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Thiokol differentials

KickerM

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Thanks All, I'm gaining a lot of knowledge from you! I'm new to SnowCats

I have an OC-4 with Drop Boxes and I dropped the fluid in the Drops and it is a heavier darker fluid then what came out of my Diff... What fluid should I use in them?

And from everything I have read on here it sounds like Shell Spirax TD Fluid for the Diff is a good Choice?
 

zspryte

Member
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I run a heavy gear lube (80 or 90 wt) in the drop boxes and Aeroshell 100 (50 wt) in the diff case - per Peterson's. My drop boxes are gears - not chains. The lube provides better protection for the gears - it is suppose to withstand the high pressure on the teeth better than the Aeroshell 100.

Snowcat Pat pointed out that if the seal between the drop boxes and diff leaks, you could get gear lube into the diff which would not be good so he runs what he puts into the diff in the drop boxes too. The stuff he talks about does better than straight mineral oil at reducing the friction on gear teeth even at higher pressures.
 

Trackrig

Member
This question is coming from a Nodwell person, but there are (some) similarities in the rear ends. Please help my education if you can.

I originally owned an RN110 that was made for the US Army in about 1964. It had a Ford 292 V8 with a Clark 5 speed behind it. It had four axles, the drive sprocket were in the rear and in those days they didn't have front idlers - the track wrapped around the front tire.

When I sold it to a friend to use for hunting, they needed to cover a lot of very rocky ground so he wanted to gear it lower for even slower speeds. What he said he did was get the rear end out of a Thiokol??? Whatever it was, he put it in and it worked fine though it was a slow as could be because it cut the speeds in half.

My Nodwell parts books say the rear end is a #15 and several places in the parts list they refer to Oliver P/Ns. I knew some Thiokols used the OC (Oliver Clark) 15 rear end. I've been told by a lot of Nodwell people the RN110 rear ends are OE15 rear ends. No one can tell me what the "E" stands for. A Bombardier parts person, who dabbled in Nodwell parts, told me the Nodwells had Oliver White 15 rear ends.

So what the friend swapped out, was the same rear end, but with lower gears, and to call it the "pumpkin" was made of aluminum instead of steel. The "pumpkin" is more like a 2' square steel box. They unbolted the axle tubes and planetaries from the Nodwell rear end, bolted them up to the Thiokol rear end and everything worked fine.

Is my information of an OE15 rear end wrong - could it be an OC15 rear end, does such a thing exist? Do Oliver White rear ends exist?

Thanks for any info you can provide.

Bill
trackrig@gmail.com
 

Dr. Zaugg

New member
Mtn Topper:
Pat does NOT use hydraulic oil! He is using Tractor transmission/hydraulic oil.
AW32 hydraulic oil is vastly different than Tractor trans/hydraulic oil. Personally, I like John Deere's HY-Gard transmission oil. Regular hydraulic oil does not have any wet brake additives. If you cannot get that I would go to nearly any other tractor dealership as this oil is the industry standard. BUT, do NOT use COOP oil. it WILL make your brake bands chatter hard when you try to turn.
Paul
 

Traction

New member
I have a super imp with a oc12 rear end. I understand that cat TDTO is an acceptable oil for the differential since I don’t have hydraulic accessories which use the differential as a reservoir. It does not have a cooler for the fluid. Would 50 wt be ok to use, or would 30 wt be a better choice? Does anybody add friction modifiers to the oil to condition the band brakes?
 

Cidertom

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I have a super imp with a oc12 rear end. I understand that cat TDTO is an acceptable oil for the differential since I don’t have hydraulic accessories which use the differential as a reservoir. It does not have a cooler for the fluid. Would 50 wt be ok to use, or would 30 wt be a better choice? Does anybody add friction modifiers to the oil to condition the band brakes?

The TDTO is a family of lube, not a single product. The only "friction modifiers" I know of are counter productive. Look at http://www.forumsforums.com/3_9/showthread.php?t=63147 about friction modifiers. With the cold temps your rear is exposed to, and the range of heat it can generate look for a fluid like TDTO-TMS or JD lo-vis HyGard.

My 2¢
CT
 

Mike Skaggs

New member
new to this forum. I have a 1965 Spryte that originally came with a ford 6 cylinder, 4 speed, and the OC-12 rear end. It was the 2 seat pick up style version and came from the Los Alamos Ski area where it was purchased new. I completely rebuilt it tearing it all the way down to to the frame. The frame needed to be repaired due to some small cracks. I had the axles straightened within specs and rebuilt the OC-12. I installed a ford 5.0 SB EFI engine with an E40D transmission. The tranny required a US Shift transmission controller (-4 model) to control the tranny. Still tuning it to get it to run correctly. I also built a full box body for it an raised the roof 6 inches to make it much more comfortable to drive. I have a set of wide tracks on it making it about 11 feet wide when installed. Trying to figure out a good way to trailer it legally so I can transport it to use. I may have to remove on track to get it down to legal width. I have a set of summer tracks for it which make it about 10 feet wide. I am looking for a set of narrower tracks to possible purchase if anyone has them.
 
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KickerM

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Load and go! Offset to the passenger side a bit and haul on Sundays or at night! Ramps up in the air to block the view from the back and extra bright lights on your trailer all help!!!! Just saying! Or if your looking for a more legal option, depending on what state your in you can get an Overwidth/Oversize permit! PS we need picks and you should start a thread of your build in the Snowcat Restoration and Rebuild Forum, it’s just common courtesies for us rebuilders!!! Lol
 
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Mike Skaggs

New member
Here are a couple of pics. I will start a thread when I get more time
 

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Mike Skaggs

New member
Thanks for the replies. Am interested in what tires people are running. The originals ar 4.5-12 NHS Goodyear which I can’t find anywhere. Mine were all foam filled but now have cracks.
 

northfork

New member
The drop boxes for the OC-4 are chain reductions. The drop boxes for the OC-12 are gear reductions available in both 2.44 or 1.83 ratio.
I just finished rebuilding my 14th OC-12 and I think I'm starting to understand it.
I've tried several different oils in the last 18 years and I now use only Tractor Hydraulic Fluid brand Shell Donax TD, or sometimes Donax TC-30. Lots of these cats have a hydraulic system that combines the rear end oil with the hydraulic oil so it has to work for both. Change the oil often, when warm, and in the spring before storage.
Steering? Don't drag the brakes!

Snowcat Pat
Wallace Idaho
Greetings Pat do you have any recommendations on an OC 15 diff oil? not to mention l operate in pretty extreme temp as cold as 15 to-40
 
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