waverous
12th-April-2010, 11:34 PM
Yes there was, a TH375 is just a weak TH400 but they can be upgraded to 400 status with 400 parts, no big deal!..
Interesting....the tranny I have is a Kenne Bell built TH400 with a variable pitch TC - is it possible this is a TH375?

veno
13th-April-2010, 09:04 AM
I found this over on ..Nasty Z28... I always thought the t375 was a heavyduty t350.. turns out we were both right....

http://www.nastyz28.com/chevy-transmission-identification.php

The THM200 and the THM250 have pans shaped like a THM350, HOWEVER, the THM200 will have the words HYDRAMATIC DIV. and METRIC stamped into the pan.
Chevy Automatic Transmission Description & Usage
THM200 - Light duty, "metric" 3 speed transmission.

THM250 - Used in small 4 cylinder cars (Vega, Sunbird, Monza) from 1973 to 1981 and some Nova/Camaro/Chevelle 6 cylinders in 1974 & 75. The 4 cylinder models have 4 large cooling holes near the torque converter, while on the "bigger cars" there are no cooling holes.

THM200-R4 - Used in GM rear wheel drive cars with the 3.8 V6, 305 & 350 Olds and 301 pontiac from 1981 to 1989. This is a 4 speed, overdrive unit.

THM350 - Medium duty 3 speed trans used from 1969 to 1989, Used in Buick, Olds, Pontiac and Chevrolet cars and Chevy & GMC light trucks until 1987. Generally used in straight and V6 and small block engines. Generally able to handle up to 400 foot pounds of torque.

THM375B - This trans is identical to the THM350, but is considered a heavier duty transmission.

THM375 - This transmission is a derivative of the THM400 sharing the external appearance of the 400. It'll be marked 375-THM on the bottom of the tailshaft housing. It's a light duty version of the THM400, has ABSOLUTELY NO RELATION to the THM375B, and was found in 1972 to 1976 full-size cars. The Turbo 375 was modified to accept the Turbo 350 driveshaft yoke.

THM400 - The THM400 was GM's Heavy-duty 3 speed transmission used from 1964 to 1990. Used on large displacement, high torque engines and engines with towing packages. Generally found in Chevy & GM trucks, cadilacs and large displacement engined, full size GM rear wheel drive cars.

THM700-R4 - 4 Speed transmission used in GM cars and light trucks with the 2.8, 3.1, 4.3, V6, Chevrolet built 305, 350 and 454 engines from 1982 to 1992.

4L60 - Early 1990's saw the 700R4 renamed to the 4L60, and "electronic" models were named 4L60E. 4L60 means 4 forward speeds, L = longitudily mounted (rear wheel drive). 60 is the strength rating (less than the 4L80).

3L80 - The 3L80 is a renamed THM400, used in the early 1990's. The 3L80HD would be the THM475 (heavy duty unit).

4L80 - An overdrive model of the THM400. The 4L80E would be the "electronic" model.

Transmissions with a suffix of "C" on the end of the type (THM200C) indicate the transmission has a lock up torque converter.

one trans I see omitted is the THM425.. this was a heavy duty THM400.. I saw these transmissions in motor homes, big trucks.. and a like

hope this helps....

Good luck

Veno

waverous
13th-April-2010, 09:12 AM
Wow! Interesting! Thanks!
Chris

62 NovaWagon
13th-April-2010, 11:52 AM
Interesting....the tranny I have is a Kenne Bell built TH400 with a variable pitch TC - is it possible this is a TH375?

It is possible!..

Longroofer
13th-April-2010, 02:18 PM
one trans I see omitted is the THM425.. this was a heavy duty THM400.. I saw these transmissions in motor homes, big trucks.. and a like

hope this helps....

Good luck

Veno

Veno, you're close, but not quite correct. The THM425 was used in front wheel drive GM applications such as the Cadillac Eldorado and the Oldsmobile Toronado. It was also used in some front wheel drive GMC motorhomes in the 1970's. Yes, GMC made a front wheel drive motor home.

I think you are thinking about the THM475. It was used in heavier duty applications such as motor homes and trucks.

My info comes from working for 5 years in a GMC dealership in the parts department. The dealership also sold and serviced medium duty trucks as well as motor homes.

WildBillyT
13th-April-2010, 02:25 PM
Veno, you're close, but not quite correct. The THM425 was used in front wheel drive GM applications such as the Cadillac Eldorado and the Oldsmobile Toronado. It was also used in some front wheel drive GMC motorhomes in the 1970's. Yes, GMC made a front wheel drive motor home.

I think you are thinking about the THM475. It was used in heavier duty applications such as motor homes and trucks.

My info comes from working for 5 years in a GMC dealership in the parts department. The dealership also sold and serviced medium duty trucks as well as motor homes.

Yeah, I had a THM475 out of a logging truck. I think it had straighter cut gears and the HD cast into the case but it was a while ago.

1969NovaSS
13th-April-2010, 02:33 PM
Only difference from thew TH375 and TH400 is the output shaft and tailshaft of trans. Both use same internal drums, sprags, input shaft, pump, valve body. I have taken many TH375 transmissions and changed the output shaft and tailshaft to the 400 style. Most Th375 came in Gm Fullsize cars from 71 thru 76. Also came in alot of motor homes and trucks around these years. Parts are interchangable between the TH375 and TH400. At one time I had 9 TH375's sitting under the bench in the garage from Racing Impala wagons in the Demo Derby. Rebuilt every one of the transmissions before putting into the Demolition car. I always used a TH400 Rebuild kit. Internals of a TH350 are nothing like a TH375 or vice versa. Trans in my one Nova now is a 375 with the tailshaft and output shaft changed to 400 style.

veno
13th-April-2010, 02:35 PM
Veno, you're close, but not quite correct. The THM425 was used in front wheel drive GM applications such as the Cadillac Eldorado and the Oldsmobile Toronado. It was also used in some front wheel drive GMC motorhomes in the 1970's. Yes, GMC made a front wheel drive motor home.

I think you are thinking about the THM475. It was used in heavier duty applications such as motor homes and trucks.

My info comes from working for 5 years in a GMC dealership in the parts department. The dealership also sold and serviced medium duty trucks as well as motor homes.

sweet.. thank for the correction..... old fogy syndrome or other wise known as CRS....

I pulled a few from motorhomes... back in the 80's and trucks...

I remember reading the tag ... another I remember reading the tag on was the M40 designation which if I remember right is a thm400

62 NovaWagon
13th-April-2010, 11:11 PM
Internals of a TH350 are nothing like a TH375 or vice versa.

The TH375"B" is the TH350, that's where the confusion comes in!...

waverous
13th-April-2010, 11:24 PM
Well, I have learned something! :yes::yes::yes::yes::yes::yes:
Thanks for the info!
Chris

slickman
14th-April-2010, 08:16 PM
This is great info!! This should be a sticky!!:yes: