"Does anybody know what would cause the diff nut on my l4 to come loose all the time?"

IRS sells a nylon nut that has no threads. When you put it on the first time, the threads are cut by the axle itself, making a super tight fit.

Posi-Lock Diff Nuts
IRS203Y Posi-Lock 8/32" Diff Nuts - Yellow (6 per pkg)

http://www.teamirsrc.com/diffparts.html

What is a good spur/pinion combo for a 12L3 with a stock p2k2 pro running on a flat carpet track. Pretty short.

Check out www.gearchart.com
Good luck.

try a 96 spur with 25 pinion to start. Tire size around 47mm to start. I would get pinions 24-31 and try those and check your rollout. Also keep in mind the tire size.

Also, i run a pretty small track and from what i learned/heared, is that using a p2k2 isnt a good idea since its mmore torquey and 1/12th kinda dont want that. Maybe i am wrong.

Can any of you guys help with the gearing for 19t and a 3 x 9 then ??

Like i keep say it dosen't need to be spot on just on the low side so i don't fry the motor.

Come on, it's my first time out with a 1/12th cat in like 6months and i just can't remember where to start with the gearing suspose i can ask on the day if all of you really have no idea though.

It's really difficult for anyone to respond to these types of questions because it is really all about roll out.

With the 19t you probably should be around 37 to 40 on your roll out. With the 9x3 I would guess about 35 to 38 on the roll out. There are so many variables that there is no pat answer. I run my rear tires at about 44mm to 43mm and with a 9x2 I gear it 25 pinion and 98 spur. You also have to take into consideration how good your batteries are as well. If you have awesome batteries then you can increase the roll out numbers.

A few posts above this one there is a link to a roll out calculator. Try using that for a better guess.

John... I'm running 32/96 with a Monster and my tires are currently 45mm....

Sorry :rolleyes: i should have said rollout as that is what i would have expected my questin to be answered in since a straight 32/98 or what ever would have meant nothing to anyone.

Cheers for answering though :nod:

A P2K2 would definitely call for at least a 100 tooth spur.... I'll normally run about a 4 tooth bigger pinion in 48 pitch over a Monster when I put a P2K2 in a TC.... Never tried in in a 1/12th, too torquey... Need RPM's....

Your rollout is too high, its at 47.5 or something. I heard rollout should range from 30-40 or so, imaybe be wrong..

My rollouts are 40.

My motor and batteries come out cool and I can pass walter at will.... hehehehe....

I run a 30mm rollout in a TC... If you were to run a monster on 4 cells in a TC you'd have to go up like 6 teeth.... 30 just sounds way too low....

Thanks for the answers and info.

Ya but it isnt so much about the how hot your batts and motor is. It has to do with the motor winding up faster or slower.

I think if you drop a few teeth your gonna see more speed. 30 rollout does seem, low that why i run close to 40.

I need to learn how to do rollout. Can someone please PM me a link to where I can learn exactly what it is and how to do it?

In rubber-tire TC racing, I've always gone by ratios.

It sounds like knowing how to do rollout is important in 1/12th because the tire diameter is always changing...


Thanks,

Soviet

Rollout is the distance the car travels per motor revolution. You can find your rollout by using this simple formula:
rollout=(tire dia. x Pi x pinion)/spur

Here is an example, (1.85 x 3.1416 x 32)/100=1.86. Using a 1.85" rear tire with a 32 pinion and a 100 spur gives me a 1.86 rollout.

D.P.