Yes, you are correct the 120mm measurement is end to end not pin to pin. It turns out that even with that I still had to grind the ends on my bench grinder and now the back drive shaft has just the perfect amount of play.

I just read this build from start to finish after, cmac, you referred me and I'm glad you did! It looks fantastic and has definitely motivated me to make my own Maxx :yipi:
Keep up the good work

Thanks so much. It was a learning process, but really fun. Good luck on your build, and let me know if you have questions. I don't know everything by a long shot,but I will be happy to help when I can.
Mike.

Yeah I've learnt a lot by reading builds like yours so hopefully my build should run quite smooth, much appreciated :smile:

Does anyone know if $299.00 for the Spider 8 diff set (on the UE web site)is for one diff or two?

Hi mate
It"s for two!

Pair
 

Yeh its a pair. Man do I feel lucky though, because I just scored a pair of those on here for $170. I could not have justified $300 when I need so many other things. They are the best 1/8th diffs for sure, but I would try to pick up a pair another way. Its your money.

I'm still trying to get my original Emaxx (3908) together and I'm trying to figure out what pinion gear to use. I going to use the stock transmission with HB Lighting pro diff's. I would like for this to be capable of at least Mid 50 mph. On the speed calculator I'm not sure which Traxxas transmission to choose. Also what pitch pinion do I need?

What motor, what voltage and what tires are you going to run?

For the speed calc, you're going to use the "E-Maxx 3905 1 speed or 2nd gear" option. I'd recommend running a 65T spur, you're going to need it to make up for the Lower ratio in the HB diffs and keep the pinion a normal size. Btw I run a 65t spur on my 3905/8 and I cant use a pinion smaller than about 18t with a castle motor because the motor will hit the trans case before the mesh gets tight enough. On 6s with a 2200kv, 24/65 gearing with the 3908 tires you'll be at 55mph before you factor any tire ballooning.

I'm going with MM 2200kv on 6s. Wheels will vary but I do have the stock wheels and tires. I also have several different aftermarket wheels and tires. Are the stock gears 32 pitch? Or something different.

Stock gears are 32 pitch. 68t spur is stock, 65t and 63t are optional, but the 63t won't work without a big pinion due to the motor hitting the trans. Nitro Revo spurs will bolt on the stock slipper and are Mod 1. But the biggest is 40t and I'm pretty sure that's way too small to use. I'm sure there are other mod 1 gears you could use, but I'm not aware of any myself.

Edit: just realize you only needed to know what "pitch pinion" not what pinion size.

Does anyone know what the largest tooth (32p) pinion gear available is ?

If I remember right, I have seen some in the 28 tooth count.
If you message Mike, I think he maybe able to make you a custome one.

Big
 

I have a few bigger ones that I picked up a while ago from Dan at Kershaw Designs. If RCM does not have what you need in his store or on hand KD has a pretty good selection on hand in various materials (derlin, stainless, bronze) and sizes (both bore and tooth size).

26t is the largest I carry in mod.8. We go up to 30t in Mod1.