For you guys using the all metal gears in the Truggy, what pinion gear are you using? I have five different ones, none of which are the correct pitch, some don’t even fit my motor. 
I’m pretty sure the truggy uses a standard 32p, or .8 mod pinion with whatever sized shaft size you have. Most are 3.175mm(1/8in).
32P is too small. Ordered this originally and it did’t fit. The gears on the spur gear are larger. https://hobbyking.com/en_us/18t-3-17mm-32-pitch-hardened-steel-pinion-gear.html
What spur are you using?
Looks like it was originally for a nitro car, which if I’m not mistaken use bell housings which are a little different.
Ok that makes sense now. I thought it was using a standard 1/10 pitch, but thats a 1/8 gear. Probably mod , but to be sure use this gear calculator to find out exactly what it is.
http://scriptasylum.com/rc_speed/gear_calc.html
All you have to do is provide the tooth count and gear diameter and it will tell you what pitch it is.
Yeah looks like “mod” based on the pics I’m seeing, however that introduces another issue, as the shaft of the motor I have is 3mm, and it would seem all the mod pinions have a 5mm bore hole. oy!
You need ‘Mod 1’ pinion gears. Most come at 5 mm ID, so you may need a shaft adapter if you are using a traditional 540-size motor.
Thanks guys, all extremely helpful! Will try they mod 1 and 5mm adapter… fingers crossed. Zzz $20 for a pinion gear+adapter… Will know by Thursday.
Apologies - did not see the post. There are Mod 1 pinions out there for typical 540 motors but they are pretty hard to find (Ofna used to make some when they were selling the Jammin’ SCT). The adapter is probably going to be the easiest.
Yeah I did look for a short while for a 3mm bore, mod1 pinion, but didn’t see anything. The adapter seems like a solid solution. thanks for the suggestions, I wouldn’t even have known they existed.
I use this https://www.conrad.de/de/ersatzteil-reely-gsc-250718-kegelrad-1058776.html with a spur gear (with mod 1 which I designed) for a hsp diff http://www.rcmaster.net/de-02024-diff-getriebe-p223879.htm
FYI for anyone building. The MOD pinion works like a charm. Definitely a tight fit to get everything installed but I had the car out today for a few laps around.