Last for 8 minutes? My wife says the same thing about me.

My fronts have a little fuzz. The rears feel normal, at least what I would think is normal.

One technique in sanding your diff ring is do a figure 8 when sanding it, not circular or up and down. You will find it more even that way.

Since were on the diff questions. How often should you replace the diff rings?

http://www.multiverse.jp/QTEQ/englis...ringtruer.html

The ultimate diff ring sander

Who sells that tool ?
Great idea.

simple , low cost diff ring polish method

http://www.rc10talk.com/viewtopic.ph...=11937&start=0

Is the trend in 17.5 non-ramping still to run the largest spur/pinion combo you can fit on the car(that yields the correct rollout, of course)?

I see most people are running 76t spurs with 52-58t pinions. The larger gears push the motor further inward, away from the axle.

I have a couple 70t spurs laying around. Are these usable in a competitive environment? Obviously I can practice with them, etc... but do any of you hardcore 17.5 12th guys actually use spurs this small?

I like to use the biggest combo I can. The more forward the motor the better the car handles.

I believe that running the motor further forward does good things, but is hard to test back-to-back. I currently run 13.5 blinky at my local track and I am running a 47/88 gearing with tires that actually have some meat on them, but in order to test it I would a have to have somehow assembled the diff exactly the same with a new spur and that just doesn't happen

You do need to keep in mind it puts more weight effectively on the center shock and reduces unsprung weight (the rear pod of a 1/12 scale car is a massive amount of unsprung weight), so springs are changed accordingly.

Wouldn't be too hard to test back to back with an axle built with each combination you want to try...

Just got my first 12th scale car and I'm hooked. Also my wallet is a lot lighter, so I'm thinking of using a old Sherline lathe to true the tires. I intend to mount a SaburrTooth burr in the tool post at a similar angle as the Hudy burr. I haven't made the arbor or the burr mount yet. Before I spend time on this, I have a few questions.

I has anyone measured the run out at the arbor on a quality tire truer? Depending on how my 3 jaw chuck closes I could have as much as 5 thous. run out.

Is the foam dust corrosive or likely to melt when sticking to oil and grease on the lathe?

What rpm do tire truers run?

Thanks

How do you guys fix the jacos front sloppy bearing holes??

I've thought about this, but I already have a tire truer, and my metal lathes aren't very portable, but I think I can answer your questions.
5 thou run-out isn't going to be noticeable at all. We're truing foam rubber, which flexes and moves, 5 thou is really nothing in this case, and the wheels most tires are mounted to have WAY more run-out anyway. My Hudy arbor on my old manual Eagle Truer has a total run-out around 7 thou at the wheel mounting/centering rings. Sometimes I can loosen the pinch bolt and mount to a different spot on the motor shaft and get the run-out down, but again, it's not really noticeable.
I really doubt the dust is corrosive, or I should say there's no evidence of it being corrosive on my 8 year old tire lathe. The foam will probably make a gooey mess with any oils and grease on the lathe table, but it shouldn't be especially hard to clean as long as you keep solvents away from the foam powder. Dryer is better for cleanup anywhere foam dust could end up.
3600 or so.
Good luck.

Take a two thin pieces of tape and run them down the wheel into the bearing hole opposite to each other. Then push the bearing into the hole. The tape will help take up the empty space and tighten the bearing. You really only need to do the outside part of the wheel.

We do this with 3 pieces of thin tape in an effort to center the bearing and minimize runnout. Probably not necessary in many cases, though.