C-4 shift linkage adjustment-help!

[BoyToys]

Any experts out there that can give me some pointers for adjusting the shift linkage for a C-4 transaxle on my Imp? I'm slowly sorting out things on this new to me machine and can only get forward motion in granny low 1st gear if I shift the lever into reverse per the diagram...dead center and straight back on the diagram. If I shift it to the left into 1st or 3rd, we move backwards as though it's selecting reverse. Would appear way out of adjustment or worn linkage.
The front transmission itself is working fine, just the rear end giving me fits.
TIA, snow season is getting closer!

 

[loggah]

Sounds like someone took the differential apart,then put it back together with the ring gear on the wrong side of the case. this gives you 4 gears in reverse and only 1 gear in forward.The other senario is they took the transaxle out of oc-4 crawler dozer and put it in the imp. In the dozer with final drive boxes would give you the forward motion.the only way to fix it is pull the axles and flip the differential carrier assembly so the ring gear is on the other side of the pinion.If you only have 3 speeds on the transaxle,soneone took a oc3 differential out of a oliver dozer and swapped it out, the oc4 differential always had 4 speeds forward.

 

[BoyToys]

Sounds like someone took the differential apart,then put it back together with the ring gear on the wrong side of the case. this gives you 4 gears in reverse and only 1 gear in forward.The other senario is they took the transaxle out of oc-4 crawler dozer and put it in the imp. In the dozer with final drive boxes would give you the forward motion.the only way to fix it is pull the axles and flip the differential carrier assembly so the ring gear is on the other side of the pinion.If you only have 3 speeds on the transaxle,soneone took a oc3 differential out of a oliver dozer and swapped it out, the oc4 differential always had 4 speeds forward.

Uggh...you sir are a ray of sunshine :-( I looked at all the shifting linkages yesterday and nothing is out of wack.
It has the original OC-4 in it. In 2017 it was serviced with a new pinion shaft and bearings, and planetary gear set...and then ran just long enough to get onto a trailer. So I doubt the owner realized he had just one forward gear at his disposal. I don't imagine the correction you suggested (flipping the carrier assembly) is something a DIY backyard mechanic such as me cold do. Not that I'm averse to trying but differential innards are a mystery to me.
I may just live with it, knowing I would be running in the lowest gear range limiting my top speed. Again, all gears in the front transmission work as they should. Am I at risk running it as-is???
Thanks much for your assessment.

 

[loggah]

I would get it fixed, with that low gear your engine RPM would be very high, and your travel speed would still be slow. Need to pull the assembly out of the machine, back off the steering brake adjusters so you can disconnect the steering bands after taking the back plate off.. take off the axle tubes and axle shafts, then the carrier assembly will basically fall out. you would have to turn it over swapping the steering bands from side to side and basically reassemble.you would have to check your pinion gear to ring gear for proper clearance while assembling.

 

[BoyToys]

Piece of cake...heh heh. Removing the dif would be the diff-i-cult part but could probably drop it with an engine hoist. The rest sounds straight forward enough until I get into it and start scratching my head. We shall see down the road a bit.
Was planning to replace the tracks and bogies anyway which would be the opportune time to drop the diff.
May just run it as-is in top gear for a while even though slow, sort everything out, then attack it. Not looking to make any land speed records. As long as this doesn't cause any internal damage.
Thanks again for the input.

 

[BoyToys]

I would get it fixed, with that low gear your engine RPM would be very high, and your travel speed would still be slow. Need to pull the assembly out of the machine, back off the steering brake adjusters so you can disconnect the steering bands after taking the back plate off.. take off the axle tubes and axle shafts, then the carrier assembly will basically fall out. you would have to turn it over swapping the steering bands from side to side and basically reassemble.you would have to check your pinion gear to ring gear for proper clearance while assembling.

I don't mean to be be pest but you've been a great help and I may just tackle this myself.
Is it really that simple? Pull out the carrier assembly, turn it 180 degrees, and stuff it back in whereas the ring gear would now be on the side opposite of where it currently is? I've attached the instructions from the manual. I don't have ready access to a shop that could do this and my biggest issue would be muscling the diff out from the Imp but is doable.

 

[loggah]

Pretty much that simple, the carrier assembly is really not that heavy . The main thing is to make sure of your pinion to ring clearance is correct . My memory says .008-.012 ,but that could be for a oc-12 been into both of them years ago.

 

[BoyToys]

Specs say the backlash for the C-4 is .006-.010, adjustable by the shims. The proeedure in the Clark manual seems straightforward. Since the ring and pinion were replaced previously I'll assume the pinion preload and depth are correct but should probably check since I'll be rotating the carrier 180° to get the ring gear on the correct side.
I think I have a suitable dial gauge indicator to check the backlash and will have to get some gear dye to check the pinion depth.
God help me, new territory!

 

[loggah]

the pinion depth should be fine,i wouldnt move it. You will figure it out for sure. make sure you dont tighten the brake bands to much when you put them back in.

 

[BoyToys]

the pinion depth should be fine,i wouldnt move it. You will figure it out for sure. make sure you dont tighten the brake bands to much when you put them back in.

Hey Loggah,
Could you walk me through the process to remove the axles from the diff? Do I just unbolt the entire axle tube assembly from the side of the diff and pull it out as a unit? Or must I pull off the track sprocket and hub and whatever else is in there to retain the axle before pulling it out? Kinda hard to tell just looking at diagrams.
I know I'll have to unbolt and remove the axle tubes anyway when it comes time to open up the diff and remove/rotate the carrier assembly.
Just took the tracks off today, getting my mind wrapped around the differential. That first, then rebuild the tracks.
Thanks!
Mark

 

[loggah]

Just unbolt the axle tube from the differential housing, it will all come out as a unit, it will be a little heavy. Ir you unbolt the sprocket ,it will make it easier to handle.

 

[BoyToys]

Just unbolt the axle tube from the differential housing, it will all come out as a unit, it will be a little heavy. Ir you unbolt the sprocket ,it will make it easier to handle.

Thanks much, appreciate you sharing your knowledge!

 

[BoyToys]

Just unbolt the axle tube from the differential housing, it will all come out as a unit, it will be a little heavy. Ir you unbolt the sprocket ,it will make it easier to handle.

Hey buddy, I'm probably a half hour away from dropping the differential. But....not able to pull the axle tube off the diff housing. All bolts removed, the thing should just pull out I presume but not happening. Even tried to lever off the flange where it seats on the diff housing. Either there's a trick I'm missing or the flange and gasket are glued in place with something nasty.
Your thoughts? BTW I left the sprockets attached only because I can't crack the old nuts loose without an air impact wrench (which I don't have).

 

[loggah]

The tube and axle should just pull out, at least they did on the imps ive worked on. you may have to break it loose with a joint wedge or thin chisel on the flange. Im assuming the differential is clean and not rusty inside. Don

 

[BoyToys]

Thanks Don. I've tried removing just one axle yesterday and did try to wedge a chisel between the flange but access is limited. Was hoping to pull the axle tubes before dropping the differential but looks like that won't be happening.
Rust inside...I suppose that's possible since this machine hasn't been run in over 6 years at least. Though I will say the oil I drained out (2 gallons between the diff and trans) looks really good and no water present, for what it's worth.

 

[BoyToys]

Hey Don, since you've been to kind sharing your knowledge...here's a positive update.
Yanked out the diff this morning, rolled it into to the shop and took off the back plate. Guess what, the ring gear is on the left side. Tell me I'm not wrong but it's supposed to be on the right side. So, as you predicted that's my problem with going forward only when the transaxle is put in reverse.
Quick inspection and all looks OK inside, even the brake bands have maybe 1/4" or so on the shoes.
Getting the inspection plate off took several spaced wedges because whoever had this apart used a gasket sealer from hell. A little bit of torch heat helped some. I'm certain the same is true with the axle tubes. Gonna take some time but I'll get them off and will rotate the carrier 180 degrees.

Now if only mother nature will cooperate I may get it stuffed back in the ol' Imp with luck. Then have to put the tracks back together, slap 'em on, and go for a ride!

 

[zspryte]

Picture IMG_2362 looks just like it does on my Spryte's C-4. A S70FS manual would help you out, and I sure someone has one.

 

[BoyToys]

Thanks. I have the manual; the pictures aren't too descriptive but the rebuild directions will help when I put this back together.
Others on here have shown pictures of their C-4 innards, showing the ring gear positioned in the right side. My symptoms are that the only way to get the cat to move forward is by putting the differential in reverse gear. All other 4 forward diff. gears will result in moving backwards.

Long story, the mechanic that had this apart years ago appears to have put the entire carrier assembly in 180 degrees rotated from correct position. At least that's what we think and would stand to reason. Sure hope that's the deal anyway.

 

[zspryte]

I think you are correct about the orientation. Look at the Jan. 20, 2007 thread "Thiokol differentials" at comment #8 by mtncrawler (on Jan. 25, 2007). https://www.forumsforums.com/threads/thiokol-differentials.7760/post-76298 Also look at Snowcat Pat's comment #10.

There is lots of good stuff on this forum but finding it is not always easy.

 

[loggah]

On the sprites with the drop boxes it changes the rotation. On the imp there are no drop boxes, final drive ,the axles go directly into the carrier assembly.Sometimes you can see the wash area on the differential case ,where the ring gear was run properly for years. Who ever put the carrier in 180 degrees off probably never ran it much. Don

 

[BoyToys]

I think you are correct about the orientation. Look at the Jan. 20, 2007 thread "Thiokol differentials" at comment #8 by mtncrawler (on Jan. 25, 2007). https://www.forumsforums.com/threads/thiokol-differentials.7760/post-76298 Also look at Snowcat Pat's comment #10.

There is lots of good stuff on this forum but finding it is not always easy.

Invaluable information, thanks for sharing! I am definitely on the right path.
Since I've been a snowat owner for just a short time you can imagine I've spent countless hours here researching everything under the sun Imp related. The search engine on this forum isn't the best, however, so I rely heavily on members such as you.
Again...thanks.

 

[BoyToys]

On the sprites with the drop boxes it changes the rotation. On the imp there are no drop boxes, final drive ,the axles go directly into the carrier assembly.Sometimes you can see the wash area on the differential case ,where the ring gear was run properly for years. Who ever put the carrier in 180 degrees off probably never ran it much. Don

Actually Don, the guy I bought it from did not drive it after it was repaired, other than to run it up on a trailer where it's sat for 6 years. He claims not knowing it was screwed up.
I guess I could run it as-is with the differential shifted to reverse and just be limited to 3 gears from the transmission up front, but I suspect that would be hard on the differential...maybe, maybe not.

 

[Idaho IMP]

Actually Don, the guy I bought it from did not drive it after it was repaired, other than to run it up on a trailer where it's sat for 6 years. He claims not knowing it was screwed up.
I guess I could run it as-is with the differential shifted to reverse and just be limited to 3 gears from the transmission up front, but I suspect that would be hard on the differential...maybe, maybe not.

I agree with the previous comments. It’s truly not that difficult. I would also suggest re-sealing the differential section and the axle tubes. Spryte Improvement, Snowcat Services and OliverCrawler.com All have gasket kits I believe. The inner seals are available For the diffs and axle tubes. I made my own fiber seals for the axle spacers for my WT 1404. I’d buy 3 tubes of Permatex green RTV to butter up all of the case caskets and axle tubes before reassembly.
If you have access to a bore scope, you may be able to see the ring gear through the fill hole on top of the diff case, or the drain plug beneath, and confirm what side it’s on

 

[BoyToys]

Dropped the diff and took it apart a couple days ago. Ring gear on the wrong side (left) as suspected. Things look pretty good in there, a little rust on one brake drum, brake shoes show virtually no wear. Waiting on a magnetic mount for my dial gauge and have already reached out to Oliver Crawler for seals and gaskets.

Funny, there were no gaskets on either the rear access plate or axle tubes, just a grey colored silicone sealer that made it a real bear to separate. Had to pound wedges in.
Question: how do you seal the mounting surface of the carrier bearing retainers without affecting the shims. Seems without being sealed it would leak oil into the axle tubes. My tubes had maybe an ounce of oil in them. Maybe it's normal that they have oil in them and drain back into the differential.

 

[Idaho IMP]

Good deal, at least you found the smoking gun with the ring gear. The carrier bearings are tricky, I didn’t seal mine. I had about a pint of fluid from both tubes when I disassembled. I figured a little oil in the tubes doesn’t hurt anything. permatex does make an aerosol sealant that is meant for thin metal shims. I’ve used it on my Willys transfer case shims to set preload. It’s a good product. I did use Loctite anaerobic sealer on all bolts that are through bored. I had a large squeeze tube of it. I’m a fan of it as it controls the weeping through fasteners. Sounds like you’re off to a good start and the light at the end of the tunnel isn't a freight train coming at you! Keep us posted.

 

[BoyToys]

Done deal kids, all is now as it should be. Tracks are back on as of today, just gotta fill her up with oil (using NAPA 85-405 tractor transmission hydraulic).