MOTOTRAX VIBRATIONS

[Jnorth]

Finally got an opportunity to do some testing on my 120 enduro kit. Initially I thought the upper idler shaft was broken by contact with the motolink arm. I no longer believe that was the cause. I removed all shock preload and spring retainer and completely compressed the suspension so that the rubber bumper in the shock was compressed about a 1/2", essential bottomed out. At that point I still had nearly a 1/2" clearance between upper wheel and the motolink. I have photos but can't post? Additionally, there was no indication on the arm that there was ever any contact. In my case I believe other forces caused the shaft to break and we may be looking in the wrong area for a fix. When the suspension leans that puts stress on that shaft also, when stuck in a hole the only thing keeping the rails from staying in the hole while the bike is maneuver out is the rear slide joint and that upper shaft. Pulling the bike sideways out of a hole puts considerable stress on that shaft and rear joint. Of those that have had a shaft break can you see any evidence that the motolink hit the wheels?

That is interesting that on your kit, the bogeys don't make contact with the moto link. They sure do on mine. (137 Mountain). When mine broke, I am fairly positive that it was due to that contact because it was my "first ride" with the updated bogey assembly and I hadn't even got stuck yet. I did however, notice bottoming out a few times. I totally agree that the side force on that arm in normal operation are too strong for that bogey assembly and rear slider to handle in they're current design.

 

[HELICO]

Finally got an opportunity to do some testing on my 120 enduro kit. Initially I thought the upper idler shaft was broken by contact with the motolink arm. I no longer believe that was the cause. I removed all shock preload and spring retainer and completely compressed the suspension so that the rubber bumper in the shock was compressed about a 1/2", essential bottomed out. At that point I still had nearly a 1/2" clearance between upper wheel and the motolink. I have photos but can't post? Additionally, there was no indication on the arm that there was ever any contact. In my case I believe other forces caused the shaft to break and we may be looking in the wrong area for a fix. When the suspension leans that puts stress on that shaft also, when stuck in a hole the only thing keeping the rails from staying in the hole while the bike is maneuver out is the rear slide joint and that upper shaft. Pulling the bike sideways out of a hole puts considerable stress on that shaft and rear joint. Of those that have had a shaft break can you see any evidence that the motolink hit the wheels?

This 3 part idler axle is going to fail , without the
The Motolink hitting it.
Check the wear pattern on the 2 aframe supports.
The idler wheels bind in the track guides , that causes vibration rattling on the joints of the axle. ( Randy has tried different wheels he knows there is a problem)
The aframe is doing the same on the outboard sides of the axle.
The 129 and 137 tracks are going to be worse because of the mechanical advantage (aframe support is attached in the same point on the rails as the 120 so the leverage on the 129 137 is greater)
TEMPORARY FIX
I built a solid axle it may bend but hopefully wont break.

 

[Norma Stitz]

Related to the A arm thing. This is the solid bushing "fix" I was sent to replace the grenaded plastic bushings. I didn't agree with their choice to put aluminum against aluminum but I installed it anyway to get going. Well, after about 3 rides here's what it looks like. The flange end has impact marks on it from bottoming against the pivot plug thing, and the hole is egged out side to side from what must be considerable forces against it. It's .045" wider inside dimension in that direction now. So, I'm really left wondering what will be a better solution here. I was going to install a fancier bushing but now that I see these two issues developing I'm not sure that will be any better solution long term. Im now wondering if I should remake the T aluminum pivot part that keeps breaking much larger, and either let it ride directly in the steel A arm or maybe even make that part larger also?

Hmm I'm now thinking about this hammering force that's impacting the face of this bushing. That force is traveling up the A arm and hammering the bogey wheel shafts which would cause the problems people are seeing on that end. So, maybe we should fix the hammering first and not focus on the bogey shafts and bolts for a minute.

 

[madmini660]

Basically the spring forces the rear of the kit down all the time, since our skid is designed using parallel arms it means that no matter where in the skids stroke you are at that the pressure on the rear end will be perfectly consistent causing the kit to plane on top of the snow very well. Yet if there are dips or rolls in the snow the skid will dip with them evenly instead of try and push through them which causes lost momentum.

Basically it causes the kit to act very similar to a snowboard from a stand still to high speed, currently it is only acting like a snowboard at high speed.

With that being said the deeper paddle will help in very deep snow, but you will notice more of the difference with the spring alone, than the track alone.

Where do we get the springs to try do you have a part# i would really like to get myn to stop trenching

 

[Seekins]

Related to the A arm thing. This is the solid bushing "fix" I was sent to replace the grenaded plastic bushings. I didn't agree with their choice to put aluminum against aluminum but I installed it anyway to get going. Well, after about 3 rides here's what it looks like. The flange end has impact marks on it from bottoming against the pivot plug thing, and the hole is egged out side to side from what must be considerable forces against it. It's .045" wider inside dimension in that direction now. So, I'm really left wondering what will be a better solution here. I was going to install a fancier bushing but now that I see these two issues developing I'm not sure that will be any better solution long term. Im now wondering if I should remake the T aluminum pivot part that keeps breaking much larger, and either let it ride directly in the steel A arm or maybe even make that part larger also?

Hmm I'm now thinking about this hammering force that's impacting the face of this bushing. That force is traveling up the A arm and hammering the bogey wheel shafts which would cause the problems people are seeing on that end. So, maybe we should fix the hammering first and not focus on the bogey shafts and bolts for a minute.

I've got a 129 mx kit and figured out what's happening and have fixed a few... Put your bike on a stand, push down on your bumper. You can watch the flange of the aluminum bushing bottom out. When this happens....all suspension locks up unless there is pressure pushing up on the front of the rails. Basically when we hit a bump with the rear of the track we have no suspension and all that force transfers thru the Y arm, smashes bushing, busts idler shsfts flexes side plates and busts the bolts on the side plates of the tunnel. That force transfers thru the entire kit, making bolts come loose and you feel it buck sometimes. The rear bushing cannot bottom or top out. I lengthened mine, moved it on the rail and now use limiter straps in front. Works amazing.

 

[HalfBrit]

I rode on this one ride. Not enough to test the reliability. Plus I stiffened the front ski and mount. It rode great. But I don't know if it was the combination or just one of the changes. It is apparent some sort of spring or rubber is necessary to stop the impact though.

 

[Jnorth]

I've got a 129 mx kit and figured out what's happening and have fixed a few... Put your bike on a stand, push down on your bumper. You can watch the flange of the aluminum bushing bottom out. When this happens....all suspension locks up unless there is pressure pushing up on the front of the rails. Basically when we hit a bump with the rear of the track we have no suspension and all that force transfers thru the Y arm, smashes bushing, busts idler shsfts flexes side plates and busts the bolts on the side plates of the tunnel. That force transfers thru the entire kit, making bolts come loose and you feel it buck sometimes. The rear bushing cannot bottom or top out. I lengthened mine, moved it on the rail and now use limiter straps in front. Works amazing.

I would love to see some pics!

 

[Moto4Life]

Where do we get the springs to try do you have a part# i would really like to get myn to stop trenching

They will be shipping out at the end of the month once they arrive, they will be going to all customers so no need to place an order as they are free.

 

[dooman92]

Related to the A arm thing. This is the solid bushing "fix" I was sent to replace the grenaded plastic bushings. I didn't agree with their choice to put aluminum against aluminum but I installed it anyway to get going. Well, after about 3 rides here's what it looks like. The flange end has impact marks on it from bottoming against the pivot plug thing, and the hole is egged out side to side from what must be considerable forces against it. It's .045" wider inside dimension in that direction now. So, I'm really left wondering what will be a better solution here. I was going to install a fancier bushing but now that I see these two issues developing I'm not sure that will be any better solution long term. Im now wondering if I should remake the T aluminum pivot part that keeps breaking much larger, and either let it ride directly in the steel A arm or maybe even make that part larger also?


Hmm I'm now thinking about this hammering force that's impacting the face of this bushing. That force is traveling up the A arm and hammering the bogey wheel shafts which would cause the problems people are seeing on that end. So, maybe we should fix the hammering first and not focus on the bogey shafts and bolts for a minute.

I agree lots of force on the slide bushing joint. My bushing is wearing very fast also. That joint (T pivot part) needs to be a heim joint like the motolink and it would solve the premature wear issues. Oh yeah no aluminum on aluminum either. Also some energy absorbing system like bumpers or springs on both sides of slide.

 

[KTMDirtFace]

They will be shipping out at the end of the month once they arrive, they will be going to all customers so no need to place an order as they are free.

Cool, will mine go to me? or to the dealer I bought it from?

 

[Norma Stitz]

I agree lots of force on the slide bushing joint. My bushing is wearing very fast also. That joint (T pivot part) needs to be a heim joint like the motolink and it would solve the premature wear issues. Oh yeah no aluminum on aluminum either. Also some energy absorbing system like bumpers or springs on both sides of slide.

I'm wondering same thing, but would a heim joint allow too much movement in the rails? I think I need to take the shock spring off and really play with this setup on the bench since it's obvious nobody has at the factory.
What people are finding out, it seems, is that if the skid has too much ability to lean, it throws the track off. Or rather, the track throws the skid off.

 

[dooman92]

I'm wondering same thing, but would a heim joint allow too much movement in the rails? I think I need to take the shock spring off and really play with this setup on the bench since it's obvious nobody has at the factory.
What people are finding out, it seems, is that if the skid has too much ability to lean, it throws the track off. Or rather, the track throws the skid off.

The ability to lean is what I think makes it more fun than my timbersled. As the lean increased because the rubber bumper got pushed off and the retaining bushing bent it leaned even more and increased fun factor. BUT, it has to be engineered for that lean. It can be engineered for lean but the rubber bumpers in the heim joint are far too weak. There needs to be a positive stop to limit total lean other than the joint. Regarding the heim joint at the rear joint, the heim joint still controls/stops side to side movement (as does the on in the motolink) but allows articulation that potentially eliminates bind. It would require testing to make sure it helps. Yeah might allow the rails to move slightly.

 

[dooman92]

That is interesting that on your kit, the bogeys don't make contact with the moto link. They sure do on mine. (137 Mountain). When mine broke, I am fairly positive that it was due to that contact because it was my "first ride" with the updated bogey assembly and I hadn't even got stuck yet. I did however, notice bottoming out a few times. I totally agree that the side force on that arm in normal operation are too strong for that bogey assembly and rear slider to handle in they're current design.

I have the 120 enduro with stock shock. Is it the same shock on your 137 kit?

 

[Jnorth]

I have the 120 enduro with stock shock. Is it the same shock on your 137 kit?

I have the upgraded MX piggyback shock on mine.

 

[w74bronco]

The ability to lean is what I think makes it more fun than my timbersled. As the lean increased because the rubber bumper got pushed off and the retaining bushing bent it leaned even more and increased fun factor. BUT, it has to be engineered for that lean. It can be engineered for lean but the rubber bumpers in the heim joint are far too weak. There needs to be a positive stop to limit total lean other than the joint. Regarding the heim joint at the rear joint, the heim joint still controls/stops side to side movement (as does the on in the motolink) but allows articulation that potentially eliminates bind. It would require testing to make sure it helps. Yeah might allow the rails to move slightly.

Be careful how much faith you put in the retaining bushing on the Moto link. Mine broke after 4 engine hours of trail riding with about 9 minutes of that sidehilling and playing. Threw the track and the Moto link would just slide independently to one side, throwing the track. We had enough hose clamps, rope and zip ties to MacGyver it home. My plan now is to cut 1" ID aluminum round tube to place between the inside of the rails and the retaining clips on the Moto link. It won't be pretty, but it will keep me out playing.

The rubber bumpers are pretty much useless. I came across the mototrax guys truck with 3 of their bikes, and the rubber bumpers were displaced on all of them. It looked like they were trying out a few different types of retaining bushings as well. I took pictures for some ideas on my own fixes, but it looked like they had some R&D parts on theirs as well, so I don't want to post the pics. I respect their efforts to make the kit better, but I don't think I should be paying them any money for improved parts in 2018 that fix problems in design, not in performance.

 

[Seekins]

I'm in the process of doing the same thing. 1"ID x2"OD tube to keep the bushings in and I'm making a mechanical stop for the lean. Honestly unless your on hard pack road I do t think the lean matters and creates more issues than it's worth. I would rather keep my track on. The 2" track is easier to keep on than the 2.5 track. The 2" spins and the 2.5 gets traction and allows you to simply drive the rails right off of it.

 

[madmini660]

I'm in the process of doing the same thing. 1"ID x2"OD tube to keep the bushings in and I'm making a mechanical stop for the lean. Honestly unless your on hard pack road I do t think the lean matters and creates more issues than it's worth. I would rather keep my track on. The 2" track is easier to keep on than the 2.5 track. The 2" spins and the 2.5 gets traction and allows you to simply drive the rails right off of it.

So im not the only one that is having problems with keeping the track on my kit i haven't got the track to stay on one ride yet only 7 hours and the track looks like hamburger on both sides ive measured everything replaced parts and still cant keep track on

Also on a side note went out today and a 10mm bolt feel out of the front suspension cross shaft that keeps rails true doesn't appear to have any loctite on threads in shaft so if you want to save alot of work and frustration take them out and put loctite on them

 

[dooman92]

I'm in the process of doing the same thing. 1"ID x2"OD tube to keep the bushings in and I'm making a mechanical stop for the lean. Honestly unless your on hard pack road I do t think the lean matters and creates more issues than it's worth. I would rather keep my track on. The 2" track is easier to keep on than the 2.5 track. The 2" spins and the 2.5 gets traction and allows you to simply drive the rails right off of it.

What 2.5 track did you use? This was on a 17 kit?

 

[Seekins]

New yetti track

You need to tighten the track way more than those little gas shocks allow. I use a pry bar or ratchet strap it to something and play tug a war

Tight track and limiting the tilt makes the track stay on. The rails drive off the front of it leans too far. Tack goes one way and rail tips go opposite.

 

[HalfBrit]

New yetti track

You need to tighten the track way more than those little gas shocks allow. I use a pry bar or ratchet strap it to something and play tug a war

Tight track and limiting the tilt makes the track stay on. The rails drive off the front of it leans too far. Tack goes one way and rail tips go opposite.

I found the same thing. tighten that track. if you just tighten it a little extra by prying with a screw driver it keeps the track from skipping.