Here's a place to discuss mods and fixes for the mototrax kits. Lets try to keep it positive. There are other threads for philosophical discussion about the company and their policies and methods. This should be discussion on how to make these kits work or work better, more reliably, capable or fun. There are people doing interesting things and it would be good to have it all assembled in one place.
MOTOTRAX FIXES tips and tricks
- Thread starter Norma Stitz
- Start date
Spent some time in the shop looking at my rear A arm and the hammering it takes in use. This hammering is why the plastic bushings have all grenaded. The fix from MT is a metal bushing, but this does not address the issue, only partly addresses the symptom.
What i noticed is that the billet T pivot, which many have snapped, had score marks on the shoulder where it's been making angry love to the A arm steel. This is what is hammering the plastic bushings. But also hammers the aluminum. And that force travels up to guess what? The idler shaft that is getting broken. So here is a problem area that must be addressed.
So I figured the shoulder needs removed to allow more stroke, and also smooth the transition because a stress-riser in this area is a bad thing.
So I cut the shoulder off and reinstalled it. Then I checked the movement on this pivot and discovered that all I've done is increase the range before the hammering starts.
https://youtu.be/KN3PxAK_RMk
https://youtu.be/9IGGU6DK2Qo
Here's that "dirt bike feel" in action
What's funny is I haven't felt any harshness from this binding while riding.
So I believe that limited straps are required here to eliminate hammering on compression at least. A nice fellow from Idaho confirmed this on the phone yesterday and he said it works fantastic on his. So I guess this isn't a tip, trick or a fix just yet.
What i noticed is that the billet T pivot, which many have snapped, had score marks on the shoulder where it's been making angry love to the A arm steel. This is what is hammering the plastic bushings. But also hammers the aluminum. And that force travels up to guess what? The idler shaft that is getting broken. So here is a problem area that must be addressed.
So I figured the shoulder needs removed to allow more stroke, and also smooth the transition because a stress-riser in this area is a bad thing.
So I cut the shoulder off and reinstalled it. Then I checked the movement on this pivot and discovered that all I've done is increase the range before the hammering starts.
https://youtu.be/KN3PxAK_RMk
https://youtu.be/9IGGU6DK2Qo
Here's that "dirt bike feel" in action
What's funny is I haven't felt any harshness from this binding while riding.
So I believe that limited straps are required here to eliminate hammering on compression at least. A nice fellow from Idaho confirmed this on the phone yesterday and he said it works fantastic on his. So I guess this isn't a tip, trick or a fix just yet.
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Haha
Yeah dude, angry love just leads to broken stuff.... haha...
Yeah dude, angry love just leads to broken stuff.... haha...
That's pretty close to what I was telling you.
You'll for sure need limit straps in front.
I moved the location of the rear tee down and back about 1" and extended the front of the shaft 1-1/2"
Limiter straps 6.5- 6.75" center to center on the front cross bars and that rear slip joint won't touch either end. Instead suspension will work
You'll for sure need limit straps in front.
I moved the location of the rear tee down and back about 1" and extended the front of the shaft 1-1/2"
Limiter straps 6.5- 6.75" center to center on the front cross bars and that rear slip joint won't touch either end. Instead suspension will work
Coupler arm
Over the last two seasons i have been running suspension that i built that (aside from the leaning property) is very much like mototrax design.
I run a ktm pds (progressive damping system) shock with no linkage. Chose this shock to overcome falling rate suspension without building elaborate linkage, way simple and extremely strong.
Thought i would put this out there, might help you guys with some of your issues.
For reference:
I would call what you all are refering to as an "A" arm, a coupler arm (or coupling arm)
Stock mototrax slide effect at bottom of coupler arm is a SEMI COUPLED suspension with no control over the rate of the rocking effect of your skid. you have some rock in your skid which is controlled by a mechanical stop in both directions.
THIS SETUP IS GARBAGE!!!!
you need to be able to dampen the coupling effect of your suspension or you will have "ANGRY LOVE"
(great way to put it by the way)
If you were to put a solid arm in you would have a FULLY COUPLED suspension, meaning your skid would stay parallel to the to the ground all the way through the travel.
Semi coupled suspension
Less damping (soft springs or shock bushing placed in your coupler arm) results in better handleing on whooped out trail/ hard bumpy snow/ playful motocross suspension. Your skid will rock easily to conform to the terrain.
Cons your skid will rock back in deep snow creating horrible atack angle and have major ski lift when climbing especially with more horsepower. You can install limiter straps to overcome part of this problem but then you limit the back rocking up effect of your skid at the beggining of you swing arm travel.
Fully coupled suspension, no rock of skid
Pros awesome in deep snow!!! Very little ski lift, atack angle stays good under power and far less trenching.
Cons horrible handleing on whooped out groomers and set up rough snow. Skid will no longer conform to terrain.
Somewhere between these two setups is a sweet spot. The stiifer your spring the closer you get to being fully coupled. Finding the sweet spot with springs or bushings is very difficult. When you increase your sping rate too much you will start to feel bouncy, no rebound control. The bushings have less of this effect than springs.
You can place a shock in the system which is way better. But then you will lose the "front of the skid up rocking effrct" this is what i chose to do because the deep snow handling of my machine was far more important to me. You can also easily adjust the coupling effect of the suspension. You can even run a mtn. Bike shock that is capable of being fully locked out so you can switch from semi coupled to fully coupled with a lever on your handle bars.
I think the best set up for the mototrax suspension would be a combination of springs in the coupler arm on both ends so you still had good rock in your skid in both directions and then add a damping only shock (no spring effect) so the shock could sit at mid stroke but the rebound and compression would still effect rock of skid.
Hope this all makes sense and helps someone out.
I spent way way to long working on this stuff thought maybe this might speed up the process.
Over the last two seasons i have been running suspension that i built that (aside from the leaning property) is very much like mototrax design.
I run a ktm pds (progressive damping system) shock with no linkage. Chose this shock to overcome falling rate suspension without building elaborate linkage, way simple and extremely strong.
Thought i would put this out there, might help you guys with some of your issues.
For reference:
I would call what you all are refering to as an "A" arm, a coupler arm (or coupling arm)
Stock mototrax slide effect at bottom of coupler arm is a SEMI COUPLED suspension with no control over the rate of the rocking effect of your skid. you have some rock in your skid which is controlled by a mechanical stop in both directions.
THIS SETUP IS GARBAGE!!!!
you need to be able to dampen the coupling effect of your suspension or you will have "ANGRY LOVE"
(great way to put it by the way)
If you were to put a solid arm in you would have a FULLY COUPLED suspension, meaning your skid would stay parallel to the to the ground all the way through the travel.
Semi coupled suspension
Less damping (soft springs or shock bushing placed in your coupler arm) results in better handleing on whooped out trail/ hard bumpy snow/ playful motocross suspension. Your skid will rock easily to conform to the terrain.
Cons your skid will rock back in deep snow creating horrible atack angle and have major ski lift when climbing especially with more horsepower. You can install limiter straps to overcome part of this problem but then you limit the back rocking up effect of your skid at the beggining of you swing arm travel.
Fully coupled suspension, no rock of skid
Pros awesome in deep snow!!! Very little ski lift, atack angle stays good under power and far less trenching.
Cons horrible handleing on whooped out groomers and set up rough snow. Skid will no longer conform to terrain.
Somewhere between these two setups is a sweet spot. The stiifer your spring the closer you get to being fully coupled. Finding the sweet spot with springs or bushings is very difficult. When you increase your sping rate too much you will start to feel bouncy, no rebound control. The bushings have less of this effect than springs.
You can place a shock in the system which is way better. But then you will lose the "front of the skid up rocking effrct" this is what i chose to do because the deep snow handling of my machine was far more important to me. You can also easily adjust the coupling effect of the suspension. You can even run a mtn. Bike shock that is capable of being fully locked out so you can switch from semi coupled to fully coupled with a lever on your handle bars.
I think the best set up for the mototrax suspension would be a combination of springs in the coupler arm on both ends so you still had good rock in your skid in both directions and then add a damping only shock (no spring effect) so the shock could sit at mid stroke but the rebound and compression would still effect rock of skid.
Hope this all makes sense and helps someone out.
I spent way way to long working on this stuff thought maybe this might speed up the process.
Springs
So Just thinking out loud.. If I put a stiffer spring on the compression side of the arm, and a lighter spring on the rebound will I gain a more controlled feel? I will be racing a 100 mile cross country race next month on my 137 on a 23 mile loop with sleds, so the whoops could get ugly!
But day to day riding I'm in the mountains in deep and steep terrain. I guess I could use straps for mtn riding and springs for trail racing?
So Just thinking out loud.. If I put a stiffer spring on the compression side of the arm, and a lighter spring on the rebound will I gain a more controlled feel? I will be racing a 100 mile cross country race next month on my 137 on a 23 mile loop with sleds, so the whoops could get ugly!
But day to day riding I'm in the mountains in deep and steep terrain. I guess I could use straps for mtn riding and springs for trail racing?
Food for thought
I forgot to mention the customer support and the fantastic communication Both Randy and Zak have given me. Understand it's a newer company and growing pains occur. Overall I am happy with my decision on Mototrax.
I forgot to mention the customer support and the fantastic communication Both Randy and Zak have given me. Understand it's a newer company and growing pains occur. Overall I am happy with my decision on Mototrax.
I have a Husaberg 570 with a129 Mototrax.
Chasing ski pressure , trenching and traction was a fine balance. Ski pressure by adjusting only the strut was a waste of time. What I found was that increasing the rearward coupling travel reduced the ski pressure. I took the shoulder off the bushing allowing more travel and put a rubber stop to absorb shock. To stop the trenching and increased deep snow traction I replaced the stock spring (350 lb) with a 200 lb spring with 3/4 '' preload
this allowed the track to flatten out for traction yet have enough spring for suspension.
This worked for my riding style I am not a motocross guy.
Helico What is the part # for the rear spring? I'm curios how well it would work? I'm running the 137 with the upgraded shock. Don't you worry about breaking the rear yoke after taking off the shoulder?
Good work roo. Yes I want to keep a playful feeling for spring for sure so ideally there's an easy quick lockout maybe a big soft donut that inserts behind the A arm strut.
This looks great man. Where did you get the spring? I'm liking the bottoming rubber you have there except it looks like if pressed the coupler would either slide right into it or cut it possibly. But, if a fender washer was welded on, or even just floating on the face of the rubber it would make it have a seat to impact. Then, a solid chunk of something could be placed there for powder conditions and easily removed for hard pack. I see you have increased the diameter of your shaft on the slider part too. Is that just a 1"x.120" tube slid over the factory part? Is it aluminum or some other metal?
Oh wow i see now you put a softer spring on I was thinking it was stronger at first. That's considerably softer too. Still holds up the bike?
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Helico,
Couldn't you also actually drop the rear bracket down about 1/2" and that would give you the same result as machining off the shoulder? Basically follow the contour of the rail that it's bolted to already?
Couldn't you also actually drop the rear bracket down about 1/2" and that would give you the same result as machining off the shoulder? Basically follow the contour of the rail that it's bolted to already?
Halfbrit's solution is essentially making the rear pivot into a tie rod end with full mobility. He tested it with good success last week so maybe it's time to look at usi a tie rod end there instead of placing all that side force on the bushing and coupler.
Yes but all that does is increase the range before it hammers just the same. It would tilt on the shock pivot as far as it needed to before hammering.
There are two issues as I see it here. We need to soften the blows to the rear coupler area to keep it happy and we need to limit the side tilting action that the small rubber bushes on the shock are not able to handle. As a bonus we could invent a quickly changeable lockout for different conditions with respect to the coupler slider.
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Right. But increasing the travel and adding a bump stop or a spring? I have noticed my rubber covers on the shock have come off a couple times. I thought ice or something pushed them out. Makes sense to me that the shock can't flex with the skid as much.
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