No i am not, i'm using fast lane diff cups and integy aluminum diff cases front and rear. I think they are ok for now, they have lasted me over two years with no problems.

If you keep the cell count down you should be fine. More cells eqaul more power and weight.

That is true. I think i would like to upgrade to some UE diffs 6 gear i think. Whats the difference with the 6 and 8 gear diffs anyways, is one stronger than the other?

The 8 diff supposed to be the toughest. The 6 supposed to tough. I got the 6 diff coming. I go from there. It will survive in front no problem. The rear will go first. I don't think I have nothing to worry about. Make me want to put a big motor back on my truck. Have drive train to support it.

How about a 7xl in a rc10l3 at 24volts? I'm thinking about a similar setup for my l3.

for 24 volts i would problably go with 8xl. Just my opinion.

In an L3, go with a way smaller motor. Something like a lehner basic 2000 or something?

Yeah, the Feigao xl motor is severe overkill in a pan car. basic xl or similar would even be overkill, though not nearly as severe. It sure would MOVE, though!

I'm looking for a speed record that can touch 125mph or even higher using a gear ratio under 2.1:1. Yep, I guess the 7xl is not a good choice at all, but the lehner xl 2400 would do the work or something with lower rpm. The kontronik FUN-500-19 motor is a very good choice, too. These kontronik motors are fantastic and I still think that its a good idea for Mike to test one of them and see for himself.

Well i received my 7XL today. I installed in my truck geared it 18/66 with 12 cells and wow what a difference compared to the 9L. Not nearly as fast but a lot more powerfull and smoother, no cogging. I am charging my 7 cell packs right now and will go out for another run to see the difference from 12 cells. Oh yeah temps were at 155 degrees after a full run, not bad i think.

Have Fun!
I like the 7XL on 14 cells best. Seems to be quite efficient on 14. Occasionally I run 16, works well too.

Thanks dafni, do you run your gearing 18/66?

Yepp, 18/66 for small tracks with lots of partial throttle, also works fine on gras, and I always keep it on 18/66 when I run 16 cells. This gearing is also great for bashing around.
20/66 for those big tracks (which I still have to find in my area :W: ) and parking lot sessions. And I think for speed runs, you could still go a bit higher.

Theoretically, 18/66 (1:18) and 14 good cells should give you 35mph. (KV rating from BK, stock tire size)

Optimal gearing depends on weight and other factors, too. So no two trucks are identical. Motor temp is a good indicator for finding proper gearing.

Yeah i just go back from my 14 cell run and yeah its fast enough for me. The temp on the motor never got above 160 degrees, which is a huge change from the 9L. I think so far i like the 12 cells for bashing because the run time is so good and i think i'll stick with for 14 cells if i ever go to a track someday. My truck is weighing in at around 9 1/2 lbs so not heavy at all.

Sounds like you like that motor there mike d. You thought you would.