Shock Valving 101 and the 07 Apex RTX vs REV-XP MXZ X

[welterracer]

Really the electronic control doesnt do much.. It doesnt make that much of a difference from soft to hard..

It only controls Compression , not the rebound..

If i had to do over i probobly wouldnt have purchased the GT.. even thou at the time i liked the black and chrome paint scheme

 

[Sapling]

You guys have a good valving stack for the front GYTR shocks that came on the GT?? I put a set on my Mountain turbo Apex and I'm not happy with how soft they are. I ordered them off of their accesorie page. Not sure what they have for valving. I tried stiffer springs and that is not cutting it. They seem to blow through the stroke. Large bump small bumpo doesn't really matter. Feels like I'm on a overstuffed couch with zero feed back. I would love to get them revalved. maybe even get a dual rate spring setup to help resist bottoming. You guys have any good ideas on these???

Seams like the right place to ask!

 

[frees-tyler]

Great Post REX!
I raced snowcross on Yamahas and know all to well the shortcomings of our suspensions. This year I rode the stock RTX Nytro for a few miles and then shipped my shocks off to Shocktech for a revalve. It has made such a difference and I can finally launch off of a jump and flat land it without fear of putting my spine thru my skull. Through the stutters it just eats them up...although my current set-up is somewhat stiffer when recreational riding thru trails.

I will be real curious to see what the new RTX SE rides like as this sled was dialed in by the R&D team wrenching for Yuji.

If someone could dial in the front and rear skid on 07-08 Phazer for all out jumping and aggressive trail riding I'd be the first in line to ship out my customer shocks!

 

[Sidewinder]

I have a 06RTX and hate the skid or shock.
Anything to be done with this?
As well I use the GYTR shocks up front instead of the Fox floats.
They are ok , but I fel they could be better.

 

[ReX]

I have a 06RTX and hate the skid or shock.
Anything to be done with this?
As well I use the GYTR shocks up front instead of the Fox floats.
They are ok , but I fel they could be better.

It is the same situation with all of the Yamaha suspensions. For some reason Yamaha uses single stage shock valving with all of their shocks - even on RTX sleds. This makes the suspension either very easy to bottom out (if it is valved softly), provide an extremely harsh ride (if it is valved firmly), or in the 07/08 RTX situation - provide a harsh ride on smoother trails and bottom out hard on rough trails with big bumps. Basically single stage valving is good for one size of bumps only (for example the stock monoshock setup typically rides very well through smaller bumps, including continuous stutter bumps, but it can't handle big bumps without bottoming out).

Compared to a good multi-stage stack, single stage valving always provides a compromised ride that either beats you up or bottoms out too easily (or both) in real world conditions (small and big bumps).

If you hop on a REV MXZ you'll immediately feel the difference. They ride very soft and comfortably on smoother trails, but when the bumps get bigger, the shocks stiffen up (2nd and 3rd compression stages kick in) and do a very good job at controlling bottoming. I spent some time on an 09 REV-XP MXZ 600 E-TEC a few days ago and once again Skidoo has their multi-stage shock valving dialed in extremely well.

The good news is all of Yamaha's higher end sleds have rebuildable shocks, including your 06 RTX (monoshock skid). I suspect that all of the shock rebuilding/revalving shops use multistage valving when they sell you a custom revalve job on your shock(s) (and probably have been for many years). Some might use 2-stage and some use a 3-stage. The only place I know for certain that uses triple stage compression stacks is Carver Performance (contact info provided earlier in this thread), but it sounds like most riders have been happy with all of the shock shops including Carver, Pioneer, Shocktech, Hygear, etc. A multi-stage setup (even 2-stage) is an enormous step up from a single stage setup in real world varying conditions.

One potential downside to a multi-stage setup with good bottoming control is if you ride hard, the shock will place higher stresses on the pivot arms. This can make them develop fatigue cracks faster than the stock setup. In my opinion it is well worth it, but if you want to ride hard you should at least consider beefing up the front pivot arm (note that the 08 Apex uses a reinforced pivot arm that will bolt on your 06; I still don't think it is strong enough for my riding style over high miles, but it is a step in the right direction).

BTW, I PM'd Chris Reid at Yamaha Canada and it sounds like they are at least considering multi-stage shock valving. Lets keep our fingers crossed (and keep asking Yamaha for it). It might not be far off to the day when Yamaha suspensions are finally on par with Skidoo suspensions. If Yamaha really wants to compete with the competition they'll hopefully do it done sooner rather than later...

I for one am hoping my next Yamaha will ship from the factory with well calibrated multi-stage shock valving (assuming it is a Yamaha; the competition is starting to catch up with their motors though and I'm not all that brand loyal - I just want the best high performance, clean running, low vibration, large fuel range, comfortable and durable sled I can find).

 

[welterracer]

Rex, why don you buy the tools and ill send you my shocks to do.. ?

 

[Sidewinder]

X2.
Im in Ontario and would glad to pay for your knowledge in this.
Shock rebuilders are like trans rebuilders.
We dont know what they are doing in there , we have to put all our faith in them.

 

[ReX]

Rex, why don you buy the tools and ill send you my shocks to do.. ?

I do have all of the tools needed to rebuild/revalve shocks, including nitrogen tank and regulator as well as shock body and shaft holding tools.

The problem is figuring out exactly which valve stack is right for a particular sled and rider. I have revalved several of my buddies sleds over the years (before manufacturers started to valve them well from the factory), but these sleds were always here, at my house, so I could take them for a ride to help dial them in. I also don't have a shock dyno so I can't actually measure the final shock's performance and build up a database of what works for certain riders/sleds and what doesn't.

I could probably do a 1/2 decent job on a 2007/08/09 RTX as well as several other sleds I have experience with (late 90's Cat ZRs, 97 Storm, 98-2000 XCR800s, etc.), but I'd only be doing an educated guess with everything else.

At best there would be lots of iterations and I think you would be better off going with a shop with a lot more hands on experience.

 

[welterracer]

as long as you wer adding more low speed valves i think it would make a huge difference

Only complaint i have is it doesnt eat the studders like it did before.. It eats the larger bumps for breakfast

 

[grooter]

can you just swap the shocks from the ski-doo into the rtx??

 

[ReX]

can you just swap the shocks from the ski-doo into the rtx??

I haven't checked the shock ends, but if they are the same - I'm fairly sure that yes you could.

One problem though is the main shock probably wouldn't work all that well. The REV-XP has very nice shock velocity through the suspension stroke. This makes it easy to dial in a soft ride that firms up on bigger bumps.

The RTX's main shock velocity is very non-linear with several suspension height regions where it slows right down to a crawl and others where it speeds up extremely. Due to the high speed regions, a REV-XP shock on an RTX would provide harsh ride. I found I had to valve it quite a bit softer than the REV-XP to provide a soft enough ride. Unfortunately this also makes it so you can't really make use of all of the suspension travel on the RTX. If you let the suspension compress too much, it gets very easy to suddenly bottom out. Yamaha's "dual shock" skid on the other hand does have very nice main shock velocity. This is the skid used in the Phazer and Nytro, including the XTX and it would allow you to make full use of the entire suspension travel. I don't know if the shock lengths are the same between the dual shock and REV-XP, but if they were, I'm sure a shock swap would work well.

The REV-XP center shock (not main shock) would probably work well to replace the center shock on the RTX (if the ends were a match).

Next time I get a REV-XP on the lift beside my RTX I'll have a look at the shock ends (but this probably won't happen unless something actually breaks on one of my buddies REV-XPs...).

 

[yamadoo]

Rex thanks for all your time.

I had Fix power sports re valve my 06 mono GT and he does not share anything of technical info.

I found it to be different, harsher on small trail 1 - 3 inch stuff, more controlled in the whooped out trails and did bottom less but still bottoms hard at times.

I turned the rebound out 4 then 8 clicks and that seemed to help the small stuff to be less harsh on compression. I already had the electronic control on soft /less compression dampening.

I / we have no snow now so can't test further, but might I get even smother stutter compression control by turning the rebound out further?

What will I feel, with less rebound dampening? I keep envisioning more rapid spring expansion, but not sure how that can be bad?

Thanks for your time and expertise

Yamadoo

 

[indica44]

I have a 09 rtx apex coming. Lets hope I can say they have the suspension problems taken care of . Will I be able to visually tell if thier is upgades to the 09 and what to look for or will I have to wait for snow to tell?

 

[ReX]

What will I feel, with less rebound dampening? I keep envisioning more rapid spring expansion, but not sure how that can be bad?

Less compression and rebound damping will ride smoother on smaller/mid sized bumps but with less control.

Once the rebound damping gets low enough, you'll start to get severe kick back over bigger bumps. This is especially noticeable when you hit a big enough bump to bottom out. After that, the suspension will "spring" back and launch the sled up in the air. If its the skid without enough rebound damping, it can often kick the back of the sled so high the seat can hit your back side when semi-standing. Inadequate rebound damping makes a sled very difficult to keep under control on rough trails, especially at higher speeds.

 

[ReX]

I have a 09 rtx apex coming. Lets hope I can say they have the suspension problems taken care of . Will I be able to visually tell if thier is upgades to the 09 and what to look for or will I have to wait for snow to tell?

If you are lucky Yamaha will have updated the shock valving, but you won't know until you ride it. If you are really lucky Yamaha will realise that good shock valving puts more stress on the pivot arms and they need to reinforce them.

I think it is more likely that they won't change anything in the skid from 08 and you'll end up with sled that works fairly well on medium sized bumps, rides very harshly on little bumps and bottoms out easily on big bumps with a huge amount of kick back (same as previous Apex RTXs).

If so, it will still be a blast to ride, but if you are riding with guys on REVs and REV-XPs you'll find it difficult to handle on rougher trails.

After a shock valving update and possibly a few reinforcements to the pivot arms it will be your best sled ever...