Alright, so im looking at buying a b4.1 FT kit and am wondering what size mod motor i should run, i have a tekin rs pro so i can run anything 10th scale i would want to. i was thinking 8.5 or 6.5 i run LRP x12 motors in my T4 a 17.5 and a 13.5, and in reality ill probably throw in the 13.5 to learn buggy because this will be my first one. but i want it to be fast. very fast. i run indoor high bite clay with a decent straight.

so, should i get the 6.5t or the 8.5t (both would be lrp x12 octawinds)???

I would go with the 8.5. I run a Tekin Redline 7.5 in my FT B4, and it's actually a bit much. Not to mention, if it's not a large indoor track, the 6.5 may eat up the straight too quickly (after all, you do have to turn at the end! )

I am one of the suckers that pre-ordered the Losi 22. Got it, built it, drove it, SOLD IT! The B4.1 is better in every way! Losi concept is good and its a good design but my option is AE has had this winning chassis for such a long time for a reason...its just that good! Losi 22-- not for me!

i really dont have much traction on my b4.1 how can i fix this

The setup for indoors clay from Ryan C is good and will work outdoors as well with the exception of the tires and maybe trying the .5 rear hubs. Using the ballast weight in front of the transmission along with placing the weight in each rear triangle and 1/2 oz next to receiver is important. The weight seems to settle the chassis. Other then that, just concentrate on the ball diff to make it smooth. BFast kit or its simple to do yourself. I use full ceramic balls with my own sanded rings and this diff is soooo buttery smooth.

Well I think I have them dialed in.

Going to race them for the first time today at SDRC Raceway in San Diego. www.sdrcraceway.com

Should be a fun time. I have a Castle 4600kv motor and a Sidewinder SCT ESC for now. Until I can get some funds for a Tekin 17.5 System. I would rather run the stock class if possible.

I will post updates on my results later but this thread really helped me get it feeling good.

My FT B4.1 is the green lid and the backup B4 is the pink lid




Got the batteries packed and ready to go.

garry. MASSIVE PICS!!! Cool looking cars tho.

Jmuck, not so interested in your balls but do you hand lap your own rings? What grit do you go to? Can you see your reflection in them when you are done?

I think my balls are very important. I hand lap my rings. I use an old female diff half to hold the rings and a absolutely flat surface such as my granite countertops. You want to sand the ring that is naturally flat. What I mean is look at the ring in profile and you will see a rounded side and flat side. Use the flat side. I use 400 grit paper and spray motor spray on the paper and sand the rings with diff half to hold it in a circular pattern. What your trying to do is eliminate the tiny little pits on the ring surface which can be seen as tiny little brown dots or speckles. it takes a while, but once the brown spots are gone, it's finished. While sanding, use the motor spray to help lubricate the sanding action. When your done, you will have sanding marks in your rings. These are critical for the ceramic balls, but if you use carbide then you will polish the rings further with 600 grit.

Nice. I have a sheet of tempered plate glass that I use to sharpen chisels and hand plane blades that has paper from 80 to 1500 grit adhered to it. I'll do some lapping next time my balls need cleaning. Ugh...that just sounds terrible....

Everyone seems pretty high on the RPM ball ends. Do they offer a bit tighter tolerance on the ball? I haven't raced my car that much and there already seems to be quite a bit of slop on the connection points with the stock ball ends.

It never sounds pretty when you use words like diff balls, female halves and lubricate.

Back in the day, I used to spend quite a bit of time balancing all my rims/tires. Anyone bother with this? See benefits to bearing life or other performance?

l Use the stock AE ball ends and never has one break or pop off. They do have a little slop, but I think a little slop is good. I replace them once a month. Remember, loose and sloppy is good.

I like to balance mine using the Du-Bro prop balancer and some balancing clay. After a couple weeks of running them, I re-balance them. It definitely helps on drivetrain and speed.