XRAY - Model racing cars

The XB4'17 setup sheet contains two check-boxes, "2mm" and "0mm", that sit below the RF block's graphic and above the RR block's graphic. This option is not described in the manual as far as I can tell. If I had to guess, I'd guess it refers to raising the entire rear gearbox by 2mm. If that's not right, what is? If that's right, what is it supposed to do? Do you seal up the bottom of the gearbox with shoe-goo to keep crud out? Cheers!

You raise gearbox but you will loose traction.
I thing best is stock setting.

This is beyond my knowledge so that I have enough.

Instead of "2mm" on the setup sheet meaning that you are running the 361262 shim to raise the gearbox (to change the driveshaft angle with the outdrives, etc), another possibility is that the "2mm" on the setup sheet means that you are using the "+2mm" rear suspension holders from the 2015-2017 car (363311/321), rather than the rear holders from the 2013-2014 car (363310/320).

This seems more likely to me. I suspect that many of the team drivers are are either confused about this part of the setup sheet or never think to use the old holders, which explains why they often leave this option blank, and when not blank it is usually set to "2mm". Most current setups for high grip have the rear inner hinge pins +0.75mm high to raise the roll center; using the old suspension holders that lower the pins by 2mm doesn't make a lot of sense.

Here's another setup sheet observation. The setup sheet allows you to specify the downstop shim, upstop shim, and "length" for front and rear shocks. The shims are clear. The graphic that shows the "length" appears to define it as the distance between the bottom of the lower shock cap and the top of the spring bottom retaining collar, but from the values in the standard setups it is plain that this isn't so. The "length" must be the distance between the bottom of the lower shock cap and the top of the plastic shock ball joint. Right?

The graphic in the setup sheet could be simplified (e.g. taking away the spring and spring bottom retaining collar, adding the plastic shock ball joint, and moving the upstop shim to the middle of the shock shaft so it does not subtract from the shock length) to make this clear at a glance.

Also the instructions say to leave 1-1.5mm of threads showing when installing the plastic shock ball joint, but if you do this you cannot achieve the shock lengths called for in the standard setups. Ideally the instructions would show you how to measure shock length, rather than telling you "Both FRONT SHOCKS must be the same overall length. Both REAR SHOCKS must be the same overall length", which are true statements but don't help enough.

We keep this option because you can still bay this parts and use it. If traction is very low and you are looking for more rear grip i recommend to use 0mm arm holders.
We use +2mm to have good balance between traction and rotation.

Those touring wheel adapters are for the M18 truck, not for M18 touring.