Bush Hog 406 (drive shaft slipped off of Gear Box input shaft) Need advise (with pic

[RickB]

I probably shouldn't even post here, because, I said the same thing Rick did(except that you inferred that the dealer put the PTO shaft on the brushog), in your other thread and you still posted a new thread.

You have 2 bolts on your slipclutch. 1 is for the clamp, the other goes thru your splines inside your shaft.............that is the one you want to look at. Put that bolt thru your slipclutch shaft, and look down the tube. You should see the shank of that bolt, and it should be 'above' the splines in your slipcltch. If it isn't, it is the wrong sized bolt(shank to narrow), if it is sticking above the splines..........it's the wrong shaft for your brushog.

EDIT: the picture you posted in your first post..............the top bolt that you see is the clamp, nothing more. The bolt you see on the bottom is the one that keeps the shaft from coming apart. That's the one to look at. And that's the one I wanted you to pull to see if it had marks on the shank...........I've seen people put the wrong size bolt in there on at least a dozen times.

If the second bolt truly goes through the splined shaft, it should be 5/16"x3" grade 8 fine thread. That is the bolt spec for the old style slip clutch and driveshaft. The photo LOOKS like it has two 10MM bolts surrounding the shaft and no center bolt. If so, that would be unlike any of the 2 later metric shipclutch/shaft combinations shown in the 406 parts catalog. A good photo of the slipclutch taken from the perspective of the gearbox (longitudinal end view) would be very helpful. I think we are looing at a generic replacement PTO shaft & clutch somewhat unlike the original later style, not to say that it can't be made to stay put and work well.

 

[Don87]

If the second bolt truly goes through the splined shaft, it should be 5/16"x3" grade 8 fine thread. That is the bolt spec for the old style slip clutch and driveshaft. The photo LOOKS like it has two 10MM bolts surrounding the shaft and no center bolt. If so, that would be unlike any of the 2 later metric shipclutch/shaft combinations shown in the 406 parts catalog. A good photo of the slipclutch taken from the perspective of the gearbox (longitudinal end view) would be very helpful. I think we are looing at a generic replacement PTO shaft & clutch somewhat unlike the original later style, not to say that it can't be made to stay put and work well.

Like you said, we need a better picture. and/or the OP can slide the clutch on the shaft and see if that bottom bolt lines up with the 'hole' in the shaft. But that bottom bolt appears to be a lot bigger than a 5/16th .

 

[pharmvet]

I will try to get a better picture from the perspective you guys described (from the gear box). Yesterday I did look down inside the slip clutch collar and neither of the bolts are involved in the the mating of the female collar and male shaft. I loosened both bolts (which are pretty much full thread and both the same size) and looked at the threads as I turned the bolts. There was no damage to the threads. I then slipped the collar back onto the shaft and it slid all the way until it bottomed out where the shaft comes out of the gear box. I moved it back an forth until the holes lined up and put a screw driver shank through the holes to hold it in the proper position until I can get a bolt for it. I figured I would install the through bolt before I tightened the two side bolts.

 

[Don87]

I will try to get a better picture from the perspective you guys described (from the gear box). Yesterday I did look down inside the slip clutch collar and neither of the bolts are involved in the the mating of the female collar and male shaft. I loosened both bolts (which are pretty much full thread and both the same size) and looked at the threads as I turned the bolts. There was no damage to the threads. I then slipped the collar back onto the shaft and it slid all the way until it bottomed out where the shaft comes out of the gear box. I moved it back an forth until the holes lined up and put a screw driver shank through the holes to hold it in the proper position until I can get a bolt for it. I figured I would install the through bolt before I tightened the two side bolts.

So the hole in your slipclutch does in fact line up with the hole on the input shaft of the cutter? And what size wrench did you use to pull the bolts out of the slipclutch?

 

[RickB]

So the hole in your slipclutch does in fact line up with the hole on the input shaft of the cutter? And what size wrench did you use to pull the bolts out of the slipclutch?

Another far-flung possibility is the pinch bolts are one size too small in diameter and don't engage the groove in the input shaft. Something is surely a little off here.

 

[Don87]

Another far-flung possibility is the pinch bolts are one size too small in diameter and don't engage the groove in the input shaft. Something is surely a little off here.

I'm thinking that the hold down bolt(the bottom one) is the wrong one. He said it was threaded the whole way, but it should have a long shoulder area. Judging by the picture we have so far, the bolt is far too large to go thru the input shaft, that's why I asked about the wrench size to remove it. But yes, one size too small will cause problems.

 

[RickB]

I'm thinking that the hold down bolt(the bottom one) is the wrong one. He said it was threaded the whole way, but it should have a long shoulder area. Judging by the picture we have so far, the bolt is far too large to go thru the input shaft, that's why I asked about the wrench size to remove it. But yes, one size too small will cause problems.

I just can't tell whether the lower bolt goes through the center of the shaft or opposite the top bolt on the outside of the shaft. My original supposition was that it fit the outside. Hence my request for a photo from a different angle.

 

[Don87]

I just can't tell whether the lower bolt goes through the center of the shaft or opposite the top bolt on the outside of the shaft. My original supposition was that it fit the outside. Hence my request for a photo from a different angle.

Yea, I can't tell either, but it seemed like it should be positioned to hit the cutout on the splines as the clamp bolt on top won't do a lot to hold the clutch on the input shaft. The one on my tiller is different than his, mine only has one bolt that contacts the cutout on the input shaft.

But IIRC, my father in law had one like his years ago, and the bolt opposite of the clamp went thru the cutout section. His clamp came loose, causing the bolt to break. He put a full threaded bolt in there, and it ripped it right off. Bending the driveshaft the second time. As a matter of fact, it bent the input shaft on his brushhog too.

 

[pharmvet]

Well, I finally got it all put back together this afternoon. Used a 3" 5/16 grade 8 bolt through the hole in both the collar and gearbox shaft.

Here is a picture of the slip clutch collar from an end on perspective. You can see how these particular bolts do not engage the groove in the shaft.

Here is a picture of slip clutch yoke on the gearbox shaft. You can see the hole going through the both the yoke and shaft. This is where I put the bolt.

And just as Rick suggested, I found a brochure zip tied to my shaft shield and it appears to be an aftermarket drive line.

Back in action !!!

 

[Don87]

So it did have a manual. That's great. Glad to hear you got it working. That one is different than what my FIL had, and different than mine also. Thanks for showing the extra pics.