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Variator Wear ??

oilline

New member
Hello. New to the forum and just bought a Snowtrac ST 4 #2317.
Just having a look over it and on the right hand variator pulley there has been some wear on a linkage shaft . Any idea whats causing this
 

JimVT

Bronze Member
GOLD Site Supporter
check st25 and see if it is broke. it is that large aluminum piece in the center.
are the rub marks fresh?
jim
 

nwerring

Member
Here is a photo of the ST-25 part in the variator. They sometimes break. If yours is broken, then I'm in the process of having some new ones made. Should hopefully be done this winter..
 

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oilline

New member
Are these things easy to take apart? Anything to watch out for? Can i disassemble the offending assembly with the engine and transmission in place. I would like to take off the pulley assembly and feel for play in the vertical shaft bearings.
Also will look at ST-25.
Also is it safe to raise the cat on axle stands on the chassis so i can run the trackes and turn the steering to try and see whats going on?
 

300 H and H

Bronze Member
GOLD Site Supporter
Do you have a parts manual with the exploded views of how this goes together?? You should get one. To do as you wish, the engine and trans stay in place. I suspect the top bearings in the left hand tower... It could be old damage, and the bearings replaced by a previous owner..

Yes you can put the cat on stands and run the tracks. This is how you set the variator center, so the machine will track straight with the steering wheel in the center of it's range of movement...

There is tons of information here on this forum. The search feature is your friend. Use it, but if you need help, lots of us are here for that to.

Regards, Kirk
 

oilline

New member
Another shot. Does this look correct? I presume the splines are see are the vertical shaft, are they visible because the pulley is pushed down at the moment?
It looks like fresh wear to me, the grease is impregnated with metal filings

 

JimVT

Bronze Member
GOLD Site Supporter
your steering drops it like that when you turn. the other pulley top comes off to take it apart. take some good pictures if you don't notice the broken part. I would suspect the variator shifted .
if it is the up right off the transaxle check the mounting bolts to it that are on the very bottom on the axle. they have been known to work loose. you may want to look at that first before tearing the varator apart.
jim
 
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Cidertom

Chionophile
GOLD Site Supporter
Are these things easy to take apart? Anything to watch out for? Can i disassemble the offending assembly with the engine and transmission in place. I would like to take off the pulley assembly and feel for play in the vertical shaft bearings.
Also will look at ST-25.
Also is it safe to raise the cat on axle stands on the chassis so i can run the trackes and turn the steering to try and see whats going on?

Easy depends on how the pins are that hold the arms. Mine were rust frozen and it took a bit to free them. Once free the variator came apart fairly easily. I wound up replacing the pins and making new bushings.

On running on stands. Make certain the track is tensioned correctly and is well free of the stands.
or
in place of running on stands, you can remove the drive chains. Should be a clip link.
 

Lyndon

Bronze Member
GOLD Site Supporter
http://www.forumsforums.com/3_9/attachment.php?attachmentid=5722&stc=1&d=1147362792
Where ST11A (the "tower" casting that houses the vertical shaft) mates to the Horizontal casting, ST10, there are 3 studs. Each has a Grade 8 nut. For it to wear like this: 1)The hardware has loosened, the most common scenario, 2) One or more of the studs have broken off, 3) a mounting 'ear' is broken.
You will not have to remove the engine or Variator to tighten it up if that is the problem, but you will have to remove some of the stuff that prohibits access.
Remove the air induction horn, and the big Belt as per the previous instructions. Try not to get the belt greasy. They are usually 13 or 14 MM. The studs themselves are not hardened. Don't torque them down too much, they can be pulled right out of the ST10 housing.
Also, check all the bushings for the 1/2 roll pins. One of those could be giving trouble.
The steel "H" frame of the variator usually ties the two towers together, but I have seen many machines that the hardware for this is loose. It tends to chew out the holes in the alloy at the top of ST11A. You will have to remove all 4 "Chives" (Pulley-halves) to inspect this.
Your machine is very near the end of Swedish production. I looked at ST4#2311 in Maine at the US importer's place, and 2318 in the Yukon Territory. Good luck with it.
 

oilline

New member
http://www.forumsforums.com/3_9/attachment.php?attachmentid=5722&stc=1&d=1147362792
Where ST11A (the "tower" casting that houses the vertical shaft) mates to the Horizontal casting, ST10, there are 3 studs. Each has a Grade 8 nut. For it to wear like this: 1)The hardware has loosened, the most common scenario, 2) One or more of the studs have broken off, 3) a mounting 'ear' is broken.
You will not have to remove the engine or Variator to tighten it up if that is the problem, but you will have to remove some of the stuff that prohibits access.
Remove the air induction horn, and the big Belt as per the previous instructions. Try not to get the belt greasy. They are usually 13 or 14 MM. The studs themselves are not hardened. Don't torque them down too much, they can be pulled right out of the ST10 housing.
Also, check all the bushings for the 1/2 roll pins. One of those could be giving trouble.
The steel "H" frame of the variator usually ties the two towers together, but I have seen many machines that the hardware for this is loose. It tends to chew out the holes in the alloy at the top of ST11A. You will have to remove all 4 "Chives" (Pulley-halves) to inspect this.
Your machine is very near the end of Swedish production. I looked at ST4#2311 in Maine at the US importer's place, and 2318 in the Yukon Territory. Good luck with it.

What do you mean by the "bushings for the 1/2 roll pins". Is it ST3007 and St 3014
 

Cidertom

Chionophile
GOLD Site Supporter
What do you mean by the "bushings for the 1/2 roll pins". Is it ST3007 and St 3014
3014. Those are the ones I had issues with. the pins were frozen to them, and they were the rotating member, which made the holes in the arms egg shaped. If you look at the pix in my above mentioned post you will see what I turned out of bearing bronze to replace them.

I'm not certain those (by themselves) could give you that much play. I would lean to the bearings. My big issue was the other variator. With the wear I had on it, on the drivers side you could get the wear you saw. I wound up turning new bearing holders, and replacing the sheave half.

Welcome to the YTPS (You're The Parts Store) repair methods.

Also for what it's worth: My trac, #2116 all of the above and the bolts were Metric, not SAE. I don't know when the change happened, but almost all of the stuff under the hood, not just the VW, on mine is metric.

CT
 

jask

Member
That is a LOT of lateral movement. I would check the bolt on the drivers end of the ST7020 to ST11A as well, and the bottom bolts of the ST25, there is so much misalignment I am surprised your machine steers well.
 

oilline

New member
Well i have found the culprit


Top bearing completely knackered. Dont know where all the balls have gone ! Tapped hole in ST11A broke away.


So what to do? Obviousley the tower is going to need to be repaired. I should be able to get it welded up i hope. Can i get the tower off in situ? Im struggling to get a socket on to the rear and side bolt due to the diameter of the socket fouling on the diameter of ST11A.

Do you think it wise to pull the transmission and strip to find the balls and any other fragments from the collapsed bearing?

Is the top bearing a standard part? What about the bearing cap, ST13A? Is that available or am i going to have to make one?
 

Cidertom

Chionophile
GOLD Site Supporter
With that damage, and the general state of "what else has?" if it were mine, the power package would be out of the chassis. I found it easier to pull the front off the trac and pull everything out that way. Others have pulled out the top, dropped out the bottom. Clean it all, and see what else is broken.

Besides, you want a fresh start anyway. Yep it's a pain, but you're better finding it in the shop than the field. Trust me, BTDT.

Here to advise, or just commiserate.
CT
 

Lyndon

Bronze Member
GOLD Site Supporter
This is just a "Long-winded" opinion but: When I go 20 miles out in to areas where no one else is, in a 30 to 50 year old snow cat, I try and make the machine reliable so that I can get back home in one piece, and so that I don't have to abandon a machine where it might get vandalized. If you live in Nome, like Don, this becomes more serious. But even for the "Week-end warrior" it's nice to go out and explore around, instead of spending you time fixing a broke-down machine. That being said, I would recommend pulling the Engine, Transaxel/Variator and seeing what else the previous owners broke/lost/damaged and fix it all.

Twice in Alaska I encountered people that had been offered a ride in a 'Track-Rig' to go hunting. Their response was something to the effect: "Uh,... No thanks, I'd rather Hunt, than spend my time fixing the track rig"

Your Brakes, and Fuel system are sure to need attention. Good time to deal with the starter too as they are very difficult to access.
If the machine breaks down it's difficult to Tow, and one needs a bigger snow cat to tow it, that or a helicopter, and they tend to be prohibitively expensive.

Go thru the Tracks, and the Wheels.

Remember: You can not call "Triple A" and expect to get roadside assistance on the side of Mt. Rainier!
I know you won't be on Mt. Rainier anytime soon, but you may have a similar place to play.
Lyndon
 

oilline

New member
To be honest I was suprised at what good condition everything seems to be in part from the bearing breaking down. Everything came apart nicely, no frozen bushes or pins. There was a general lack of grease and the grease hoses were broken off
I will strip the whole lot in the summer, but for now I just want to get it functioning again as I have other projects on the go and a non steering Snowtrac can't just be pushed around the garage .
I ll get the opposite side bearing cap off to measure up to make one.
Hope I can get the tower off in situ . All the debris from the top bearing shouldn't of got past the bottom bearing so I don't need to worry about bits of metal in the bottom end
 

oilline

New member
Tower off no problem. All the debris from the collapsed bearing was contained in the tower above the bottom bearing. Oil seal diameter for top bearing a bit chewed up. Will see if it's salvageable when I get the old outer bearing race out. Don't know how I'm getting it out though. Can't get a puller on it, can't knock out from the back. Will then see about repairing the broken mounting flange. Would like a replacement tower really if anybody has a spare. Ultimately I could make a new tower if all else fails.
 

oilline

New member
ST2016A oil seal diameter ground down to 33mm to remove the damage caused by loose ball bearings getting mashed around in there. Not all the damage removed but enough to get an oil seal on




Making of a ST13A




Not a good picture but note the damage below the bearing diameter where the remains of the old bearing made a bit of a mess.


Boring out to remove the damage and fit a sleeve to get back to 52mm diameter
 

Cidertom

Chionophile
GOLD Site Supporter
Nice work. I've had to make several parts so far. Very glad I have lathe and mill. And know how to use them.

TEW
 

oilline

New member
All back together now and good as new.

Repairs to the variator tower

Sleeve fitted and recess milled for grease port


Top face milled flat


Bearing cap completed


All assembled before fitting
 
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