Allison and 3rd gear, SLAM!

[Swayse]

Edge juice box in hot mode, foot to the floor. It sometimes slams into 3rd gear, not just a firm shift, it slams into gear. The best I could decribe it would be like this, foot to the floor in N then stick in D, BOOM. It has done this about 6 or 7 times. I'm a little worried about this, it's done this too many times to think it's just another Allison brain fart. Another thing it has done only about 4 times, it won't shift out of 3rd. WOT it hit the rev limiter in 3rd and stay there a few seconds, real fun when racing. 13,500 miles so I still have a lot of warranty left. Any ideas?

[mark45678]

I would try to "relearn" the TCM. to do this drive to some place like a large parking lot and put the slector in 1st at about 50~60mph 3 times in a row{let it coast to 10 mph} then drive it hard for about 20 up shifts. by doing this the trans learn how hard it has to apply the clutches to stop slipping. Dont worry your ecm will not over rev the motor! I try not to make large changes in the power settings often...it seams to confuse the tcm! EXAMPLE tow/haul set at 2 and drive set at 2

[ 12-13-2002: Message edited by: mark45678 ]</p>

[mackin]

JK said we are fooling our selves with this as it doesn't work in that way....Takes reprograming,reflash of the TCM.....

Now that's out of the way...I've been following the Torqshift intro to the public....They can disconnect the battery to get back to relearn, interesting....


MAC

[CanadaKev]

Swayse,
Mine did it too :(
Figured it must be juice related. Was running ver.3.2. Once in a while, under hard acceleration she'd slam into 3rd. And I mean, SLAM!!! Felt like someone took a 15lb sledge hammer to the rear diff :eek:
Gives you a real bad feelin'.
Ran it without the juice for a week, and I couldn't get it to do it again. Have since been running 4.3('bout 3 months) and it hasn't occured. Hope it's gone. ;)

Kev

[Swayse]

I hope it's juice related, I'm running 4.61 HOT. The only reason I don't think it's juice related is that I've been running 4.61 for a few weeks before it started to do this. It only seems to do it the first few times I get on it that day, after that it's fine. But, it don't do it all the time, and it only does it in HOT. Maybe I should try disconnecting the battery and see if it will relearn. I've tried the 50mph and rip it down to 1st thing and few times, I can't tell a difference.

My brother in law just bought a new 6.0 PSD, he loves it.

[Swayse]

It's starting to do it in L3, and even at part throttle. But at part throttle it don't slam, it just shifts real firm, and stumbles a little after. I would try it in l1 for a few days, but it takes forever for the allison to learn a power level. I don't want to get caught off guard at a stop light. :D

[RVGuy]

I've incurred this same thing. Twice while towing, once not towing. In all cases, I was mildly accelerating and while in third gear, the tranny slips, jerks and goes on. I am running the HOT Juice version 4.61 also.

It reminded me of a car I once had many years ago that would do the same thing when the tranny fluid was low and after turning a sharp corner or coming to an abrupt stop....causing areas of the tranny to lose fluid.

[Swayse]

It hasn't done this in a long time, hopefully it's gone forever.

[SteveO]

Best advise I can give you...

Get the latest Software version and do not change HP levels.. Keep the Box on the same setting all the time...

If you change HP levels you need to reset the "Adaptive Learn" with TECH II or some other type of Diagnositc reader/programer or live with it until it SLOWLY adapts to the HP increase/decrease...

[technician]

Dont' know if this applies.....

I don't have any juice all stock :( (for now)
However my allison would ocassionaly on decel act like it hit neutral then slam back into gear. My buddy has an 8.1 HD and his did same, he said that there is a TCM reflash for the problem. I had dealer reflash mine 4 months ago and it hasn't done it since. Might be worth a try.....

[Swayse]

I try the reflash. Now to get the dealer to agree to do a reflash. I have a loose mirrow on my truck that I wanted fixed under warranty, he wanted to keep it for two days just to look at it. He told me I counldn't make an appointment to have it looked at, it was first come first serve and they were two days behind. Ok, lets see, I live 70 miles from that dealer and leave it there for two days for them just to look at it and tell me it's not under warranty. No thanks. I need to find another dealer.