‘05 IQ 440 Rear Skid Modification

The rear skid on the 2005 IQ 440 has several issues that affect acceleration and resistance to bottoming. These issues can be fixed a number of different ways, the following steps will detail how we relocated the rear skid in the tunnel to improve acceleration and almost eliminate bottoming with almost no adverse effect on steering under power.

The Polaris engineers made drastic changes to the chassis and front suspension of the ’05 IQ 440 and these changes made a huge positive difference on how the race sled performs. The drawback to the front end and chassis changes were less acceleration and less resistance to bottoming in the rear skid. The Engineers made several improvements to the ‘04 skid and they attempted to carry those changes over to the ’05 but because the front end of the ’05 is almost 3” higher directly under the motor this lifted the front of the skid approx 2’ off the ground. From the foot rest rearward, the ’05 & ’04 are almost identical (part # are not the same on many parts because the arms are narrower for the ’05 tunnel) except for one significant difference, there is no lower mounting hole for the front or rear arms of the skid.

Some History:

We received our ’05 IQ’s the second week of Nov. 2004 and within a few days we noticed a huge problem with acceleration and sag in the rear skid. Our ’04 440’s would out accelerate and take big jumps much better than the ‘05’s, it wasn’t even close on acceleration. The IQ would just spin where the ’04 would hook and be gone. And there was a 4” dead space in the top of the rear skid travel on the IQ. Under hard acceleration the front of the track would be about 2” off the ground just spinning like crazy. At first we thought the bottoming was caused by the new W/E shocks , we revalved at least 10 times and tried at least 6 different spring rates, different limiter straps, and all the linkage and coupling options the Polaris skid offers but none of this helped. Anytime you would land off of a huge jump the rear skid would bottom and if you cranked up the spring preload it became just too harsh to ride through the woops.

At the Duluth opener we realized that every Polaris team was being affected by this problem, even the teams with Ohlin, Fox, Axis, Ride FX shocks, all of them. The rear skids were not right. The most apparent thing was how the IQ’s would just get smoked on the start, it was ugly, even the Amsoil boys had not figured out the solution, yet.

When we got back from the opener we were determined to make the rear skid on the ’05 perform like the ’04. We inspected the front arm shock and coupling and compared everything to the ’04 sled. Right away we noticed that the front of the track is about 2” off the ground and during rear skid compression, the front arm shock doesn’t even move until the rear bumper has moved down 4 to 5 inched from the top. On the ’04 the front of the track was on the ground and the front arm shock moved immediately when you push down on the bumper. The first experiment was to put a 2x4 block, on its flat side, under the track just where the rails start to curve up toward the drive shaft. When we pushed down on the rear bumper the front arm shock started compressing immediately and there was no 4’ dead spot where the suspension was soft and useless. The skid felt awesome, no dead zone and you could not get it close to bottoming even with a 300lb man bouncing on it.

The first thing we tried was shortening the front suspension shocks by 1.25”. This lowered the front of the skid and improved the front arm shock performance but there was still about 1.5” of dead spot in the rear. Plus this affected the front suspension performance. When we shortened the front shocks by 1.75” the skid performed awesome. The ‘05’s would accelerate just as hard as the ’04 and you could land from a 100’ jump 25’ in the air without hard bottoming the rear. But the front end on the IQ was not the same and it would bottom hard, even after revalving several times, we broke a few A-arms and decided that was not the proper fix. We felt we had to do one of two things, have custom built rails made (not legal in pro stock racing) or relocate the rear skid mounting positions. We tried several versions of the skid relocation and this is what we found to work best. The revised skid mounting position does increase the rolling resistance of the sled because of the increased angle of attack on the track but the acceleration and anti bottoming were well worth the tradeoff.

Experiment with different thicknesses of blocks under the front of the track and see how they affect the way the skid responds to pushing down on the bumper. After we completed this modification we had to soften shock valving and spring rate on a few of our IQ’s because both shocks are now working together. Some of our competitors on IQ’s did not think they had a problem with the rear skid. Once they rode one of our IQ’s they would immediately realize the potential of the sled and bring theirs by for the modification.

It may not be for you but if you want to get rid of the dead spot in the rear suspension and improve acceleration then you might consider this modification. If you experiment with blocks under your track and do not like how it affects the suspension then you will not like how your suspension performs if you make this modification.

Now, what you have all been waiting for. I wasn’t going to just give you the solution without making you read my long winded dissertation above. HaHa.

1. Remove the rear skid and set aside.
2. Look inside the tunnel and see the Pilot Holes or Dimples the Factory provided to move the skid to a new location.
3. Drill a new 7/16” hole directly below the stock holes.

Note: Basically you are lowering the front mounting hole .3/4” but the distance between the front and rear mounting holes must remain exactly the same as original or the skid will not perform correctly. Now use a snap punch or some form of centering punch to mark your new mounting hole.

4. Use a sharp pilot bit and drill a pilot hole for the new mounting position. I prefer a sharp 3/16” pilot hole for this application. The key is sharp because the bit cannot wander, if it does then you may have problems.
5. Next, use a sharp 7/16” bit to drill the front mounting hole to its final size. Do not allow the bit to jump around or the hole will be slightly out of round and prone to wallering out.
6. Now repeat steps 2 through 7 on the other side.

The rear mounting hole does not change.

Note: There will be just about a ½” of space between the original and the new mounting hole, I know this sounds close and you may be concerned that the lower hole will hammer out and crack into the upper hole but this did not happen on any of the sleds we modified. During suspension compression, the torque of the front arm is actually trying to move the arm forward more than it is up. If you are concerned with the close location of the new mounting hole and want to see where it will be, before you drill, then after you make your final mark, like in Step 5, use the 7/16” washer and center it up on your mark. Use a black magic marker and color the tunnel using the washer as your template, this will show you exactly where the new mounting hole will be. One thing to keep in mind, the skid mounting bolts must be checked for tightness after each heat and quite often during practice, but this is true on most of the suspension bolts and regardless of whether this modification is done or not. Just ask anyone who has had a suspension bolt come loose.

Also, NEVER turn the skid front mounting bolts around where the nut is facing outward toward the footwell. The shoulder of the stock bolt is not long enough and the threads of the bolt will wear against the mounting hole in the tunnel and woller the hole out bigtime, not to mention wear a hole in your nice riding boots. AN bolts eliminate this problem and we replace almost every suspension bolt with the proper AN bolt but it is not necessary for this modification.

Ok, That is all for the front mounting hole and once the skid is out this procedure should take about 20 minutes.

Next, the more difficult part, and when I describe these steps you will think that the rails may become prone to breakage but we did not have one rail failure on any of the sleds we modified.

Note: The rear skid of the ’05 IQ fits tight in the tunnel and when delivered from the factory the track was pretty tight even with the rear axle in its most forward position (with the track adjuster bolts loosened up all the way). Because of this tight fit, the rear axle and track adjuster assembly has to be relocated approximately 1” forward. If you have a really stretched track and there is more than an inch of forward axle movement available, then you may not need to perform this modification. If your track is already stretched, then put the skid back in the tunnel and use the new lower front mounting holes. If you have trouble getting the rear torque link bolts (rear skid mounting bolts) back in then your axle is not forward enough and you will need to modify the rails. With the skid in and the track adjusted roll the sled to a normal riding position on a flat level surface. The front of the track should be 1.5” lower, almost touching the ground. If it is not then lay down and look at the limiter straps, there should be no slack in the straps, if there is slack in the limiter straps then your track is too tight. If the straps are tight then remove the strap bolts and see if the front of the rails drop down. The limiter straps should not be tight and they should not have slack in them, they should just limit the front arm shock from topping out at full extension. We ran 2 sleds with no limiter straps, and they performed perfectly but there is risk of front arm shock damage if you choose to not run limiter straps. The shock tops out and the top washer on the compression stack tries to beat itself into the threaded cap of the shock. We used a different top washer on the compression stack on the sleds that we removed the limiters. You need to know what you are doing, and you need to service the shock regularly if you chose to eliminate the limiter strap, the shock will try to beat itself apart from inside if not maintained properly.

Here are the steps if you need to relocate the rear axle. The rear axle needs to be moved approximately 1” forward, maybe a little bit less.

1. Remove the rear axle assembly and place all parts back together to the side.
2. Remove the rear scissor stop and place it back in the front hole but do not tighten it up completely.
3. Remove the axle adjuster assemblies from the rails and put off to the side. You will have to drill out the factory rivets to get the adjustor blocks off. Use a sharp bit and a centering punch, you will damage the adjuster if you get off center.
4. Now, reinstall the rear axle with only the two inner wheels and the aluminum spacer. Leave out the two black plastic spacer blocks and the washers on the inside of the axles. Place the black plastic adjuster blocks on the outside of the rails but leave off the outer wheels and there is no need to tighten anything up.
5. Push the axle forward until the two wheels hit the aluminum scissor stop. Push the plastic adjusters into place and use a Sharpie to mark on the rail where the axle slot in the rail will have to be enlarged (enlarged forward only). The black plastic adjuster blocks have a 3/16” reveal on the inside that fit into the slot in the rail and you will need to use the reveal as your template. This it the material on the rail that must be removed so the axle can be relocated forward. Mark both rails in this fashion.
6. Remove the axle assy. and put it aside. You should make sure you get all the wheels, spacers and washers in the right position if you do not already have that memorized from previous axle removals.
7. Use a die grinder, cut off wheel, Sawsall, Recip saw, air powered hack saw or what ever you are comfortable with to remove the material in the rail where you made your marks. Keep in mind that the adjuster block needs to fit in this space and only remove enough material to allow the block to fit in snugly just like the factory slot. We found a sawsall or air powered hack saw would work perfectly and it took only about 5 to 8 minutes per rail after the first few times. Use a die grinder to remove the extra material within your marks.
8. After you have removed this material from the rail place the adjuster block in the slot and make sure it is not binding.
9. Use a file to clean up any sharp edges or burrs on the slot in the rail, these act as stress risers and can cause premature failure of the rail.
10. Repeat this procedure to both rails.
11. Now reinstall the entire axel assy. with all wheels, blocks, washers and spacers. Leave the axle loose and push the axle forward. The inner two wheels should just barely touch the rear scissor stop.
12. Now look at the rear axle from the side and see the end of the rail. See that it extends past the diameter of the wheel just a little, use the sharpie or a magic marker and blacken the rail where it extends past the wheel. This will have to be removed by grinding or a saw.
13. Now take the outer two wheels off and with the axle in its forward most position place the threaded aluminum adjuster blocks back in place and mark their new mounting position.
14. Mark where the two new holes will need to be drilled to mount the aluminum adjuster block. This should be about 1” toward the front of the rail from the old holes. Repeat on both rails.
15. Drill the new holes with a sharp ¼” bit. Repeat on both rails
16. Mount the aluminum adjusters back to the rail in the new holes using the proper length ¼” AN bolt and Nylock. If you know how to use aircraft rivets then you can use them instead of AN bolts but do not us just a Grade 8 ¼” bolt, the threads on the shank will eat into the rail and cause problems in the future. Repeat on both rails.
17. Next reassemble the rear axle and tighten the aluminum rear scissor stop.
18. The skid is ready to go back into the tunnel.

When you get the skid back in the tunnel refer to the Note: above about limiter strap adjustment.

I am sure you are thinking this is a very difficult procedure but it is really very simple and can be performed with simple tools in about 2 hours. Every IQ that we modified needed the axle relocated for the skid relocation to work properly. The only parts you have to buy is four ¼” AN bolts, nuts and washers, they can be found at any aircraft parts stores for under $4.

One more time, if you want to get rid of the 4 to 5 inch dead spot in your rear suspension this is one easy way to fix it. If you aren’t sure what I am talking about “dead spot” then place a 2x4 under the front of your track like described above and push down on the bumper. As a result of lowering the front of the track there is more track on the ground and the IQ can finally accelerate like it should, everything is not trying to rotate to the back half of the track. A stock Cat or Doo will smoke an IQ out of the hole until you get the track on the ground. There are other ways to get the front of the track on the ground but they have serious effects on big jump performance.

This procedure is very long winded but it is free, we are just trying to get as many red sleds to the winners circle as we can no matter who is riding them.

Good Luck

If you have any questions or comments please send me an e-mail to  info@akracing.com