Clark Transmission Frame Mount Studs and Bolts Leaking

[GlenT]

I just got my dead Brother-in-law's OC-3, serial 1WH384, which I read would put it as a 1951 model. It that hasn't been used much for the last 25 years. The Clark unit was very low on fluid and there was a lot of oil on the pan under the unit (part of Anderson Dozer package?). There were also one 5/8 stud broken on the front mount. upper left, and one frame side to Clark unit 5/8 bolt broken lower right front. I was able to get the remains of the broken stud and bolt out. I removed the bottom two studs on the front mount and poured kerosene in the Clark unit and it came out the front bottom stud holes and the lower right front bolt hole.

I also removed the seat and noticed the mounting holes went all the was through the case. This got me to thinking the Clark case to frame mounting holes were also drilled all the way through and the studs/bolts kept the transmission fluid in. This may be wishful thinking on my part. I really don't want to pull the Clark unit this early in the game.

So, are the Clark unit mounting holes all the way through the case?
If so, maybe I will be able to just replace the studs and bolts with new Grade 8. What type sealant would work good in the mounting holes?

I plan to pull the rear cover now to see what the gears look like after being low on fluid. What should I look for to see if being low on fluid hurt anything?

Thanks!

[Robert Barbour]

The stud holes were not all the way through when the machine was new.  Those studs were a problem area and often broke.  Often when drilling out broken studs the hole was pushed through into the oil compartment.  I would use G8 or L9 bolts with loctite to seal the holes.

[GlenT]

I have the case seperated from the frame now and the shift cover and rear differential cover removed. The 4 bolt holes in the differential 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 bolts are 5/8" so they are original.

Any recommendations on what type Loctite to use to seal the 5 holes that are through the case?

Thanks for the reply.

[Robert Barbour]

I would use the medium Loctite which is blue in colour.  Did you have studs or bolts?  They were all studs originally.  The original size was 5/8".  Now the studs are better because the thread that goes into the case is over size ( compared to a bolt ) making for a tighter fit. I would think Zimmerman's could supply the proper stud.

[GlenT]

Thanks Robert, I ordered lots of stuff from Zimmerman's  yesterday including the front studs. I'm happy to hear they are oversized because the three regular studs that remained were all different and were a little loose in the case. Do you know if the side bolts to frame are supposed to be oversized?

[Robert Barbour]

Yes each side should have 8 studs and 4 at the front.  The coarse thread on the stud is oversize to be a tight fit as that is to remain in the housing on dis-assembly.

[Blake Malkamaki]

If the studs are loose, LocTite makes a creamy bolt and bearing retaining material that can fill larger voids than regular LocTite. I used it on the crank pin on my Rumely steam engine years ago.

Make sure with any thread locker that everything is really clean to start with.

[GlenT]

Blake, the creamy Loctite seems to be working well. I used it on the 5 bolts that did not have pockets and used medium Loctite on the 3 studs that had pockets. The only leaks now are the bottoms of the axle housings to the Clark unit. I jacked up the OC-3 42 under the drawbar, loosened the 6 nuts on each side, and re-torqued to 140 ft-lbs the nuts starting with the bottom nuts and working to the top but still a little seepage. The seepage wasn't at all there for a day when it was in the 40s here in MN but then yesterday there was a little when it got into the upper 50s. I suppose that 90w mineral oil doesn't flow too well in the 40s. Any ideas on stopping the seepage without removing the final drives? I wonder if I pulled the axle housing out a 1/4" and worked #2 Permatex into the gap and re-torqued the nuts if that would stop the seepage (can I do that)? Or, should I just forget about it (it's my OCD working overtime).