Allison 6sp: Hard downshifts

[dordtrecht5]

Could anyone help me understand why these transmissions slam down on the 3-2 2-1 whenever I have changed filters or added fluid. Upon the first drive after build, it did this: I changed filters and reset taps. It improved. I have driven 2,000 miles or so and changed filters, did it again but improved over time. Had a leak around pan gasket and fixed that, but was obviously a touch low on fluid so I added fluid and now it is slamming downshifts again. Why? Should I have the taps reset and change the filter again?

I should also add that it seems to do the same thing, just not as hard, after I have used the lockup controller.

 

[dordtrecht5]

Anybody?

 

[dordtrecht5]

Interesting. 92 views and not one person to offer anything.

 

[x MadMAX DIESEL]

I've wondered too and everyone says its "nature of the beast". Which I think is just an ignorant statement. I would like to know why also.

 

[Mike L.]

Clunking on a downshift could be anything. Sticky trim valve or gain valve, leaking internal harness, or dirty connection at the TCM harness. PSM can cause it also. It could also be internal with a clutch pack being to tight. When you reset the taps; only set the problem taps.

 

[x MadMAX DIESEL]

Mine only does it in first if you slow down really fast, after running it hard before.

 

[dordtrecht5]

Clunking on a downshift could be anything. Sticky trim valve or gain valve, leaking internal harness, or dirty connection at the TCM harness. PSM can cause it also. It could also be internal with a clutch pack being to tight. When you reset the taps; only set the problem taps.

Thank you Mike. Could a clutch pack being too tight also cause a flared upshift? I'm going to reset taps just like you said and put the stock TCM tune back on it and see what happens. I just hope it isn't the converter, or something else internal.

I appreciate your input, Mike L..

 

[dordtrecht5]

Mine only does it in first if you slow down really fast, after running it hard before.

This is exactly what mine is doing. The morning after I originally posted the question, it didn't do anything ... smooth as silk. After driving in city traffic and a bunch of up and down through gears, without one hiccup, I got it on a ramp and pinned it. Shifted smooth going up through 4th and I let off. Came to my exit and had to stop at a light ... Clunk coming down 2-1. Sometimes it will clunk hard shifting into reverse. No real consistent pattern, except that it has done the same thing with each spin on change.

I do want to say that I love the ML-G converter. It couples at about the same time as the the turbo hits on my street tune, so it's fun.

 

[Mike L.]

Thank you Mike. Could a clutch pack being too tight also cause a flared upshift? I'm going to reset taps just like you said and put the stock TCM tune back on it and see what happens. I just hope it isn't the converter, or something else internal.

I appreciate your input, Mike L..

This is the main reason I quit selling kits. Too many problems. I decided I would be safe selling converters only. Don't know if I will do this again.

 

[J17HENRY]

My truck started down shifting hard and it was because it had set a code off because the thermostat had stuck, Just a thought hope u get it figured out.

 

[bluessmax]

Put a 100% bone stock tune (ECM and TCM) and see if it still does it after a little driving.

 

[Mike L.]

Remember; just because you don't have a lit up CEL does not mean you don't have a code. The only way you will see these hidden codes is with a Tech 2. EFI will not show them and neither will any other scanner except an Allison DOC.

 

[dordtrecht5]

Thank you guys. This is good info to have. The only decent people around here that have Tech2 is Hucksdorf and they even reset taps when I referred that in my past post. It is strange how this happens and then it doesn't, then does again on a different day out of the blue.

Somebody else told be to do the bone stock tune as well. I need to get off my dead ass and just go out and do it, I keep making excuses though.