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st4

C

caddyman

New member
Hi, I found a st4, it has a small idler behind the drive sprocket, when did they change to a large, the owner says the track came off, is that common on them, can they be changed to a large wheel? It's dor sale, maybe not the best model to buy??
 
the transition years for the big wheel was around 1972. they also changed to a 3 band track, which was more prone to throwing tracks because of how far apart the drive sprockets were. the 2 band models are the most desirable because of robust grousers and the narrow mounting of drivers. I have done a big wheel conversion using a high quality torsion axle to get rid if the failure prone boggie set up on the #1 position the boggies work great in soft snow but get over stressed when running for long periods of time on hard pack ,ice, or dirt especially with a filled or solid wheel
 
Ok, so do you mean this is more desirable, 2 band track, the grousers are a very low profile, not a lot of grip
 
unless you are trying to high mark those little grousers, in combination with the steering system, will preform as well as larger machines with more horse power and more aggressive tracks. the later model 3 band rigs had a stamped grouser that was less robust and didn't provide much more traction. I have a Thiokol 2100 alpine groomer I now use for freighting it has 5 foot wide tracks 5 inch deep j style grousers and weighs in at 9 k it will pull and climb like a goat but that was what it was intended for. I have never had the snow trac stuck if it ceases forward motion I just back out of it and it actually will out preform forward motion in reverse. I have climbed hills in reverse it wouldn't go up in forward gears.
 
Ok, is there replacement sprocket available, grousers or track guides, the sprockets on this one are allmost worn out
 
I would need to see some pics the grousers wear for ever there have been some reproduction runs of guides I can't spare many more as o have one track with some holey church going guides and I will be having to replace them soon I will be recovering another one next winter than I should have spare parts I would need to see the sprockets they have to be worn down to about 5/16 of an inch before they start breaking off I have a have located a new set of sprockets I'm going to tru to steel one to make a mold.
 
I had a chance to look at the st4, sprockets are beat, need replacement, I wonder if they where brazed up and then cut to the original profile how that would hold up, also the front small idler wheels look like they can travel up high enough to touch the drive spockets as both side had groves cut into them is that a common problem?
 
my st4 lost a track prior to me buying it. the rear axle wasn't checked and the wheel slid out and derailed it.
st4 is one of the most dependable snow tracs. lots of us don't have the big wheel on the front . overload and speed causes problems. they are built light.
silicon bronze is what I used when fitting my new sprockets. it sticks good. I am sure you could use it to build up the teeth. use a wire feed welder.
more than likely the bushings are shot on the front boggie spring. is the two bobbies tilted some?
a rebuild of them was posted a couple years back.
the grousers cant be found and some of the castings.
I am sort on them . I just keep welding them and stay away from rocks.
if the price is fare and you can do the work I wouldn't pass on it.
most fixes and total rebuilds have been posted. find out why the track came off and what damage was done.
jim
 
it will be a lot of work but you can build them up and regrind them with a wire feed and nickel bronz wire as a plus side they will were a lot better that way.
 
Did you find the serial# ? if you have it and any pics or info please post them up after you decide ( you know you want it..) , it would be nice to document as many as we can.
I have been reading up on TIG welding Silicon Bronze and am going to order a few lbs of rod to play with- looks very promising. J&T foundry in North Pole Alaska also has new castings.
 
The reason your drive sprockets are grooving the from boggies is because the main axle housing is too far to the rear..

This is were you make the adjustment to the drive cahins in the engine compartment. When you loosen the drive chain, the axle housing pivots to the rear. When you tighten the chains, the axle housing pivots to the front, away from the wheel. Check out your chains, as they may be too short, and won't alow the axle to pivot away from the front boogie far enough.. Comprenda?

The Roller cahins that are under the hood are metric, as SAE No.80 is not wide enough through the rollers to work, it won't for long. It will damage the sprockets eventually. See if you can wiggle the rollers back and forth over the front drive sprocket. There should be clearance between the side plates of the chain, and the sides of the sprocket. Other wise suspect an SAE chain is there, and remove it ASAP and replace with the correct metric..

Two band track ST's rule if you want to not have detracking issues. There are several theads here if you do a search. It is one of the reasons I have a two back small wheel machine..

J&T foundry in Alaska are the go to's for new track drive sprockets. I have a set for mine..

Regards, Kirk
 
My St4 has new drivers casted from the north pole foundry at the alaska foundry. They are very nice and worth the money. You could probaably get them from Snow Trac web site in Sweden as well as other parts. Good luck and hope it works out for you.
 

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Mine is a Frankenstein conversion with a small wheel and three band track. I only put 50 miles on it and had no track slippage in snow. Nome snow Trac puts serious miles on his and knows the in and outs. With low profile grouses I can not see problems throwing tracks.
 
word I got from a friend in Fairbanks, they closed down building is empty.
wonder what happen to the sprocket patterns?
friend of mine in South Carolina works with a foundry. he said he can get em cast but needs a pattern
 
Maybe akimp, would be willing to do something his look real nice and would be perfect for the pattern, there is a foundry a hour form me that does oil field work , they would be a place to ask also
 
akimp said:
Mine is a Frankenstein conversion with a small wheel and three band track. I only put 50 miles on it and had no track slippage in snow. Nome snow Trac puts serious miles on his and knows the in and outs. With low profile grouses I can not see problems throwing tracks.
Click to expand...

The reason the three band track models throw tracs has to do with the drive gears being spaced wider appart, and the wheel guilds running inside, or between the sprockets.

They de track when the track line is forced to tilt against say a rutt or if you are parralelling a deep truck track, and the track line tilts. At about 30deg of tilt they will toss them. Two banders can stand more than a 45 deg tilt and stay on. When it comes off it will raise hell with those tall, and some what weaker wheel guides. Cross ruts, don't run with them, and all is fine.

To bad about J&K foundry. Hopefully some one in AK can find the former owners and the patterns for the ST drive gears.

Regards, Kirk
 
warren has a mold I think it is the thicker sprockets that Lyndon designed.. it may not be the new style mold.
 
as far as sprockets go I got salvage rites to one out of nome with almost new sprockets. I will make a run out there this summer to prep the machine for extraction there was one extra sprocket like new out there. I also have a local guy who has a set of 4 new ones I'm trying to get a hold of him to borrow one for a mold but by mid summer I will have one for a mold.
 
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