OC-3 Bolt-On-Frame (1951) and Later OC-3 Frame Differences

[GlenT]

I was reading old posts and found one that said the OC-3 frames were changed after 1951. Can anyone describe the differences?

I have my 1951 OC-3 drive train together now except for the new steering bands. I had to remove a broken stud from the front and a broken cap screw from the side frame to Clark Unit. I also replaced the upper shaft bearings. I was happy to see I could tilt the Clark up and back to get at the shifting mechanism without removing the tracks. I'm hoping the rest of the drive train from the Clark to the tracks is good.

Some trivia, the 4 bolt holes Clark Unit to the frame on the sides are through the case. For the front transmission to frame, the bolt hole closest the shift plate (upper right) is through the case but the other 3 are not through and have pockets inside. All my bolt/stud holes are 5/8" so they are original. The 3 front studs with pockets in the Clark have medium threadlocker and the other 5 frame to clark (4 on the sides and 1 on the front) have Permatex thread sealer (the white creamy stuff). The 3 studs have anti-seize where the nuts are. I should be able to tighten all 8 of the connections periodically since I have read they tend to work themselves loose. Comments?

[Doug424]

They changed it since the early version was a bad design. The holes on the sides of the frame that mount the trans case would get worn, and further damage would occur to the casting. I've seen them stripped , and some break out the corner of the casting.  It seemed like a good idea that you could easily tilt the trans case, but they just didn't hold up very well. The later design had the frame extend all the way back to through the final drive mounts. The frame is sandwiched between the trans case & final drive housing, This was much stronger, but a real pain to work on. You need the remove the final housings and all the studs need to come out to free the trans case. I guess the early design was OK for the lighter duty farm machines, but as the OC-3's became more industrial machines with loaders and dozer blades installed on them, the early design failed quickly. I've repaired a lot of the early style frames by welding solid bushings in place of the open slot dersign where the studs are. 

You DEFINITELY need to periodically tighten all of the studs that hold the frame to the trans case. If your frame is good at the attachment points, that's the only way it will last.

[GlenT]

Thanks for the info. Doug. Mine is the old, weak type (1951 OC-3 serial no. 1WH384).

I have the Anderson dozer setup where the Anderson supports are bolted to the side of the frame and there are angle iron supports from the Anderson supports to the sides of the Clark rear cover, two bolts on each side. It is the standard Clark rear cover. I am hoping the angle iron supports from the Anderson supports to the sides of the Clark rear cover will help strengthen the Clark to frame connection enough to avoid problems pulling out logs on my low land. I plan to  replace the existing light angle iron supports with heavier angle iron supports and run them also farther back than the Clark rear cover to mount a John Deere float ride seat (I'm 6' 3" and find the pressed steel seat pretty cramped).

I think the Clark unit is okay but I haven't added the GL1 fluid to it yet. When it was tipped up, I didn't see any cracks. I put in new 3 inch studs in the Clark three front bolt holes to frame with pockets and a grade 8 bolt in the bolt hole without a pocket (closest to the shift cover). For the sides, I put in grade 8 bolts (no pockets there) with new collets. All the bolts have Permatex pipe sealer (the white stuff) and the three front nuts have anti-seize. I plan on torquing these 8 nuts/bolts regularly.

Do you happen to have a picture of the newer style frame mounting?

Also, what do you think a good torque to the Clark to frame nuts/bolts would be? I torqued them to 90 ft. lbs. when I installed them. I don't want to pull the threads out of the 63 year old Clark unit casting.

Thanks again Doug.

[Doug424]

I'll try n post a picture of the later style frame setup. As far as torque,,, that's a good question. You could follow standard torque specs for that size bolt, but taking into consideration how good the threads are in the cast iron would be a limiting factor. In my opinion, I would just tighten them to what my gut tells me is "tight" and then keep an eye on them to be sure they stay tight.  Rather than pipe sealer, I would use loctite, there are different grades that would help seal as well as lock the bolts in place.

[GlenT]

Thanks Doug, I'm looking forward to seeing some pictures of the new frame setup. I have been giving the little grey cells a workout trying to find the best way to reinforce the frame to Clark connection.

[Doug424]

I tried to get the photo's on here and even though I chaged my camera settings it still tells me my file size is too large. If you send me an e-mail at: lathemill@juno.com, I can send you the photos

[Blake Malkamaki]

Ok Doug (and others),
I just doubled the allowable attachment size to 900 KB and upped the attachment folder size. You can make your attachments bigger and easier to view now. We have much more space available than we used to.

Blake

[GlenT]

I received frame fix pictures from Doug and Jack in NB and my brother-in-law of the frame fixes. I also spoke to Landis Zimmerman. The field fix Oliver put out had 5/8" U-bolts and 3/8" angle iron. The U-bolts hold the Clark Transmission/differential tightly against the front frame plate that also has a gasket keeping the oil in the lower shaft front bearing.

I also think angle irons should run from the bottom of the frame back to the bottom of the Clark differential back plate. These angle irons would help stop the tendency of the Clark unit to torque clockwise (looking at the right side) and try to seperate from the frame under pulling or pushing load. The angle irons are easily fastened to the Anderson dozer mounting. I'm not sure how it would work with the Ware loader or others but should be fairly easy.