2018 Hard Shifts - Chevy and GMC Duramax Diesel Forum
2017+ L5P Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

 3Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 25 (permalink) Old 08-06-2019, 12:17 PM Thread Starter
 
Join Date: Jan 2011
Posts: 8
2018 Hard Shifts

2018 CCSB High Country.. Built late Feb 2018. 14,000 miles, bone stock. Dealer serviced, fluid level is ok hot, just over the high mark. Not towing, not using tow/haul mode or exhaust brake.

I keep getting some firm shifts on random days, but can't get it to do so for the dealer.
Seems completely random, but is especially noticeable 3-4 and 4-5.
This seems to happen mostly when the trans is up to temp (160-180 depending on how hot it is here)

Dealer says I'm all up to date on software and calibrations

Any thoughts?
4wdaaron is offline  
Sponsored Links
Advertisement
 
post #2 of 25 (permalink) Old 08-06-2019, 12:45 PM
Senior Member
 
Join Date: May 2018
Posts: 670
Someone with more knowledge might have a better idea, but I would take a pint of fluid out. The Allisonís donít like to be over serviced.
hdrolling and Sierraluva like this.
MIkey52 is online now  
post #3 of 25 (permalink) Old 08-07-2019, 04:50 AM
DuramaxForum n00b
 
Join Date: Apr 2019
Location: Sunshine State!
Posts: 10
My 2019 2500HD Z71 has had hard shifts since day one! Took it back to the dealer within a few days of purchase and was told it was NORMAL! Was told the new vehicles shift all over the place, not to worry about it! Yah Right! Just spent $65,000.00 for a harsh shift when my old 95 4L80E still shifts smooth as silk! GM needs to FIX their problem. Truck now has about 6500 mi. on it and it has not changed. It also has a shudder under heavier acceleration. A lot of people here on this forum claim the fluid change to TES-295 really helps. I think I am going to try the fluid change. If I had to do it all over again and know then what I know now, I would not have bought the truck!
Highmaster is offline  
Sponsored Links
Advertisement
 
post #4 of 25 (permalink) Old 08-07-2019, 04:53 AM
DuramaxForum Veteran
 
hdrolling's Avatar
 
Join Date: Apr 2011
Location: Grays Creek, NC
Posts: 1,418
Garage
Quote:
Originally Posted by MIkey52 View Post
Someone with more knowledge might have a better idea, but I would take a pint of fluid out. The Allisonís donít like to be over serviced.
I would do the same, better to be a little below the hot mark vs above it.

My 18 shifts great.
Sierraluva likes this.

2018 3500HD LTZ DRW

My build thread https://www.duramaxforum.com/forum/b...lly-build.html

GM DRW club member #224
hdrolling is offline  
post #5 of 25 (permalink) Old 08-07-2019, 06:07 AM
DuramaxForum Fanatic
 
redwngr's Avatar
 
Join Date: Feb 2011
Location: SW Ont
Posts: 5,518
Mine has the random 'harsh' shifts the OP reports - I think the 4-5 is the most common one on mine, and with normal or slightly above acceleration into traffic. Not harsh enough that I think it is causing damage, but harsh enough to be annoying.
So far, I also can't produce them at will. It has about 20,000 miles, but has done it regularly since new.

I've not been able to correlate it to trans temperature (but I rarely see 180 on mine)

Did take the dealer tech that does the Allison work (and drives one of these) out -- but of course it didn't do it. As I'm writing this I wondering if that was because we were driving in the city, so speeds may not have been high enough to get 4-5 occurring at a high enough rpm for it to happen - time for some experimenting.

None of the previous dmax/allies I've run did anything like this.

2018 GMC 2500 L5P CCSB 4x4 Denali - Mineral Metallic; previous '11 LML, '10 LMM and 04.5 LLY
redwngr is offline  
post #6 of 25 (permalink) Old 08-07-2019, 09:02 PM
DuramaxForum n00b
 
Join Date: Nov 2012
Location: Vilonia, AR
Posts: 18
Well add me to the list ...my 2018 has done this since day one. Everytime I bring it in for service or anything I make them document it so when I'm out warranty and this tranny kicks the bucket I can refer back. It never does it for them. I have 53K on my truck. Actually doesn't seem to do it in Tow/Haul Mode when I'm towing my travel trailer.
Denali2012HD is offline  
post #7 of 25 (permalink) Old 08-08-2019, 12:24 PM
Junior Member
 
Join Date: May 2019
Posts: 47
Mine only does it once in a while and usually only right before coming to a complete stop.

2019 GMC Denali HD 3500 SRW Tri-Frost

-S&B Filters CAI

-Bilstein 5100s

-Mountain2Metal Tranny Cover
MrGraff is offline  
post #8 of 25 (permalink) Old 08-08-2019, 02:40 PM
DuramaxForum Fanatic
 
redwngr's Avatar
 
Join Date: Feb 2011
Location: SW Ont
Posts: 5,518
Quote:
Originally Posted by MrGraff View Post
Mine only does it once in a while and usually only right before coming to a complete stop.
Mine does than one sometimes too. Like it didn't get the torque converter unlocked soon enough.

To me, it doesn't feel like it's the same issue as the 4/5 shift.

2018 GMC 2500 L5P CCSB 4x4 Denali - Mineral Metallic; previous '11 LML, '10 LMM and 04.5 LLY
redwngr is offline  
post #9 of 25 (permalink) Old 08-08-2019, 04:09 PM
DuramaxForum n00b
 
theJman's Avatar
 
Join Date: Oct 2018
Location: New Joisey
Posts: 17
My 2018 does it as well. It doesn't always happen, and the amount of harshness varies too. It's very schizophrenic.


2018 GMC Sierra 2500HD, DMAX, CC, 4WD
theJman is offline  
post #10 of 25 (permalink) Old 08-09-2019, 11:09 AM
Junior Member
 
Join Date: May 2019
Posts: 37
my 15 has harsh shudder shifts from 2nd-3rd it is intermittent and i can not replicate or cause it. but i can also not find a solution to it.

2015 Duramax LmL
5" exhaust no Muffler
PPEI 5 stage Tuner
Fass 150 lift With Sump
Edge Insight cts2 With EGT Probe
Big Daddy Yum Yum is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevy and GMC Duramax Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome