Baseline for new to me '10 M8 SP

I recently purchased a 2010 M8 SP 153. I'm looking for a good baseline setup for the suspension before I start riding it... I am roughly 225lbs with gear. Sled is all stock except for MBRP can, scratchers, frog skinz and gauge lifter. I'm coming off of a Polaris Gen II SKS and I am not especially familiar with the Cat suspensions...

Currently, the sled has the rear of the skid in the lower mounting hole. Front of the skid is in the stock location. Ski shocks are at 100psi. I'm not sure what the skid shocks are set at. limiter straps are full loose. It currently has wear bars with no carbide.

I've already ordered the 5203 bearing, and fluid for the DD. I'll be pulling that apart for inspection this weekend. I'll also be changing the plugs. I've also ordered an anti-stab kit, I noticed it already has anti-ratchet drivers, I'm not sure if that is stock or not. I'll be checking the track tension and alignment. How loose can I safely run the track with the BDX anti-stab? Is 2.75" of unweighted sag too much?

My riding is a fairly even split between trails and midwest powder. I will bang some ditches from time to time as well...

I know the front shocks are set way too high, I was thinking I would set them to 55 as a starting point, rear shock I was thinking 130. I'll check the front shock preload, but I was thinking of setting the preload at 0 to 1/8". Does this sound like a good overall starting point? Should I leave the rear mount in the lower position, or move it back to stock? Any other suggestions?

Lastly, I will be replacing the wear rods with carbides. My last 5 sleds (Polaris wedges, evos, and Gen II) I ran the standard Bergstrom skegs (not the triple point,) and was very happy with them. I'm also considering Stud Boy shapers or a dually of some kind. I'm not sure how bad these sleds dart on the trails, but that is a concern of mine... What is a good carbide to use with the stock ski? 6 inch or 8 inch?

Any feedback or advice is appreciated!

clutch said:

If it were me I would put the rear arm in the upper hole. In the lower it has way to much weight on the front and you will fight it to handle and get on its edge. Front shock I think I ran about 65 lbs. Front skid shock spring ran about 3/8-1/2 of preload, and rear shock around 145-150. Great sled, they worked pretty good all around. The stock skis dart horribly on the trail. I ran SLP slt skis, but there are lots of options on those. I weigh about 215 in my gear.

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Thanks, sounds like I'm headed in the right direction at least for a starting point...

MI1M600EFI said:

I can suggest a few things based on my '09 Sno Pro... First, pull all four shocks and send them to Andy at Gas Shock Repair. I had him do 2011 valving in mine, but he has a valving package that would probably be better for you at 225lbs. The factory valving was downright awful until 2011, and no amount of air pressure changing will fix it.

I run about 50psi in the right shock and closer to 55 in the left. My sled seems to like it that way... Either there's a little more weight on the left side or my sled is bent... I think the rear is about 120-130 for me, so 150 might be right for a heavier rider. You're heaver than I, so I'd crank up the front a bit. I turn it down for trail to put more weight on the skiis, and crank it up for off- trail to take some weight off.

I detest frogskins. I just pulled them off the HCR that I bought. I think they restrict too much airflow. I've been in powder headlight deep and some gets under the hood, but I've had no ill effects from it. I have a melted oil bottle as proof that the venting is barely adequate in the best of conditions...

I can't comment on anti-stab... Never had an issue. I run the track 1.5-2".

I did the wide bearing 3500 miles ago and haven't had an issue.

These are great sleds!!! Mine has ~5500 miles on it and aside from being on it's second primary, I haven't done much aside from gas, oil, and belts. Probably time to put some carbides on it...

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Thanks for the input. I will probably get the shocks revalved. However, not right now. That's something to do during the off season.

jim said:

Loaded question...depends what you want.

I set mine up for climbing...my goal is to keep the nose down and the sled moving forward in the steeps. I run the rear/rear shock at 160 PSI (very stiff) and the arm in the upper hole (closest to running boards). I run the front/rear shock with minimal preload (seat the spring and turn a few times). And I run the front shocks very low (25 PSI max)...I like the sled to fall over and comply during sidehilling.

My set-up will keep the nose lower when crawling along during a steep sidehill or climb. And it gets up on the snow well. But you will have heavy steering. You want light steering, wheelies and ease of casual riding around, more pressure in front/rear shock and less in the rear/rear. Could it be better, yes. But you get the idea. Depends what you are looking for. There is no "right" set-up for everything.

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Naturally each rider and situation will be different. I was just looking for a starting point that is reasonably balanced. I can and will adjust from there. Due to there being 100psi in the front shocks, my assumption is that the adjustments are way off...

Cat800 said:

“ I'm also considering Stud Boy shapers “

I run these and they make a world of difference on the trail and in heavy snow. It turns better on the trail and does not dart as much.

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Ugh. Not thrilled with the idea of dialing out darting, but it seems to be a common theme.





On a side note, for some reason I thought the 2010 got Float 2s, but now I'm starting to think I'm mistaken? Are the Fett Bros air chamber worthwhile?