6 Speed Transmission Issues

[fishrman]

I have had this shudder issue with my 2017 Silverado 6 speed trans. since day one. I only have 6000 miles on it now. First time I complained. Took it into local dealer about 2 years ago. They looked at it, had it over night. Told me it was "just the nature of the beast". A shudder in a brand new truck isn't anything that seems natural to me!! I have had many new vehicles and never experienced this issue before. Now, I have contacted the dealer I purchased it from and they are to look at it tomorrow. They have already told me that I wouldn't need to leave it all night as they new how to fix the issue! Here is hoping they are right!! I have a feeling when I get it there they will tell me I have the 6 speed trany and therefore no service bullitin on it and therefore they can't help me! Sure hope I am wrong!

[JFREED]

My transmission in my 2015 Silverado will not engage in first gear or reverse until it reaches about 1200 RPMs once as it has come up to operating temperature what do you think that issue could be? I’ve had the transmission rebuilt and it has had fluid change multiple times. Thanks in advance

[swathdiver]

3 hours ago, JFREED said:

My transmission in my 2015 Silverado will not engage in first gear or reverse until it reaches about 1200 RPMs once as it has come up to operating temperature what do you think that issue could be? I’ve had the transmission rebuilt and it has had fluid change multiple times. Thanks in advance

Sounds like a pump issue.  If yours were mine I would want to put a Tech-2 on it and see what the solenoids are doing.

 

What was replaced when the transmission was rebuilt?

[ArkAlex]

Im new to this forum.  I drive an 18 GMC Sierra, bought new.  Currently has 113k miles on it, mainly HWY.  I will occasionally pull a 4 wheeler, nothing serious.  It is in the shop currently getting the transmission rebuilt.  It has the 6 speed.  

 

Had no issues up to a week ago, then it started lagging with acceleration.  Then hard shifts to complete failure.  The local transmission shop I took it to said they rebuild 4-5 a week.  Probably bigger issues here that should have triggered a recall.  

[JFREED]

On 9/30/2021 at 5:48 PM, swathdiver said:

Sounds like a pump issue.  If yours were mine I would want to put a Tech-2 on it and see what the solenoids are doing.

 

What was replaced when the transmission was rebuilt?

The torque converter was going out and it was rebuilt back at the first of the year. So then it had the typical Chevrolet bump which I was told was a relearning process but it continued to get worse to the point I had to go back and he reset the pressures in the transmission. Then recently I had this problem mentioned. Now he’s replaced the TCM, reprogrammed it,  rebuilt the solenoids again everything else looked fine. But he thought that it may be the pump then talked himself out of that even after a dealer mechanic said that was the issue. 

[JFREED]

I have a video but it will not let me load it up you can hear that it sounds like the pump is trying to build up pressure

[swathdiver]

15 hours ago, ArkAlex said:

Im new to this forum.  I drive an 18 GMC Sierra, bought new.  Currently has 113k miles on it, mainly HWY.  I will occasionally pull a 4 wheeler, nothing serious.  It is in the shop currently getting the transmission rebuilt.  It has the 6 speed.  

 

Had no issues up to a week ago, then it started lagging with acceleration.  Then hard shifts to complete failure.  The local transmission shop I took it to said they rebuild 4-5 a week.  Probably bigger issues here that should have triggered a recall.  

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 miles.  When you get yours back, "flip the pill".  They easily run 300K miles with regular servicing under the severe service maintenance schedule.  Some have gone to 400K+.

[ArkAlex]

Just got my truck back yesterday.  How do I "flip the pill"?  I don't want to drop another $3700 in 100k miles from now.

Thx!

[JFREED]

Well it wound up being the pump but the shop didn’t want to admit it. They bypassed the thermostat already, it was running much cooler. I still don’t have it back yet they were waiting on a new pump. Approaching 6 weeks. 

[MikeBMW]

9 hours ago, ArkAlex said:

Just got my truck back yesterday.  How do I "flip the pill"?  I don't want to drop another $3700 in 100k miles from now.

Thx!

@dieselfan1 and @Grumpy Bear You're up!

[Grumpy Bear]

9 hours ago, ArkAlex said:

Just got my truck back yesterday.  How do I "flip the pill"?  I don't want to drop another $3700 in 100k miles from now.

Thx!

 

6 minutes ago, MikeBMW said:

@dieselfan1 and @Grumpy Bear You're up!

 

This is a better method in that it provides a pressure relief. 6L80/90 8L and 10L all use the same parts kit. 

 

 

 

[ArkAlex]

Thanks Y’all!

[RandyxGM]

On 3/19/2019 at 10:24 PM, 1SLOW1500 said:

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. 

I know this is an old subject but I just had my 2014 Silverado 6 speed replaced. Never had shudder prior which makes me think it had d tune before I purchased. Shudder is really bad as I drive the thing easy. I have a dyno tuner in my area that will tune this thing but as you say, most don't understand the shudder issue and what causes it. Even my trans shop which is reputable asked me to share with them how to fix shudder in these things. Here is what I have picked up and will be giving to my tune guy:

 

Disable DOD

Tcc apply pressure ramp

Tcc desired slip set to 0

Apply and release set 317 and 319

Zero out the TCC slip, disable the torque converter for gears 1-4 and only allow it to lock in 5th and 6th. But I increase the speed at which it does lock so it doesn't do it at 30mph type of thing. I push it out to above 40mph and nearly 50mph for 6th gear.

 

Anyone have anything else to add? Thanks in advance and I hope someone see's this.

 

 

[pokismoki]

get a torque converter from the 2500 6L90,  you might also have broken fins inside the conveter.

 

install aux trans filter

 

install trans cooler, and delete the thermostat in trans

[Black02Silverado]

6 hours ago, RandyxGM said:

I know this is an old subject but I just had my 2014 Silverado 6 speed replaced. Never had shudder prior which makes me think it had d tune before I purchased. Shudder is really bad as I drive the thing easy. I have a dyno tuner in my area that will tune this thing but as you say, most don't understand the shudder issue and what causes it. Even my trans shop which is reputable asked me to share with them how to fix shudder in these things. Here is what I have picked up and will be giving to my tune guy:

 

Disable DOD

Tcc apply pressure ramp

Tcc desired slip set to 0

Apply and release set 317 and 319

Zero out the TCC slip, disable the torque converter for gears 1-4 and only allow it to lock in 5th and 6th. But I increase the speed at which it does lock so it doesn't do it at 30mph type of thing. I push it out to above 40mph and nearly 50mph for 6th gear.

 

Anyone have anything else to add? Thanks in advance and I hope someone see's this.

 

 

That pretty much covers it.  A billet TC is a must as well.