6 Speed reliability.

[Wylie_Tahoe]

Still on the hunt for a new Yukon. It was stated that 09 was the year the 6 speed started. So my question, how is its reliability v's mileage?

Thanks,

 

[jmil1974]

The trans itself: strength and reliability are quite good, especially compared to the 4L60/65/70s. 6L80/90s been holding good power for a dozen years. If you are more than stock and have it out, upgrade the converter, get a deep pan with a drain plug, and get a good tune.

 

[swathdiver]

Still on the hunt for a new Yukon. It was stated that 09 was the year the 6 speed started. So my question, how is its reliability v's mileage?

Thanks,

The transmission was first introduced in 2005 and was first used in the trucks in 2007. 2009 Was the first year behind the 5.3 engine.

In this generation truck, the first sign of trouble are the plastic solenoid discs that fail at around 165K in vehicles where the transmission was never serviced. These can be rebuilt on your kitchen table without removing the transmission for about $110 plus fluids.

The next most popular issue has to do with the torque converter clutch disc material coming lose and fouling the transmission's pump.

Then there are drum and piston cracks that occur and bleed off pressure preventing shifts.

Having said all that scary stuff, these transmission are far more reliable than the old 4-speeds they replaced and it is not uncommon to see them exceed 300K miles with regular service. We have even seen them exceed 400K miles.

Just as you can send out an engine oil sample to a lab for analysis, the same can be done for your transmission. I did and the report was stellar and it's at around 170K miles now.

A BlackBear tune modifies the transmission's settings for performance and durability which many of us also had done.

To summarize, it's a wonderful transmission and don't let internet hysteria deter you from purchasing one of these great trucks.

 

[Joseph Garcia]

^^^x2^^^ I've got 145k miles on mine, and it works just fine. I also have a BlackBear Performance tune on the transmission (as well as the engine).

 

[Meccanoble]

I'm at 240k and currently running fine. I did have a stuttering issue at times during low throttle over 30k miles ago, especially if going up hills but that was all but eliminated with Lubegard transmission fluid change. I dont tow, I purchased car at 120k. Fluid/filter changed twice since ownership.

 

[donjetman]

I hear the weak link is the torque converter.
Today we have 174k miles on our 6L80e. When we bought the truck 3+ yrs ago, it had 131k miles. I changed the torque converter while I had everything out to do the rear main seal, etc.

Today I'm changed the fluid and filter for the second time since we bought it. I sent a sample of the Dexron VI to a lab for analysis.

 

[usaf27]

I hear the weak link is the torque converter.
Today we have 174k miles on our 6L80e. When we bought the truck 3+ yrs ago, it had 131k miles. I changed the torque converter while I had everything out to do the rear main seal, etc.

Today I'm changed the fluid and filter for the second time since we bought it. I sent a sample of the Dexron VI to a lab for analysis.
View attachment 369222
View attachment 369223

What did you lab results come back with?

 

[donjetman]

What did you lab results come back with?

Here's the thread with results (Good): https://www.tahoeyukonforum.com/threads/atf-lab-results-dexron-vi-43k-miles-on-fluid.134360/

 

[robgreg75]

My torque converter lock failed at 191K miles, we were on a trip so just kept driving it. I ordered a torque converter, a rebuild kit for the tranny and one of the Sonax valve upgrade kits for longevity. I drove it about 1000 more miles before I got all the parts and did the rebuild. By the time I did rebuild it the tranny would not stay engaged at factory idle, I had to up the idle to 800 rpm (I have HP tuners) to keep it from slamming into gear as the rpms came up. So the converter had spit metal into the tranny.

When I took it apart I replaced the clutch packs since I already had them in the kit but the factory clutches all had 0.002" of wear or less so they didn't need to be replaced and would have easily lasted 500k miles. The Sonax valve kit seemed to be a worthwhile update too. It is now at 269,000 miles and the tranny works like it was new, or even better as it hasn't acted funny in 77,000 miles since I rebuilt it. I would get some hard shifts at times before the rebuild.

 

[Just Fishing]

I had mine apart recently.
180k, it was a proactive rebuild since i knew i had trash pass through the pump...

Everything looked great, it could have kept going for a while longer.

Clutches were good, but a bit glazed looking.
I think it had the original fluid @ 170something where i bought the tahoe...

I had a broken wave plate in the 2-6
I think that helped to firm up some of the shifting. Lol

Pressure switch Laminates were failing, didn’t have long.

Otherwise it was a very clean rebuild.