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Handling Upgrade: Convert your ProCross Skidframe to 2016 Specs


(11/16/2015)

2016 Arctic Cat CrossTrek displaying the flat cornering prowess.

Sometimes it’s the little things that produce big results.

Arctic Cat suspension engineers proved this old axiom with a couple small calibration changes on the rear suspension of 2016 129- and 137-in. trail sleds that impressed me and other snowmobile journalists who rode these machines.

The change: a new dual-rate spring for the front track shock on 129- and 137-in. models, plus new rear torsion springs for the 137-in. models.

The result: Improved cornering precision and suppler comfort over trail chop.

The upshot: it’s change(s) anyone can make on their previous model year ProCross sleds.

In talking with engineers Brian Dick and Jeff Olson, the spring change(s) for 2016 were the result of an ongoing process to improve the cornering and handling prowess of the ZR line. Feedback from some Arctic Cat customers as well as their own considerable seat time on these machines indicated that, for riding trails with lots of corners, there was a desire for more aggressive carving and less tendency for inside ski lift.

 

New dual-rate front track shock springs for Arctic Cat snowmobiles.

Their solution was a new dual-rate coil spring for the front arm shock of the SLIDE-ACTION skidframe. A new 55/250-lb. rate spring (shown at right) on 2-stroke models replaces the previous 90/250-lb. spring on 129-in. 2-strokes and 110-lb. spring on 137-in. 2-strokes.

For 4-stroke models, a change to the 90/250-lb. spring (left, above) for 2016 replaces the previous straight 135-lb. spring on both 129- and 137-in. models.

The lower rate portion of the new dual-rate springs provide more sit-in compression of the front shock, which results in more ski pressure and flatter cornering. Likewise, the lower rate portion of the spring means softer initial compression when hitting light chop on the trails, literally “taking the edge off” of small bumps.

Once the front arm shock uses the first 1.75 to 2.5 in. of travel (depending on the spring), the low rate portion of the spring collapses and the rate effectively becomes 205 lbs. 250 lbs. according to Olson. So the stiffer portion of travel remains for hitting the big stuff and/or using the full range of the shock travel.

A complementary change on the rear arm of 137-in. machines comes in the form of lower rate torsion springs for the rear suspension arm. The new springs require 16.5 lbs. of force per degree of movement, compared to 18.5 lbs. on the previous springs. The compression valving was also lightened on the rear shock to better match the revised spring rate.

 

Arctic Cat engineer Jeff Olson working on 2016 rear suspension.

I’m one of those riders who prefers when my sled delivers aggressive cornering with the skis planted on the snow. Over the years of riding various ProCross machines, I’ve found THESE tailored set-ups deliver the kind of handling I prefer. The new spring changes for 2016 make a significant improvement for riders like me, probably as much an upgrade as the setup modifications mentioned in that story. I HIGHLY recommend it.

If you’re looking for a similar change on your machine, these are bolt-on changes that require about an hour or so of shop time, and that don’t cost an arm or a leg.

 

Arctic Cat engineer Jeff Olson working on 2016 rear suspension.

What you need:

The 55/250-lb. front shock spring for 129- and 137-in. skidframes on 2-stroke models is part number 2704-927. Cost is about $35 U.S. from your local dealer.

The 90/250-lb. front shock spring for 129- and 137-in. skidframes on 4-stroke models is part number 1704-736. Cost is about $35 U.S. from your local dealer.

To update the lighter rear torsion springs on 137-in. skidframes, you need both Right Side (P/N 2704-026) and Left Side (P/N 2704-027) springs, each about $55. Getting the new lighter valve code isn’t necessary, but it’s worth doing the next time you get your shocks serviced. 

Note: when changing to the new front shock spring, be sure to set the spring retaining clip so there’s only .05-.10-in. of preload on the spring when the shock is fully extended. Once installed on the front arm with the limiter straps in place, the shock will compress slighty to give a tad bit more spring preload.

If you’re like me and planning to run this setup for this coming season, I’d appreciate hearing back from you about the results.

 

UPDATED 11-19-15: Below are the springs that came stock on previous years' ProCross machines:

2012 - 129” 2- & 4-Stroke Front Arm Spring was 90/250 Lb. 1704-736.

2013 - 129” 2- & 4-Stroke Front Arm Spring was 90/250 Lb. 1704-736.

 

2014 - 129” 2-Stroke Front Arm Spring was 90/250 Lb. 1704-736.

2014 - 129” 4-Stroke Front Arm Spring was 135 Lb. 1704-461.

2014 - 137” 2- & 4-Stroke Front Arm Spring was 135 Lb. 1704-461.

 

2015 - 129” 2-Stroke Front Arm Spring was 90/250 Lb. 1704-736.

2015 - 129” 4-Stroke Front Arm Spring was 135 Lb. 1704-461.

2015 - 137” 2- & 4-Stroke Front Arm Spring was 135 Lb. 1704-461.

 

2016 - 129” 2-Stroke Front Arm Spring is 55/250 Lb. 2704-927.

2016 - 129” 4-Stroke Front Arm Spring is 135 Lb. 1704-461.

2016 - 137” 2- & 4-Stroke Front Arm Spring is 90/250 1704-736.

 

Thanks for reading. And happy cornering.

Flat cornering on a 2016 Arctic Cat ZR.



Comments (30):

yamahabandit says:
11/16/2015 9:38:00 PM

Sounds to me,that the Procross will be dialed in close to perfect just in time to be replaced by the next generation chassis.
Very good article as usual John.
John Sandberg says:
11/17/2015 8:07:00 AM

Thanks Bandit.

An observation I heard 20 years ago by uber snowmobile industry guy Greg Marier, and that I've parroted ever since because of it's astute accuracy: The best model year of any particular snowmobile is its last, because all of the bugs have been worked out of it.
Greg says:
11/17/2015 1:43:00 PM

John-
and here I thought you weren't listening ...

Keep up the great work at Arctic Insider!

Greg
MNCAT says:
11/17/2015 1:44:00 PM

Jon,
Could you please clarify this...

"Once the front arm shock uses the first 1.75 in. of travel, the low rate portion of the spring collapses and the rate effectively becomes 205 lbs. for 2-strokes"

I assume this is just a typo. Did you mean to say it will be 250lb/in and not 205?

Thank you,
taperk600 says:
11/17/2015 4:57:00 PM

John..... as true as Greg's statement you mention above is..... (and I fully agree with it) .... you should be careful saying stuff like that (" The best model year of any particular snowmobile is its last") as you KNOW someone will read too much into it and next thing you know, people will think that you are confirming that this is the last model year for the ProCross chassis as we know it....... a little stirring of the pot, and WHAM... John at AI said it's so, AND he must know something the rest of us don't. A new chassis IS coming for 2017..... can just hear it now !!! LOL !!!

I agree with the change Cat is making to help plant the front ends. I've been lowering the initial rates on my ProCross sleds with great results. Maybe I should ride my LTD at bit the winter BEFORE tearing out all the QS3 shocks and replacing them like planned......
Cannondale27 says:
11/17/2015 5:41:00 PM

Maybe if you guys would get the rebound right in the rear shock you wouldnt need to be messing with springs?
easyrider says:
11/17/2015 9:03:00 PM

Is it being suggested that these spring changes could also be done in the rear skid of an RR?
Rob says:
11/17/2015 9:03:00 PM

The 12-13's turbos already have the 1704-736 spring.
John Sandberg says:
11/18/2015 7:47:00 AM

MN CAT: Yep, it was a typo. Fixed. Thanks for noticing.

taperk600: My comment about last models years being the best is truly not a hint, only an observation that I wholeheartedly agree with. Scientific studies have shown that second-to-last model years are just 3.37% less great than final model years. Third-to-last model years are 7% less great. Or something like that.

easyrider: No, these front arm springs will not work on the RR models because they will interfere with the remote reservoirs. The spec on the 2016 RR model springs is 100/250 lbs., with a transition at 1.55 in. They are a narrower outer diameter to stay clear of the reservoir.

Greg: I always listened to you (except for those times when you told me to ride sensibly).
taperk600 says:
11/18/2015 6:10:00 PM

John.... I completely agree also..... the last of any series of sleds is the best ! Simply saying "SOME" might stir the pot and run with that.
Todd U says:
11/19/2015 7:30:00 AM

The 2012 1100 N/A already has the 1704-736 set-up....
TD Max says:
11/19/2015 8:49:00 AM

"The spec on the 2016 RR model springs is 100/250 lbs., with a transition at 1.55 in. They are a narrower outer diameter to stay clear of the reservoir."

How does this compare to the 2015 RR? I believe we have the same 100/250 rate, but the length of the low rate portion seems very short and tightly gapped.
Paul Hein says:
11/19/2015 12:59:00 PM

John, on the preload, .05" - .10" , that's really not much. Do you just tighten the retainer until it contacts the spring and then a hair more ? Hard to measure huh ? This is one of the first things I've done to all new Arctic Cats I've owned. Loosen that front shock spring as much as you can.
Sounds like something I'll be doing but it'll have to wait until I pull the shocks for service. ; )
John Sandberg says:
11/19/2015 1:56:00 PM

All: There were a few statements and questions about which springs came standard on previous years' ProCross sleds. I've updated the end of the story to show what they came equipped with from the factory.

Paul: Yeah, you basically put only enough preload on for the spring retainer to do its job, because when you install the shock and limiter straps, the shock will compress some and effectively create more preload.

I personally back off the preload no matter where I have the limiter straps set to, because I think cornering and small-bump compliance is better with light preload on the front arm.
John Sandberg says:
11/19/2015 1:58:00 PM

TD MAX: You are correct, both model years come with 100/250 springs. The '15s came with P/N 2704-228 while the '16s come with P/N 2704-755. Different wind to the spring.
Darin Meacham says:
11/19/2015 5:14:00 PM

When I look up the specs for the spring It has a larger diameter than the stock spring the stock spring has a inside diameter of 1.870" the spring with part number 1704-735 inside diameter of 2.33 "
Darin Meacham says:
11/19/2015 5:16:00 PM

sorry 1704-736
bkf_2013RR says:
11/19/2015 8:53:00 PM

Sounds like a good simple handling setup...think I will give it a try
I Bleed Green! says:
11/20/2015 4:00:00 PM

It is nice to see that team arctic is still continually improving these machines. I don't believe the procross / proclimb is going anywhere soon, they may give facelifts, new and different power options, and evolvement in aspects of the machines, but the basic chassis is solid. I would imagine changes to the mountain sleds would come first. Great info as usual John.

Let it Snow!
Don H says:
11/21/2015 7:06:00 PM

John....You listed the 2015 and 2016 129” 4-Stroke Front Arm Spring as the 135 Lb. 1704-461. Would you recommend trying the 90/250 Lb. 1704-736 on a 2015 129" 4 stroke? Thanks!
Aaron says:
12/1/2015 12:43:00 PM

Go figure 2704-927 is back ordered till February
TD Max says:
12/3/2015 8:23:00 AM


My 2015 Viper RTX LE (129 4 stroke) is essentially the RR sled and has the dual rate coil in it over a Fox Zero pro (upgraded to DSC) so I can only assume that it is this one:

2015 - 129” 2-Stroke Front Arm Spring was 90/250 Lb. 1704-736

It works well FYI.

TD Max says:
12/3/2015 8:28:00 AM

I just wanted to elaborate on what Cannondale said about the rebound. I have the RR shock pkg and the rear rebound adjuster along with the crappy Yamaha tuner skis. The sled pushed like crazy when I had my rebound set up tight the way that I liked it. At Cannondale's suggestion I opened it up and I could not believe the difference in handling. I now have Curve skis which are much more positive so I can start to experiment with tightening the rebound up a touch and see if I like it.
R Hillman says:
1/6/2016 12:16:00 PM

I have the stock spring # 1704-736 in my '15 el tigre' 8000, it is loosen by 3/4's of a turn from stock. I'm a big guy, (250) should I stay with the stock spring? or would this 16' spring still be an improvement? I had the front Fox floats re-valved by Fett Bros. for a softer ride recently.
thanks for an interesting article
Jason says:
1/30/2016 9:57:00 PM

Just did this upgrade to my 14 SR Viper. What a pain in the ass. The upper idlers are pressed on the shafts which turned a simple fun project miserable without the special puller that you need I guess. Managed to remove the snap ring and get the plastic wheel off the bearing, then pull the bearing with a regular puller. Not impressed. Sanded the paint off the shaft so the bearing slides on with a lot less interference. Had some trouble getting the two rear bolts lined up, but eventually got it. Anyway, it's done now but and I can't wait to try it when we get more snow. The original springs were quite stiff. Now I have a couple inches of "sit in" which I am happy about.
Trose168 says:
2/3/2016 3:10:00 PM

Is it important to revolve or is it not necessary. If so what should be done to the front and rear shock.
Eric Duchesne says:
9/15/2016 7:11:00 PM

I, could you tell me why in 2017, in the parts catalog of an Arctic Cat XF7000 cross-trek they came back whit the old parts number 1704-236 insted of 1704-736 (2016 model). Regards'
Michael says:
2/6/2017 8:47:00 AM

Hi I was wondering if this setup will work for my 2014 yamaha sr viper ltx 137. I am about 350lb and I'm shure my toungh bage and gear weigh another 20 lb at leas. I have a hevery single rate spring about 200lb in the center curentry.I find the sled to ride pritty heard and push the corners a lot. But when I ride hard through lots of molgales it sakes it up pritty good. I'm loking for more of a big comfortable couch ride when riding easy but still soke up the big ones when riding more agresavley. Any help would be awesome thanks for your time.
Kevin Seery says:
3/9/2017 8:58:00 AM

Hi I have a 15 ZR8000LXR 475miles. My ride weight is 265. My stock suspension is turned up all the way and still bottoms bad on the rough trails. Arctic Cat has a heaver torsion springs #2704-560 to replace my #1704-576 stock springs. With that said;

I have a question to you about this progressive front track spring. Because of my weight would I be better off upgrading my spring to the 90/250 4-stroke spring even though I have an 800 two -stroke?

Thanks Pa- Kevin
Rob says:
12/1/2017 6:23:00 PM

I just had this installed on my 2014 SR Viper LTX SE. The sled is in the garage and it seems stiffer than before. Any thoughts?

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