I would start with 15T and go from there.

Really? I thought that would make it undergeared?

The 1550kv tekin motor is rated for 5s max so conservative gearing will probably be your best bet to start with if going 6s. With 6" tires and 15/44 gearing you're looking at 52mph

http://scriptasylum.com/rc_speed/top_speed.html

I cant speak for the 1550kv, but IMO the 1350kv & 15T feels good w/the large MX38 6.91". I do like going up To ~18T w/the original Badlands 3.8 5.85". I have sense switch to a 16T w/the MX38, because the T8 w/15T just gets a decent mesh as it's pressed against the center chassis brace.

I'm running the Tekin 1350kV combo with a 17T on 6S with the 6.89in Trenchers. It's right on the edge of overpowered beyond reason :lol:

At 2/3 throttle ~50mph it will flip over instantly if you peg the throttle. It's also pretty close to overheating by the end of the pack, of course it's near 100deg F where I am too.

Get the 15T and the 17T so you have them both on hand, they're cheap anyway. If your temps are good on the 15T and you need more power, you'll be ready to go.

I plan on running the 3.8 Badlands, but switching to the big joe 2's from time to time. They measure 6.6" tall if Im not mistaken. Perhaps i should try 16t Pinion?

So if you're close to overheating with the 6.89" tenchers and 17t, i should be fine with 16t and the 6.6" joe 2's? Or should i safe It and go 15t.

Like boot stated, I'd get 15-17T. Then you are covered. I just don't like how the T8 rubs against the center brace w/15T installed.

Yeah, you guys are probably right but i actually found a castle mod 1 16t Pinion laying around so Im gonna try that for starters.

Thanks for the tips guys! Really looking forward to build this kit:)

I just shaved a bit of the center brace off to fit a 15t comfortably :)

You're going to love it! Be sure to use threadlock everywhere a screw goes into metal threads. I missed a couple of places and within the first week they backed out and got lost in my yard.

Cheers! I will make sure to use threadlock wherever it is needed. Thanks for the tip! :)

I need a little help.... Under full throttle I'm hearing an intermittent loud gear skipping noise. I checked both ring and pinions and they both look perfect. Mesh is good. both diff couplers are on tight. Pinion is tight. What am i missing? Could it be a snapped pin that holds the spider gears? The truck drives perfect (no noise) except when I stab the throttle going real slow or at a standstill. If it helps i'm running a HW max8 and HW 2200kv motor with 15t pinion and proline mx38's.

I've never seen a broken cross pin. Have you opened the center diff?

I have not. I guess my next step is to check all of the diff internals. This is my second mt410 build. I only have a pack thru this truck. I pulled the front and rear again and now the front ring and pinion look to have some metal shavings present. There is no sided to side play, and the mesh seems to be good. I'm a bit lost. The answer seems to be shim the diff, but it doesn't need it.

update: I shimmed the front and rear diffs. 2 shims for the rear on the gear side and 1 shim for the front on the gear side. There is a very very minimal amount of play now. It still making the noise when I do a quick stab of the throttle. I have to be missing something...