2015 GMC Sierra shifting issue

[hondaoneal22]

Good morning everyone,  

 

I recently purchased a 2015 GMC Sierra SLE 4x4 with 114,000.  The truck came with a 6 inch lift and 35inch tires.  When I accelerate and get around 45 MPH the vehicle starts to shudder for a few seconds and stops.  It almost feels as if the vehicle is in the wrong gear.  I used someone's computer and it seems like the issue is happening between 5-6 gear.  If It pretty much goes away.  The transmission fluid looks clean, maybe a little over full but not by much.  Does anyone have any ideas? Could I adjust the shift points with a tuner to correct this issue?

 

Thank you

[Ozer]

Hi, welcome to the forum..

You are going to learn a lot about these trucks here.

The shudder you speak of is mostly the torque converter issue the 2014 and 15s have, among other years.

The transmissions on these trucks suck. Mine went out at 120k miles, i had to get a full rebuild. Mine would do it on lower gears as well.

Rule out a misfire by scanning for codes. If no codes are showing then check all connections for spark plugs and wires. Some tend to come loose and cause misfire and shudder. 

[hondaoneal22]

10 minutes ago, Ozer said:

Hi, welcome to the forum..

You are going to learn a lot about these trucks here.

The shudder you speak of is mostly the torque converter issue the 2014 and 15s have, among other years.

The transmissions on these trucks suck. Mine went out at 120k miles, i had to get a full rebuild. Mine would do it on lower gears as well.

Rule out a misfire by scanning for codes. If no codes are showing then check all connections for spark plugs and wires. Some tend to come loose and cause misfire and shudder. 

No codes, I already changed out the  plugs and wires on Saturday to be safe. 

[Ozer]

No codes, I already changed out the  plugs and wires on Saturday to be safe. 

That's what I did when mine started shuddering. Thinking it was a misfire I changed plugs wires even new coils.
Ended up being the TQ. Very common issue. You're out of warranty which sucks. I paid out of pocket for a rebuild. Cost me 2700. Deealer wanted 5k for another GM trans.

Sent from my SM-N960U using Tapatalk

[CamGTP]

A tune should have been just for the 35's alone. The shifting schedule would get changed a lot with it knowing the real tire size.

[hondaoneal22]

Update:  I took the truck to a local mechanic.  While driving his computer showed the Torque Converter Clutch Slipping.  He quoted me around $1400 for just the TC and $4400 for the whole transmission.  The truck has a 114,000 miles on it.  I'm on the fence on what to do. Is this a good price?

[CamGTP]

Call around, get more quotes.

 

A GM re-man transmission on GM parts direct is $2,900, so local prices at a dealer should be around that as well. A new Torque converter on the same website is $265. I am assuming you have the 6 speed auto here.

 

So with this ball park in prices you are at $3,100ish plus the labor and fluids. I don't have the R&R time for a transmission but that's likely several hours. Add tax and yadda yadda and it's up around $4,000 I'd say.

 

But $1,400 for just a torque converter and labor sounds high.

[flyingfool]

look on the bright side , at least it's not the 8 speed trans. because there is almost no parts available for full rebuild,  and the pump on the valve body is driven by a bicycle chain, lol   8 speeds are fuked up. hit eject, or unload it on a used car dealer if you do have the 8 spd.

 

sorry . dont buy lifted anything , or moddified trucks , everyone is selling thier **** up projects

Edited February 15, 2020 by flyingfool

[flyingfool]

16 hours ago, CamGTP said:

Call around, get more quotes.

 

A GM re-man transmission on GM parts direct is $2,900, so local prices at a dealer should be around that as well. A new Torque converter on the same website is $265. I am assuming you have the 6 speed auto here.

 

So with this ball park in prices you are at $3,100ish plus the labor and fluids. I don't have the R&R time for a transmission but that's likely several hours. Add tax and yadda yadda and it's up around $4,000 I'd say.

 

But $1,400 for just a torque converter and labor sounds high.

sounds about right for a dealership.  nowadays they charge $200-250 just to do a trans filter and fluid swap. pull a trans, inspect  the stator, install new TC , if not a new stator also, slap it together, recalibrate , top up fluid.  I say $1400 is about right. 

[Shawn Snobelen]

Thanks for all the info I have a 2015 GMC Sierra 1500 4x4 6-speed and I have the same misshift and shuddering but it doesn't do it when I'm in trailer tow mode what's with that?

[diyer2]

Doing a trans service is where I would start if you haven't yet.