Need help with Allison Pan Removal

[Andyrv6av8r]

So let me preface this by saying that i had a catastrophic failure of the front drive shaft in my 1078 while at max speed on the interstate. Busted axle yoke, transfer case yoke and the driveshaft itself. Not a pleasant moment let me tell you. In the process of disintegrating, it knocked a hole in my transmission pan/module and I have to replace it. I have taken all of the bolts out and dropped it about an inch. But I can't figure out how to disconnect the main wire harness that passes through the upper flange on the transmission and is a part of the module. The plug you see in the photo may come apart but I haven't figured out how yet.



This is where it passes through the flange in the transmission



The main wiring harness in question and plug mentioned.



This is a plastic cover on the wires inside of the pan/module. It covers the wires inside.

 

[fuzzytoaster]

Take the transmission body harness off the transmission pigtail by twisting/unthreading it. There is a large flat washer on the front side of the transmission pigtail that you break free and can feed it back through the transmission housing.

 

[Suprman]

I have a pan casing if you can swap over your solenoids. Which you usually can.
Will

 

[Andyrv6av8r]

I have a pan casing if you can swap over your solenoids. Which you usually can.
Will

Thanks Will. My intentions are to weld up the hole if I can ever get it off he truck. The driveshaft knocked a corner off and put a pea-sized hole in it so hopefully a quick Tig job. I have located another module assembly nearby if needed. If I can get this wiring harness loose I can get rolling on repairs. From what I read from Fuzzy, that plug comes apart in my picture.

 

[Suprman]

Theres a couple different styles of the pan. Its hard to tell from your pics. The pigtail will separate and come off. On the trans you can see the bracket where the cab to trans cable meets you can disconnect that, remove pigtail connector and then you can drop the pan down and have more room to work with.

 

[Ronmar]

There are 3 different types of trans harnesses used. Two of them are like the one shown in the top of this diagram, with a sealing tower that plugs up into the main housing and is held there with a clip. You disconnect the connector, remove the connector nut from it’s bracket, pull the locking clip(105) and pull the entire pigtail down thru the hole in the case above the control module.

The other type seen in the lower part has a connector inside the housing and the harness separates there. One of your pics leads me to believe y0urs is this type by the square block shown in the gap between main and control housings.

the type used is determined by trans serial number.

 

[Andyrv6av8r]

Mine was like the top one and I got it apart finally. Came out with the help of a motorcycle jack. as it's a bit heavy. Now to decide how to repair or replace. Here's some pictures of the module and the small hole from the driveshaft.

 

[Ronmar]

Cool! I got the impression from one photo that yours was the internal connector type, but nope, it is clearly the sealing tower... Glad you got it apart!

 

[fuzzytoaster]

I'd weld it, replace the main gasket, and service the transmission filters while the manifold assembly is off. I dropped a manifold exactly like yours and it was a PITA. Go ahead and ohm out your solenoids too just to be safe (4.5 ohms is near perfect). You'll have to be extra careful not to pinch anything when lifting the manifold back up into position.

 

[Andyrv6av8r]

This is either the cause or result.

 

[wheelspinner]

This is either the cause or result.

Ouch. Those bearings are pretty tough. I would think that is a cause and not result. How is the oil level in the diff ?

 

[Andyrv6av8r]

Oil level is good. I serviced both axles myself with no leaks ever noted.

 

[Ronmar]

This is either the cause or result.

You cannot judge pinion free-play until the yoke is torqued in place, as it pre-loads the input bearing pack... I think if you throw a yoke and a nut on there and snug it down a little you will find it tightens up considerably...

 

[Andyrv6av8r]

You cannot judge pinion free-play until the yoke is torqued in place, as it pre-loads the input bearing pack... I think if you throw a yoke and a nut on there and snug it down a little you will find it tightens up considerably...

I was hoping that was the case. Thank you for clarifying that.

 

[Ronmar]

You can also judge a little by looking at the seal. If it had been that loose when the yoke was installed, the seal would have been deformed/destroyed in just a few revolutions...

 

[Andyrv6av8r]

You can also judge a little by looking at the seal. If it had been that loose when the yoke was installed, the seal would have been deformed/destroyed in just a few revolutions...

Makes perfect sense. The seal looks fine.

 

[Andyrv6av8r]

So I got the pan welded up this weekend and it should be fine. Got to get new gaskets and filters and get this heavy chunk back in. Anyone know where to find a pan gasket? Then on to yokes and driveshaft.

 

[Third From Texas]

Likely a $20 part from Allison.

Or a $200 surplus part (on the bright side it will have a NSN).

 

[wheelspinner]

Andy I have NAPA filter sets

 

[Andyrv6av8r]

So I got everything put back together today and all seems well. No problem with the transmission and it shifts normal. That was my biggest concern. No leaks from the welded pan or vibrations after a 15 mile run. Thanks everyone for their input and suggestions.