I am unable to engage my D47U pony into the diesel unless I brake the pony down to stall speed with the clutch (lever on the left). I have adjusted the clutch throw and it seems right--when pony/diesel are not running, it engages about half way through the full clutch throw. Also I am using 5W oil to minimize viscosity drag.

Is there a part in the pony clutch housing that I need to replace? What is the fix?

I,m not sure but I,m wondering if the clutch discs are warped and hanging up from it.You may have to pull that little cover off the front and disassemble the dics & pieces in there to see their condition. You seem to think it,s adjusted ok so can,t think of much else till you do check it out.

Depends on what you mean by "won't engage".
Is it a case of clutch movement is ok but the drive sleeve/dogs won't latch or stay latched.......then remove the little round cover on the bellhousing by your left foot and peer in there as best you can to see what is going on.
Candidate causes are:
Mounting bolts have dropped out of the sleeve.
Worn latches or engagement stop or both.
Sleeve not installed properly so that latches engage flats on the stop.
Bent engagement arm (in bell housing) caused by holding/forcing the engagement hand lever.
Thrust button missing.
Rust/lack of lube, gummed up.

Unless it's a minor cause usual procedure is to pull the whole assembly and check it out.

Thanks for the help. When I said it doesn't engage, I meant that it is like trying to shift a manual transmission in a car from neutral into grear without engaging the clutch. The grears grind and the only way to engage is to pull the pony down to stall speed.

I will open up the front of the housing and look.

Start by backing off the clutch adjustment....better to loose than to tight.
Are you using and getting brake function before attempting to engage?

my d2 does the exact same thing...i'm working on it too..i'll let you know..an will follow this situation.

Old Magnet is correct about having the clutch adjusted right. Ed ponte from the Cat Night Gang showed me the trick of draining the oil out of the stater pinion and replacing with ATF. Next make sure when engaging the pinion, to pull back on the clutch lever the oposite way of clutching to activate the clutch brake. This is where the ATF really works good in braking the clutch, so, ... no grind:D . -glen

The last time I rebuilt a pony clutch assembly I used a trick an old Fordson tractor mechanic showed me. The Fordson uses a metallic disc clutch similar to that of the Cat pony engagement clutch. Over time the discs will flatten out causing them to stick against each other when covered in oil, resulting in difficulty getting the clutch to slip when disengaged. He showed me if you "dished" every other disc in the pack the same direction they would spring apart better when disengaged. You don't have to dish them much, only about .020" or so. Any more and it may be difficult to get them to flatten against each other during engagement. All the discs in my pony clutch were flat so I did this and it's worked great ever since. Leave the brake discs flat though, you want them to drag. The pony doesn't lug at all at low RPM under braking and the pinion engages without any gear clash, even with 30wt. oil in the clutch. It worked good for me.

I was using 30 wt. oil. Recently I switched to Marvel Myst. oil. Didn't seem to help. I'll try the Xsm. oil.

Thanks,

When I got my "new" D4, it had about the same problem. After trying to adjust the clutch, it dawned on me that the adjuster (the part with the spring loaded pin) had somehow backed clear off and was wedging itself against everything. I pulled the side plate off and threaded it back on the shaft, replaced the plate and started adjusting again. This time it worked the way it should.

Then it was time to fix a stuck left steering clutch but that's another story in itself. . .