I recently purchased a 2008 Silverado 1500 2 wheel drive with an automatic transmission. What year did their tranny quality start to go south?
There really isn't a distinct time that GM transmissions went downhill. The guts of the 4-speed, rear wheel drive had their roots in the early 1980s, the THM-700. When they started phasing the 4-speeds out in favor of 6, 8 and 10-speeds, they went massively downhill. GM built transmissions in Toledo, Ohio during the time they were producing the 4-speed. Now, multiple assembly plants produce transmissions, including foreign ones. It's cheaper to make for GM, but that doesn't save money to the end user (you).
the 6 speeds came in when the government started pressing for stricter economy and emissions numbers. I'm guessing around the mid to late 2000's. Many models were killed off around that time because GM did not want to invest the R&D to make them pass.
Yeah, and GM's continued declines in QC no doubt had an influence in that as well. 'Tis the American way, I guess, lol. Build cars as cheap as possible, sell them for as much as possible.
Not just cars. I'm hearing Boeing is going the same way.
Yup, anything to appease the shareholders. I'm a fan of Boeing, but I won't ride on a 737 MAX. When the FAA trusted Boeing to certify their own planes and they started lying about MCAS, which was the source of the problem. Then, the door plug issue. If they can't get door plugs right, we have some issues. Sad, for a legendary aircraft manufacturer.
Pretty much when they became "New GM". After bankruptcy.
GM has a long history of selling the public bad transmissions such as the Triple Turbine, Turbo Glide, Flight Pitch, THM200, Dual Path, and Roto-Hydramatic to name a few that were, to be kind, not all they could be.
However overall quality has certainly gone down post-bankruptcy after which you'd probably be hard-pressed to find a good one.
I thought the 3-speed THM-200s were a more durable, to be honest. Heck, when I was refilling my Pontiac's transmission, it used a gallon of transmission fluid and it still drives great. I didn't know it was that low, my driveway is overgrown gravel. Had I known about it, I would've shut the car off, lol.
The early THM-200s were meant for the subcompact 4-cylinder 1600cc Chevette but GM installed them in their "downsized" full-size cars in 1977 when equipped with six cylinder or small V8 engine. They couldn't really handle the torque of the V8. (I think it was improved later on.)
https://www.youtube.com/watch?v=tmzqHe0Dw4A&t=1047s
(Although the above video is about the 1977 full-size Chevrolet, it pretty much applies to the others in GM's lineup as well.)
Seems like a typical thing for GM to do. Haha. That just seems like common sense. Subcompacts and a "reduced" full-size cars are the complete opposite of each other.
In the case of the THM200 it wasn't really the transmission itself that was bad (it did OK in the Chevette), but the misuse it was put to. Hey, it's GM, even when they manage to come up with an otherwise great product like the 1977 B-Bodies they have to screw up somewhere, right?
The difference in weight is probably key, there, lol. Mine must have been relatively babied. I'm only the 4th owner so far, haha. The original owners owned the car for 35 years, a man bought it and drove it for a few years, he needed $$ for a divorce, so he sold it to my father-in-law. His wife drove it for a few years and my father-in-law blew up the battery while charging it. There it sat for 3 years before I came along. Haha.
I'm with @justin-shepherd and @mmj. Not just GM, but any transmission manufacturer going above 4-speeds to meet emissions.
Late 2000s
