Bob-Cat 61" ZTR - Spindle Bearing R&R - ???

[constable]

I just purchased this machine (ZT-200) and have been restoring it over the past few weeks. I decided to pull the deck and do a rebuild. Welded all cracks, re-inforced the seams, sandblasted/painted. Replaced the idlers, sharpened blades, new rollers, yokes, casters, etc...

One of the spindles was spinning a tad rougher than the rest, so I decided to pull them all and replace bearings. My parts are all ordered and should arrive tomorrow afternoon.

I've searched these forums already and I've read some general tips regarding spindle bearing replacement.

I was wondering if anyone had info that is specific to the Bob-cat spindles. The bearings are 38348-01's (sealed). I know there's a snap-ring that holds the lower bearing up. Then there's a 1.5" nut that sits between the housing and the blade. The upper bearing is visible from the top, now that I have the pulley removed.

I'm guessing I start off by removing the large lower nut and removing the snap ring. What's next? Just beat the shaft out?

If you all have suggestions, let me hear them...

I'm experienced with tools and mechanic work, I just want to know the correct order so that the task goes quick and smooth.

[Restrorob]

I just replaced a set last week like this;


With the spindle housing/assembly still mounted in the deck. Removed the blade and pulley, Then the large nut on the bottom. I used a block of wood and a hammer and drove the shaft up from the bottom until flush with the housing, I then used a old Taiwan deep socket (all their good for) the same size as the shaft and drove the shaft the rest of the way up out of the housing. The right size socket prevents damage to the threads and burring the inside hole that could prevent the blade bolt from being re-installed.

Then removed the snap ring and drove the lower bearing from the housing with a long drift.

I took the shaft and laid it loosely in my vise and again with a block of wood and socket drove the top bearing from the shaft, Cleaned the shaft up then layed the new bearing across my vise the drove the shaft down through the bearing.

To clarify vise usage, This is shown installing the new bearing on the shaft;

http://i107.photobucket.com/albums/m314/Restrorob/BobCat/BobCatSpindleBearingInstall.jpg


I then installed the lower bearing and snap ring and set the shaft back through the top then drove the top bearing into the housing and the shaft through the lower bearing at the same time with the block of wood.

Yeah, I do have a fancy shop press but have found I can work a little quicker with a vise rather than fiddle fart around jigging things in the press.

[constable]

I, too, have a press... and yet I always end up playing around on the big vise. Thanks for the reply. Depending on when UPS shows up with my bearings, the job should be complete by night time.

[Remington4]

Hello constable,

Don't forget to apply 150 ft lbs to the big nut when tightening. New conical washers are always good to use as well, as they apply clamping force to the inner bearing race. Last but not least tighten pulley and blade bolt to 70FT lbs.

You should be good to go.

Thanks,
Remington4

[Restrorob]

Thanks Remington4,

Can you tell us how you hold the shaft from turning while torquing the nut ?

[constable]

Can you tell us how you hold the shaft from turning while torquing the nut ?

I was wondering about this too. Now that the blade and pulley are off, I don't have an easy way to hold the shaft in one spot.

[Remington4]

Yes,

I use an old metal sprocket with a 1" hole, clamp the sprocket in a vise, slide the spindle shaft in the hole and insert a square key. Then you can go to town on your torque.

You could go to your local dealer and see if they have an old 1" spindle pulley that is trashed out, as it would be a nice tool to have around. Just mash the thing in your vise and you got yourself a spindle jig...


Thanks,
Remington4

[ericg]

Remington4, are you saying that if 150 foot pounds of torque are not applied to the nut, that this will effect bearing life. Most of the posts on Lawnsite do not reference the 150 ft lb issue. Most say tighten nut and that is it.


Eric

[Remington4]

Hello ericg,

Yes, you are correct, those spindle assembly's are designed to have the 1" nut set to 150 ft lbs, if someone goes with tight, they may run into trouble as the inner races may float on the spindle shaft and blow out the bearings.

Last but not least tighten pulley and blade bolt to 70FT lbs and you'll have yourself one durable assembly.

Thanks,
Remington4

[constable]

Did the whole job last sunday. I had all three spindles disassembled and rebuilt within an hour. Had the entire deck back together and on the machine in another 1.5 hours. Would've went a lot faster with a helper.

As for the spindles: I used a short 1 1/4" impact socket to drive the bearings into the housing. The outter diameter of the socket was just a hair narrower than the bearing itself. Worked out well.

I used a deep 1 5/16" impact socket to slide into the spindle housing. I used that to drive the lower bearing out of the housing. Again, that socket fit perfect into the housing.

[slyoung1245]

What is the best way to get that big nut off, to replace the bearings?

[constable]

Breaker bar and a big socket... if I remember right.

[tacobell]

are the threads on the big nut right or left handed?

[Restrorob]

are the threads on the big nut right or left handed?


Lefty loosey.....

[pugs]

are the threads on the big nut right or left handed?

They are right hand.

Where did the info on torquing the large nut come from? I dont see anything about that in the book for those mowers. Have rebuilt plenty of them without torquing that nut without any problems.

This is all the book says:

BLADE BOLT TORQUE: 70 FT-LBS (95 Nm)
WHEEL HUB NUTS: 225 FT-LBS (237 Nm)
ENGINE CRANKSHAFT BOLT: 50 FT-LBS (68 Nm)

Although most of the time we replace the spindle assemblies these days. The new bearings usually are quite loose in the aluminum housings if you try to replace them. I know this older 61 probably has the cast iron 4 bolt housings though which are quite pricey to replace so rebuilding is the better option.

[constable]

Yes, they were very pricey. But the bearings were a TIGHT fit... I don't see a problem there. I think I'll be good for a while, especially since this is now a residential machine.

As for the torque specs: I have no clue, I just cranked it on as tight as I could. No problems yet, and it's been 8 months.