Duramax Diesels Forum Truck of the Week
  #1  
Old 02-16-2018, 08:12 PM
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Default Trans feels like it's slipping.

My lb7 has 268k miles and the trans every so often it'll feel like it's slipping, but never goes to limp mode of throws a dtc. Also sometimes it'll shift nice and firm other times it'll shift very smoothly. I've also noticed it does it more under half- full throttle, could the TC be failing? I'm running amsoil low viscosity in it.
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Old 02-16-2018, 10:30 PM
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A healthy stock Allison will never have a firm shift. They will shift smoothly if everything is working right. Firm and hard shifts can easily break hard parts. On a good built Allison, they will shift pretty smoothly even with big HP.

So if you are feeling some firm shifts, it might be a warning sign. I lost a transmission when the trim springs broke (found that out later), and the ECU couldn't control the shifts well. It shifted firm, which I didn't know was a problem, so I ignored it until one day it just broke a shaft on a 30% throttle 3->4 shift leaving work.

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Old 02-17-2018, 07:23 AM
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Originally Posted by DAVe3283 View Post
A healthy stock Allison will never have a firm shift. They will shift smoothly if everything is working right. Firm and hard shifts can easily break hard parts. On a good built Allison, they will shift pretty smoothly even with big HP.

So if you are feeling some firm shifts, it might be a warning sign. I lost a transmission when the trim springs broke (found that out later), and the ECU couldn't control the shifts well. It shifted firm, which I didn't know was a problem, so I ignored it until one day it just broke a shaft on a 30% throttle 3->4 shift leaving work.

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Yeah I plan on doing a built trans, but first is fixing my injectors. Looks to be roughly 10-11k I need to put into the truck to be mechanically sound. Hope I can get this job I just applied to cause then I could afford that and more. Lol
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Old 02-17-2018, 07:45 AM
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Quote:
Originally Posted by Philv View Post
My lb7 has 268k miles and the trans every so often it'll feel like it's slipping, but never goes to limp mode of throws a dtc. Also sometimes it'll shift nice and firm other times it'll shift very smoothly. I've also noticed it does it more under half- full throttle, could the TC be failing? I'm running amsoil low viscosity in it.
Why are you running low viscosity in AZ I would have thought it would be for cold places ?
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AFE Blade Runner,AFE Momentum CAI,DHD Big Air intake Y pipe, DHD fuel block,DHD pcv reroute,MBRP 4 inch exhaust,DHD 3 inch downpipe,BD driver's side manifold,DHD pass side up pipe,DHD 3 inch intercooler hot&cold pipes, ATI damper,Empire pin kit by Big Foot on & off road shop, FASS fuel system,5/8 inch pickup, FASS fuel filter delete, EFI live,V2 & lap top , 5 position switch 250 hp big tune, shimmed fprv by Crank it up , built SunCoast Allison 1078 converter aftermarket trany mount by Limitless Diesel,ARP head studs,grade C gaskets,tig-welded water pump,T stats by Blackout performance,MA t case brace , Kriptonite motor mounts,MA pump rub kit,HD drive shaft 1480joints by Greensburg machine,BDS Recoil traction bars, PPE finned deep pan , Mike L trany cooler, PSC pump, 5100s, Sulastic Shackles, Curt com 2.5 hitch
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Old 02-17-2018, 08:23 PM
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Quote:
Originally Posted by torqued2dmax View Post
Why are you running low viscosity in AZ I would have thought it would be for cold places ?
That's what amsoil recommends. My brother also runs low viscosity in his lbz.
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Old 02-17-2018, 10:03 PM
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If you think it's slipping now, that lift and big tires you're now talking about will kill it. Start saving for that rebuild.

I would've just put Dex3 or Transynd in it and called it a day.
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Old 02-17-2018, 11:45 PM
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I would've just put Dex3 or Transynd in it and called it a day.
This x100

The Allison is one of the first clutch-to-clutch transmissions made, and as such it is picky on fluid more than most for holding power and shift quality.

Dex3 is cheap and readily available, and is what I run. It works perfectly, as that's what it was designed for. Transynd works great too, and lasts longer between changes, but is hard to find and expensive, so I don't think it is worth the hassle.

I wouldn't run other fluids in the Allison, even if Amsoil says too. They are in the business of selling their oil, not saving you money.

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Old 02-18-2018, 12:28 PM
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Viscosity to a point is to protect parts , low viscosity high temps = broken or warn out parts . Do not run WOT in 5th till you are ready to slug your way over to Mike Ls , its on its last leg .
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05 CC/LB DRW LLY Allison
AFE Blade Runner,AFE Momentum CAI,DHD Big Air intake Y pipe, DHD fuel block,DHD pcv reroute,MBRP 4 inch exhaust,DHD 3 inch downpipe,BD driver's side manifold,DHD pass side up pipe,DHD 3 inch intercooler hot&cold pipes, ATI damper,Empire pin kit by Big Foot on & off road shop, FASS fuel system,5/8 inch pickup, FASS fuel filter delete, EFI live,V2 & lap top , 5 position switch 250 hp big tune, shimmed fprv by Crank it up , built SunCoast Allison 1078 converter aftermarket trany mount by Limitless Diesel,ARP head studs,grade C gaskets,tig-welded water pump,T stats by Blackout performance,MA t case brace , Kriptonite motor mounts,MA pump rub kit,HD drive shaft 1480joints by Greensburg machine,BDS Recoil traction bars, PPE finned deep pan , Mike L trany cooler, PSC pump, 5100s, Sulastic Shackles, Curt com 2.5 hitch
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Old 04-05-2018, 07:20 PM
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Just a little update. I did a drain and fill with amsoil torque drive, and the trans shifts much better. I didn't realize how much it was slipping until it grabbed with the torque drive. I just hope when I have the cash and do the 45% sac injectors, the trans won't explode.lol
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  #10  
Old 04-05-2018, 07:29 PM
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Your tuner can keep stock power levels with the new injectors.
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Old 04-06-2018, 03:59 PM
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Quote:
Originally Posted by zakkb787 View Post
Your tuner can keep stock power levels with the new injectors.
Which tuner will do that? I'm not running one and have been looking for the right one.
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  #12  
Old 04-06-2018, 05:12 PM
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Quote:
Originally Posted by Philv View Post
Which tuner will do that? I'm not running one and have been looking for the right one.
Youíll need to run efilive with those SACs.
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2011 Yamaha YFZ450X
2003 Yamaha YZ250
2003 Kawasaki Z1000
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