My modified throwout bearing performance update

[sevy]

My cub gets about 20 hours of use every fall with the sickle bar mower keeping my old fields from going to brush, and then probably about another 20 hours plowing snow in the winter. I also tow a cart and grade the driveway on occasion, but that only amounts to a few more hours of use per season.

I had the tractor split to replace a whole bunch of worn parts, and this included a brand new throwout bearing install with a pre-soaked bearing, which unfortunately, fell to pieces while plowing snow.

In the fall, I decided to try the automotive type bearing instead of another graphite, only I wasn't happy with the thought of my new pressure plate fingers striking the steel face of the roller type bearing every time it first engaged. I bought a thin piece of carbon fiber, and used some special epoxy adhesive to adhere it to the face of the bearing which comes into contact with the fingers. My intent was to eliminate any friction/wear of the fingers themselves as well as prevent eventual gouging of the face of the bearing from the fingers, hopefully eliminating the disadvantages of using the roller type bearing.

I did my sickle bar mowing with the new bearing in October, and plowed snow for the first time this past week, and I thought it might be a good time to post my results. So far, the clutch is very smooth and quiet, even with the quick changes from forward to back while plowing. Once the snow season is over and the weather a bit warmer, I will pop off the inspection window and get a close look to see if there is any visible wear?

In the meantime, here are some photos:











About 12" of dry powder, which plows beautifully. The short blade means lots of passes, which is hard on the clutch. Cubbie loves to gulp down the cold(10 degrees), dense, oxygen rich Adirondack air! I continue to be amazed at how much snow this little tractor can push!

[Don McCombs]

Nice job!

[SamsFarm]

Steel fingers of the clutch making contact with the steel face of the bearing type throw out bearing is common practice!

I would like to add the bearing type to my cub when this one is wore out!

I think I put it in around 2005!

Keep us posted!

[inairam]

I think the auto-style bearing get a lot of negative press on the site. They were used on the A-140. For some applications that require a lot of clutch work ( like a loader or snow plowing), it is probably a better option. I had one on my loader from PO and switched to a graphite and it did not last a year. You are always on the clutch with a loader.

Looking to see your pictures on how the graphic held up.

[ScottyD'sdad]

Too much snow for me, Scott!
I'm happy with. the steering thrust washers on the loader cub loboy, so far, that you made for me.

Ed

[sevy]

Hi Ed,
So glad that the carbon fiber washers worked out! Never got my wood stove connected in my shop, so the sickle bar mower you gave me will have to wait until spring for its cleanup. My old sickle bar cut pretty well, but it is not nearly as tight as the one you gave me. Interested to see how the adjustable guards will work on it?

[Jim Becker]

. . . They were used on the A-140. . . .

Most of the Super A and a few 100 were built with a graphite bearing. The design of the Cub bearing carrier is more of a problem for a ball bearing. Sevy's modification attempts to address the carrier situation. We are hoping for a good report after he has some more operating time and a chance to give it a close inspection.

[inairam]

Jim I should have said my 130 and 140 and not assumed the earlier models. Thank you for the correction

[inairam]

. . . They were used on the A-140. . . .

The design of the Cub bearing carrier is more of a problem for a ball bearing. Sevy's modification attempts to address the carrier situation.

Jim what is the issue with the carrier and the ball bearing?

[Jim Becker]

The throwout bearing of the A-140 tractors is mounted to a retainer or sleeve with a machined center. That slides on a guide sleeve that runs on the clutch shaft. Thus the bearing is supported by and remains centered on the shaft. The yoke applies force to push the bearing against the fingers but does not support the bearing. Since the bearing is centered on the shaft, it is centered on the axis of the crankshaft and clutch. So when it contacts the fingers, once it has spun up to engine speed, the contact points of the bearing on the fingers remain essentially fixed relative to the fingers. It all turns together.

The Cub, on the other hand has no throwout bearing support from the clutch shaft. The bearing hangs from the yoke. Since the yoke pivots on yoke pivot pin, the thowout bearing moves through an arc. So through most (if not all) of its motion, it is not in direct alignment with the crankshaft/clutch axis. The contact between the bearing and each finger is constantly moving in a little circle. Granted, not a large circle, but those three contact points never get any lubrication. By the way, if there is any wear to the yoke or the yoke pivot pin, alignment could get a lot worse, adding horizontal misalignment to the built-in vertical.

As a side note, some of the early ball bearing replacements were poor bearings. Some evidently weren't even designed as thrust bearings. The high failure rate of these junk parts got some early red flags going on the ball bearings. It took longer for them to chew up some clutch fingers and make that shortcoming more obvious.

[inairam]

Jim Thank you.

Sometimes there are posts that people support as law ( graphite bearing ) but the logic as to why is not laid out. Your post makes a lot of sense to me and I do not think I have seen this before.

[tst]

I do a lot of clutch work here for customers and have tossed every ball bearing setup I took apart as everyone had failed, I do not install them

[SamsFarm]

Sounds like a hydraulic bearing type throw out would be the ticket!





(The 1000 post) lol

[tomstractor]

The VW type 1,bug, used the same type graphite bearing , mounted the same way, with no support, for many years. I have replaced many clutches,maybe many thousand and never presoaked one and have never had a failure. They never even had a grease fitting on the bearing. The Germans must have figured out how to make the graphite to stand up to every day use.
The later higher power bugs did use a bearing and a support for it. I have worked on the VW bugs since 1963.

[Jim Becker]

As I recall, the VW had a ring attached to the fingers that the throwout bearing contacted. That gave a lot more contact area than the Cub bearing has. That must help. I don't know if that was all the early bugs or just certain ones.