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Just got a 1404 Thiokol Imp

T

Treewizzard

New member
Hello all, I am new to this whole site but hoping to find some info to help me with this Imp poject. Need to find out what kind of oil is best for the rearend and where I might look to get a manual for some other specs. Thank for any help.
 
Treewizzard said:
Hello all, I am new to this whole site but hoping to find some info to help me with this Imp poject. Need to find out what kind of oil is best for the rearend and where I might look to get a manual for some other specs. Thank for any help.
Click to expand...


The manual just says 50 wt. I use Aeroshell 100 (50wt) as do a lot of other guys. I seem to remember it takes about 7 quarts.

It had Shell Spirax 50 wt gear oil in it when I got it but it seems to steer better with the 50 wt aircraft engine oil.
 
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I will look into the other oil. I am going to pull the plate off of the back drive axel so I can check it out. Is there anything specific that Ishould be looking for regarding the steering bands?
 
You can get 50 wt at any airport with an aviation business. It is a standard aircraft engine oil. Any brand will work.

Take a look at the brake linings when you get them out. It the rivets are getting close to the surface, it is time to reline them. The rivet head is usually about half way into the lining when it is new.

If they are worn, Snowcat Pat at Sprite Improvement can reline them for you.

You can see Niks old ones here at http://www.forumsforums.com/3_9/showthread.php?t=58427&page=3 Post 56. The new ones are at Post 252.
 
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I talked to Mr Zimmerman, of Zimmerman's Cletrac. He's the one that rebuilt my C4.

The issue he says is that the rear end has a bunch of bronze seals in it. He stated that the big deal is you need to have GL-1 spec oil.

I chose to go with Amsoil Powershift. It's a full synthetic that's made for steering transmissions like the Imp.

It's sure not cheap!

The achilles heel of the IMP is that rear end. It's the most expensive part. In talking to Mr Z, he said that the downfall is usually water in the rear becoming ice, and then snapping a tooth on the ring gear. One of the main culprits is snow going in the shifter boot on the top of the unit. Something to keep an eye on.

So.. whichever oil you use.. make sure to keep the water out of it! I'm thinking of pulling mine a couple times a year and letting it settle out ( or heck, even freeze the whole jug in the chest freezer) to make sure there's no water.

Or.. use something cheap, and keep throwing it at it!

Welcome to the forum. Read up a bunch on here. Lots of info.

JP
 
GL-1 spec oil is just engine oil in heavier weights. GL-1 is an inactive spec, thus it's unavailability. It is generally used in vintage transmissions with bronze bearings. The higher spec GL-3, GL-4, GL-5 and other high pressure lubricants contain sulphur and phosphorus which can damage copper alloy bearings. (That's what makes it stink) The Lubrication spec sheet for the 1402 and 1404 Imp recommend straight 50 wt engine oil and specifically prohibits extreme pressure lubricants. (sulphur additives)

The only readily available 50 wt engine oil nowadays is Aircraft.

https://www.opieoils.co.uk/pdfs/gear-oil-FAQs.pdf

This is the is the Lubrication page from the Thiokol 1402 manual. The entry for the transmission on a 1404 is the same.
 

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Jeff

This is the oil I went with. Read it off to Mr Z when he had my unit in for rebuild. It shows GL-1 spec.. and mentions it's Cat certified too. seems like good stuff.

http://www.amsoil.com/shop/by-produ...hift-transmission-fluid-sae-50/?code=CTL05-EA

easy enough to come up with 50wt airplane oil.. thought the full synthetic was worth it. maybe not.

I think the idea of ice in the rear is scary. I think that pre-heating with a magnetic drain pan heater might become S.O.P. seems like cheap insurance.

For the cost of the rebuild.. I for sure will drain and inspect the fluid a couple times a year.

JP
 
That looks like good stuff. Aircraft oil is about 6-7 bucks a quart and I live on an airport so it was an easy choice for me.

I think the only vent on the gearbox is through the shifter boot so make sure it is in good shape. Your hot engine cooling air goes down the tunnel warming and melting the accumulated snow plus the heat generated in the gearbox will suck in moist air when it cools. The main thing is to not fall through the ice somewhere.

A heater might be a good idea. I don't have electricity where I store mine.
I drained the oil this spring and didn't have any water in it but I only used it once this year.

Keep us all posted on your progress.
 
Rebuild got a new boot on the shifter, and all other seals and such.

Oil was closer to 50 a gallon. It's made for exactly what I'm using it for. I'm curious about temps in the oil under load. I had designs on a cooler setup with pump. It's fallen away this fall due to other projects. I plan to shoot an IR gun at it and see what kind of temps it's running in low snow, pulling conditions.

JP
 
snow cat pat says if you can't touch it with bare hands it's too hot if you can hold your hand on it you should be good you want to see around 150 degrees.
 
I run mine 2 -1/2 miles up a steep road in low and 2nd gear and the gearbox stays cold but I only have 30 horsepower and don't tow anything.
 
I've been running Shell Donax TO-4 for several years and haven't had any problems. While the Thiokol manual recommends 50 wt engine oil I had a vague memory that newer brake bands don't like to be soaked in engine oil. As such, I looked for an oil designed for "wet brakes". At the end of the day I don't know how much it matters, but that's what I ended up doing.

Ron

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I will for sure be opening the rearend up and checking everything. My plans were to make sure it was all sealed back up and I did notice the boot that it has on the shifter, it seemed to be in pretty good shape but I am still going to replace it just for cause beings I will already be tearing it apart. I am picking up the 1404 I bought and using parts from the 1402 as well to put all this together. It should be interesting project having both of them side by side to work on. I will have picture pretty soon and more to follow
 
I think the difference is Jeff.. You're likely dragging your rear in fresh snow... cooling the unit.

I'll be grooming on packed trails.. and won't have that cooling.

That's my theory anyway.. we'll see

JP
 
That could be. With my blazing 30 hp under the hood I can only do about 15 mph, downhill, in 4th gear.

Most of the bearings in the transmission and differential are ball and roller with the exception of the bronze bushings in the planetary part of the differential. The carrier and axle bearings are tapered roller. So the main heat generators are the bushings and brakes. Maybe I just can"t go fast enough to generate any heat.

The 1402 book says to adjust the brakes for 1" travel on the handle. That seems way too tight to me. I have mine at about 4" so my brakes are running freely. If I set it to the book, they are obviously dragging and would be generating heat.

Next spring when I bring it in for maintenance, I'm going to re-arch the springs up about 1" and add a helper leaf. I still have the stock 1402 springs but with all the extra weight of the new cab, it needs a little more suspension height to get the rear end out of the snow. I can't go more than about 1" or the track guides will hit the cross frames.
 

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I had my springs all re arched this summer. I've got nothing on the back deck (may add a fuel/tool box) so I think I'm good there.

Previous owner had a few 80lb or so pieces of cutting edge he had on the back deck for when he mounted the plow on. We'll see how it goes.

JP
 
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