While the thrust bearing does increase longevity the trade-off is that itadds drag. A diff built without a thrust bearing will be "freer"

For those who already have a slapmaster thrust bearing and have found it to add more drag than you like, it spins much more freely and works great if you flip the two slapmaster washers so that their flat surfaces touch the caged balls rather than the machined-in groove side. With the flipped flat washers, my thrust bearing equipped diff now spins just as free as it did when I used a regular diff cone riding on the outer bearing. The more "normal" diff cone setup (without a thrust bearing) does ask that plain outer bearing to do a job that it doesn't like. Time will tell how long this revised slapmaster assembly will last. After a full weekend of running mod, it stayed super smooth and totally free. Seems like that was a good suggestion that Brian posted a while back.

Darn how did I miss that post! I'll have to go back and find it.

And last just as long if its properly maintained. But I check over my entire car after every race day; nothing else to do while I wait 2 weeks to run again, lol.

I'll ask again

My diff is free. it will turn against the drag of the motor. And the diff will do it's job even with a bit of drag. Spinning diffs are overrated. In most cases the only difference between a "free" diff and one with a bit of drag is a slight difference in rear bite, very slight.

Depends on the layout. A superfree diff is indispensible on a track with several 180's.

I used to think that as well as I used to only run on asphalt. After running carpet a few times now I was quite surprised how much of a difference it made there.

I usually drop 6-7 teeth and then go up from their depending on temp. I drop that many just to make sure i dont burn anything up.

In a class where tenths count because you're losing them for eight minutes, not five, very slight isn't good enough. A free, but slip-free diff is an essential component of a good handling 12th car.

Thrust races make the diff stiff and 'lazy'. There is nothing wrong with the ballrace used as a thrust race providing the diff is glass smooth and has absolutely no slip at all. They last much longer if you have a belleville washer between the nut and the thrust cone, as this takes the side knocks when you hit the boards.

I have run Corally thrust races for ages, and couldn't believe the improvement in turn in and power out from corners when I switched back to a ballrace. The ballrace must be very clean - no grease or oil - and then have one drop of synthetic oil in it to help with friction on the cage. Any grease or thick oil and the ballrace will slip, meaning you have to do the diff up tighter.

Here's the definitive diff-building advice from the man himself - Dave Irrgang.

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

One last tip - make sure to use a steel ballrace, and not a ceramic one. The ceramic ones have to be done up tighter as they slip more due to the ceramic coating. HTH

Good thing Bodine wasn't using a ballrace in Vegas. Otherwise he may have really blown everyone out of the water.

You guys are great! Actually, I have been playing with the back side of the thrust washers since before Vegas with no issues. I just have not endorsed it just yet. Yes, I have noticed just a bit more parasitic drag with the grooved washers vs using the cone & belleville washer. I have always felt that the car can easily be set up around it. I have been telling a few drivers to flip their washers to test. I tell them if they blow their bearing out, I will replace it.

I still say, if you want to reduce your diff maintenance and increase your reliability; run a thrust bearing. If you are bent on having the silkiest diff and don't mind keeping a constant eye on it; use the cone washer.

Brian

That was quick. Were your ears burning?

I think that's pretty much what I said a few posts back. Thanks for the back-up.

Around what are these worth? Interested in one just don't want to pay more then there worth.

Here's a link to the one Im looking at
http://www.hobbytalk.com/bbs1/showthread.php?t=308384