Installation and Review: KMOD Gen II Coupling Suspension

[christopher]

After months of patiently waiting 2 large boxes arrived from KMOD that contained all the parts for my new KMOD Gen II Coupling Suspension.


1st box contained the Custom Blue powder-coated Ice Age Rails that KMOD had manufactured for my Nytro.
Packed in the rail box were there Anti-Stab Kit, Ice Scratchers, Billet Two Wheel rear axle, KMOD custom Ice Age rails and all required Ice Age Hardware.

The 2nd box had all the remaining goodies in it.

 

[christopher]

Once I unpacked all the bits and pieces and laid it all out it looked like this.
All of the parts were well wrapped in either Bubble Wrap or Foam wrap to ensure it survives any shipping including his international overseas customers!. Probably fair to say he "overpacks" all of the parts to make sure they arrive clean and unblemished.

The 4 Rail Cross Shafts that secure the two rails parallel to each other.

Front Arm Upper and Rear Arm Upper Cross Shafts that bolt the suspension into the tunnel.
25mm 7075 Aircraft Aluminum (Very Strong) with idler wheel lock collars.

Rear Drop Brackets that rivet and bolt into factory OEM Holes on the tunnel.
These came pre-drilled for the unique geometric mounting of the KMOD Skid.
(this pair came polished to match my particular tunnel)

 

[christopher]

Shock Features

• 100% Billet Aluminum Construction
• 100% High Speed CNC Machined to Exacting Tolerances
• Hard Coat Anodized Aluminum Bodies for Exceptional Wear Resistance
• Highest Quality Synthetic Blended Fluid
• High Strength Delrin Bushings
• Variable Pitch One Piece TRS (Triple Rate Springs)
• Cutting Edge Computer Aided Design Software
• Cutting Edge Fluid and Thermal Dynamic Modeling Software
• Elegant Lightweight Ground Up Design
• Progressive high flow Piston Design
• Low stiction 5/8 Diameter liquid black nitride shafts
• Progressive Valve Codes
• Internal Blow Off Valve
• RAP (Rapid Adjust Preload)
• NEST (Seal Technology)
• APV (Anti Pac Valve)
• TRS (Triple Rate Springs)

The Raptor mono tube front track shock with Triple rate single spring.
Custom Valved and Calibrated for the KMOD coupling suspension.

Raptor 20 position piggy back compression adjustable rear track shock custom build for KMOD suspension.
Dual rate rear spring with RAP (Rapid Adjustable Pre-load)
The dual rate spring offers a very complaint ride on the trial while ramping up for the big hits.
This shock is SUPER ADJUSTABLE with 20 user selectable "Click" dampening position and a nearly infinite pre-load.
THis shock can be dialed in for a 130lb up to a 260lb rider with Big Boost, all in 1 shock/spring combination.

 

[christopher]

Rear Pivot and rear arm cross-sharft assembly.
The KMOD 3-position Coupling Block Assembly.

Lower Shock Mount Cross Shafts with washers and lock collars.

Front lower arm cross shaft with spacers and washers.
Billet Two Wheel rear axle with adjuster blocks.

Equal Length Torque Arms
(these are interchangeable, as the KMOD system uses the same arm in the front and in the rear)

Note:
This photo is slightly distorted from the angle it was shot at.
The arms ARE 100% identical in sizer and shape.

Arctic Cat, new Tri-Hub Dual Wheel rear assembly.
KMOD decided to use this because the Tri-Hub design is considerably stronger than two separate wheels
This style of wheel will stand up much longer to heavy use and abuse! (Tail Landing / Big Hits)

Rear Arm Upper Idler Wheels.

"BEEFY" Limiter Straps

Anti-Stab Kit

New Set of Ice-Age Scratchers included in all KMOD Turn-Key suspensions

Small Bag: KMOD drop bracket mounting hardware.
Large Bag: Ice Age Rail mounting hardware.

 

[christopher]

In leu of the standard White Ice Age Hyfax, I opted to upgrade to a Hyperfax.
So first thing we did was to replace the standard Hyfax that comes with the kit with an upgraded Hyperfax that I picked up from SLP in Idaho Falls.

These Ice Age Rails are custom manufactured just for KMOD.
The arm spacing has been stretched to accommodate the forward arm mounting in the tunnel keeping the rear mount similar to stock.
(KMOD needs this custom rail to allow for their lower ride height and more efficient rate of rear spring)

The Hyperfax slid onto the new rails with ZERO EFFORT.
What a huge change from last summer when I replaced my OEM Hyfax with a new Hyperfax and had to struggle to get them on.
The quality of the custom Ice Age rails was instantly evident as this rail was a perfect match up to the new Hyperfax.

These rails are based on a Polaris Extrusion and require Polaris compatible hyfax.

Kevin getting ready to break off the screw..

NOTE:
I failed to take a photo of Kevin trimming this hyperfax.
He cut the front edge at a 45% angle to accommodate the KMOD Anti-Stab kit.

 

[christopher]

Of course it would be TOO EASY if something didn't go wrong with the install!

So right off the bat the set screw for the Hyperfax broke!
Dang thing snapped clean off.

Set it in the vice and got to work on extracting the screw.

While this would have bothered me, it didn't phase Kevin from KMOD in the least bit.
Just make sure you take a moment and CENTER PUNCH the screw so the drill bit goes directly into the middle of the screw and not off to one side.

In just moments he had drilled out the core of the screw and then extracted the remnants of it.

And installed a significantly better replacement screw from Ice Age that was included with the kit with the original Hyfax.
Should have been smart enough to just use that one from the beginning, but I thought it was best to use the one that came with the Hyperfax instead.

 

[christopher]

With the Hyperfax installed, now it was time to trim it to fit the rails perfectly.
Gotta love a guy who works on a snowmobile with a SAWZALL!!:face-icon-small-hap

His Sawzall makes quick and simple work of fitting this Hyperfax to the Ice Age Rails.

Then out comes the rasp to file it down a bit.

 

[christopher]

With the Hyperfax properly mounted, Kevin installed the two Jounce Bumper stops.

Then bolted the Polaris Tri0Hub rear wheel together on the Billet rear axle.

Mounted the rear axle adjuster for proper track tension.

 

[christopher]

To begin the rail assembly, Kevin first "temporarily" installs one of the shock cross shafts in the front Torque Arm mounting position.
This parallels the rails equally side to side and front to rear.
(This one was only done temporarily to hold the position of the rails parallel so he could then get the Anti-Stab kit installed.)

NOTE:
Its much better if you have a friend to help you hold rear of the rails down and flat on your bench while this shaft is tightened, As it will try to twist!!
This will ensure that you start your rail assembly flat and square for all the subsequent components to be installed properly.

Mounting the front Anti-Stab Kit.
Pay attention while your doing this to KEEP THE RAILS FLAT on the bench.
If one of them begins to LIFT up, your torquing the rails and they will twist and cause great unhappiness <VBG>

After the anti-Stab has been installed and the rails are square / parallel, Keven then removed the temporary cross shaft.

 

[christopher]

NOTE:
Refer to the photos and description of mounting the rear shock for specific details on how the shock goes onto the shaft and is properly centered.
LINK

Assembling from the front to the rear Kevin next installed the front shock mount.
He first installed the Front Shock Cross Shaft with the shock mounted and centered on it.

And i should mention the LOCTITE.
Nearly every bolt on the skid was loctited!

With the anti-stab locked down, and rails parallel, he rotated the front shock backwards (Why you can't see it in this photo) and installed the next Cross Shaft.

Note:
Front Cross Shaft, shock and cross shaft assembly, and front arm assembly were all installed only FINGER TIGHT.
Then, only after all of them were in place did he go back and tighten them down fully (with someone holding the back of the rails down flat on the bench while tightening)

Installing front arm with one aluminum spacer and wear washer on each side of the arm.
This centers the arm properly between the two rails.

I knew there was a reason I bought that air compressor!!
With all the front parts in place and parallel Kevin then tightened everything down.

Installing the shock to arm mounting bolt.

Closeup shot of the Zirk fitting for getting your grease in place.
Kevin told me that in general all the Zirks need to be greased once or twice a year, EXCEPT for the lower rear pivot shaft which should be greased every third or fourth ride.

 

[splaterwin]

So right off the bat the set screw for the Hyperfax broke!
Dang thing snapped clean off.

Exact same thing happened to me installing my Hyperfax bolt. Hyperfax supplies cheap bolts.

 

[Super Sled]

Looks awesome so far, Christopher!

 

[christopher]

Exact same thing happened to me installing my Hyperfax bolt. Hyperfax supplies cheap bolts.

Ya.
I would have to agree with you.
The replacement bolt that Kevin installed was 100% better/stronger.
I would advise AGAINST using the bolts that come with the Hyperfax, while I WOULD strongly recommend using Hyperfax itself!

 

[christopher]

Looks awesome so far, Christopher!

Thanks.
Will get the next round of photos and comments up today.
Just got to late last night to press on.:face-icon-small-hap

 

[christopher]

Next he attached the limiter straps to the front of the suspension.

Based on his own experience with Yamaha Nytros Keven decided to install the limiter strap with a specific amount of length.

Inserted the front arm upper cross shaft, spacer and idler wheels.

Attached the spacer.

Attached the wheels.

Make sure to center the shaft so there is an equal amount of shaft protruding from each side of the lock collar.
Attached the lock collars and inserted the set screw with Medium Strength Blue Loctite.

 

[christopher]

Here Kevin is taking a measurement of the limiter strap adjustment.
Default setting for the Yamaha Nytro is 12.5 inches from the bottom of the rail to the upper arm mounting hole.
This tends to be set in the 12.0 to 12.5 range on most sleds.
It can go as low as 11 or as high as 13 because the front shock allows that much range.

And the front end is done.

 

[christopher]

After a quick test fit of the rear arm, he prepares to insert the rear pivot assembly.

Installing the pivot with spacer and wear washer on each side figer tight.

Removed upper shaft from pivot and preparing to installing the lower rear arm

Installing the rear arm with the shaft previously removed from the pivot now installed in the arm.
(the shaft comes installed in the pivot for ease of shipping purposes only)

Arm properly installed in the Pivot.

This shows the arm camed over backwards which can NEVER actually happen once it has been fully mounted.

 

[christopher]

Installing the shaft in the rear shock with wear washer against shock body and then lock collar against wear washer on both sides.

Measured to ensure the shock was dead center on the mounting shaft

Shock goes in.

And gets bolted into place finger tight.

 

[christopher]

Rear Clicker shock gets bolted to the arm.

This shows the rear pivot arm coupling block assembly.
As the suspension compresses and touches the rear blocks it couples the front and the rear arm together.
They move up and down equally and in unison together.

NOTE
With KMOD's equal length arms the front/rear arm ratio remains consistent.

There are three positions to this 4 sided block.
(2 of the faces of the block are the same, thats what we end up with 3 different settings)

This is a Three position coupling system
#1 Mild, this is the THINNEST of the 3 faces on the block.
Great for general all around riding and most hills.

#2 Medium, this is the middle thickness
Better transfer control than #1, but very boon-docable, with good all around riding.

#3 Extreme, this is the THICKEST of the 3 faces.
Chute climbing with very predictable control for technical maneuvers.

The shaft to the right with the block blocks on it controls the degree of coupling or how fast the system changes over from non-coupled to fully coupled.

 

[christopher]

With the rear arm and shock in place, Kevin moved on to the rear axle next.

He started off by fitting the rear axle adjusting blocks..

Once they were fitted he began grinding off the powder coating for the rear axle as the tolerances would not allow it to fit with the powdercoating still in place.