Thiokol differentials

[Snowcat Operations]

THOMAS,
Did you find a replacement OC12 yet? I may have one for you if you havent. Sorry but I just read this post.

[mkntrakes]

Originally Posted by Snowcat Operations

THOMAS,
Did you find a replacement OC12 yet? I may have one for you if you havent. Sorry but I just read this post.

so what do you have?

[Snowcat Operations]

OC12. No drop down boxes with the 6.14 ( I may be wrong on the gear ration but its the lowest gear).

[Sisu]

Great thread,

I have the dreaded C-4 rear in my Ractrac Sprite (=Thiokol Spryte). The previous owner told he replaced the gearbox some time ago. Its fully working, and so far no probs - although I'm trusting his words because I've yet to drive it myself...

Could someone tell me what are the weak points of these C-4 rears? Maybe I could fix the probs before they occur, I have full CNC-machining facilities so I'm not afraid of some work. Still, I would really like an C-12 which I haven't been able to find from here...

I'd really like to fit hydraulics and snow plow but with C-4 it seems stupid thing to do

[Snowcat Operations]

Yes. A snow plow is a bad idea with a c-4 equipped Spryte. Unfortunately theres nothing much you can really do to improve it. There are several OC12s floating around. They run from about $2,000 for a very good used one to $6,000 for a new one that has never been used. I can get both.

[Sisu]

The biggest problem is getting the thing here, it might even double the price (first land transport inside US, the shipping in a container to Europe, land transport in Europe, then EC Tax 10% and on top of everything Value Added Tax 19%...). I'm not sure if the maker of my "Thiokol copy" ever used OC12 rear, if they did - then I have a chance of finding one from here - but to be honest, these parts don't grow in trees here.

[mike2]

Originally Posted by Mainer

Here's the back-end of my 61 Trackmaster. Just bought it and have it in storage...haven't had a chance to touch it or dig into it at all. Runs well as-is but I'd still like to do a chassis-off restoration. The previous owners went through a few 1/2 ton Ford pick-up back-ends and then went up to 1 ton and it's been fine. They pulled a 2,800 lb drag with it.

how did they hook up the rear ends are there two drive shafts

[vwdevotee]

Hi. I'm totally new to the super cool world of Snow Cats, but I have a differential question. From looking at pictures of the OC-12 (and making the assumption that most are of similar operating principle), they look like regular open differentials with band brakes on the output flanges, and then reduction boxes going out to the drive sprockets. Is that basically whats going on? I've read that for fast track layers this is a pretty inefficient approach, and that most military fast track layers use a sexy triple differential system. Can anyone speak to this? Thanks!

[Snowtrac Nome]

Originally Posted by vwdevotee

Hi. I'm totally new to the super cool world of Snow Cats, but I have a differential question. From looking at pictures of the OC-12 (and making the assumption that most are of similar operating principle), they look like regular open differentials with band brakes on the output flanges, and then reduction boxes going out to the drive sprockets. Is that basically whats going on? I've read that for fast track layers this is a pretty inefficient approach, and that most military fast track layers use a sexy triple differential system. Can anyone speak to this? Thanks!

the older armor like the m113 family simply used some thing like a bombadiar weit a toeque biasing diff and band brakes to steer and a set of disc brakes on the output shafts for piviot steer the mo modern tanks are now using a varrator system like the snow trac but instead if a belt they use essentialy 2 automatic transmissions on either side of an open diff i describe it this way be cause with out the power flow diagrams its the best way to describe it. they use plannitary gears and clutchesto varry speed between outputs through the differential this is done for both steering effeciency but also traction and high speed control imagin running at 50 mph and de clutching a track and braking one side to steer even if only for a second.

[fischerrc4]

Boggie,

Would you have any info relating to the routing, and hook-up of the cooled OC-12, hydraulic lines? My Differential is filling completely full to the top case cover, and I think it may be hooked up wrong.

Snowcat Pat has completely rebuilt my unit, and it has "0" hours. My choice of lube is Chevron Synthetic All Weather THF.

The Cat is a 1976Thiokol 2100C

Thanks for any tips,

fischerrc4
WA State

fischerrc4@yahoo.com

[Av8r3400]

I don't want to hijack this thread, but is there an exploded view or disassembly photos of one of these differentials somewhere?

I'm inexplicably drawn to understanding mechanically, how they work...

[MNoutdoors]

Originally Posted by Av8r3400

I don't want to hijack this thread, but is there an exploded view or disassembly photos of one of these differentials somewhere?

I'm inexplicably drawn to understanding mechanically, how they work...

go back to the snowcat main page here on the forums there is one there that I sent in pdf format several years ago part A and part B

[sheep_mtn_jon]

Originally Posted by Snowcat Operations

Hi Guys,
Just a quick note in reference to rear diff fluid. SNOWCAT PAT suggest in a phone call to him that I try Caterpillar TO-4 30 weight. Man am I impressed! changed the fluid once before to something that was used for trans and wet brake bands but the stuff was really thick and heated up quick. The new TO-4 steers a 100 times better and so far seems to run ALOT cooler! I cant believe how much easier it is to now steer. I use probably Half the pull force to turn. I cant find the container I used for the first diff change and I dont remember what it was but this TO-4 is GREAT stuff! Thanks SNOWCAT PAT!


CATERPILLAR "TO-4": $67.95 5-Gallon bucket

Is this oil still working out for you in your C-4 diff? Why 30 weight vs. the recommended 50 weight?
Thanks-

[Snowcat Pat]

Because Sno-ops machine has the OC-12 (1450 Super Imp) where yours is the OC-4 (yes let me repeat that "OC-4") in a 1404 Imp.

While I'm being insistent I'll add that I don't think shell Aeroshell aircraft engine oil is nearly as good as TDTO transmission oils. From what I've seen looking inside and rebuilding these diffs.

-Pat

[sheep_mtn_jon]

I ended up going with the Caterpillar TDTO 50 weight in my 1404. I did notice an improvement in steering, but not to the extent that Snow Ops did.

[Snowcat Pat]

Not just the steering but also better protection of the gears and bushings. ZDDP.

-Pat

[PJL]

Our 1988 LMC1200 has the OC12 with drop down boxes, hydraulic pump and cooler. No other hydraulics on it. What would be the best oil for it and how much will that setup take? I've poked around here and it seems that Shell Donax TD would be a good choice. Except now Shell calls it Spirax. Thanks.

[Snowtrac Nome]

any of the tractor oils or wet disc clutches I run amzoil power shift in mine I'm not sold on one oil being better than the others because its some one like shell that makes the oils sold by the tractor company's like cat or john deere. those oils by the way have a good following here I wanted synthetic oil my reasoning for amzoil

[PJL]

Thanks for the info Snowtrac. Any idea how much I need? I have heard from 6-8 gallons.

[Snowtrac Nome]

if you have drop boxes and no pump its about 5.5 gallon too fill to the plug if you have no plut add another gallon over the plug for additional cooling as per snowcat pat