1980 Corvette transmission question.

[Don I.]

Hello again. All of my past collector cars were all four speeds. My 1980 Corvette is an automatic. I understand that they used the three speed TH350. Now, when I first start out I'm assuming I'm in first gear. The thing is I feel 3 more shifts after that. So, do I have a TH400 in it instead? If so, that's the wrong transmission correct? I have the L48 engine. I have the 1,2,3 on my shift console plate. Is there a way to check if the transmission was swapped out? Everything looks untouched underneath. Thanks, Don.

[Edward J.]

Re: 1980 Corvette transmission question.

Don, I am trying to think when GM made the THM350 IN 1980 if that was the first year for the lock-up torque convertor which would have made it the THM350C. if this is the case, After the transmission shifts into 3rd, the lock-up torque convertor will be engaged shortly after, This feels like another shift. This feature was a way for GM to improve the fuel economy.

[Jim T.]

Re: 1980 Corvette transmission question.

Don for sure, you do have the Turbo 400, as far as I know in having one, it only shifts from first, second, and to third going forward. No torque converter lockup.

According to the Corvette Black Book, 1981 was the first year for the Corvette to have the torque converter lockup in second and third gear.

[Edward J.]

Re: 1980 Corvette transmission question.

Jim, the THM350 should be the 80, I cannot remember the last year for the 400THM.

[Jim T.]

Re: 1980 Corvette transmission question.

Edward, Again according to the Corvette Black Book, 1977 was the last year for Corvettes with the M40 turbo 400.

[Alan D.]

Re: 1980 Corvette transmission question.

The 1977 only had the Turbo 400 transmission if it has the L82 engine. The L48 has the THM350 transmission.
Al Dieterle

[Don I.]

Re: 1980 Corvette transmission question.

This concern was driving me nuts so I went to the garage, grabbed a light and had to take a look. The oil pan is a TH350. It had 3 ninety degree bends and one corner without one on the passenger side rear. I also noticed it's stamped MV4. I looked on the web and the ttransmission is a TH350C. So it does have the lockup torque converter. It was introduced in 1979. So my next question, was it used in the Corvette in 1980?

[Don I.]

Re: 1980 Corvette transmission question.

Upon further study on the web, late built 1980 Corvette's were switched over to the TH350C. Apparently it's a better transmission over the regular TH350. Because of the lockup it gives you better MPG and it operates cooler. I guess you learn something new everyday. Sorry to bother you folks!

[Joe L.]

Re: 1980 Corvette transmission question.

This concern was driving me nuts so I went to the garage, grabbed a light and had to take a look. The oil pan is a TH350. It had 3 ninety degree bends and one corner without one on the passenger side rear. I also noticed it's stamped MV4. I looked on the web and the ttransmission is a TH350C. So it does have the lockup torque converter. It was introduced in 1979. So my next question, was it used in the Corvette in 1980?

Don------


Two automatic transmissions were used for 1980. Cars with L-48 or L-82 engine used the MV4 THM-350 trannsmission. Cars with the LG4 305 cid engine (California only) used the M33 THM-350 transmission.

The 1981 THM-350 transmission with lock-up toque converter was coded MX3.

[Don I.]

Re: 1980 Corvette transmission question.

Thanks Joe!

[Edward J.]

Re: 1980 Corvette transmission question.

Don------Two automatic transmissions were used for 1980. Cars with L-48 or L-82 engine used the MV4 THM-350 trannsmission. Cars with the LG4 305 cid engine (California only) used the M33 THM-350 transmission. The 1981 THM-350 transmission with lock-up toque converter was coded MX3.

Joe, You gotta love California, 305 cubic inch's of nothing. for a corvette there could be nothing lower. other than maybe the Olds 307 cu. in.