Tranny 101 or How a Dummy Repairs a Broken Fork!

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Tranny 101 or How a Dummy Repairs a Broken Fork!

Postby Rudi » Mon May 11, 2009 9:23 pm

Over the last little bit there have been a bunch of threads on Fork problems in the tranny. The How To was in a PowerPoint Presentation, and even thought he viewer files are available, it seems to be causing some problems viewing, so I decided to reproduce it as an html style file. I still need to play with the formating, but here it is.

Tranny Repair 101 :!: Or How a Dummy Repairs a Broken Fork

Whilst I was out hauling stuff around my back 40 so to speak with Granny my 1947 Cub, I was suddenly brought up short when I could no longer shift gears :shock: :!:


She was stuck in first gear. I had been hearing a fair amount of noise, but it was at the same level as long as I have had her which is about 2 or 3 months at that time.

Fearing the worst, I nursed her back to the shop, shut her down and proceeded to worry. What am I going to do? I certainly did not have the skill or knowledge to be tearing into a tranny, that much I already knew. I also did not have the money to send her to the Dealer to get fixed. So, like all good Cubbers, the first place I turned to was Where else eh? So after a little bit of encouragement, I popped the top off the tranny and peered inside. Not knowing what to look for, left me at a disadvantage, but upon consulting our trusty Cub Bible the GSS-1411 Service Manual, I gingerly felt around inside. First thing I found was a loose set screw. With albeit some trepidation, I removed the screw and pow :!: , next thing I knew I had a broken part which turned out to be a fork in my hand. Thought my heart stopped. Quickly I consulted the manual again. Okay, just gotta remove this and I can go get it replaced or welded. Consulted the TC-37F, and found out which part I needed. Quick call the Dealer. Oooops, not such a good idea. Seems the part is going to take 10 days to get here as a stock order and cost me $86.00Cdn or 2 days and add $40.00Cdn for shipping. Nope! Don’t think so. Quick, call Alton. Hmmmm, going to cost me $25.00Cdn (not bad), but I gotta go get it – 2 hour drive, can’t do it until the following week. K, well give me buddy Gerry a call. Yup, he can weld it. All I gotta do is take it out and bring it over. Yeah right! Like I really want to do this eh :?: :?:

Got the first piece out, no problem. But how to get the rest of the fork out? Hmmmm, oh I don’t want to do this I thought to myself. All that was going around in my mind was the horror stories of guys who have done this and have lost that darn Poppet Ball :!: Do I really want to do this :?: I decide – Nope, not right now. Got to get me courage screwed up! So, off to the board I go again seeking advice on the possibility of taking the fork out without having to remove the rod….. Nope, can’t do that either says the guys. But don’t worry they said, you can do it! Yeah right and pigs fly guys! I ain’t no mechanic, not even a shade tree mechanic. Heck, I ain’t never even seen a Poppet Ball before. How am I going to know what it is especially after it falls into the tranny case? After some more fortification from the guys on the board and about 10 cups of coffee, I finally screw up the courage to attempt it. I make sure that my thumb is over the bore hole for the Poppet Ball, just in case. I tap the vise grips with the rubber mallet. The rod slides ever so gently into the rear of the tranny case. BUT – I do not feel anything hitting my thumb? I remove my thumb and peer into the bore. No ball! I look at the Parts Manual again. Geesh, no spring! Hey what is up with this?


This pic shows a close-up of the bore hole and the detents in the shifter rail.

Well, something to investigate a little later on. Now that I had the rail moving,I found that it did not move readily and had to be worked . I had to jiggle the rail back into the rear of the housing, slightly rotating the fork as I went. I could get about an 1/8” movement, then I would have to jiggle the fork, get another 1/8” and so on until the rail was far enough to the rear to remove the fork. I finally get the fork out and drop it off to Gerry. Later the next day, he drops the welded fork off and leaves it on top of Granny’s seat. I wasn’t home, was off getting one of my daughters at work. My wife tells me later that night that Gerry was by and went down to the shop and then left. Oh well, will check in the morning as it was way too late and dark. Then a thought hit me. Dang, I forgot to take pictures of the broken fork :oops: :roll: :shock: After all, I have been pestering my fellow Cubbers to take pics, add narratives and submit the article for the Manual Server’s Maintenance Tips and Techniques section. Here I was, forgetting to do the very first thing. Hmmmm, not too smart! Anyways, I decided to document my first foray into the world of Cub Tranny Repair 101. With a little persuasion from Lurker Carl, here is my first stab at it. Hope it works!


Here we can see the 1st and reverse fork removed with the shift rail slid back into the rear of the tranny case. I did not want to remove the expansion plugs as spares would take 10 days to get. The rails do not slide back easily, as I found out.

Now that I have the welded fork back, it is time to venture back into Granny’s Tranny. I am trying to figure out how to do this, so I consult the GSS-1411 again, read up a bit more on the threads on the board. After about an hour I figure I have built up enough courage to attempt the next stage. You know, it really isn’t that difficult to put the fork back on the rail and it is not all that difficult getting the rail to go back up to the bore. A little bit of lubrication helps, there is still a little friction to deal with while sliding the rail forward. Put in the new spring and the new Poppet Ball. Now, come the tricky part. This is the part where everybody seems to have a little difficulty. Some vent a little cloud of blue, some get a little liquid courage, some have a coffee – me had a coffee (read several) and a couple coffin nails (read many) and I still could not get that darn Poppet Ball back into place. Did a little more investigation. Should have done it before. Seems that the original spring was in the bore – just compacted in with dirt and sludge. Hmmmm, good thing I had already drained the tranny and started it’s first flush. So, pack up the new spring, clean the old spring and stick it back in the bore after that is flushed out with some kerosene. I grab my vise grips, gently work the end of the rail up to the edge of the bore. Carefully I slide in the Poppet Ball, compress it carefully into the bore with a small diameter brass drift. I then gingerly try to release the pressure on the drift as I slide the rail in. Wow! Gee that was easy! Looks like I got it! So I then start trying to align the fork with the threaded hole for the set screw. Hmmm won’t go in! Geez, the rail is turning.

That shouldn’t be I think. I look to see where the detents are – hmmm not aligned. Guess it wasn’t so easy after all. I start taking everything out again. Hmm, I see the Poppet Ball is not in the bore, so it must be up by the expansion plug. Grab me little magnet, out comes the Poppet Ball and promptly falls into the tranny case! Just out of curiosity I try sliding the rail in. The detents still don’t line up! Why? Start poking around in the expansion plug bore with a dental pick to see if there was dirt or gunk in there. I feel something move but it won’t come out, In goes the little magnet again, thinking there is some filings or something. Whoops, out comes a Poppet Ball – looks like that is where the original went to. Damn, why did it have to do that? Start feeling around in the tranny case for that darned ball with a magnet. Seems the only thing I can find is gears. My father-in-law popped over after about an hour of me searching in the tranny and not finding anything. Says to me “ why not check the drain plug?” “Well, already did that Dad.” I says. “Well check it again!” I do – Don’cha know, out comes the Poppet Ball. I keep trying to get that durned Poppet Ball to go in place but it just won’t do it. Consult with the board again, and I get this suggestion – “Use a ¼” brass drift.” Well, I thought that was what I was using – but it was actually about 5/16’ in diameter. Look around for a ¼” drift of some type… no luck. Then it dawns on me – hey, I have 5mm chain saw files! Not only that, the files are long enough to go between the manual lift and the tranny case to fit into the bore hole! This is gonna work I say to myself.

Shur’nuff’ slick as can be. I pressed the Poppet Ball down with the file, grabbed the vise gripped rail and slid her right into position! Slowly releasing pressure on the file and keeping the sideways pressure up on the rail it finally caught. Wow! Heard the click as the ball seated into the detent. Now I felt real good. This had been going on for a couple of days, I was afraid that Granny would be stuck in the shop forever. I sat down, had another coffee and a nail as I contemplated what I had just done! Only one worry left. Would the fork line up with the thread for the set screw? With cautious optimism I peered down at the fork. Yup! There were the threads. That set screw went in slick as can be, no fidllin, no fussin, no mess! Boy, can I ever tell ya, that sure felt good! Sometimes, even though we feel we do not have the ability or the dexterity do perform some maintenance job on our Cubs, we just have to get in there and as EZ says “Do It!” This repair, once I got over my uneasiness, was actually fun!


Brass Drift and the Poppet Ball


5mm Chain Saw File and the Poppet Ball

As you can see there was quite a bit of difference in the clearance between the drift and the file. Without sufficient clearance the shift rail will not be able to catch the poppet ball while it is still depressed in the bore. This is what caused 90% of the difficulty I experienced whilst doing this repair. As Mr. George Willer said – “This was a real confidence builder!”


Here you can see how the forks line up. The tranny is now in neutral :!:

Now that the fork is back in place, the next job is to make sure that the case is ready for the new gasket.


Ensure that the complete surface of the tranny case is scraped clean. Do not forget to clean the threads and any orifices that you see. Once completed, wipe it down with kerosene to pick up any small particles of dirt and stuff. Now, you are ready for the gasket.

The gasket is Part# 351546R1 and is available at your local CaseIH Dealer, on-line at or also on line at


One thought. I hadn’t said too much about this, but I had drained all the goop – looked like the Petitcodiac River was in there. I had also flushed the case 3 or 4 times with kerosene. Make sure that your tranny case is good and clean. Re-fill with kerosene and run it around the yard for a while. Then drain the kerosene. Re-fill with the proper quantities of SAE-90 gear lube as recommended in the Owner’s Manual. If you prefer Hy-Tran over SAE-90 that should be fine too. I hope you have enjoyed this article. It is the best I can do. Never been one for point and point but prefer the narrative. If you have any suggestions, you know how to get hold of me!
Confusion breeds Discussion which breeds Knowledge which breeds Confidence which breeds Friendship

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