not enough axle length - mbs matrix 2 + rockstar hubs

I suspect it’s the lacroix 72t pulley that has built in spacers that’s making it too long to screw the nut on.

Still purchasing what I need, had these pulleys on hand I guess they don’t work. I was going to buy the $20 MBS 72t nylon pulley with the spacers that don’t come out as much, but I wanted to use the aluminum 72t.

No issues with using the MBS pulleys right? what pulleys do work with this setup? or are you forced to use all MBS stuff?


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Just move the mounts further in? Or does the lacroix pulley have a bearing?

Usa a pulley that doesn’t have a bearing. That frees up a ton of axle length.

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Can the bearing be removed?

the bearing can be removed but I don’t see how that’ll free up any room as the pulley slides all the way down the axle. I guess its the length of the built in spacers that messing it up? I realize im basically asking if MBS stuff works with MBS stuff, but just want to make sure before buying the wrong item

Also having another issue with the motor pulley alignment…am I forced to use grub screw to secure it in place? Weird how the circlips just spin around the axle instead of hugging it - the circlip i placed on the inside can slide down if i push it…

Use the appropriate grubs screws along with the key to secure the pulley to the motor shaft. I would not bother with the outer c clip, since you will likely have to eyeball the pulley alignment once you figure out your wheel pulley situation.

Once you have it figured out, I would use Loctite 680 retaining compound (a small amount) on the shaft right before final securing with the grub screws.

If you do, be careful, as it sets quickly and takes a torch to remove. However it holds very securely and I’ve never had it break in use.

Either way, when you’re cobbling a drive together, you have to finagle the alignment and fit.

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the circlips dont stay put without sliding down the axle (if i apply force). They also spin around the axle instead of hugging it which is weird as it doesn’t do that on my lacroix axles

I got some 271 Red on hand, will this work?
Blue loctite where the grub screw is or the stronger compound there as well?

Is it just my pulley and alignment that needs fixing? or are these lacroix pulleys 100% not compatible

Maybe my caveman approach isn’t for everyone but I would use a cutoff wheel to cut the spokes holding the bearing assembly in place. Then again those do look like nice pulleys and damaging them might not be for everyone.
This way no need to buy new pulleys.


No, they are designed for different purposes.

I’m specifically talking about securing the motor pulley onto the motor shaft. No circlip is necessary. Just the key, grub screws, and a small dab of slip fit retaining compound.

You may not even need the compound if the motor pulley has 2 good grub screws and a key.


Trust in Mario…his sorta a big deal


The circlips just there to prevent the pulley from sliding off the motor shaft, torque gets transferred via the key. With good tolerances the circlip should not move, if it does however thats not that big of a deal. It only gets annoying if they are that loose that the motor pulley starts to rattle.

You are supposed to remove the bearing from the 72t pulley if you are using it on matrix ii. You also need to push your motor mount farther onto the truck hanger.

That’s how it is setup on lacroix jaws 1.0 boards.

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shit u right. was too occupied with my battery I just threw the motor mounts on quickly before playing around with everything.

ty for the help everyone

I have matrix II axle length issues. I NEED the space, no other way about it.

I’m not proud of how I got here. I have the other longer axle. Advice on removing the stock axles?

I drilled and reamed the old axle out after several cycles of torch and fridge did not move it one iota.


I don’t really know how these work and they’re out of stock so this probably doesn’t help at all :joy:

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Use a spacer off the end of the hanger and the thread of the axle itself. Tighten the nut against the spacer.

The axles are splined and cold pressed in, the only way to get them out is by pulling them out.

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I knew this was here somewhere…

How to remove matrix ii axle → - website launch - #1513 by wapkoen

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F’in A! I knew they felt splined. Shit was rocky at 11mm-12mm reamers and bits.

Nice find. Thanks.

@glyphiks like an internet stranger is going to tell me what to do.


It was super effective. Damn.