I need help where's our wrench men at? Allison Repair

[jd 9760]

I'm changing the rear seal on my 654 Allison in my 923. I got the drive shaft down no problem but I can not get the nut off the back of the trans to remove the yoke. It appears to be lock tighted and I applied a little heat to release the lock tight but I can not budge that nut. It looks like a right hand thread nut but a 3/4 drive breaker bar will not move it. Thanks for the help

 

[NDT]

Impact wrench.

 

[jd 9760]

Impact wrench.

I would like to but my impact wont fit between the trans and the transfer.

 

[quickfarms]

What does the Allison manual say?

 

[jd 9760]

What does the Allison manual say?

i'm not sure i dont have one. i was hoping some one here could just tell me oh ya just do this type of thing. i cant believe its as tight or stuck as it is and i'm not sure how much heat i can put on it

 

[swbradley1]

I think before I would run the risk of ruining the tail end of my transmission I would read the manual.

 

[jd 9760]

I think before I would run the risk of ruining the tail end of my transmission I would read the manual.

I don't disagree but at this time I don't have access to an Allison manual and Allison doesn't seem to be posting them online where I can find them. The TM for the truck just says remove nut yea if only it where that easy! I was hoping some one on here would have done this before and could give me some pointers or helpful directions. I can't believe I'm the only one to take one of these apart! Oh well I'll give it another try tomorrow.

 

[swbradley1]

Actually I just posted that I had never heard of anyone having one go bad. Seems like you are the first and from Ohio at that. Good luck.

 

[porkysplace]

I don't disagree but at this time I don't have access to an Allison manual and Allison doesn't seem to be posting them online where I can find them. The TM for the truck just says remove nut yea if only it where that easy! I was hoping some one on here would have done this before and could give me some pointers or helpful directions. I can't believe I'm the only one to take one of these apart! Oh well I'll give it another try tomorrow.

Heat on the shaft is a bad idea . I would try a breaker bar and a 6 pound sledge to get impact to break it free . Price out a new tranny then decide how much heat you want to put to it.

 

[swbradley1]

Have you tried putting some acetone/ATF mixture on it? Mix some up and let it sit a day and try it again.

 

[quickfarms]

What is the torque spec for the nut in the TM?

The Allison mechanics tips list the torque as 600-800 ft lbs

http://www.allisontransmission.com/documents/test/MT1357EN.pdf

 

[jonesal]

Ya, that's the correct spec. The manual will call for a special service tool that will attach to the yoke that is nothing more than a long handle/shaft so you can hold it while you remove the nut. I cringe when I read the phrase "break it loose" on an Allison. I think an inpact wrench on the back of that trans could be a mistake. You are asking to damage something and then you have a giant mess. It will likely take more than 600 ft-lbs to break it loose. I made my tool by using 1/4" plate, drilled the holes (the large one in the middle I used a torch) and welded it to a very long handle.

Al Jones
'84 M923

 

[jd 9760]

Ya, that's the correct spec. The manual will call for a special service tool that will attach to the yoke that is nothing more than a long handle/shaft so you can hold it while you remove the nut. I cringe when I read the phrase "break it loose" on an Allison. I think an inpact wrench on the back of that trans could be a mistake. You are asking to damage something and then you have a giant mess. It will likely take more than 600 ft-lbs to break it loose. I made my tool by using 1/4" plate, drilled the holes (the large one in the middle I used a torch) and welded it to a very long handle.

Al Jones
'84 M923

Thanks for the advise I actually gave up on it today and put the drive shaft back in. I have to have the truck drivable next week and I ran out of time to get parts. I was able to thread a couple bolts into the housing to hold the yoke, that worked well. I can't get an impact in there so little risk of damaging with that. I talked with the local truck shop and they told me the same thing you did about enough torqe. Thier idea was a 4' pipe on my breaker bar. Kind of like what you did. I'll have to work on it again later when I get time. It doesn't leak alot maybe an ounce or two after I've driven it but it's making a mess of my concrete so I thought I would fix it. Thanks again for your experience.

 

[jonesal]

The -23 TM WP 0376 says you're also going to need a "mechanical puller kit" for the yoke. If they are friction splines, the nut will be the easier of the two tasks.

Al Jones
'84 M923