D4 7u Counter Shaft End Play

[mbscat]

Okay so my dad is working on his D4 7u. He pulled the engine and is rebuilding it. He noticed the input shaft to the transmission was a little loose and decided to continue tearing down into the transmission to evaluate its condition. It turns out the input shaft bearing was worn out and the housing for that bearing was damaged. He noticed about 1/16 inch end play on the gears on the counter shaft. The gears seemed to be unnecessarily sliding back and forth. He went ahead a took apart the counter shaft and found nothing out of the ordinary the gears look good, the spline on the shaft is smooth all the way along. The Cat service manual does not address end play allowance for this shaft. Does anyone have any experience here? When it comes to Cat parts and gears sliding around loosely it just doesn't seem to fit. Every where else it seems like you need a 20 ton press to work on it. Open to what other people have experience. By the way he has a full machine shop so he can make modify or fix anything so don't hold back a suggestion because you doubt the tools are available.

[Old Magnet]

That clearance information seems hard to come by. Found these in the 78A D4 Service Manual Specs.....seem reasonable to me.

The countershaft gear set should not be sliding back and forth.

[mbscat]

Thanks for the information. Any idea on where to purchase a transmission service manual?

[Old Magnet]

No, I'm not aware of a specific transmission manual....my accumulation is from gathering bits of info here and there, usually from service manuals and whatever is learned from working on my own stuff. Never has been a whole lot of transmission topic discussion here that I recall.

[mbscat]

Okay so the end play on our counter shaft is too much. Any suggestions about how to reduce it. Hardened shim stock? Machine down the shoulder behind the bearing on one end?

[Old Magnet]

How much do you need? Just off the top of my head I'd say if it's under about 0.010 in. I'd consider taking it off the shaft if more a hardened shim would have a good chance of surviving.

How about a couple of pictures of what your addressing?

[edb]

Hi Team,
seem to remember that the mild? steel spacers used to wear on these transmissions. As to how much is worn off which one is impossible to say. We used to fit new ones as needed back in the day after checking the amount of wear against new ones.

I did dismantle some trans's where the spacer ends had been reclaimed by welding and machining, so that is a possibility.

I believe that there needs to be some end float in the gears and spacers as the end washers need to be clamped tight against the shaft ends so that the bearings are also clamped tight from moving.
I guess another way of looking at it if the gears and spacers were tight then oil could not get in to lube the splines and fretting corrosion (rusty colored goo) and wear would occur.

I think 0.015-0.020" would be a good clearance to go for--these trans's are forgiving and simple.

As to which spacer to build up, maybe a bit on each unless you can get your Dealer partsman to request factory drawings--only available on request if the part is not available.

Hope this helps.
Cheers,
Eddie B.