http://forums.pelicanparts.com/uploa...1676136501.jpg

Well the magnet didn’t look so bad and the fluid is still in good shape. I will have to check with the first owner, I seem to recall him saying he got the transmission replaced under warranty. But that might have been another vehicle I bought from him….

Nope, he said original trans, actual mileage is 134K.

I’m hoping the cooler temps here keep it surviving.

190 F seems really excessive. Just breaking down the fluid at that point.


I get nervious when my 4r100 gets that high.

Yeah, before I changed the filter I saw about 196 driving up a mountain pass (2000 foot gain), in around 50F temps. I will see if any temp drop occurs next week. My Suburban does have the tow package so maybe a bigger cooler but I’m not sure….

I’m putting a 6L80e hooked to a 5.3 (LC9) in my ‘85 Land Rover Defender. Turns out there are a few things you can do to help the 6L80e’s reliability. One is to replace the flex plate, as the factory plate tends to flex & ultimately crack. Pretty easy to do. The second (as alluded to earlier) is the Sonnax ZIP kit. It’s a series of upgrades that ‘fix’ some of the inherent weaknesses. I did mine in about a day. https://youtu.be/0YEzuUsXITE

Also search for Gary Ferraro on YouTube.

A very good friend had a 2015, be bought new, not a lot of miles and definitely not ha4d. After his 3rd transmission under warranty and it was close to out of warranty, he went and traded it in on a new Ram when they were making good deals on them. He is still very happy with it.

Ms Rockets 2010 Tahoe has 250,000 miles. No issues to date. I’m not sure what transmission that has.

I got 200,000 miles out of the transmission in my 2001 F150 when I had to rebuild it. I’m at 178,000 miles with my 2014 F150. Knock on wood, it’s still good.

Interesting read. Why didn't GM just put in a known durable Allison transmission in their trucks like their old diesels? It is that much more? I understand its only a 6 spd and may not be a fuel efficient. After all, I think they own Allison?

cost. There's bruce Jenner parts that GM uses in the regular cheb/GMC that they won't use in the caddy due to extra noise.

Ram dumped Aisin for a reason and it wasn't bc they're more durable than the 68RFE....

That Aisin is a good tranny.

Does it cost that much more to have a Allison then the typical GM tranny? I am asking because I have no clue.

It's my understanding that Allison are built in house at gm tranny plants. I know a plant guy that was talking about a line of military application Allison's that they ran maybe a few years ago.


This is different than dodge that just sourced the cummins and aisin, then shipped it all to Mexico to be put together.

I got my truck back last Friday. Full rebuild with all of the updates. According to the owner of the shop, the aftermarket guys like Sonnax have really stepped up and there are updated parts now that weren't available as even as recently as 18 months ago. Was about $1800 in parts, and $2200 in labor (or the reverse of that, I don't have the receipt in front of me).

I also have the new thermostat - did a 10hr road trip today, MA into VT and back. Highway, mountain roads, soft and muddy dirt roads, etc. Temps averaged 121-140F. They used to be 190-194F no matter what, that's what GM had them set for. He also highly recommends synthetic trans fluid.

The line item part cost for the t-stat was $84, but there's no part #.

I'd recommend that since you are in CO pulling grades, and it should be easy to do.

Not surprising. I had a great conversation with the shop owner that just built mine and he said they rebuilt instead of replace as GM was not (still are not?) using updated and improved parts that the aftermarket has developed to fix the now-known shortcomings.

Is the new t-stat a superseded part from GM? I did see where guys reverse the internal “pill” in the OE t-stat to create a straight bypass. Usually drops temps into the 140F range. Wonder why GM wanted the operating temp up high? Synthetic Dexron VI in mine. I still haven’t taken a long drive up hill, been really cold of late too.

Check out this guy. Seems that GM transmissions are a bit of a specialty for him.

https://m.youtube.com/@performancetransmissionsll1573/videos#bottom-sheet


Sent from my iPhone using Tapatalk