Rear suspension

[Studroes144]

Just got around to pulling my rear shock out to get sent out. For those that didn't catch the topics early in the season I installed softer cat torsion springs on my ltx se because I was experiencing a very harsh ride. With stock springs and me on the sled (230lbs) I had zero sag in the rear suspension. Finally with softer torsions I was able to get two inches of sag with we on the sled. As soon as I got off it would rebound the shocks back all the way. Around 1800 miles my center shock blew out. Sent it to Ian at monster performance here in NY. He is great to deal with and VERY knowledgable about these sleds and how the suspension works. Got the shock back from getting revalved softer and rebuilt. He said it was in terrible shape and there were a lot of worn parts and major signs of moisture in the shock. Anyways I got the shock back on and could instantly tell it was much softer and could tell the suspension was actually working some now. Now I say it was better, which it was, but still far from a plush ride. My rear shock since day one has had a bit of a chuck in the shaft. I could notice this when I pushed down on the rear of the sled and then released and put pressure down again right away..almost as if I were simulating ride fast over little choppys. The play in the shaft was very noticeable! That last few rides of the season I had my dad ride mine and I'd ride beside him and watch how the suspension moved and you could tell there was some movement on the front skid shock but it seemed as tho the rear shock was just drastically holding back the skid from having any suspension travel. I know YamahaTim has mentioned the same exact issue with his ltx se. Well just pulled the rear shock out and it is just like my front one was. It is so stiff that even with all my force I can't get it to come close to fully collapsing..rebound is also very slow. I can get the shock compressed maybe 2-3" at most and it takes 10-15 seconds to fully rebound back. Now with the sled sitting flat on the ground..keep in mind I have softer torsion springs on and the rear shock is out. With no rider the sled has 1 inch sag which is basically how it should be. When I get on the sled it will sag roughly 2 inches still. This is with both torsions on softest setting and no rear shock in. This is more the less just informational for the guys getting the 2015 sleds and those complaining of a harsh ride with your 14s. I got 2300 miles on a pretty harsh riding viper. Granted, this sled riding harsh is still far more fun than my old apex, but I can't wait for snow next year and to actually have this suspension working right. Anyone that is buying a 15 viper and concerned about a stiff ride..I highly recommend that as soon as you get your sled, pull your rear shocks out and send them to a pro that has experience with this chassis and shocks and have them set them up properly for you cuz they are extremely stiff and the sled will ride you all winter long. Hope this can be of some good info to the up and comers with the new vipers. Oh and just for the record..if you send your shocks out when they are new and have them valved softer you should be able to get a real good setup for $150-$200 for both rear shocks..if you wait until they blow out..believe me it gets more pricey lol.

 

[cannondale27]

Yes I don't know why they basically removed all sag from the sled. It's hard to compare the ltx to anything else since it is a new length but if looking at the Rtx,standard and a 2012 cat the differences are huge. Even rebound which you would think should be same or maybe a bit faster on a Rtx is actually slower. Makes me believe they messed up.

 

[Studroes144]

Yes I do have to think it is a mess up. I drove and rtx se this winter for like 2 miles and it felt much much more plush than mine. Also the base ltx I've driven a few times drove much nicer than my ltx se. And I've talked with some guys riding the new 137" procross..both cat and yammi guys and they don't have any complaint on rear suspension but some guys do have complaints. Seems as tho the shocks are just very inconsistent. I've driven a 2012 f800 snopro and a 2013 1100turbo snopro and they both ride beautiful for me. Seems that cat has it pretty well figured out with the shocks. Hopefully yammi can learn a lot from this first year in the suspension department

 

[vsmpowered]

Roes How much sag those cats have compare to yamaha?

 

[weasel33]

Thanks for the good info 144. My nytro was the exact same way, I could jump on the back end of my sled and could not get it to compress one inch. Even when I went to the 15 sneak peek show those sleds were the exact same way, no sag at all with me ( I'm around 190 lbs. ) on them. My brother who tilts the scale at 240 lbs only got around a half an inch sag. So before my rtx le sees any snow it will be revalved and softened, and I also bought a set of custom axis triple rate duel compression and rebound coil over shocks for the front if I can't get the fox rc2 to perform the way I want. The best part of it all is that the guy I met and will be riding with is a shock guy from Penske ( parent company of custom axis ) who has a place in New York and will do the fine tuning of the shocks after he does the revalve. Maybe we could meet up in New York sometime and ride together.

 

[Studroes144]

Roes How much sag those cats have compare to yamaha?

I honestly don't remember if they had much or any sag. I'm not too concerned about getting sag because it seems like any procross sleds have any sag. I guess as long as it rides properly that's the main concern.

 

[vsmpowered]

the only reason im worried about sag is because i get no traction and im not putting studs in

 

[Studroes144]

I hafta think that these stiff shocks are one of the main reasons that a lot of people are complaining about lack of weight transfer. The softer torsion springs did help my sled some with weight transfer so no doubt that getting the rear of the sled to sag more is going to help with traction too.

 

[TestMaster]

A friend has a 2014 xf 1100T snow pro limited and his rear shock is also stiff and slow to rebound, 10 seconds or more. I'm not sure why both AC and Yamaha are having similar problems unless both of the shock manufacturer had the same problem with configuration which is very unlikely. The only other factor is selecting the wrong shock configuration/part number from factory stock. The problem with that scenario is that I can't imagine a suspension that would require a shock with that calibration.

My 2014 Viper LTX SE feels stiff while riding and while evaluating the movement of the rear suspension felt stiff with the rear suspension on full high setting I could not get the suspension to deflect without jumping. I then set the rear torsion springs to full soft and the suspension did compress easier and I could actually get about 1/3 to 1/2 of total movement. At that time I noticed that the shock took an extend period of time to rebound 6-8 seconds and the suspension did not rebound to full extension as it did on full high setting. When riding at this softer setting the ride actually felt harsher than the stiffer setting. I believe the suspension was fully collapsing under repeated bumps because of the slow rebound and was actually hitting the stop.

Both rear shocks will be rebuilt or replaced at at HyGear Suspension by this fall.

 

[Studroes144]

How my sled was setup..even with the soft torsion springs, I could fully compress the rear shock and it would fully rebound with a couple seconds. That is on the softest setting with soft torsions. With the shift out rebounding on it's own it was 10 seconds or more. So that leads me to believe the torsion springs for these sleds are just very stiff but the shocks are totally outta wack. I did notice that with my original torsions on the stiffest setting it prolly rode best..more than likely because it was actually rebounding some like you said and not blowing right thru the stroke of the shock..but at the same time it rode terribly stiff on on every bump. I'm just hoping greatly that the revalve totally solves the harsh ride and lack of weight transfer..maybe that's high hopes but it's all kinda pointing in that direction in my opinion.

 

[TD Max]

Is the Yamaha shock calibration different from Cat? It would seem that some believe this, but I have my doubts.

I'm not saying that the valving is not wrong, but I do want to point out that how a shock compresses and extends "in hand" is quite a crude measure of it's valving. Shocks tend to vary based on oil temp/viscosity so they need to be set up not to fade to nothing. Also when installed the shock faces things like spring rate machine weight, and leverage ratio.

Again they are probably valved too stiff, but casual observations of how a shock works on a bench don't tell us a lot.

Just my $.02

FWIW I anticipate having mine revalved probably before they hit the snow.

 

[vector-devil]

i wonder if the 2015 vipers will be the same way or if they have made changes

 

[Studroes144]

I agree compressing a shock my hand doesn't say much but with a properly valved shock and good steady pressure you should be able to fully compress a shock between two hands..again I agree it's very crude judging a shock like this but when you put on end of the shock on the ground and me (230lbs) on the other end and can only move it 2-3 inches then no doubt it's valved way too stiff. You can see this on the sled as well while it's in motion as the rear of the skid doesn't really seem to move and holds backs the rest of the suspension from really working at all

 

[vsmpowered]

According to hygear the rear shock was valved with 1000 psi on dyno compared to 300 psi like most shocks fwiw just passing info. The front rear shock on other hand is soft

 

[Studroes144]

Ya I agree the middle shock was prolly close. On mine it was still too stiff..according to who revalved mine..but clearly the rear shock is extremely stiff..more than likely it's causing a lot of the major complaints about the sleds ride and attitude