Shimming Skis, How much is too Much

[provfisherman]

Been reading here about how shimming your skis can help with tracking issues as well as carbide wear. So I have shimmed my skis to address those two issues, but now I am worried that I may have put in too much shim. How do you know if you have shimmed properly?

 

[olivia317]

Been reading here about how shimming your skis can help with tracking issues as well as carbide wear. So I have shimmed my skis to address those two issues, but now I am worried that I may have put in too much shim. How do you know if you have shimmed properly?

1/4" thick piece of aluminum worked perfectly for both Nytros and my RX1 with Apex conversion. Did it with factory skis and Slydogs. Skis should tip up when off the ground. Carbide wear will be very even with a little more on the leading edge.

 

[provfisherman]

Okay Thanks. I do not understand something though. If the skis's tip up when off the ground, how does that make the leading edge of the carbide wear, at that angle, shouldn't the trailing edge wear more?

 

[olivia317]

Okay Thanks. I do not understand something though. If the skis's tip up when off the ground, how does that make the leading edge of the carbide wear, at that angle, shouldn't the trailing edge wear more?

The weight carried by the ski is not balanced front to back. Front of the ski carries significantly more weight. This is what causes your darting/tracking issue. By adding the shim you are effectively stiffening the back half of the ski rubber, thus transferring more weight to the rear of the ski. Too much transfer(too much shim) will cause the ski tip to run so high you will plow through deeper snow instead of float over it. Finding the right "balance" takes some experimenting. More shim results in less steering effort, can literally go no handed on the straightaways, just can't turn. Not good. No shim results in darting and heavy steering effort. All my sleds are shimmed 1/4", this gives me the best performance.

 

[provfisherman]

Okay, I think I get it. From your explanation I likely have too much shim on my unit. Sitting on the ground, the carbide is perfectly flat, but the ski rubber has a very large deflection on the back half, which is the part that makes me nervous. I used a section of a radiator hose as my shimming thinking that by using rubber based, I would gain some 'give' in the shimming. Not sure that is valid, but wanted to try something. My MP is a bear for darting and pushing through corners, so am using shimming as an attempt to alleviate some of that. I made changes/adjustments to the suspension last year and that helped, but still more to do and I was hoping that this shimming would help solve some of that.

 

[olivia317]

Okay, I think I get it. From your explanation I likely have too much shim on my unit. Sitting on the ground, the carbide is perfectly flat, but the ski rubber has a very large deflection on the back half, which is the part that makes me nervous. I used a section of a radiator hose as my shimming thinking that by using rubber based, I would gain some 'give' in the shimming. Not sure that is valid, but wanted to try something. My MP is a bear for darting and pushing through corners, so am using shimming as an attempt to alleviate some of that. I made changes/adjustments to the suspension last year and that helped, but still more to do and I was hoping that this shimming would help solve some of that.

Sounds about right to me. When you lift the sled off the ground the front of the ski should come up first. Shimming is hard on the back half of the ski rubber.

 

[grizztracks]

Didn't the Venture MP come with the dual keel Tuners? The purpose of those skis is to reduce darting. Is the sled studded and how much carbide on the skis? Poor suspension setting can also affect darting. Many Yamaha guys ditch The Tuners due to poor overall performance. If you are running the Tuners I'd replace them with a single keel ski. Yamaha's older single keel skis with shims and StudBoy deuce bars work better than the Tuners. For a MP sled a wider ski like the Curves probably would be a good fit.

 

[provfisherman]

Don't disagree with the wider ski option, but unfortunately, I made a decision when I first bought the unit to install Rollerski wheels to protect my driveway and garage. Those things are ski specific and not too sure if they are available for some of those other skis. Besides, the price of those wheels really makes a change of skis a tough pill to swallow. Kind of stuck with the tuners at this point. Also understand that suspension adjustments have an affect on ski grip and I have done some of that and it helped. No studs and 6" carbide on the inside, 2" carbide on the outside, this also helped. Just trying additional options to get his animal to corner better.

 

[grizztracks]

Have you checked the toe out on the Tuners?

 

[provfisherman]

Yep do it at the start of every season.

 

[trail traveler]

Don't disagree with the wider ski option, but unfortunately, I made a decision when I first bought the unit to install Rollerski wheels to protect my driveway and garage. Those things are ski specific and not too sure if they are available for some of those other skis. Besides, the price of those wheels really makes a change of skis a tough pill to swallow. Kind of stuck with the tuners at this point. Also understand that suspension adjustments have an affect on ski grip and I have done some of that and it helped. No studs and 6" carbide on the inside, 2" carbide on the outside, this also helped. Just trying additional options to get his animal to corner better.

My wife's sled is a 2014 Venture MP that I switched to Curve skis. I wanted to add wheels to protect the carbides when needed. I found that BOP (Barn of Parts) was modifying retractable wheels for the Curve ski. I ordered two sets from him to do the same for the Viper. They were easy to install and I will get to try them out this year. Here's a link to that thread if it helps.
https://ty4stroke.com/threads/retractable-rouski-wheels-on-curve-skis.144297/

 

[provfisherman]

Well thanks for the info, but I am only interested in the Rollerski wheels. Looked at the Rouski ones when I was planning the install and the Qualipieces brand was a better style in my opinion. The Rouski mounts on the ski and without modification such as BoP is doing, they cause the ski to flex. The Quailpieces Rollerski mounts by replacing the ski attaching bolt in the spindle attachment instead of the plastic ski body. I know, not significant, but I prefer solid metal mounting to metal instead of to plastic for things like this. Besides that, changing to a different ski and having to also purchase another set of wheels (regardless of brand) in order to make those skis work with the wheels, just does not make sense somehow. I want to reduce darting etc, but there has to be a simplier way to do it then to start changing skis/wheels.

 

[grizztracks]

I understand that you spent money on those wheels but I always weigh out what's more important and in my opinion handling is way more important than sticking a set of wheels under my skis. You started by saying you have a darting problem and then later stated you want it to corner better. If both are true then you're describing the problems that many have already experienced with the Tuners. If you are set on sticking with the Tuners and want to eliminate most of the darting then slap a set of Snowtrackers on them. It'll help with the darting but will never correct the well documented issues with a dual keel ski design.

(borrowed this picture of the snowtrackers on tuners from another post)

 

[provfisherman]

Well yes both of those things you say are true, I do want to reduce darting and improve cornering, but I am pretty set on sticking with the tuners. With some of the things that have already been mentioned (adjusting suspension, adding carbides, etc.) both the darting and corning has improved, but I am looking to improve those things even more and I am hoping that shimming the skis will help do that. I am not against adding things like snow trackers, but those also have issues that add to the problems (increased steering effort) and therefore I want to try as many other options that I can first before I spend more money on a problem that may not be solvable to the extent that I think it should be. At some point the outcome is no longer justified by the money/effort input and I believe I might be approaching that point. I think that if I can get this shimming thing right (which is why I asked the original question) and possibly fine tune the suspension some more, I might reach that point.

 

[provfisherman]

Like that shop in the picture, but something is wrong with a shop that clean.