How To's  

Retro-Fit an M10 Suspension into a 1998 SKI-DOO Formula 583

02/07/2004

Retro-Fit an M10 Suspension into a 1998 SKI-DOO Formula 583 Deluxe

The purpose of this article is to assist anyone who is planning on installing an M-10 suspension into a Ski-Doo S chassis. The directions sent with your suspension are very detailed and accurate but we at Jere's Repair thought that a little hands on experience might be helpful, besides it gives me a excuse to drop the wrench and pick up my camera while my son Corey is holding the whole suspension up for a photo.

First I would say that this isn't something you would want to attempt if you are not used to a certain amount of fabrication; second it helps to be a little brave with the grinder and drill; and third if your doing this job on your wife’s sled make sure that she’s not around because she’s not going to like the parts falling out of her sled when your getting things out of the way for the new suspension.

Lets start with our 1998 Formula sled.

For the fun of it, you might want to take some measurements off the rear bumper just to compare notes when the job is done. We didn’t see any large amount of rise as far as ride height goes, which is good because this way you don’t knock the geometry out of the front end.

Take note of the position of the old suspension in the sled.

When your M10 is installed things should look real close as far as the position of the rear axle. This is not a big thing unless you mess up on the installation, then your going to have trouble with track adjustment.

Lets get started. You’ll need a hoist to lift the back of the sled and you need to lift most of the weight off the sled and then loosen the rear axle bolts and loosen the track. Then you can go ahead and take the cross shaft bolts out of the suspension. Then raise the sled up so the front cross shaft is below the tunnel and pull the sups. out starting with the front first.

The instructions say you may need to remove some of the material from the old suspension brackets so you can install the new side plates for your M10. Run to the window and make sure your wife’s gone and grind the brackets out completely.

We tried to leave some material because we wanted the support for the running boards but by the time we were done there wasn’t enough left to be of any value, so just cut them out and be done with it.

This is what falls out the bottom when you’re done punching the rivets out. Now you understand why I was looking out for your well being.

When you look up in the tunnel this is what you should see.

We didn’t punch all the rivets out in hopes that some won’t come out only because we didn’t want the holes to show.

Next comes the most important part of the whole project, mounting the side plates Fast sends along a very nice template but be very careful you follow the directions to a tee.

The most important part is the locating of the hole in the front of the template. If you get this the same on both sides of the tunnel you have half the job whipped. Make sure that you cut the axle hole in the template just the way they say or else you will be off on the front hole which will make the suspension set out of line. The template will have to be cut for a round axle on the right side and a hex axle on the left side. Once you’ve got the right side marked for the front hole you will be instructed on how to line up the rear holes. Heres a helpful hint drill a 1/8 hole on your mark in the front and stick a 1/8 drill bit though the plate into the hole and this will hold the plate aligned ( we cheated and used aircraft cleco fasteners). The plate is already drilled for rivets and marking spots. We aligned the taper on the plate with the taper on the tunnel and then used hole( B) instead of (A)

Like the instructions suggest; everything looks a lot neater and its easier to get both sides the same.

The most important thing is that if you make any kind of adjustment to the right side you have to measure to make sure you do it the same to the left.

You’ll notice that the hole (B) comes real close to the running board, it’s an allen bolt so that’s OK. You may have to grind off a couple of rivet heads on the outside of the tunnel so the outside support plate sits flush with the tunnel.

What ever you did on the right side, do it on the left, unless it was a mistake. It's a little tough holding the template into place because you're dealing with a hex shaft. You need to make sure the template is sitting on the hex shaft correctly. When you have marked the front hole on the left double check yourself by measuring from the axle to the hole on both sides and make sure they're both the same. That way you're square in the tunnel and square in the axle. Being square to the axle is more important than the tunnel because you want your track to run even on your skid rails of the suspension. If you just go and hold the left rail in the rear so the taper matches the tunnel taper the way you did on the left side there’s the chance that your front hole could be higher or lower in the tunnel. So before you just assume the tunnel isn’t bent or a little out of square you need to hold the left plate in place and then check the front hole for up and down. I chose to measure from the top of the tunnel down to the front hole on both sides and adjust the left hole to be the same as the right. You probably will be very close; hopefully you won’t need to move the plate down in the back because there isn’t much room for the ( B ) hole and the running board. I would say that if you need to move that far your tunnel's bent and you need to do some body work.

Follow the directions for drilling the front armholes and remember that when you drill the back cross shaft holes your using the (B) position instead of (A). When we started putting in all the pop rivets, after inserting the spacers that they give you, we felt better about using 3/16 pop rivet washers between our rails and the tunnel, without the washers our air riveter would draw the plates in and cause them to bow.

Next step, Let your wife back into the shop because we gone to come out with the pretty pieces now.

You already had to open the box to get the front arms out for measuring up in the tunnel. So now lay everything out so you can see how it goes. There are two different length spacers in the box. Make sure you don’t mix them up, two for the front arms and two for the back upper idler wheels. Short ones in the front.

Don’t tighten down the arm bolts until you’ve got them even with each other by putting them on the floor and holding them in place with your knees while tightened the end bolts.

Don’t hook anything else up at this time. The instructions tell you to install the rear idler wheels but you might as well leave them off because there just going to keep falling off when you put the suspension in the track; and don’t forget your wife’s in the shop so you don’t need a reason to cut loose. Fold the arms like the instructions say, don’t worry it’ll work out

It's now time to install the suspension. Rear wheels go in first and then swing the front end into place.

Not bad at all since I was holding the camera. Now is the part where you’re glad you folded those arms over like the instructions said.

You can put those rear idler wheels on now and the spacers. Check the instructions those wheels have a right and wrong why to go.


Swing the front arm forward.

Then lower the sled down a little so the front arms go up into the holes you drilled when putting the side plates.

The moment of truth, did you or did you not get the holes lined up?

What a relief they fit, go ahead and tightened them up.

Now lower the sled and line the rear cross shaft up with the side plate hole (B) and install and tighten the allen bolt. How many times did the idler wheel spacers fall off?

Time to start hooking things up. Hook the front shock up first. You may have to raise and lower the sled a little, shove a milk crate or 4x4 under the front, but ours went together real easy.

Now hook up the rear shock some, pressure may be required to get the bolt in, but it goes real easy.

OK drop the sled on the floor and wait for the applause.

Looks good,everything moves up and down Ok, no binding.

From here on in it's good to go by the manual. This suspension can be so fine-tuned that it’s going to be different for everyone. Once you’ve made up your mind on what you want for a ride, you can hook the front limiter strap. Lift the sled and slide a block of wood under the track and let the sled down to were you can get enough slack in the strap to put the bolt through, small hands are a help. If that doesn’t work grab the camera, that worked for me.

The one major adjustment on the sled is also the one you will probably experiment the most, but once you’ve got the ride you want you’ll probably leave it alone; and that’s the adjuster bolt on both sides of the skid rail. Basically what this does is change the angle the rear shock sits in the skid rail, and that will change the ride. The steeper the angle, the stiffer the ride. It doesn’t take much to make a big difference.

One thing Fast does is make a very nice guide for you to go by and it is very accurate but this side bolt adjustment is something you can do along side the trail and make your day a whole lot better. (There’s even a couple of handy wrenches that come with the M10 just for the job.)

There are also shock adjustments, which can be made, and the guide goes into detail on those adjustments according to use and weight of the riders. (Hint don’t ask her just guess and set up the best you can.)

Each shock has a pre load adjustment on it, and the rear shock has a bottoming out spring as I call it

.

These can be adjusted separate from the pre load. I don’t think this is going to be something your going to do along the trail.

Put the sled up in the air and adjust the track tension according to the instructions and make sure you track is running straight. Grab the grease gun, give it a few shots, and give a blast down the flat. Pat yourself on the back and quickly throw out the old pieces, cuz' here she comes

Hope we’ve been some help and we'll see you on the trail

Jere and the gang at Jere’s Repair