When is it spinning out(starting off the line ,when you break?
If it is loose it should not spin the car out

Coming out of a turn, When coming out of a chicane going into the straightaway.

Yes a slipping diff could do that because it may give more drive to one wheel while the other is slipping. IMO diffs should slip under only very extreme conditions if EVER!

I agree, as I too have been learning how tight a 1/12 diff should be. A local racer has been instructing me to go tighter to get out of the corners better.

I noticed that my rear tires do not wear much differently from left/right now that I have been running my diff tighter. With a tighter diff I have been able to get out of corners quicker, and get off the line straight during the start.

My problem is that I ran Touring Car for so long, that I had to re-learn how to tighten a diff.

I run a 12R5 with Kimbrough spur.
My question: I have 6 balls in the spur. What difference if i would use 12
12 instead of 6? would it be smoother?

Thx

Well i really dont know why, but everyone i have talked to in the past have said use the outer wholes.

you should use all 12 balls. it will allow you to have a smoother, longer lasting diff. it will also allow the diif to be a little looser as you don't need to apply as much pressure ont the balls and rings to have the diff not slip.
E

wrong forum, whoops!

twelve balls in the outer holes allow for the pressure to distributed evenly across the diff ring, thus allowing for smoothe action.have you tried the Slapmaster Diff kit? It really does smooth out the action and makes for a more consistant action.

anybody know of an online store in canada that sells prs pinions and spurs?

thanks

I searched this and got a lot of old answers and most of them were all over the place. So I am asking again -
What is a good rollout starting point for 13.5 Speed Passion for a fairly tight carpet track?

Any help is greatly appreciated.

Thanks
Tim

I would start around 68mm and go from there.

Just a curious question about why the front arms on 1/12 scale cars have evolved to the lengths that they are? Would longer upper arms be of benefit or would it screw with camber gain and bump steer or something else?

There are some who do run a longer upper arm. Some people take one of the extra caster blocks, cut the top part off, and place that between the caster block and the arm spacing it out. The CRC front end has a long upper arm conversion for it that I am running on my car now.

So what is the benefit of a longer upper arm in your opinion?