Could be anything from a seized bearing on one side to poor setup... Etc. Just need to take it apart and inspect every little component for signs of wear

Balance
 

Ever tried balancing your tires? Excessive vibration affects handling and wears out your suspension components faster.

You should first look at tweak, e.g if the chassis sits flat on a flat board.
Anything else could be useless if there is just tweak.
Then have a look at your diff
Cheers

Softer rear springs, shock position(less vertical), 4 hole pistons with heavier oil, rear diff - 1300CST oil, front diff - 2.5m Gravity oil.
Let off/brake earlier entering turns. Smoother throttle exiting turns.
Someone told me "slower is faster". Sounds crazy until you try driving that way.

If all else fails, get a TC6.2. It's a much better designed car. Easier to drive.

Tire balancing? Can you give a noob an example of how to do that?

here's one I've been using for a while now and I've been very happy with it so far:

+ YouTube Video

Tire balancing
 

There are different balancers on the market, some specifically for car tires. I use a Du-bro prop balancer since I also fly rc planes. There is also sticky back balancing tape in rolls available at AMain Hobbies among other online shops.

I can't post the URL's for the equipment but go to AMain Hobbies and look up tire balancing. They list the Losi and Du-Bro balancers along with the balancing tape.

The process is simple, once your tires are mounted and glued, you place the tire on the balancing jig and the heavy side will rotate to the bottom. You then cut a piece of the balancing tape and stick it on the inside of the rim at the highest point. Experience will tell you how a big a piece to start with.

Depending on the imbalance, the tire will now rotate to the new heaviest point. In some cases, you will need to make a bigger or smaller trial weight and replace the original weight. If it rotates not quite all the way down, you might have to move the balancing weight one way or the other to find the exact placement.

The real key in balancing tires is to make sure you have the tire exactly centered on the balancing spindle to begin with. When you reach the point where you can spin the tire and it never stops in the same position, you are very close.

Take note when you are holding your car and revving the motor. Do the tires look like they are wobbling and the turnbuckles appear blurry because they are vibrating so hard? This can translate to loss of traction because of poor contact due to the vibration.

If you race VTA, balancing is a must as the HPI tires and rims are so big and heavy it makes a huge difference in the handling.

Just bought a TC6.1 WC for TC 17.5 class. What would be a good setup to start out with. I have a TC6 that I run for VTA but I'm not sure if that setup would do well in a different class. The track that I mainly run at is 73 x 40 carpet medium traction. Also what is a good brand of rubber and wheels to run? I've heard of sweeps but never ran them.
Wil

Your via setup should be a good starting point if it handles well on the same track then adjust from there for the skinnier tires and lighter weight. I've run sweeps, much mores, and sore for tires prefer the sorex 32 and 36 shore on pavement

Thanks I'll start with my VTA setup then and go from there.

Hey Bill, does the balance stay consistent after a race day or do you rebalance them ??

Honestly, I might check the balance once a month and usually they hold their balance but sometimes the clay might fall off if I get tangled up in lap traffic or take a nasty hit into a wall so it might be worth inspecting your clay at the very least and checking your balance periodically. I guess it's all about how anal you want to be about it.

in off road we would cover the clay with CA glue, that would keep it from falling off, but the tires were done at the end of the day so never bothered to check. Will try balancing some on road wheels :tire:

Has anyone had the problem of the rear end fish tailing just slightly for the 1st couple of feet when starting at a complete stop?

rear diff is probably too thick... I like to run 80W shock oil in my rear diff.

Also try lowering your rear center of gravity.

Here's what I recently experimented with my TC6 on the rear links and I couldn't get my rear end kick out no matter how hard I hit the throttle in today's racing:

https://farm8.staticflickr.com/7071/...46cca6af_b.jpg