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SV200 differential service

On my sv 250 there's a plug on the driver's side on th back side of axle.
It was recommended to use TO4 oil 50w.
Check the differential cover mine was loose and letting water in.
 
I was told to use SAE 90 and to stay away from a multi-weight. It sounds like that is what my new to me machine has always used. I've seen different opinions on this. I have a 1971 SV200.
 
Just before his passing, Brad at Minnesote Outdoors advised me on the diff fluid for my 74 SV200 "either CAT T-04 30 or 50 WEIGHT or Amsoil power shift 30 weight or 50 weight".
 
Thank you for the tips. I took the cover off this evening. The drain plug looked difficult to work with, so I removed the oil using a pump I had on hand for marine engine oil changes. The oil looked pretty good, no water. I could see some metal dust mixed in with the oil towards the bottom of the pan. I found no hunks of metal with a magnet. I'll put new oil in tomorrow. I am not a mechanic and no experience with differentials before. The gears looks fine to me except the shaft spline gear does have some wear. Is that wear concerning? Pics attached.
 

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The close up picture is the pinion gear with wear. I have never looked at one before, but from what I can tell from other pics on this forum and the internet, I probably don't have something out of adjustment. I think maybe just wear from age. My guess of what to do is to take the cover off once per year and monitor. Hopefully I don't see chunks start coming off the ring and pinion. Sticking with seems to have worked well for this machine, I am going to put straight 90 weight oil in. I'll report back if that causes any steering issues. Straight 90 is hard to find but found some at Napa in 5 and 1 gallon quantities.
 
90W is like silly putty at sub zero temps. That is the only issue I have with the stuff.
In cold temps you want to start operations slowly for sure, giving it a chance to liquefy once again.
SV 252 rears had a drive shaft driven pump that puts oil straight on ring and pinion as in heavy use it is needed to keep the pinion gear cool. Once Apon a time Bombardier suggested ATF in these rears, but it was not viscus enough..
30W or 50W Hydraulic, brake, and Transmission oil would be my choice here.
Your pinion gear shows some wear and light damage from metal in the oil. I don't think this is a big deal yet. But you should keep an eye on it each year or two..
 
Thank you for the reply on this. I intend to try to park her inside my heated shop during major cold snaps. I wonder if anyone has installed an oil pan heating pad on the pan of the differential. Not sure how long that pad would last there, though my trails do not have brush that will scrape upon the underside.
 
In a shop you will be just fine with 90W

I run 80-90W in my Snow Trac, but like you it normally is inside.
At -20 you sure notice the extra drag in the drive train for a mile or two.
When you only have maybe 60hp you tend to notice it.
On our large Ag tractors on the farm normally we let them run 20 min or so before attempting to move them, and then slowly at first.
They all use the Ag HTB (Hydraulic, transmission and brakes) oils in 20W, and even that thin oil has drag that is noticeable for several minutes.
 
Pull the diff out, check bushings on planetary gears, the ring and pinion are also very poor shape, I would not trust it for long trips, maybe fine for short distance, my guess is it had water in diff at one time
 
Wise choice if that is what you found.
The chunk is put together with timing marks. Be sure you understand how to put it back exactly as you found it when you take it apart.
Water in the Diff is common on these. The welded up case forming the rear of the frame exposes them to lots of snow and cold and the resulting condensation.
Parts are available, but currently Minnesota outdoors parts are in transition. There is a member here who worked there. He might well be able to supply you with what you need. I have to dig a bit to find his handle here.... Hang on....
 
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Bombardier sprockets and tires

I have sprockets And tires , for bombardier bombi , j5, sw , ski dozers, these r the sprockets that mn outdoors sold for many years, I also have access to bombardier parts , I worked at mn outdoors for many years.
www.forumsforums.com www.forumsforums.com
218 bryan

I had the pleasure of meeting Bryan. Very knowledgeable fellow. My bet his is for now your go to.
I don't have a phone # however. Maybe able to get that with a little work.
 
I won't be able to pull it apart, but I am looking for someone in the area who is willing to work on her and do stuff like that. Since there are no chunks missing, I am hoping it will be ok for awhile around my property. I can also transport it if there is a shop near NW Wisconsin. Minneapolis or Wausau not too far. I spent some time cleaning up the old gasket material. Some small abrasive pads on a drill helped a-lot. I used a shop vac and some cardboard to help keep the old gasket out of the pan. I am going to use some gasket material that the local NAPA says is designed not to harm anything if it gets in the differential. Pics attached. I am almost ready to add new oil and put it back together so I can move it around again.
 

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Many have drove worse, for longer. Keep the work up getting it "right" but don't let that scare you from having some fun. Going out with others is the best bet if you can.
 
Adding a remote breather to our SV200 diff and probably the auto trans to help keep the water out and maybe get rid of any that sneaks in.
 

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I was told the differential assembly on this SV200 is the same as an SV252. Mine was some wear as pictured above. I hope to find someone to help repair it at some point. Where are replacement parts available? I know MN Outdoors was a good source.
 
I have been running the SV200 to help groom my small trail system. The 90 weight oil that I put in the differential seems to work fine even when very cold. I was told the straight 90 weight gear lube is similar viscosity to the other 50 weight oil being recommended here. However, I've noticed a few challenges that could be fluid related? The auto transmission (a C4 I'm told) is very, very difficult to shift until it warms up. Next, she is extremely difficult to turn when you've got the 8' x 20' drag on the back and you've got yourself in a tight spot requiring you to climb one side out of soft snow or turn on a dime to avoid a tree she has started pushing towards (I'm lucky she's not sitting out in the woods stuck).
drag.jpg
 
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I have found that Prinoth can sell me a new pinion and wheel for the differential, so that's good. I was worried I wouldn't be able to find one. What is not good is the price. I don't notice any issues when I run it. I'll keep digging around...
 
Does anyone have a current or superseded part number for the ring and pinion set for the SV200/SV250? The young-ish parts guy at Prinoth in Quebec is having trouble finding the 1970s parts.🧐
 
Can anyone share what was involved in replacing the ring and pinion? I am about to order new ring and pinion for my SV200 and have a local shop willing to do the work, but they have not done one before. We have the Bombardier differential instructions which are 35 pages and discuss complete disassembly using some special tools. Hoping they can just slide off the ring gear after minor disassembly. Local shop has typical repair tools, press, lathe, etc. as they have worked on a few other snowcats and many vintage tractors, etc.
 
The chunk has to come apart to remove the ring gear. Not aware of any special tools to do so. I did a 252 some years ago.
If you have the manual, it is a huge help. There are timing marks on the planetary sets you must be aware of when you reassemble.
Otherwise, it is a pretty straight forward operation.
Setting pinion depth requires a dial indicator for measuring clearance/backlash. This is typical of most any differential, and the procedures
are basically the same.
 
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Reason you being told to use TO-4 or motor oil is because the ep gear oils will degrade the bronze bushings in your steering differential.
 
The shop is going to check the lash and replace driveshaft bearing. Will visually monitor for further wear. Would like to monitor oil temps in differential. They can probably install a sensor and gauge. What temperature range would be considered normal for the SV200 differential?
 
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