2wd : Mxus 3k 3t in a motorcycle fork

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csc   100 W

100 W
Posts: 139
Joined: Dec 13 2016 7:40am

2wd : Mxus 3k 3t in a motorcycle fork

Post by csc » Feb 04 2018 3:40pm


I've just disassembled my front wheel for maintenance, good occasion to show with more details how I installed an Mxus 3k 3t in a Showa 35mm reversed 50/125 cm3 motorcycle fork (was installed on Rieju mrx 50, derbi senda sm 125, etc) (this should work with any fork having the same axle design)


(https://www.spomotoscooter.com/index.ph ... iece=72989)

I noticed that this kind of fork, on the "non-disc" side, has exactly the same axle diameter than the plain part of the axle on an MXUS 3k (aka not the bolt tightening part of it, but the circular plain part on which you put the bearings). Therefore, it would accept quite a lot of hubs, I guess.

The non disc side of the fork has not been modified. It has a native bolt/nut axle locking system (check all the pictures below to see exactly what I mean).
non disc side no mod.jpg
non disc side no mod.jpg (101.96 KiB) Viewed 397 times
The lock has easily been reproduced on the disc side - a straight cut and two holes. This disc side has a smaller axle size, so it had to be quite a lot modified to let the mxus axle go through and let the bolts be tightened. As a clean aspect is not strictly necessary, as soon as the final result is simili flat, I saved a few hundred euros through a home made job performed with some kind of a "butcher style".
modified disc side 2.jpg
modified disc side 2.jpg (155.36 KiB) Viewed 397 times
But the torque arms have been made of special hardened steel, by a professionnal. These cost me their weight in gold (almost) !!!!
torque arm 1.jpg
torque arm 1.jpg (140.6 KiB) Viewed 397 times
The disc side TA has a flat side that forces the bolt and therefore the axle angle :
torque arm disc with flat.jpg
torque arm disc with flat.jpg (138.16 KiB) Viewed 397 times
They fit exactly in the holes that you'll find underneath the fork :
torque arms go there.jpg
torque arms go there.jpg (99.41 KiB) Viewed 396 times
When inserted it looks like this :
torque arm inserted.jpg
torque arm inserted.jpg (190.42 KiB) Viewed 395 times
Hub and torque arms tightened : 72v 120 amps battery/ 240 phase peak + 40 amps regen on front wheel with no issue (rust underlines what I'm talking about) !!!
hub and TA tightened.jpg
hub and TA tightened.jpg (142.98 KiB) Viewed 392 times
I also had to make a spacer that fits with the plain part of the Mxus axle :
spacer.jpg (87.73 KiB) Viewed 390 times
It goes there ("non disc" side) (notice the area where the motor axle will fit exactly the fork's original axle hole, and its associate tightening system) :
spacer installed.jpg
spacer installed.jpg (105.03 KiB) Viewed 389 times
The disc cover was modified to accept a motorcycle disc : more pictures later

And sorry but oddly I can't move nor remove this picture showing the disc side mods, that I'd have preferred to place above (??!!) :
modified disc side 1.jpg
modified disc side 1.jpg (134.36 KiB) Viewed 400 times

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