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6 Speed Transmission Issues

Ohiozr2

By Ohiozr2
in Troubleshooting & Recalls

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1SLOW1500
1SLOW1500

slip over demand. It can be tuned out. 

DeePa
DeePa

Just took it for a 55 mile or so test drive. It’s always an uneasy feeling to drop 500 bucks not really knowing what the results could be.    This truck is so much smoother and more relaxing

swathdiver
swathdiver

The 6-speeds were fine until they put them in your K2s.  GM added a thermostat which keeps the trans temps up at 195 all the time, which makes Uncle Sam happy but kills these transmissions by 100K mil

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1SLOW1500 Senior Enthusiast

1SLOW1500

Posted
Posted

Love that post I have been trying to tell people how good these trucks can really be, but it's like selling a idea people just can ever believe. 

If you want you tune redone that shop should cut you a break. As the credits are already paid for. I would run 91. All you need now if you dont have it yet is catch can and 8quarts of oil MAX. And you are all good to go.

Keep us posted as you get more mileage on it. 

  • 1 month later...
Jc hevy New Member

Jc hevy

Posted
Posted

Why is it that they might be doing a class action lawsuit with the v8 for the transmission but not the v6 what the F***! V6 does the same thing. 

nluchau Enthusiast

nluchau

Posted
Posted
4 hours ago, Jc hevy said:

Why is it that they might be doing a class action lawsuit with the v8 for the transmission but not the v6 what the F***! V6 does the same thing. 

Do you mean the 8L90 and not the 6L80?  

1SLOW1500 Senior Enthusiast

1SLOW1500

Posted
Posted

The 8l90 is a 8speed do you mean the 6l90? 

The 6l80/6l90 are almost the same the output shaft is different and the gearing. Making the housing just a little longer. 

  • 1 month later...
Sandy Clarke New Member

Sandy Clarke

Posted
Posted
Makes he wonder if I know him....this a Michigan location?

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Who does tunes in Michigan?

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1SLOW1500 Senior Enthusiast

1SLOW1500

Posted
Posted
Who does tunes in Michigan?

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Michigan was the power house of good performance shops for a long time. We lost a few of the best like Urban from w2w he moved down south. But still have Walsh in commerce. And bill Briggs. Lingenfelter and katech. Vector in Brighton. Also with the GM proving grounds in Milford there are a hand full of gm employees that offer tunes.
Not to mention the tuner guru off then all Greg banish, he teaches tuning now but is arguably the best in the USA sells books and movies on tuning the pros use.
Just stay away from Livernois, very bad news shop.
Also some great chassis and fab shops. As well as diesel.

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  • 7 months later...
Jj14 New Member

Jj14

Posted
Posted

I have a 2014 gmc sierra and it doesnt shift out of 1 if it trys to it acts like you are pressing the breaks then jerks really bad. There is also transmission fluid coming out of the bell housing.. torque converter maybe?? Also has been making a wining noise when setting at idle. Its been doing that since i bought it 9 months ago

hondarider94 Enthusiast

hondarider94

Posted
Posted

I feel this happens to my truck as well.

It's gotten pretty bad and doesnt seem to get better though. I feel a shudder when accelerating slowly- like slowing down to a stop light then it turns green and I accelerate. I also feel the shudder shift the first couple shifts in the morning or when it's cold. Also downshifts 3 2 1 very rough at times - you can see it kick up the rpms. It just seems to have lots of problems. 91k miles. I have not flushed the tranny yet.. but I was told at 91k miles I shouldnt. It is not low on tranny fluid and it is still orange (from dip stick atleast).

 

I think I need to bring it in

 

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JB45 Enthusiast

JB45

Posted
Posted

I'm glad this thread is getting additional comments on it because I have been reading through it lately. I just bought a 15 GMC Sierra with the 5.3 6l80 with 22,000. I love everything about the truck but the transmission. Similar issues to what you guys are having, but I don't think it is mechanical, at least with mine. It's like it can never decide to lock/unlock/shift down. And inevitably, it chooses the highest gear with the lowest rpms, which for a guy coming from a 04 6.0 with a 5 speed standard is infuriating. I can't believe how awful these transmissions are, especially for how low of miles these trucks have. I think it all goes back to the TCM and adaptive shift patterns. I'm hoping one of the gurus from this site will give us some answers, I'm ready to pull the trigger on a trans tune before my first payment. 

  • 3 weeks later...
Doublebase Enthusiast

Doublebase

Posted
Posted

Yup, been experiencing the same thing since day one, seems to be getting worse now. Feel it on the highway when going up an incline...truck will  shutter, feels like a misfire almost (and once it did actually throw a misfire code cylinder 5). 

 

I've done two tranny services since I've owned it since new (now at 47,000 miles). Pan looked good, no metal shavings, not a lot of debris on the magnet, fluid looked good. And listen, I can live with "this", I just don't want to have to throw a transmission in it as soon as it gets out of warranty. Know what I mean? If it blows at 150,000? I guess I could be "ok" with it, but not at 60,000

  • 2 months later...
nschornfishing92 New Member

nschornfishing92

Posted
Posted

Has anyone had this issue even when the temp is not cold, I drive a ton for work and have out roughly 60k on my 2016 the past year. Never had an issue with it until this weekend driving back from a Wisconsin bass fishing tournament pulling my boat, up hills, down hills in tow haul and not in tow haul both seemed the same. Chugging and major lag between 1st-2nd and 2nd-3rd, didnt seem to matter whether it was in v4 or v8 it still had the problem almost like the gears are partially stripped and it doesnt want to engage...if I really get on the gas, which I dont like to do (not a fan of beating on my truck like that) it doesnt have the issue but if I'm accelerating from a stop like normal it is really bad

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