Corner weighting and balance of suspension

[Mike P]

Mike P are you concerned with the balance of the sled front to rear? Everyone says the Apex is nose heavy but according to this and if we what a 50/50 (do we want that??) I'm at like 38/62. When standing it goes to 40/60. I was expecting the opposite. I am toying with moving my skid mounting locations forward to help lighten the front but not sure now.

I'm actually not sure what conclusions I can draw here. I have a pile of lightweight parts I was going to install, custom tunnel, and push more weight to the rear, but i'm really torn after seeing these results on what I can actually do. The main issues I have is it trenches, and plows straight in deep snow off trail.

Trail manners are impeccable, I can and have outrun most any other sled in the tight twisty woods with it. Its a Ferrari on trails. Its also a top speed master with the narrow track it REALLY has long legs and will do 150+ on dream meter (like 130ish on radar). I don't really want to wreck any of that.

What would you do with it?

The Apex has always been known as a trail sled and it sounds as tho you have your Apex dialed in pretty good for trail riding. Off trail is another world all together. Different approach to weight transfer, rider position, gearing, clutching as well as suspension travel. The ability for the front end of an Apex to float in deep snow and carve a corner is daunting task, made even more difficult due to the chaise design. They are trail rockets with a design that compliments trail requirements. They are fast at the top end and keep pulling hard with a very tight and short suspension. To convert an Apex to a truly "off trail" "mountain sled" would mean giving up a lot of what keeps her out in front on the trails.

Just my $.02

 

[kinger]

I get that, I'm trying to understand what design makes a good all around set up. What is crazy is that a new Pro in that vid is FRONT heavy without the rider where as the Apex is REAR heavy without the rider. In fact a pro loaded with 200 lb rider is the exact same weight dist as my Apex with no rider. My sled is already where I thought I wanted thinking it would have 60% heavy in the FRONT vs the rear when in fact it appears the apex chassis is pretty well balanced. The rear bias may also explain the freakish top speed of these things in that there is very little pressure on the skis under heavy accel.

So my conclusion is I don't have a weight bias issue, it must be the approach angle that is causing the heavy front and push in deep snow? If not what makes a sled 'pop' up out of the snow?

 

[kinger]

Refining my conclusion more, standing still the Apex is bearing its weight on the REAR not the front, under power the Apex puts MORE of it's weight on the track and not the nose, way more then any other sled, what makes it feel heavy in the nose is the fact that everyone removes the 16" wide track to help sidehilling/carving/etc, this then reduces the 'buoyancy' of the track to support the overall weight of the sled which causes it to 'sink'/trench/etc in the snow giving a false impression that its nose heavy when in fact its rear heavy and you need more flotation?

One fix was to make a shallower approach angle so Drop and Roll the chaincase, this moves the weight bias more to the front and takes the emphasis off the track and suddenly the 15" tracks seem to work better, the trade off is that it makes it steer harder because your turning more weight then you were before the D&R.

Another fix was to remove weight, but the Apex was designed with 'extra' weight in the rear which is why its so easy to drop 80lbs or so from the sled, this however moves the bias to the front, now the sled steers harder, and actually makes handling worse because the sled is too heavy to overcome the new weight bias.

It appears the Apex is a very well balanced machine stock, with stock levels of flotation. Its unnecessary to transfer weight bias with modding, its more important to reduce overall weight and relocate items from front to rear in order to maintain the same percentage split as stock. Take a sq-ft print of the stock maverick and make sure you try to keep the same footprint so if you reduce the sled weight 25% less than stock you could run a 25% smaller track all things being equal.

Now this is all based on my GT stretched to a 151 with a ZX2 rear suspension, I better find a stock MTX to compare!

 

[Mike P]

Refining my conclusion more, standing still the Apex is bearing its weight on the REAR not the front, under power the Apex puts MORE of it's weight on the track and not the nose, way more then any other sled, what makes it feel heavy in the nose is the fact that everyone removes the 16" wide track to help sidehilling/carving/etc, this then reduces the 'buoyancy' of the track to support the overall weight of the sled which causes it to 'sink'/trench/etc in the snow giving a false impression that its nose heavy when in fact its rear heavy and you need more flotation?

One fix was to make a shallower approach angle so Drop and Roll the chaincase, this moves the weight bias more to the front and takes the emphasis off the track and suddenly the 15" tracks seem to work better, the trade off is that it makes it steer harder because your turning more weight then you were before the D&R.

Another fix was to remove weight, but the Apex was designed with 'extra' weight in the rear which is why its so easy to drop 80lbs or so from the sled, this however moves the bias to the front, now the sled steers harder, and actually makes handling worse because the sled is too heavy to overcome the new weight bias.

It appears the Apex is a very well balanced machine stock, with stock levels of flotation. Its unnecessary to transfer weight bias with modding, its more important to reduce overall weight and relocate items from front to rear in order to maintain the same percentage split as stock. Take a sq-ft print of the stock maverick and make sure you try to keep the same footprint so if you reduce the sled weight 25% less than stock you could run a 25% smaller track all things being equal.

Now this is all based on my GT stretched to a 151 with a ZX2 rear suspension, I better find a stock MTX to compare!

There is another issue to consider that can affect the sleds ability to float the front end, suspension design and travel. Imagine taking an RMK and reducing the rear travel by half and then move the engine forward a bit. Then add weight and lower the A-arms. I really love Yamaha. I like 4-stroke power and reliability. My SR Viper RTX-SE can handle trails as good or better than any thing out there. If I need to go off trail to connect with another trail I am aware of her limits. I own three Apexs, all trail rockets out of the box. After getting my Viper dialed in with the turbo I don't ride them any more. The stock suspension on the Viper is Fox-air and I'm not a fan of the feel and ride characteristics of air. There is also the reliability and limitations of the stock shocks. I'm not trying to change the design of the sled by performing on terrain she was never designed to handle, only to compliment and enhance the performance of a the SNO-PRO chaise.
I'm not sure that you will ever be able to effectively convert an Apex chaise to handle off trail or in the mountains to the level of performance your looking for. She was built to harness the power of the R1 motor and rail on the trail.
Imagine a street bike in the woods or on dirt. Mod that bike all you want its still a street bike.

 

[Mike P]

I was looking back thru some old threads and found this one. It may give you some info that could help you with your off trail conversion;

http://ty4stroke.com/threads/super-sleds-skinz-custom-apex-mtx.106096/#post-938796

 

[kinger]

Here is the updated corner balancing of my new sled which started life as a MTX. This is a FULL weight 07 Apex SE with a Impulse race turbo kit on it. Also FULL of fuel which is over 12 gallons on the impulse sleds. You can see it moved the weight bias back 2%. I'm currently converting it to my trail rocket with the parts from my 151 GT that is the first one. I will re-do this a third time after that. I'm hoping I don't remove to much weight off the rear with my lighter suspension, and track. I like that the impluse moves the weight of the fuel behind the rider instead of the stock set up. We shall see!

 

[kinger]

Just to followup in case there are any die hard apex fans out there HAHA. Look at my impulse MTX weight balance after I installed the ZX2, reverse, and small light 151 track. It moved the weight with me on it 6% to the front. crazy. At this point all the weight I am going to reduce needs to come from the front I think. Stock wise it appears the sled likes to carry 2/3 weight on the track and 1/3 on skis.

 

[kinger]

I updated this in my garage section of this forum. Enjoy

https://ty4stroke.com/threads/kingers-boosted-garage.82795/page-23