I was told that on an LB7 (5 sp.) the weak link in the trans. when towing was the 4-5 shift. On the LMM (6 sp.) does this still hold true, or is it the 5-6 shift? Thanks. :)

The Allison's weak spot is 4-5, 5-6, 6-5, 5-4. The 6 speed Allison really only improved the holding power at the low end gears, believe that is why only a Transgo Jr. kit vs. the full Transgo kit that is used in the 5sp Allison. Don't quote me on this, but I take it easy on those shifts with the power turned up some. Chris

The Allison's weak spot is 4-5, 5-6, 6-5, 5-4. The 6 speed Allison really only improved the holding power at the low end gears, believe that is why only a Transgo Jr. kit vs. the full Transgo kit that is used in the 5sp Allison. Don't quote me on this, but I take it easy on those shifts with the power turned up some. Chris


I beleive thats incorrect,I was told by MIKE L that letting it hit 5th/6th towing its fine.

So they had to bolster all the clutches.Im pretty sure thats why there is no "LOCK OUT SWITCH"

The Allison's weak spot is 4-5, 5-6, 6-5, 5-4. The 6 speed Allison really only improved the holding power at the low end gears, believe that is why only a Transgo Jr. kit vs. the full Transgo kit that is used in the 5sp Allison. Don't quote me on this, but I take it easy on those shifts with the power turned up some. Chris

Not correct. The 5 Speeds in 2001-2005 were weaker in 5th because of C2 clutch capacity (C2 used in 4th and 5th) at around 750 ft-lbs input torque. Its capacity was increased by over 30% with the 6 speeds used in 2006 and later.

Therefore, the 6 Speed version improved the holding capability in the HIGHER range gears. This is why only the Transgo Jr. kit is needed to put full pressure to the trimmed (shifting) clutches. (C2 has main pressure on it in 5th and 6th). You can guess what the next "improvement" will be...