Questions for D owners

[bo dawg 476]

4 hours ago, Sarge said:

Ok - from what I've learned with my own nightmare on the D's Sundstrand pump there is no Lovejoy coupling that will fit that shaft without a lot of machine work. The two main issues are the size of the shaft (9/16" or so) and 17 spline count. The other, the coupling itself - it's cast iron, not cast steel. So, over time, hard loading or shock loads - the splines will fail. That picture of the D-160 coupling is a red flag - either someone has had it apart and reversed it, or they moved the engine back tighter against the pump from a stripped shaft, or both. That rubber puck should not be flexed in that manner when it's right. The more I look at it, looks as though someone has put spacers on the engine flywheel side to shove it tightly against the pump splines - not good.

 

Now, that said, it can be repaired - but there's a problem. There are no new couplings available unless you get crazy lucky and score a NOS one from somewhere. I found a "decent" used one that still had some wear already showing on it - very tough to determine if one is worn or not until it's in your hands and you can fit it against the shaft splines. Mine had failed miserably, blowing the teeth off both the pump shaft and internal splines in the coupling when I snagged the front blade on some concrete. Repairs were not cheap as I had a lot of machine work done to the repair to make it work - knock on wood, but so far it's holding well.

 

LJ Fluid Power in Michigan is your friend for that pump and any parts needed. They even went to the trouble to have new shafts made to repair pumps that are stripped - $280 I believe. On mine, I sourced a good solid used pump, a C-1*1 model rear input pulley that is splined and spent about $400 at a machine shop. Had the shop machine a keyway into the pump shaft and wire EDM (look it up, cool process for cutting) a matching slot in the pulley center which has to be indexed/timed properly to match the splines. The old, stripped coupling was bored out to accept the C-series hub after I machined off the factory weld and removed it. That was pressed into the old coupling and welded, very carefully. So, now the coupling has a C-series splined pulley center with a key and a set screw in it to make a more robust connection. 

 

There is a chance a Lovejoy coupling could be used - but you'd have to machine that pump shaft into another shape to make it work, and that shaft diameter is already too small. The problem with the design is that shaft is sized to allow the pump housing cover to come off - so if you wanted to weld the shaft into a bigger diameter the aluminum pump housing cover would need matching work and its shape will really not allow that. Be aware that the shaft on that Sundstrand pump is some seriously hard material - the machine shop wiped out some cutters trying to get the key slot done. Also, the cast iron coupling is very high in carbon and does not weld very well nor is it easy to machine. I'd bet this process cost the 2 shops at least 5 cutters...

Due to the location of the pump, coupling and associated hydraulic parts working on that D is a frustrating endeavor, but it can be done. I do love mine now that it's fixed, the extra weight, 3pt hitch and a frame that can withstand a tremendous load is nice to have around here. I have a fairly detailed thread somewhere around this site about the whole repair process - might want to check it out.

 

Sarge

 

So what should I do then? It does have some build up of washers between the rubber piece. Do you have to pull the motor to work on it?

It does whine if the engine doesn't have enough rpms when you engage the travel starting out.

[Sarge 3,462]

If it's holding for now - leave it alone as most were never engaged very far into those splines from the factory. Just be aware that it can blow it out suddenly, so I'd keep it close to home since moving a dead D is quite a job. Easiest way to work on that area is to remove or shove the engine forward unless you have the rear pto system. Pulling that pump out of there is absolutely no fun at all, even though I've turned wrenches professionally for years it was a struggle just due to the design of the machine. That said, if you have enough experience in mechanical parts and some local help from shops the job overall can be done. If I ever get enough time I'd like to re-visit this issue and find a better solution to stop so many D's being parted out due to that coupling design fault. That Kohler K series twin opposed engine generates a tremendous amount of torque - far more than that little cast coupling is capable of handling. 

 

The whine is normal - you're pushing those piston blocks in a bad way at lower rpm's - hydro systems need full rpm's to make power efficiently. The noise is a warning to knock it off before it becomes damaged.

 

Sarge