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Suspension Tear Down

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Rear Suspension Tear Down

First Posted on Wednesday November 6th, 2002

Today I tore down the rear suspension. I had a couple of things in mind when I did this. One, all of the bearings in the wheels needed service or replacement. The steel A-frames were showing some rust, and that needed to be addressed before it went from surface rust to a structural issue. They will get wire wheeled, degreased and painted with a high quality paint. Finally, it involved a general cleaning, polishing and greasing of the shafts and such.

Tearing down the skid frame is really just rote disassembly, so I won't cover it in great detail. There are a few key things to remember though.. The first is to be orderly about it. I keep the parts lined up in sub-assemblies so that they go back on the same way they came off. It saves a lot of hunting for parts and a lot of re-work.

My sled has Fox shocks on it, and those need a little extra attention. It was the recommendation at the dealership that they be rebuilt on a yearly basis, though few people did. I have seen the inside of a year old shock that was just full of rust water, and yes, it sure needed attention. On this sled, they still have the same gas that they had when they built it in '94. I am rolling the dice to be sure. Not only could they meltdown/blowout and end a weekend of riding, they are really expensive. They are a nitrogen charged shock with adjustable valving that runs $200-300 to replace. Maintaining them seems to be the better bet. They really take the majority of the beating. They are not something you can do at home. They are charged to like 2000 psi, not something to tinker with at all.

The other thing, and this is really important.. is to make sure that the shafts that get cleaned and greased don't have grease in the bolt holes. These holes and bolts should always be cleaned with a grease free solvent and blown out with compressed air. The only thing that holds these bolts in through all of the pounding is the Loc-tite. Loc-tite does not lock tight when the threads are coated with grease. This is a sure fire way to have a suspension melt down on you if you skip this step. 

I started in the front, pulling the limiter strap, shock and eventually the A arm. I did take pictures so it would all be the same on the way back together. Again, there is nothing fancy here, just basic disassembly.

The back carrier was equally simple, just one bolt at a time until I was down to the rails. I did leave a couple of the cross shafts in between the rails to keep it as a unit, but other than that, it came off of the rails.

I did encounter some problems along the way. One was the track adjusting screws had seized inside the rail. Even my biggest impact couldn't snap it loose, though it did give it a nice twist.

These are an ongoing problem across the brands, and it is just sad. We have sleds that do 120 in 800', but putting a dab of never-seize here is beyond the manufacturers.

I know that the Cats had the riveted on piece available separately (~~$15), but if memory serves me, Polaris had you replace the rail. I could be wrong. These rails have not been otherwise damaged, and if it is only available as an assembly, I will be going with either the cat part or one that I machine. Polaris is still in the dark ages of on-line parts sales, but I looked up the rails on the same year cat, and they were ~$120 each. Not gonna do it..

The other problem I encountered was that most of the wheel bearings were junk. Even after being cleaned out as described in the last report, they were not worth saving. The balls that run in the bearing race had rusted and were pitted. While they would have probably held up a few seasons with repacking, I am not willing to bet valuable trail time on that, or worse, have it come loose and damage the suspension or track.

As we covered in the last update, bearings are cheap if you buy them from the bearing dealer and not the snowmobile dealer. I Iooked up the bearing number on the net, and found the manufacturer store. It has them in 2 or 4 packs for $16 and $30 Canadian, or $10.25 and $19.20 American at this moment's current exchange rates. Compare that to the dealer price of $14.95 each and you understand why I advocate going direct on these. Replacing all 6 is about thirty bucks direct vs $90 at the dealer. I support my dealer, but I like my way $60 better.

Most of us have NTN bearings in our sleds. Some use other brands, but these are the common ones in mine. Identifying your bearing is half of the battle. Sometimes the manufacturer name and part number is lazer cut into the outer race of the bearing, sometimes on the edge, sometimes on the outer diameter. In many cases, it is the name and number on the oil seal as shown below.

On the left, I see that I do indeed have an NTN bearing, on the right I see that it is a 6205LU, a common bearing.

With the exception of servicing the high-end shock absorbers, tearing down a suspension is no big deal, it really isn't. You need to be meticulous about the order of the parts for reassembly, and you need to remember to keep bolts and bolt holes grease free. Beyond that, most of it is cleaning, greasing, and replacement of parts.

As far as specialty tools, I used a snap ring pliers on the wheel bearing circlips and an impact wrench on the bolts. Beyond that, it was basic sockets, hammer, and normal hand tools.

If an ounce of prevention is really worth a pound of cure, an hour in the shop doing preventative maintenance saves 16 hours of trail time missed because the sled is broken..

See you on the trail!


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