Fascinating read from a former GM Hydramatic engineer

I rode with a coworker that drives a 2017-ish Silverado 1500 and noticed his tranny does a weird clunk about 50% of the time right before coming to a stop. Like a hard downshift or something. Talking to my buddy that has the same generation of truck, he said his does exactly the same, among other weird stuff! He was told this is "normal on the 8 speed!" WTF!

Anyway, looking around I found this thread on LS1tech. I found it fascinating, from a former Hydramatic engineer, no less! He discusses/compares the THM400, et. al., 4L, 6L, 8L, and 10L transmissions. He sheds light on newer transmissions, and unfortunately, it's evident the newer units are not going to live longer than our archaic 4 speeds!

Anyway, I'd thought I'd share this if there's anyone suffering from insomnia...

I have a 3 year old monster in my truck, runs so smooth I'm not even gonna think about touching it.
Besides, I have enough engine issues to deal with right now.

Our Camaro does the same thing despite 2 reprograms, a new valve body and and a new internal harness. Fluid has been changed twice.

Iv always heard that the more gears a transmission has, the more expensive they are.

I wonder if someone makes a conversion bellhousing to use the ZF 8 speed. It's much better than GM's 6 or 8 speed. I haven't owned a 10 speed GM yet. I did have a Ford 10 speed for a while and it would occasionally get confused, I'd take the ZF 8 over it.

I bought a new 2018 Z71 1500 w/6 speed. It never felt right. Clunks,shudders and once going up a steep incline briefly the transmission seemed to just stop working! After hearing from others at work with same and worse issues, I took mine into dealership to do oil change and check transmission. When I picked it up they said “No Charge” for oil change(that was a first), and said they couldn’t find anything wrong with transmission. That was what was written on paperwork. He then said many are adding an extra qt. of fluid or if I wanted they would pull transmission and replace the pump! I left and noticed on mileage they had driven over 100 miles. Next day I called a friend who knows a local transmission shop. That guy called me and said they are doing new pumps and torque converters(he recommended billet) for 1-2 of these trucks every week. That BS shouldn’t be happening on a $55K truck w/45k miles! I called dealership to see if they’d throw in a new torque converter, they said NO! So I got rid of it and I’m glad I did. My daily driver is now my 1996 K1500 that just hit 56K.
Btw- I can’t remember what thread these photos came from on this forum, but if I recall correctly, he said he was a GM tech and these photos were from I think a 2018 6 speed. He also said he see’s this routinely in these.

look at that crap! that's worse than any unknown mileage 4L60E that I've opened up!

Found that thread:

Check this video out. 8L90 teardown. I really like this guy. I think he's in the Houston area. Anyways, that thing's crazy: chain-driven oil pump integrated into the valve body! Say, what? LOL.

I'll have to watch this tonight:

thegawd said:

look at that crap! that's worse than any unknown mileage 4L60E that I've opened up!

Click to expand...

My 38K mile 60E was worse.