I'm working on putting a longer track in, I'm using extensions and I plan on setting the skid back. What are you guys doing for the front holes? It looks like I'll only be able to come back a little over an inch before I hit the bulkhead support.
what exactly are you doing? what length track, what sled, whats there now? answer these questions and i can answer yours.
I have a 136" track om my '99 Mountain Max and I'm swapping on a 156". I was under the impression you can move the skid back 2.5" and use 121-136 extensions.
2.5 will put you into ths steering hoop/foot support. i would go back 5" and then get 5" extensions. i have a sled in my driveway that i did a 121-133, and then added extensions to go 141. moved the skid back six inches. have another one i did 121-141, moved back 4-5 and added extensions. i am about 30 min south of you. lousy picture taker, but give me your email and i will see what i can do. figure it this way: 156-136=20. 20x.5=10. 10x.5=5. that = 5"on the setback and 5" for extensions. much more reilable setup than 10" extensions, and you can change the approach angle to newer geometry.
How did the sled handle with the skid set back that far?
I have noticed the skids on the newer cats and doos are moved back quite abit. Does this help with the ride, can a person move the 121 skid back 5" and then only have a 2.5 rail extension for a 136" track. If the ride would improve, I may look into this for next season. Al
Never mind, concerning the skid relocation. I just talked to Tom Hartman, recommended maximum to relocate aft is 3" Way to much ski pressure with the Pro Action chassie if moved any further aft. Al
gild
New member
Hmmm
I'm back 15" from the stock front mount hole but using 01 MMax rails and 162 track and I don't have enough ski pressure until I switched to Fox Floats so Icould jack the front up. The stock 00 and up MMaxs are back 7" from the stock SX, SRX and older MMaxs frt holes. 01 SXR
I'm back 15" from the stock front mount hole but using 01 MMax rails and 162 track and I don't have enough ski pressure until I switched to Fox Floats so Icould jack the front up. The stock 00 and up MMaxs are back 7" from the stock SX, SRX and older MMaxs frt holes. 01 SXR
I ended up moving the skid back 4.5" and building 5.5" extensions. I'll let you know how it does.
i am surprised that tom would contradict himself, or you misunderstood. i have installed 2 of his kits that moved the skid back more than 3". never a problem with heavy steer. you wont even clear the steering hoop at 3" converting a short track sled. what sled were you talking about extending? in addition to the 2 kits, i have done countless relocates of my own design, along with a few from other vendors without heavy front end issues. maybe strike up another talk with tom to clarify before giving up on the idea. relocates work.alswagg said:
Snowdad4, I was too surprised that Tom Said to not relocat. I told him it was for the pro action suspension 200 SXR. He somewhat quoted as "this is a coupled suspension, and moving back would give extreme amounts of ski pressure" I can see that this could give more ski pressure as now the fullcrome point is moved back on the chassie, but If the skid was converted to a non coupled I bleive it would work great. Al
Forgive me for using metric measurements, but somehow they feel more accurate to me than say 2 1/8 inches. If you wish to convert, 1" = 2,54 cm.
I've had three extended Yamaha's. A 1997 MMax 136 => 151", a 2001 MMax 141" => 151 and now a 2002 Viper 121" => 151.
With the MMaxes I had a '01 Mmax skid that has a H-shaped front arm in the suspension while the Viper (like rest of shorty 2-stroke Yamahas) have a W-shaped arm that is longer and attaches to a different place in the track tunnel. Now what I needed was to install 8T non-slip drivers to accommodate a 2" lug, and the W-arm is installed just too close to the drivers, so the whole skid needed to go backwards. This also meant that I didn't have to get hugely long sliding frame extensioners.
In the end the skid as a whole moved back some 11cm, and the extensioners brought the rear axle back some 27cm more, so a total of 38cm. In addition to that, the rear suspension arm moved back in relation to the sliding frames as well by 8 cm, to limit the strain on the sliding frames.
While doing this, all three shafts that connect the skid to the chassis also moved downwards. The front one moved the least, the middle one next and the rear shaft is now attached to a drop bracket. However in relation to each other they are now more or less as far from each other as originally.
The end result: an extended sled with increased ground clearance in the rear, but what rested pretty much on skis and skid front shock. The rear axle was practically in the air, so it was somewhat nose heavy. That was fixed by narrowing the "rail gauge", which lifted the nose up by 4-5 cm and gave increased ground clearance in the front. Loosening the control rods in the skid also helped. Now I have a Yamaha that suits something other than lake racing.
Oh, and pics or it didn't happen:
extensioners:
and ready (track loose though). Notice the drop bracket and the new location of the rear arm and control rods.
Here you can see the old holes for the shafts and new locations.
I've had three extended Yamaha's. A 1997 MMax 136 => 151", a 2001 MMax 141" => 151 and now a 2002 Viper 121" => 151.
With the MMaxes I had a '01 Mmax skid that has a H-shaped front arm in the suspension while the Viper (like rest of shorty 2-stroke Yamahas) have a W-shaped arm that is longer and attaches to a different place in the track tunnel. Now what I needed was to install 8T non-slip drivers to accommodate a 2" lug, and the W-arm is installed just too close to the drivers, so the whole skid needed to go backwards. This also meant that I didn't have to get hugely long sliding frame extensioners.
In the end the skid as a whole moved back some 11cm, and the extensioners brought the rear axle back some 27cm more, so a total of 38cm. In addition to that, the rear suspension arm moved back in relation to the sliding frames as well by 8 cm, to limit the strain on the sliding frames.
While doing this, all three shafts that connect the skid to the chassis also moved downwards. The front one moved the least, the middle one next and the rear shaft is now attached to a drop bracket. However in relation to each other they are now more or less as far from each other as originally.
The end result: an extended sled with increased ground clearance in the rear, but what rested pretty much on skis and skid front shock. The rear axle was practically in the air, so it was somewhat nose heavy. That was fixed by narrowing the "rail gauge", which lifted the nose up by 4-5 cm and gave increased ground clearance in the front. Loosening the control rods in the skid also helped. Now I have a Yamaha that suits something other than lake racing.
Oh, and pics or it didn't happen:
extensioners:
and ready (track loose though). Notice the drop bracket and the new location of the rear arm and control rods.
Here you can see the old holes for the shafts and new locations.
And the math here is simple. Add a 10" longer track, move the rear axle 5" back, either by moving the whole skid or installing extensioners or both. 20" inch longer track, rear axle has to move by 10". Simple as that, but rumours that you cannot move the skid x inches is BS, as long as you keep the whole act together.
gild
New member
Jrfin
The H arm and W arm are the same centre to centre distance, one is not longer than the other. You could use a W arm in the MMax suspension but you have to remove the two front idler wheels one on each side. You cannot go the other way and use an H arm in a shorty suspension which has a W arm because the rails hit when compressed.
The H arm and W arm are the same centre to centre distance, one is not longer than the other. You could use a W arm in the MMax suspension but you have to remove the two front idler wheels one on each side. You cannot go the other way and use an H arm in a shorty suspension which has a W arm because the rails hit when compressed.
gild said:
You are correct, sir, my bad. As the picture below shows, the H-arm in the '01 MMax skid is connected to the sliding frames in a different place than the W-arm in the '97 MMax skid, resulting in different placement of holes in the tunnel.
gild
New member
breaking W arms
Since you have both together look at he bottoming stops of the W arm verses the H arm. The W arm bottoming stops are close to the pivot point causing a huge load on the W arm when fully compressed. Just like a nut cracker, no reinforcment is gonna save the W arm. Sooner or later its going to break. Some guys take out the rubber stoppers and this helps somewhat but is a poor design for a bump sled. The H arm bottoms on the bumpers on the rail which causes no load on the H arm. It hits the main crossover shaft which doesn't load the H arm at all. How many people have changed an H arm, I bet not many. What do you think?
Since you have both together look at he bottoming stops of the W arm verses the H arm. The W arm bottoming stops are close to the pivot point causing a huge load on the W arm when fully compressed. Just like a nut cracker, no reinforcment is gonna save the W arm. Sooner or later its going to break. Some guys take out the rubber stoppers and this helps somewhat but is a poor design for a bump sled. The H arm bottoms on the bumpers on the rail which causes no load on the H arm. It hits the main crossover shaft which doesn't load the H arm at all. How many people have changed an H arm, I bet not many. What do you think?
Well I've never had to change or fix either arm, since trail riding bores me and there are a lot better bump sleds than Yamaha, if I ever wanted to ride trail. I know a lot of guys who ride trails and have had to fix/reinforce the W-arms for said reason. The design is indeed crappy. One has to wonder why Yamaha didn't make the H-arm for shorty trail models but kept on making the W-arm, even though a lot of them broke up.
I keep the bottoming rubber stoppers in the original place, but bottoming is a non-issue in the powder anyways.
I keep the bottoming rubber stoppers in the original place, but bottoming is a non-issue in the powder anyways.
I just think having the skid relocated back would give a better ride, basically centering the weight better between the skid and ski's. I am thinking of relocating 5" back and add 2.5" extension's. Al
gild
New member
load
It does put more pressure on the centre shock causing it to bottom more. That OE front sag on the SXr also causes easier botttoming of the centre shock
It does put more pressure on the centre shock causing it to bottom more. That OE front sag on the SXr also causes easier botttoming of the centre shock
ikeever
New member
- Joined
- Sep 10, 2003
- Messages
- 113
Oh man, you guys got my head spinning. i'm doing a 2001 sxr conversion to a 144" (141" stretched to 144") using my W arm off the sxr. if anyone could give me some good relocate measurements, i would really appreciate it. I though stock mtn max 2000 and newer measurements from the axle would work, but i'm don't think they will....because that measurment is with a H arm??? also using viper mountain drop brackets. thanks guys.