P6 thrust bearing dodged a bullet…

[Ronmar]

I am very glad I did this! Looked great inside, popped off the outer clutch pack snap ring and lifted out the clutch pack and carrier, discs and spacers look great. Center tower bushing, springs and piston look great, roller bearing looks OK until I try and lift it out.. The front/outer race and needle carrier lifted right off with no resistance leaving the inner race behind on the center tower…

It was just a matter of time before the outer race and needle carrier popped forward off the inner race and down to rest on the carrier. Then the lip on the inner race and crimps that are supposed to hold it all together, would have methodically chipped away at the composite roller carrier until it released the rollers to thrash around in the clutch-pack and on into the rest of the transmission…

Whew!

Inner race is still on the center tower.




after I lifted out the thrust bearing inner race…

 

[MugOfPaul]

Are you going to replace with the composite washer “upgrade”?

 

[Ronmar]

Are you going to replace with the composite washer “upgrade”?

Sort of

 

[Plasa]

Do you have a transmission that is affected by the Allison letter to change the bearing if transmission is before a certain serial number?

 

[Ronmar]

All transmissions prior to maybe feb 2011(need to check s/n on the bulletin)

Here is the basic chain of events. In the 90’s they produced with a particular p/n bearing, lets call it A. I think they knew about issues then, because even the military LMTV manuals produced in the 90’s say to replace this bearing WHENEVER you are in the transmission/transfer case for any type of work.

At some point Allison officially acknowledged the failure with a tech bulletin stating that the type A roller thrust bearing should be replaced with a improved roller thrust bearing with a new P/N, lets call this one B… they also listed a s/n break point where production included bearing B.

At some point, I assume because bearing B was also failing or they suspected a possibility of failure, they issued a second tech bulletin directing that you replace bearing B with a composite thrust washer 3 times as thick as the A or B roller thrust bearings… that was feb 2011 and they again listed a S/N breakpoint where this bushing was included in production…

I have no idea if a bearing B has failed, but Allison said replace it with a thrust washer, and they shifted production to the thrust washer…

here is a link to the most recent failure discussion. It has links to previous discussions and the tech bulletins…

1998 LMTV Hot transmission - No drive

Hi everyone, I am in the process of un hack jobbing my 1998 LMTV, previous owner did some questionable things, I've already replace the motor due to a cracked block. I had the driveshafts balanced and then did a test drive, transmission felt great - smooth shifts and no issues over 50 or so...

www.steelsoldiers.com

 

[NDT]

If you cut the bed away to allow cover removal, how many hours are we looking at to do this repair? Do we have to drain the fluid?