Amazing. Are you a career mechanic or something? It's like you're speaking an alien language, lol.
I think this should be stickied...this kind of info is invaluable.
I think this should be stickied...this kind of info is invaluable.
Shock Valving 101 and the 07 Apex RTX vs REV-XP MXZ X
- Thread starter ReX
- Start date
smacho
Extreme
Those changes in the shocks really improved the ride -- I think this must be the most important mod.
I still find it hard to belive Yamaha does not just build it this way -- or atleast have it as an option.
I still find it hard to belive Yamaha does not just build it this way -- or atleast have it as an option.
chadman
Expert
smacho
Extreme
Catapolting was most annoying -- on mid-sized (and larger) bumps it would compress and kick back far too fast. On small bumps, it was far too hard - no energy absorbed. felt lots of sharp jabs. Big bumps and bad timing on bumps would bottom out -- just pushed through.
All the smaller bumps are just gone - I see them, but do not feel them. Mid sized lift me, smooth landing & no catapolt from free rebound. Large bumps lift/launch the sled - land smooth, and controled without a big bounce. It eats all the energy.
Far "softer" feel.
I rode 100+ miles today & do not feel like a can paint that had got'en skaken
Other settings: Floats @ 50 PSI; Straps 1 hole up (shorter); Springs (coil & torsion) where Bruce set it Pioneer (I'll look in the moring), transfer - one turn in from red.
All the smaller bumps are just gone - I see them, but do not feel them. Mid sized lift me, smooth landing & no catapolt from free rebound. Large bumps lift/launch the sled - land smooth, and controled without a big bounce. It eats all the energy.
Far "softer" feel.
I rode 100+ miles today & do not feel like a can paint that had got'en skaken
Other settings: Floats @ 50 PSI; Straps 1 hole up (shorter); Springs (coil & torsion) where Bruce set it Pioneer (I'll look in the moring), transfer - one turn in from red.
bashley
Expert
I don't have the knowledge, time, or patience to rebuild shocks so my question is: If most everything in the XP and RTX shock is identical, why not just put an XP shock on the RTX?
Is it more economical to have it rebuilt by someone else?
Is it more economical to have it rebuilt by someone else?
chadman
Expert
smacho, thanks for the info. What did the shock job cost you?
ReX
TY 4 Stroke God
chadman said:
The specs I have given are all for the main skid shock, which is the rearmost shock in the sled.
The center shock was also revalved, but I'm using a stack from Mike Carver at Carver Performance (and can't share it). If you send your shocks to them, they can revalve and rebuild them for you.
BTW, I was out riding as much as I could on the weekend and still can't wipe the grin off my face. I can't get over how well this thing rides now. We rode everything from the smoothest trails, to trails full of stutter bumps, to trails that haven't been groomed this season yet with over 2 foot stutter bumps. The performance everywhere is exceptional.
Smacho, that "softness" with this setup keeps taking me by surpise. I'll get on a groomed trail with up to about 1.5" bumps and I keep thinking that the shocks have disconnected or something, the way the bumps simply dissapear. I literally can't feel them and it feels like I'm sitting on a soft couch or something and just floating down the trail. It is a strange sensation that I haven't got used to yet. I'm used to not only feeling the bumps, but being jarred when hitting these little bumps. As soon as I get on a rough trail though, I know the suspension is working fine. Once the bumps get into the 6-8" range and above, I know it and I would have to describe the ride as "firm", but still not painfully harsh. Once the bumps get into the 1.5 foot range, the suspension starts to feel like its really working. It might "just" bottom out very lightly here and there, hitting these bumps at just the wrong speed (often I can only tell by noticing that the thin layer of ice is being knocked off the bump stops). 2 foot bumps and it starts to more consistently, but still lightly bottom out and if I hit the throttle and skip accross the top it is less likely to bottom out (but with 2 foot bumps I don't like to do this much because I don't want to wreck something). This is the absolutely perfect setup for me.
The only issue right now is believe it or not we actually have too much snow. I buried my sled once and the guy I was riding with buried his REV-XP twice. The snow is so deep that in one area at the front of my house it is up to the roofline. I still haven't dug out my front door and the snow is 1/2way up the door right now.
The only reason I wasn't out sledding all weekend was I spent at least 15 hours plowing and shovelling snow (so far). My truck is getting a major workout and even with the Detroit Lockers at both ends and narrow 35" tires, I still had to install the tire chains all around in order to push the 8 foot plow through the 4+ feet of fresh snow on our laneway (the banks are very high). I've never seen snow locally like this before!
We are going sledding tonight. Hopefully we'll be able to break a trail all the way to the local trail. To be honest, I'm not even sure we'll make it...
smacho
Extreme
The rebuild on mine cost ~$200 - but it was in their shop and that included shop time for removal & install. It was in for the first service (oil, filter change & checkup?), and had rear heat exchanger installed too- total for service, shocks, heat exchanger (and all installs) was ~$550. Picked it up Saturday morning - put on over 250 miles since-
I got out for a few hours this morning -- and what I like best about it was that the sled seemed balanced -- What I felt it in the handles bars is what I felt in the skid. When the front lifted, the back did too. Before the revalve the Fox floats would eat a bump, and the rear would amplify it.
Now if the floats eat the bump, so does the skid.
Balance it good.
Now this is the sled I wanted! :rules
I got out for a few hours this morning -- and what I like best about it was that the sled seemed balanced -- What I felt it in the handles bars is what I felt in the skid. When the front lifted, the back did too. Before the revalve the Fox floats would eat a bump, and the rear would amplify it.
Now if the floats eat the bump, so does the skid.
Balance it good.
Now this is the sled I wanted! :rules
ReX
TY 4 Stroke God
silversurfer said:
I'm a mechanical engineer and my career is in mechanical design and finite element analysis. I'm a consultant (now) and have done quite a lot of work on things like the Canadarm2 (specifically the SPDM), satellites such as Radarsat, and these days have moved into opto-mechanical design where one of the tasks is to ensure optical elements are positioned to within extreme tolerances over a wide range of temperatures (my most recent thermal compensation system positions a MEMS array of 48 2D mirrors to within "approximately" 0.00003 mm (0.001 thousandths of an inch) while the operating temperature varies anywhere from -5°C to +85°C; the challenge here was the production cost for the system had to be less than $50 and it had to work while experiencing mechanical shock and vibration).
Since my first ride on a 1971 Arctic Cat, over 30 years ago, sledding has always been my passion. Even though I have thoroughly enjoyed building custom vehicles in the past (race cars and off-road trucks, including a 1200hp twin turbo engine and several custom automatic transmissions), I'd prefer to purchase a snowmobile ready to ride (and spend my time sledding, not wrenching). I am very picky and demanding of my snowmobiles though and want to be riding the best performing machine for aggressive trail riding (and this 2007 RTX now hits the mark - after a fair bit of suspension tuning...).
I have to admit I've often thought it would be fun to do some design work on snowmobiles, but have never pursued this line of work.
ReX said:
Yeah, thought it might be more than that (no, I am not saying mechanics are dumb by any means, I've met more than a few who are very intelligent). I work at an engineering firm (doing A/R); you're obviously a little smarter than the average bear. Glad to see you have such a passion for the sport.
Posts like this are what makes the site great. Thank you for sharing your knowledge with us; this certainly has helped more than a few people here already.
smacho
Extreme
The floats are set at 50 PSI -- no other changes.
GotJuice
Expert
Thank you VERY MUCH!
Thank you so much for this post!I have an 07 Apex Mnt. SE but have installed the gas shock from the touring sled in the rear and the heavy torsion springs. (I go 300lbs ready to ride)
I know longer bottom the rear skid but it's like a jack hammer over anything from 6" to 24" going down the trail. Hammers me bad and you guys described it perfectly!
I assume this aluminum bodied shock from the Venture is also rebuildable and I can have this modification done to mine as well. Would you perhaps have any recommendations for a mnt. sled, and a guy of my weight? I really appreciate your input. I too agree, my sled is $12000.00 for 2009 and they can't even valve the shocks properly.....makes me wonder how something so crucial and easy discovered could be missed so big by a compnay known for "quality" products....FRUSTRATING!
Thank you so much for this post!I have an 07 Apex Mnt. SE but have installed the gas shock from the touring sled in the rear and the heavy torsion springs. (I go 300lbs ready to ride)
I know longer bottom the rear skid but it's like a jack hammer over anything from 6" to 24" going down the trail. Hammers me bad and you guys described it perfectly!
I assume this aluminum bodied shock from the Venture is also rebuildable and I can have this modification done to mine as well. Would you perhaps have any recommendations for a mnt. sled, and a guy of my weight? I really appreciate your input. I too agree, my sled is $12000.00 for 2009 and they can't even valve the shocks properly.....makes me wonder how something so crucial and easy discovered could be missed so big by a compnay known for "quality" products....FRUSTRATING!
welterracer
TY 4 Stroke God
I wish there was a way to increase the low speed compression on my rear shock of my mono..
IT handles the large bumps with ease.. but the little studder bumps make the sled chatter as it doesnt obsorb them the way it did like when it was stock
IT handles the large bumps with ease.. but the little studder bumps make the sled chatter as it doesnt obsorb them the way it did like when it was stock
ReX
TY 4 Stroke God
welterracer said:
If little stutter bumps are making the sled chatter, there is too much low speed damping in compression.
Very likely your shock has single stage valving - unless it has been specifically updated with a multi-stage stack.
It shouldn't be difficult to revalve the shock to really soften off the low speed damping, while keeping the high speed damping where it is now.
The only problem might be the remote adjustable shock control. I have no idea how the GT's control works and it might mostly control low speed damping for all I know. Depending on what shock speed the remote control affects the most, there are still ways to get around it and get the ride you are looking for.
Does it tend to stiffen up the sled over small bumps or does it seem to control bottoming out without making little bumps harsh?
