Transmission help.

blue8135

Diesel Addict
Dec 12, 2010
106
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East Texas
Acts like it has lost all shift settings. Flaring, banging shifts up and down, ran hot this morning. LBZ with Mike L clutches and converter. About 80k on build. I have a feeling what the answer is but wanted to get more opinions.

The kicker is, on one key cycle the thing will shift smooth as butter. The next, starts this crap.

Checked fluid this morning when I got to work. Everything was fine. May have a little too much fluid. I checked it at 180° and was about halfway of hot marking. Was 225° this morning and was at the top or slightly above the hot marking. No codes, no cel

It acted exactly like it does when you reset taps. Except this time it got hot

Got a P0777 code on way home

Started off shifting fine from work. After a few miles I noticed a harsh downshift. Then acting like it's slipping in 1st. Everything goes to pot. Then, I was basically coasting downhill and when it got to speed, it shifted to 6th and got the code. Won't clear and seems to be hung in 5th(limp).

Fluid is dark but doesn't smell burnt. Filter magnet had very little material on it. Dumped filter and strained it through a paper towel and nothing really.
 

IOWA LLY

Yes, its really me
Feb 23, 2007
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80K is quite a few miles on a transmission that sees a lot of horsepower. But with your description it could also be a bad tcm perhaps.

Do you have access to another tcm to try?

I would also pull the internal filter and open it up. Seeing what's inside (or not inside) will help with diagnosing what's going on.

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blue8135

Diesel Addict
Dec 12, 2010
106
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0
East Texas
Only around 550hp or so. Trying to determine if an LMM TCM is interchangeable. I'll get more fluid and drop pan to check filter. The spin on looked flawless.
 

IOWA LLY

Yes, its really me
Feb 23, 2007
2,275
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It really sounds more like an electrical issue to me. But a hurt Allison can make you wanna pull your hair out sometimes. They don't always fail in an obvious way.

That's why cutting open your filter is a good place to start. Even if you find nothing chances are it was due for an oil and filter change anyway. So no harm done by starting there. However, if you find debris, there's no sense looking for problems elsewhere.......

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blue8135

Diesel Addict
Dec 12, 2010
106
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East Texas
That's what I was thinking too. Seems that if a hard part was failing, it would do it all the time. I did a drain and fill last oil change. But it won't hurt to do it again
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
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What clutches were used in the build and who did it. Have you pulled the pan and looked at the sump filter. Could be delamination. Need more info.
 

blue8135

Diesel Addict
Dec 12, 2010
106
0
0
East Texas
What clutches were used in the build and who did it. Have you pulled the pan and looked at the sump filter. Could be delamination. Need more info.

They are a clutch of your design back in say 2012? I got the kit at the same tie you took delivery on a pressure spring you designed. A friend of mine that had built several with Suncoast kits did mine.

I'll drop the pan in the morning. Just something about it being 100° in East Texas, in a garage, with the evening sun shining in that talked me out of getting too deep with it yesterday.
 

blue8135

Diesel Addict
Dec 12, 2010
106
0
0
East Texas
Here are some pics
 

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blue8135

Diesel Addict
Dec 12, 2010
106
0
0
East Texas
Very well could have been just dirt that fell in when I pulled the pan. I don't know. It's hurt bad is all I need to know