Allison 6sp: Trans not wanting to take 3rd?

[WolfLMM]

Stock trans and new built unit both not wanting to shift into 3rd at WOT.

Engine revs to 3500 and hangs there for a moment then it shifts.

No codes. SC built unit, and the stocker did the same thing? Fires all other shifts perfectly.

The shifting with Mike's springs is incredible! Just need to figure out this 2-3 upshift.

 

[Mike L.]

Stock trans and new built unit both not wanting to shift into 3rd at WOT.

Engine revs to 3500 and hangs there for a moment then it shifts.

No codes. SC built unit, and the stocker did the same thing? Fires all other shifts perfectly.

The shifting with Mike's springs is incredible! Just need to figure out this 2-3 upshift.

Call me.

 

[Dmax87]

Come up with anything?

 

[WolfLMM]

Truck is making too much power, rpm difference between turbine sensor and output shaft is to great, tcm won't command lockup. Therefore I'm hitting the rev limiter. Gotta talk to some tuners now about tcm tune.

 

[duramaxzak]

I guess that's kind of a good thing! Lol

 

[jc1843]

Try a new fuel filter-- that will affect the shifting- if you let off the throttle and it shifts

 

[CaptPhil]

Does it do it with a stock TCM tune that has 3200 rpm shifts?

 

[WolfLMM]

Yes stock tcm tune. Brand new filter.

 

[Mike L.]

Try a new fuel filter-- that will affect the shifting- if you let off the throttle and it shifts

With a plugged fuel filter you will be having shift problems at low rpm as the engine will not rev for lack of fuel. Wade is achieving high rpm with a no shift and therefore hitting rev limiter and the TCM will not command an upshift at that rpm.

 

[N2BRK]

before the lift pump, back when I had the Banks tuner, mine would sit there on the higher tunes and rev to the moon on the 2-3 without shifting, unless I peddled. I think MMLMM made a post about this back around '09. I added the lift pump and it snicked them off as expected.

What tuning and supporting mods do you have, Wolf? I ask because while the TCM tuning is great, people survived many years without it and didn't hang shifts You might need something else first.

Wally

 

[Bonestock]

Truck is making too much power, rpm difference between turbine sensor and output shaft is to great, tcm won't command lockup. Therefore I'm hitting the rev limiter. Gotta talk to some tuners now about tcm tune.

Bumr man. Same thing happened to me 1st go around with a Precision sled puller converter. I pulled the Precision and sent it back to be tightened up but in the mean time went with a 1054. I really like the 1054 in stock turbo stock fuel lmm.

 

[WolfLMM]

I have a lift pump 150gph. I logged this with a snap on scanner, I'm not getting TCC lockup till top of 3rd gear wot. I am above the 500 rpm slip limit. Best we can figure for right now.

 

[N2BRK]

ok, you must have a lot more power/mod than I thought then. My buddy's LMM max effort with WMI was locking up midway through 3rd (built trans) before we used the new tables to bump up the slip limit. Now it locks at the top of 2nd like it should If you have a V2, give it a shot!

 

[WolfLMM]

Would you mind walking me thru that? Honestly I'm a little nervous missing with tcm tables.

 

[N2BRK]

PM

 

[WolfLMM]

Ok, Mike was correct. No 2nd lockup, blowing thru converter. Logged with EFI and snap on scanner. Through the gracious help of N2BRK, I got a tcm tune to fix this 600rpm slip limit.

Truck now blasts thru all gears with authority. This is the smoothest best shifting allison I have owned to date ( I've had 5 built units now). Suncoast and Mike have really developed a fine shifting trans in all conditions.

Now I got to get to the track and make some passes.

Thanks for all the help fellas, I'm slowly catching back up to speed.

Waid

 

[N2BRK]

Awesome! I hope that you like the 5% bump for the 285 tires too. It's nice to give back when I can, since I'm always asking for advice and help :hug: