V2 Mid motor conversion for Tamiya MF-01X

This is updated version of my MF-01X conversion. Designed from scratch, it addresses feedback from users as well as my own findings and ideas. This version is much more modular, I will post number of modifications as remixes and encourage anyone to post their own - I uploaded the step file for easier editing.

As with the previous version, S, M and L wheelbases are supported with the stock chassis inserts and modified stock propshafts, with longer wheelbase variants possible through their combinations or custom inserts. 

The conversion replaces A2, A4, B10 and B11 chassis parts (+number of other kit parts mounted to them). Disassemble this part of the kit, as gears, axles, screws and other parts are reused in this conversion.

If you didn't build the previous version, you'll need these extra parts:

The M-chassis gear set (#54277 or #50794) is used again to create identical gear ratio to other Tamiya M-chassis. Other required parts are:

• Two 850 bearings for the gear set
• Two 1150 bearings for the prop shaft (you can use kit 1150 bushings or stock 850 bearings/bushings can be reused with adaptors)
• 5x40mm gear shaft (#13550027)

If you built the previous version, you'll only need two extra 1150 bearings used for the propshaft - these replace the 1050 bearings used before. This change was made to unify bearing sized used on the chassis.

Screws:

To assemble the gearbox, you can reuse kit BA6 3x10mm self tapping screws, the kit contains all screws needed with one exception - one of the screws may be used for servo horn. In that case, you can use the BA3 3x10mm machine screw from the same set of servo saver screws.

Eventually, you can use M3x10 machine screws to build the whole gearbox. You'll need 24pcs total, including screws for the body mounts and connection to the rest of the chassis.

The motor is mounted using the stock 3x27mm screws and metal plate. Correct pinion position is same as the kit one - you can use stock “pinion stopper” part, both MF-01X and M-chassis gear set variants work.

List of improvements:

• separated suspension arm mount - easier repairs and improved durability thanks to different printing orientation. It allows for toe-in settings and other mods - I'll add some variants to remixes.
• Improved cooling with an integrated fan pocket for a 3010 fan. In the case the fan is not used, it can be replaced by a grille, this provides marginally improved cooling compared to V1 (important information regarding fan use bellow)
• New gear layout with more rigid inner gear holder.
• New motor mount with separated gear cover - easier gear maintenance and possibility for future mods, including sheet metal mount.
• All screws are now reused from the kit.
• new gear layout provides space for short M-05 adjustable top links (optional, model available in remixes)

There were other minor changes for easier printing and assembly. Different gear layout resulted in shorter propeller shaft compared to the previous version - just drilling a new hole  for the cross pin, using the included jig, is enough to address this. 

Printing

I recommend printing from PETG, the model is designed for 0.2mm layer height and three perimeters with a standard 0.4mm nozzle.

Activate “solid infill threshold” and set 15mm^2 value - this is to fill up small areas around the suspension mount screws.

The motor mount should be printed from ASA or similar high tempeature material, to make it more resistant against motor heat.

Supports are necessary on some parts, but you can activate “don't support bridges” to reduce amount of support material. Make sure that supports are not build in blind holes - it's difficult to remove them afterwards. All such holes have pointed ends, so you can set up support threshold angle to keep slicer from generating supports under them.

For optimal results, try higher temps and lower fan speeds with slow perimeter speed - this should provide maximum Z strength for PETG parts.

Important information regarding fan use:

Motor magnets interfere with the fan's hall sensors. Depending on motor type, fan type and relative position of the two, fan may need to be rotated in the pocket to work, but some combinaions may perform poorly or not work at all. Test your configuration before closing the gearbox. I tested mine on a Sunon 5V fan and cheap no-name fan with positive results.

V2.1 Update:

This update makes a few changes on the main gearbox design:

• added tabs to stabilise the suspension mount
• added recess for M3 nuts in the suspension mount attach points. It now requires M3x10 screws instead of stock self-tapping screws
• added blind hole, which is in line with mounting point of the internal gear shaft mount - after drilling, an M3x20mm screw can be used to clamp the entire gearbox together for additional reinforcement of the gearbox. 
• small changes for future modifications

additional V2.1 changes:

 - modified motor mount and gear cover to move the 5x21mm shaft closer to the motor + additional reinforcements.