issue Transmissions Issues/Problems

[andyhaug]

How does poor shifting increase MPG? How can the flaring possible increase the MPG at all? I would think decrease. I think overall it severely decreases my MPG because the worse it shifts the harder I drive it.

[Newell33]

How does poor shifting increase MPG? How can the flaring possible increase the MPG at all? I would think decrease. I think overall it severely decreases my MPG because the worse it shifts the harder I drive it.

I've always thought the same thing. The shift flairs and the confusion that I feel can't possibly improve mileage. It's horrible tuning, plain and simple.

[Timmay35]

Hi I have a 2015 Sierra All Terrain 6.2L w/ 8sp. I have 3500 miles and have been experiencing the same issues with the transmission as described below, rough shifting, not finding the gear then slamming into gear and jerking forward, hesitation, clunking and shaking all over at any speed. This truck is brand new with a 53k sticker price. I took it to the dealer twice, the 1st time they replaced the left side motor mounts and reprogramed the transmission, the 2nd time they told me they were unable to duplicate concern and it was normal operating characteristics. Strange because they acknowledged the issues on the 1^st visit and now they say it’s normal that they don’t see any issues but the truck is driving the same way as always. What should I do, I don’t even want a truck any more after all these issues, it’s nearly impossible to drive in heavy traffic. Lemon Law, Dealer Buy Back? Does anyone have some helpful information?

[drstimpy]

I'm about to pick up a 2015 Sierra 6.2 8sp with max tow. On my test drive I noticed very severe banging with up shift in lowish gears under light throttle. Before I picked up this one, I test drove another that was perfect...and faster. Mine seems slower and shifts poorly. Do I just not take it home?

 

 

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[nadrojcote]

I'm about to pick up a 2015 Sierra 6.2 8sp with max tow. On my test drive I noticed very severe banging with up shift in lowish gears under light throttle. Before I picked up this one, I test drove another that was perfect...and faster. Mine seems slower and shifts poorly. Do I just not take it home?

Some must watch while others must sleep

Have the dealer check to see if theres any outstanding tsb's or recalls for the truck. Have then complete any that are and take it for another drive.

[drstimpy]

Will do...thx

 

 

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[Donvan514]

I don't know if I'm noticing a tranny issue or a drive line issue. My truck will "slam" on occasion when decelerating and reapplying the gas. This happens at lower speeds. The tranny doesn't slip from what have noticed... I've read this whole post and it seems like there are a few different issues here. Does anyone have a similar slam when at lower speeds and transitioning off and on the gas pedal?

[hezman]

Donovan514 - the problem is both the tranny and diff. Have a 2014 SLT 6.2 with 17K miles. At lower speeds around town, clunking is always present when changing loads on the driveline. I know exactly the problem you are having and have experienced that also. It is a pronounced noise and very alarming when it happens. My situation occurs when I accelerate, back off the pedal and then get back on the pedal. I think the combination of excess lash (which the dealer acknowledges) in the differential and the transmission searching and then quickly downshiting creates the noise and can be felt throughout the vehicle. Beautiful truck otherwise, but I'm going to move on as I am getting tired of the dealership 'normal' position.

[nadrojcote]

If you have a clunk when decelerating try tightening your u bolts on the rear axle. Lots of people have had issues with axle wrap because the ubolts arent tightened to spec. Almost all of these trucks will make a clank when the transmission purges air on the first 2-3 shift, but a thud like clunk is most likely caused by axle wrap.

[drstimpy]

I have 300 miles on mine and I'm pleased to report that the transmission misbehavior I experienced on the test drive is gone. Before I took it home, the dealer let their transmission expert check it out. I wish I knew what he did! If I find out I'll post it up

 

 

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[drstimpy]

Are those 78 foot pounds?

 

 

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[nadrojcote]

Are those 78 foot pounds?

 

 

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theres conflicting info on that, 78 or somewhere around 100, I did 100 on mine and I haven't had a clunk since. I originally used clamps on my rear leafs then found out it was just loose ubolts causing the problem.

[hotrodz37]

theres conflicting info on that, 78 or somewhere around 100, I did 100 on mine and I haven't had a clunk since. I originally used clamps on my rear leafs then found out it was just loose ubolts causing the problem.

 

Just curious as to where you've seen 100? Everywhere I have seen said 78 which does seem a tad low. I saw another post that said 54lb first pass and then 130 degrees second pass, whatever that equates to.

[nadrojcote]

 

Just curious as to where you've seen 100? Everywhere I have seen said 78 which does seem a tad low. I saw another post that said 54lb first pass and then 130 degrees second pass, whatever that equates to.

that's the post I was referring to. I think that 78ft lb is too low as well and its probably the reason most of these trucks end up loosening off.

[drstimpy]

The fasteners look like they ought to be able to handle 100

 

 

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