Built allison slams into drive or reverse after warmed up

Sean73T

New member
Nov 29, 2018
4
0
0
Built 6spd Allison by Mike L. Truck runs flawless shifting through gears cold or warm. Doesn't hesitate to go into gear, it just slams into reverse or drive after the truck has reached operating temp. More going into drive than reverse. It feels like the drive train is moving one way and then suddenly has to go the other. When I put it into drive the truck will lurch forward ever so slightly. You can clearly hear a loud bang when going between reverse and drive. I always am at a standstill and pause in neutral. Stock TCM. EFI tuned by Idaho rob on a DSP5. Thoughts?
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
4,152
1,262
113
Larsen, Wisconsin
Built 6spd Allison by Mike L. Truck runs flawless shifting through gears cold or warm. Doesn't hesitate to go into gear, it just slams into reverse or drive after the truck has reached operating temp. More going into drive than reverse. It feels like the drive train is moving one way and then suddenly has to go the other. When I put it into drive the truck will lurch forward ever so slightly. You can clearly hear a loud bang when going between reverse and drive. I always am at a standstill and pause in neutral. Stock TCM. EFI tuned by Idaho rob on a DSP5. Thoughts?

Call Mike L. That said, how old is the trans? Have you done a reset/relearn with a Tech 2 or Snap-On?
 

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
Don’t reset anything. It was already done. Leave it alone till you talk to him. Go check the fluid level.


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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,667
5,813
113
Phoenix Az
I'm giving him time for his morning coffee before he tries to convince me to buy a demon and get rid of the truck again:roflmao:

its 10:30 there, hes old but he aint that old :roflmao:

Don’t reset anything. It was already done. Leave it alone till you talk to him. Go check the fluid level.


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once again, THIS!