Allison 6sp: 2 to 1 downshift neutral

[nsolimini]

When coming to a stop or slowing down to where my transmission will shift from second gear back to first, what would cause a neutral feeling if I get back into the throttle too soon? If I get back on the throttle too fast, the truck will act like it is in neutral and then jump into first gear (no bangs or any noises). If I give it a few seconds before I get back into the throttle, everything is fine.

Transmission details in my signature. This is something recent and did not happen right after any of the modifications.

 

[Chevy1925]

How many miles on the internal filter since the build? has it ever been changed?

if not

drop the pan, pull the internal filter, split it open, takes pictures and post them here.

 

[WolfLMM]

Every built trans I've ever had, did that. A new internal filter will probably cure if. At least for me it did.

 

[nsolimini]

That is what I thought too, changed the spin on and the internal. I saved the internal to cut open, but havent done it.

 

[DAVe3283]

Neither of my transmission builds did that. Though it is a 5 speed, so maybe this only happens on the 6 speed?

So you changed the internal filter, did that fix the issue for you?

 

[Mike L.]

Built Allisons sometimes shed clutch material till broken in. Depends on which clutch material was used.

 

[nsolimini]

Raybestos clutches. And changing the internal filter seemed to help with frequency but did not solve it.

 

[TowU4Free]

Just out of curiosity did you ever experience a "bump "when coming to a quick stop and it doesn't downshift to first until you are stopped ? I think these two things go hand-in-hand my best guess is some seat time and changing that internal filter like you did are the best bets but what do I know I'm just a keyboard warrior

 

[nsolimini]

Tomorrow on my way to work I will try the quick stop, I haven't noticed before but I also wasn't really paying attention to that. Also, it will go into first while moving it just seems like there is a longer than normal delay going into first and if I hit the throttle while it's between that shift it will go into neutral for like a second or two.

 

[2004LB7]

Are your shift points adjusted, or anything else in the trans tune?

 

[nsolimini]

Tried a quick stop today with no bumps or anything noticed from the trans, I even activated my ABS lol. Stock trans tuning, I have not messed with that.

 

[Jesseh72]

Did you happen to figure out what the cause of this was? I am having the same issue at low speeds before it gets into 1st I am getting a false neutral. It has happened 3x out of the blue. I have never had any prior issues. I have about 2-3k on a suncoast build. Mine has alto clutches new ppe deep pan & filter and a new external pan. Fluid level is good and does not smell burnt.

 

[melms23]

Mine has done the same thing once in a while since ithe has been built. I changed the spin on and internal filters with 30k on the built trans and it didn't make a difference.

 

[Jesseh72]

Well thats good to know. I read somewhere else a guy had the same issue he said that cleaning his abs sensors fixed it. I am not sure how this could be though. Seems a little far fetched for me but I guess anything is possible.

 

[Mike L.]

Well thats good to know. I read somewhere else a guy had the same issue he said that cleaning his abs sensors fixed it. I am not sure how this could be though. Seems a little far fetched for me but I guess anything is possible.

All your module systems are in line talking to each other. If there is a problem with one of them; it will effect all of them. To what extent we don't know.

 

[c20elephant]

Well thats good to know. I read somewhere else a guy had the same issue he said that cleaning his abs sensors fixed it. I am not sure how this could be though. Seems a little far fetched for me but I guess anything is possible.

Not really, a friend of mine has a TECH-II and we cycled the ABS module on mine after replacing the flexible brake lines and bleeding the entire system. The transmission did shift differently (crisper) after it was done. That was short lived as the Allison TCM always remembers what it did not what you're gonna do at the next traffic light....

 

[WolfLMM]

Quick stop or rolling through a yield sign, mine hits neutral everytime now.

 

[WVRigrat05]

Mine used to do it quite a bit after George did my trans, I called him and he told me to not drive with two feet (I'm bad for that) and it actually has only done it twice since then when I'm in a lot of stop and go traffic.

 

[c20elephant]

Mine used to do it quite a bit after George did my trans, I called him and he told me to not drive with two feet (I'm bad for that) and it actually has only done it twice since then when I'm in a lot of stop and go traffic.

I don't know anyone that uses 2 feet..:violent: bad habits are difficult to break to say the least. I get less driveline thunk (had a nasty one) even after greasing the yoke and a few other items to fix it. Helps being a bit more careful how I apply the brake/throttle making sure I'm completely off the throttle before I apply the brake and visa-versa ....

 

[WVRigrat05]

Yeah, you save a half a second using both feet, adds up over time lol.