In recent months my tranny has been shifting funny, usually first time driving each day before getting to operating temps. When driving in my neighborhood with lots of speed bumps, as I slow for the speed bumps, between 10-20 mph, the trans down shifts into first, feels like a lot of clutch clatter with a standard. try to give it some throttle and it barely moves until the chatter stops and shifts back into second. it did it once near 20 mph and the tach shot up near 3,000. Took it to the dealer they said there were no codes, which I told them there wasn't and it never turned on the cel. they test drove it and said everything is normal for this truck.
So, is this normal to have the truck feel like you jamb on the brakes and shake the whole truck like you have a bad clutch in a standard? Most times I am not even on the brakes, just coasting to a stop or speed bump. All I've done to the truck is MBRP front pipe, egr blocker and finger stick. The trans was service about a month before this all started.
Thanks for any feedback anyone can provide.

Like all vehicle diagnostics, I think you should start with the cheapest/easiest thing first -- 1. check the fluid level and make sure it's right, and 2. try having the dealer reset the TCM/'trans learn'? Might have just mis-learned that down shift.

If that doesn't work, I'd go back to the trans service you described having done a month ago and see if anything got screwed-up... Who did the service? Was it a flush or just a pan drain or did they/you pull the pan, or what?

FYI -- mine will downshift to first under the conditions you're describing, including the big rev increase because first is such a short gear and the somewhat abrubt upshift to second as soon as you get into the throttle again, but I don't get the chatter you're describing. Also, FYI, from what I've read here, TCM DTCs may or may not trip a check engine light on the dash, so that's not always a reliable indicator of whether you've got a code stored or not. It may be that the code cleared itself by the time you took it to the dealer. Next time it does this, try to get it scanned very soon thereafter.

The service was just draining the pan and changing the spin on filter. Th etruck drove fine for about a month before this problem came up. The trans relearn has been reset with no improvement. I have a scanner so I can regularly check for codes but have never had any come up.

:confuzeld

Fluid level is OK?

Yes, fluid level is ok.

Somehow this does not sound like a trans problem. Rpm would not shoot up because of a trans problem. It will only shoot up if you pressed the throttle far enough or you have an engine problem. You mention that you have had this problem for a couple of months.

the one time the rpm's shot up high, i may have been trying to accelerate just as it down shifted. I tried driving one morning when it was acting up, shifted into 2nd, still down shifted weird, put it 1st and it stayed in first, never acted weird. Not really sure how to describe it, I just don't like how this nearly $50k truck drives. One of very few complaints I have, overall, extremely please with how this truck works.

It could be that you are new to the Allison. It is a different breed and a champion to boot.

I think I know what your talking about. It feels like the truck shudders as it down shifts. Then pressing the accelerator it will rev up and abruptly shift back to second, right?

This, for me, only happens when the truck is cold. After normal operating temps are reached these symptoms no longer occur.

I think the tranny shifts this way to warm itself up. I beleive it is normal.

Thats what i'm talking about. What bothers me is that it never did this for the first 9 months of owning this truck, even all through the winter when I lived in Massachusetts. Now I'm in southern Texas and it starts? Doesn't seem right to me, even if it is "normal" for these trannies.

Do you have your foot on the accellerator at all when it makes the downshift? I ask because if your foot is on there at all you can really make the truck buck back & forth when you're going over a bump -- the throttle input is kinda touchy there for some reason, and the gearing is so low that you'll really notice it. So, try taking your foot all the way off the pedal when you're going over the bump. Also, just for sh!ts, try putting it into Tow/Haul.

I'm pretty sure it never did this the first 9 months of owning the truck because you didn't live on a street with all those speed bumps. It seems like the symptoms you're describing might just be a product of this particular stretch of road.