Transmission issues

[thomasinnv]

I have an alison 740 with atf in it. (I don't know what kind of fluid, I just know it's red). Lately I am noticing it takes more power to get it moving. I have verified that the brakes are not sticking.  It rolls fine in reverse, but when I accelerate in first gear from a stop it seems like it's slipping. It seems to be worse when it's cold, not as bad when warm but still not quite right. I got stopped on an 8 percent grade due to road construction and when I started up again I was afraid it wasn't gonna make it, it seemed like forever to get some speed going and it was really winding up. I have driven this thing all over the country through many mountains and I know what is normal and what is not, and something ain't right.  Under full throttle acceleration tq locks up at 17 and it shifts into 2nd gear at 19. There appears to be no slippage when the tq is locked, all all other gears are good and solid. Once it's moving it goes fine but it definately has a startability problem. Am i toast? Or is it possibly an adjustment? Btw, the fluid level is good, nice bright red color, and no burnt smell.

Ideas?

[Geoff]

Maybe if you drained the fluid and took the pan off you could look signs of failure.

--Geoff

[azdieselman]

A slipping stator clutch will cause poor startability but run fine at highway speed.

A stall test with an accurate tach should show a problem.

[luvrbus]

You have test plugs on a 740 to check the pressure that is where you start,if the pressure is low in first the clutch pack is gone

[thomasinnv]

Cliff can you expand on that please? Which plug/where is it located, how much pressure am I looking for, and I assume the pressure is checked with it in gear?

[bigred]

Is it actually taking off in first gear? The owners manual says that my ht755cr may take of in first or second gear.but it does not say under what circumstances it takes off in second versus first.Mine at times is sluggish  on take off .Not as bad as yours,but it still don't jump away like it does in reverse.Do you get a lot of black smoke on take off ?? If so may be an engine/blower problem.There is a write up currently that covers this in detail .Look in topics look for "black smoke".

[thomasinnv]

It is definately a trans issue, not an engine or fuel issue. It is definately taking off in first gear. It's definately slipping for some reason. I don't know where to put the pressure guage or how much pressure to look for or I would. I can figure out most stuff engine related, but when it comes to auto trans I'm in the dark.

[bigred]

Your best bet on that may be a call to Allison.Maybe you will luck up and actually get someone that knows what they are talking about.From the experience I've had ,your chances are about 50/50 lol.

[Scott & Heather]

So the mighty 740 can actually fail huh? I've heard they were bully proof


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