New Guy with M920 and Transmission issues

[CE2Mike]

Hello Everyone,
This is my first post. I want to thank everyone for the wealth of information and your helpfulness to people. I have been viewing for a little while and now have some MV units I need help on. I just picked up a 920 from Nellis AFB. Most of the truck issues I can fix with my mechanics. The truck runs fine, shifts fine, but has a high pitch whine in the transmission. The whine stops when you put it in gear, and it is speed sensitive. As I roll the truck slow and stop the whine followes. Any help on what this might be is greatly appreciated.
R/Mike

 

[NDT]

Welcome to the site. I do not think we have discussed your issue here before. As you may know, the Cat transmission has disk clutches on the input and output shafts that disengage below a certain engine RPM to allow gear changes. The "mainshaft" spins when in neutral, which explains your noise until gear engagement, because if the truck is not moving, the mainshaft is not turning. Whine almost always means compromised bearing. Is the lube full and in good shape? Also make sure the PTO is disengaged?

 

[Derrickl112]

Do you have any more pictures of the truck in your avatar?

 

[goodguyzy]

Obvious things to check are to make sure the PTO is not engaged, the air shift front axle/middle axle is off. If you need any parts for the tranny I have 5 that im trying to sell cheap. goodluck.

 

[CE2Mike]

I do. I bought it as a PLS. I think KW competed with Oshkosh at some time and made a few prototypes. It had a 9 speed auto shift with a Cummins N14. I put a fifth wheel and some water tanks on it. I also had a 90 ton tank transporter I put behind it. We used it at FT Irwin for a few years.

 

[CE2Mike]

Thanks I will keep you in mind once I get into it

 

[Derrickl112]

That's what I thought it was! Another SS member has one of them. Cool truck!

 

[CE2Mike]

The only thing with this truck was, It had GKN axles. We tore up the first axle and I couldnʻt find parts. I found a ring and pinion in Spain. Loadall trash trucks use the same GKN stuff.

 

[CE2Mike]

For what itʻs worth I found the problem whine. The PTO wasnʻt shimmed right. It looks like it was replaced and now that I shimmed it the transmission has no noise.

 

[M1075]

Super sweet KW! I have 2 of those, with consecutive serial numbers. I bet yours isn't 1 or 2 digits off.

 

[goodguyzy]

Good to know.