over/under output shaft and direct drive clutch

Kell

Member
Disassembled an over/under tonight and noticed two things that concern me. First, the teeth on the direct drive clutch plates appear to have cut into the gear on the input drive shaft. More so on the inner plates, the innermost plate has cut almost halfway through the spline on the gear. I don"t think this is normal wear and suspect it is due to the direct clutch slipping, even though I never noticed any problems with the o/u before taking the tractor apart. Secondly, I took a look at the output shaft where the sprag clutch rides and found it to be dark in color but very smooth where the rollers ride. The edges seem to have slight wear on the shaft, from the spring clips on the sprag, I suspect. The sprag itself doesn"t look terrible, there is some wear on the inside where it rides the shaft, but the outside is clean and so is the inside of the sun gear shaft it tucks into. Probably going to replace the sprag regardless, but wonder about the output shaft. In this condition, should it be replaced? Took a photo, should be attached.
a135723.jpg
 
Here's a photo of the gear affected by the direct drive clutch plates. Any advice is appreciated, this is my first time going through one of these units completely.
a135746.jpg
 
I've rebuilt 3 or 4 of these in the last couple of years for our tractors and have seen examples of both of your pictures, so I'll offer my 2 cents (mostly because my opinion is not worth much more than that). 1st, I doubt very much that the cuts on the direct drive splines are the result of the direct drive clutch slipping, rather I would suspect that someone somewhere along the way has had a tendancy to drop the clutch, or shift the O/U under very heavy pulling loads. In any event, there is a lot of useful life left in those splines , and as expensive as a new shaft will be, I would put it back together as is and not worry about it. Not sure what you pulled it out of, but counting the marks tells me it's not out of a 2-180 or 2-155 with the heavy duty O/U because you only had 6 friction plates in it. If you're still worried about it then consider replacing the direct drive clutch plates and frictions with those from a 2-180, the heavy duty O/U has 7 frictions and thinner steel separater plates. This adjustment will more than likely get the alignment of your teeth such that they won't be riding in the same worn grooves on the hub. This will also be expensive, and unless its a tractor that you're planning to run a bunch of HP out of, then I doubt it would be worth the expense.

2nd, on the shaft where the sprag rides, the one from our 2-180 had a large amount of material transfer from the sprag to the shaft itself, so I put the shaft in a lathe and used emery cloth on it until the shaft was polished smooth again. Measured the shaft and it was all within spec tolerances (shaft had not worn it is tough as all get out, just the sprag had started breaking down and transferred onto the shaft), so I put a new sprag in it and it works perfectly.

3rd, replace the sprag. Costly, but its just not worth taking a chance while you're there, IMO.
 
Thanks very much Mitch. It came out of a 1750.

Yeah, after thinking on the input shaft issue, it must be wear that was caused by running a heavy load and shifting the o/u from under to direct. Picking up speed with 5 bottoms in the ground, maybe. I am worried the notches in the splines may cause slipping, not allowing the clutch to fully engage, but it didn't seem like direct was slipping at all before I pulled the unit from the tractor. I doubt that the damage was done over a short period of time, so maybe running it would be OK... for a while. Will probably replace most of the separator plates as a couple barely have any teeth left.


Definitely replacing the sprag and will look into cleaning up the output shaft as you suggested.
 
that input shaft is out of an early o/u it has the square cut splines later o/u had rounded splines the later friction discs will not work on that shaft. if you are concerned about the disc hanging up on those splines a good machine shop can fill them in and recut them.As far as the output shaft I would clean it up and put in a new sprag.
 
have seen many of these new and old, the wear is normal as far as the notches in the shaft,if i was to gaurantee the work i would put new shaft.if it was my own i'd probably reuse both shafts
 

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