Drop and or FORWARD roll?

[kinger]

Hi guys, posting this in nytro mtx because it seems to be the fabricators hang out. I am thinking about a new chassis for my apex and have been toying with eliminating the front bulkhead cooler. I am thinking of doing the opposite of a traditional drop and roll where you drop the chain case and roll it backwards, which forces your rear suspension backwards and makes the front heavy.

Instead I would possibly just drop it, or just roll it FORWARD bringing the suspension forward to make the front end light and control that with my coupling and limit strap on the skid, or do both a drop and a forward roll. I would like to get the approach angle down to that 18-20 degrees area but more importantly move the center of mass closer to the center of gravity and make the sled more rear biased. With the 151 ZX2 at full transfer I can only get about 3-4" of ski lift vs when it was a 121 I could almost wheelie it backwards. It also trenches which may be in part to my narrow track. The goals here would be to allow it to feel more balanced and lighter steering. It would be a crossover sled so I could adjust the pins on the ZX2 for Iowa ditch riding (ie skis in the air and light flickable feeling, or dial it back to trail where I get good steering traction for icy corners.
Any thoughts or negatives to this that anyone sees?

Thank you!

 

[Off Trail Mike]

Kinger:

I really like ur thinking. The biggest issue with heavy front ends on Nytro/Viper is the inability to move the engine any closer to the drive sprockets due to cooler and electric starter motor so mass centering is rather limited. Getting rid of the cooler improves this and also allows u to run a taller lug track which would be more fun to drive IMO.

The big issue is the bulkheads....which you would have to create from scratch, but I think you'd end up with a much better handling sled.... Taller lug, shallower approach angle and more central mass....win,win,win!!!

Now if you could figure out how to relocate the sh*tty starter location from behind the engine and move it up front like every other sled, then you'd probably have a real game changer on ur hands.

My 2 cents.

OTM

 

[kinger]

Thanks OTM! I was wondering if I was crazy or not. The starter is a good point on the nytro, on the apex its in front

Either way at least on the apex the chain case is facing the rear, even rolling it forward with no drop will move the DS forward 1-2" and down probably 1/2-3/4" This might be enough without having to worry about the starter. I suppose if you go to far it wouldn't steer unless you really played with the rear suspension coupling and limit strap.

 

[Off Trail Mike]

Wow.....had no idea the Apex starter was forward!!! Explains a lot when riding those two sleds. BTW.... still think you're crazy attempting this build but that's what the fun is all about. These old sleds are simply templates....maybe 70% complete....you just add mods to make it 100% ur sled and that's it.

Best of Luck

OTM

 

[Sportsterdanne]

I think you are going in the right direction.
On my build i installed the front clip to get the spindles at the same distance from the driveshaft as a Nytro with skinz forward a-arms. But i moved a 155 skid to the rear to fit a 162 track and that kind of counteracts the forward spindles a bit and gives a longer "wheelbase" in total.
I think Polaris driveshaft to skid geometry looks the best with the rails so far forward that they pass just in front of the outer track drivers when compressing the front of the skid, one negative thing is that they cant use regular anti ratchet drivers and have to use two regular drivers and a center anti ratchet driver.

My future build will copy pro RMK geometry eventually with spindles a bit forward (like skinz polaris a-arms).

I have been looking a bit at the starter as a limiting factor at engine placement on the Nytro, and if i remember right you would have to put the engine more vertical to move it closer to the front of the tunnel if the starter wasnt there, and that might not be better, i dont know.

I have heard a theory about the Apex engine - The crank turns opposite of the clutch due to the reduction gearing and that may cancel out a bit of the gyro effect. I have not ridden a Apex but some people say its easier to throw around than the Nytro.

 

[kinger]

I think Polaris driveshaft to skid geometry looks the best with the rails so far forward that they pass just in front of the outer track drivers when compressing the front of the skid, one negative thing is that they cant use regular anti ratchet drivers and have to use two regular drivers and a center anti ratchet driver.

This makes so much more sense to me now! I was always wondering why in the heck they did that. As I get smarter on chassis geometry I see what they are doing. Thanks for that! I think this give me enough to play with on CAD now. Just wanted to make sure I wasn't crazy. It seem the problem with the nytros is starter is in the rear, apex fixes that but the apex motor is TIGHT to the rear cooler, so we can't go forward with out removing that.

OTM I think it would be crazy to modify the entire chassis, that is something I wont do BUT if I could sneak the drive shaft forward and or drop it, than build my plate tunnel idea I can shave weight and move the Cof G closer to the C of M. I think that is a win win but it feels like there is more to it than that. This is primarily a trail sled so I need to compromise and get something so it steers but also is nimble in the Iowa ditches.