Cub Cadet 1810 Driveshaft Bolts Breaking

geezer2017 · Jun 1, 2009

I have an '89 CC 1810 with a 18HP Kohler Magnum which I replaced over the winter with a rebuilt block. I replaced the entire drive train including all brackets/coupler arms front and rear because they were badly worn, primarily the pressed bushings at the flywheel end and at the hydro shaft. I had no issues until this spring when I started to mow. I started shearing off the rear bolts at the hydro end of the drive shaft. I replaced the original bolts with grade 8 bolts and still was shearing them off. I also sheared off a spring pin that holds the rear coupler arm to the drives shaft. I see absolutely no wobble in the drive shaft and the shaft coming out of the hydro has no slop that would cause the drive shaft to wobble and put pressure on the bolts. It got to the point that the bolt holes on the coupling assembly that mounts to the hydro shaft started to round out! I ended up drilling the holes out to 7/16 to see if I could salvage this $120 part. I got through a mowing weekend before last and the bolts held. While mowing on Sunday, the front spring pin connecting the front coupler to the drive shaft broke off. This coupler is bolted through the rubber flexible disks to the drive flange assembly. The hydro shaft does not appear to be worn and there is no slop that would cause the drive shaft to wobble. I'm beginning to wonder if the hydro pump is starting to lock up when it gets hot or is resisting the drive shaft to the point of shearing off these bolts. I can rotate the hydro shaft fairly easily using a punch through the shear pin hole and but I can't spin it using my fingers. I'm not sure how much resistance I should get from the hydro pump. I am a complete loss to figure out what is causing so much resistance in that drive shaft to shear off Grade 8 bolts and spring pins. If anyone has any idea's or suggestions, I would SO appreciate it. I just invested $1500 putting in the rebuilt engine, new starter and drive train so I'm not about to dump the tractor. Thanks.

jimdiesel1 · Jun 2, 2009

I'd suggest that you check the transaxle attaching bolts, especially the front 2 (located where the fenders slant down to the foot area). They are 3/8-16 capscrews as are the rear bolts which attach through the axle carriers. These bolts have frquently worked loose on those models over time. If they are loose or missing you may want to loctite them (use 242 blue) and retighten carefully.

geezer2017 · Jun 3, 2009

Jim,

I spoke with a local CC dealer service manager yesterday who suggested the same thing. There are brackets toward the front of the trans that bolt to the trans and to the frame and he said loose bolts will cause the trans to twist on turns that could bind the crank. I checked the bolts on the front trans/frame mounts and they seemed to be tight but the bolts on the axle carrier to the frame were a bit loose. Those appear to be the only mounting bolts that I could find. I'm going to put the drive shaft back in this week and give the yard another whirl this weekend and hope for the best. Thanks for your reply. I don't know what else this could be.

jimdiesel1 · Jun 3, 2009

You may want to ask around at some dealers for used parts, that is what I do in these expensive times. Provided the driveshaft is not bent you should be in business with the bolts tightened. Remove the spark plugs and crank the engine over to inspect the drive shaft visually. If in doubt, pull it out. Also double-check the engine mounts, both the base plate as well as the actual engine mount bolts. I have seen loose bolts at both these spots.

geezer2017 · Jun 4, 2009

I have the drive shaft out. I took it out to inspect all parts but they all look ok. The rear coupler on the hydro started to get the bolt holes rounded out but I drilled them out and used bigger bolts to try to avoid buying another part. That was an expensive part, $120 or so. I had replaced the entire drive train so that's why this was getting pretty aggravating to have this keep happening. I'll double check the engine bolts but I just put in a new block last winter so I would hope that hasn't loosened up yet, but you never know. Thanks for your response and I hope this issue goes away. The Cadet dealer said that I was smart to keep this tractor because it was so much better built than newer ones. I would agree with him after looking at the new ones. This one's built like a tank in comparison and I have $850 tied up in a snow blower. The new blower I saw at my local Farm and Fleet was $1,100 and it was a piece of junk. I'll keep this one til it falls apart.

magicalj · Jun 4, 2009

I beleive you should be able to spin the hydro pump by hand without to much effort. If it's really hard to turn, you probably have a bad pump.Since you don't have hydraulic lift, if you need a new pump, you should be able to get one shipped to you for under $50. You need a nonported one. The ported ones are the expensive ones.

AJ

Carl_NH · Jun 5, 2009

I agree with magical on ease of turning the hydro since you have checked and rechecked the shaft alignment. You might want to check out / email this guy on that aspect.

Hydrostatic Transmission - Transmission Rebuild

I had my 1811 apart two weeks ago to replace the relief valve (worked out fine) and for you to be rounding off the coupler bolts and shearing the roll pin that takes quite a lot of force, and alignment would be my first guess, second then would be the internal works possibly a valve hanging up or as you suspect the pump itself.

Does the engine labor a lot before it stops, does the hydro sound "normal"? Anyway good luck on your mission and hope you get it worked out.

geezer2017 · Jun 7, 2009

When I put the drive shaft back in, I found I probably have at least 1/8" vertical movement in the shaft end at the engine. It looks like the drive cup may not be centered or something. Trying to remember back on putting the flywheel back on, I thought the the drive cup was held on with a bolt into the crankshaft so I have no idea what could be out of center to cause vertical travel in the drive shaft. Before I pull that engine again to find out, I was hoping somebody could provide some insight. Maybe the hole in the drive cup is worn or the bolt in the drive shaft is coming loose. I should have checked that while I had the drive shaft out. I hadn't notice the play in the drive shaft until I used Jimdiesel's tip and removed the plugs and cranked the engine. Then I saw the play in the shaft.

geezer2017 · Jun 7, 2009

Also, I replaced all the drive drain parts so the couple bushings are in good shape and are not worn. The only way I could envision there being vertical movement in the drive shaft at the engine end that the drive shaft or drive cup is not centered on the flywheel and I can't quite envision what would make it do that. I can understand alignment with the transmission being an issue but the problem I think is definitely with the vertical movement of the drive shaft at the engine.

magicalj · Jun 7, 2009

Is your coupler missing the bushing? It should have a brass bushing in the center of it that is like a heim joint. That bushing will also wear out. You might need to replace the entire coupler. It looks like they are only $20.