Hello all, when I go racing my RC18T on a local asphalt parking lot track, I have severe understeer. I literally need to slow down to a crawl to turn, but I am great on the straightaways. My truck is mostly stock except for ProLine Road Rage tires. I will be getting adjustable turnbuckles today and start working on adjustments and I don't know what to work on first. Here's my current setup:
Rear shocks - 40 wt. oil, stock mounting locations, blue springs, dogbones level
Front shocks - 40 wt. oil, stock mounting locations, blue/gold springs (understeer on both), dogbones level
I enter the corners fast, but the car PUSHES in the turns pretty bad. I can't get back on the throttle unless the truck is almost straight again. It seems as the truck just doesn't want to turn. I still managed to finish 1st in the A-main and I beat the lap times of the fastest 1/10 brushless mod car with lipo. I just got a new mod motor to go faster, but now I need to set up the truck to turn with some speed. Do I need more traction in the front or rear? Do I need more toe in, toe out, camber? I'm lost! Please help!!!
The Road Rage tires in my experience has been if you are not on the perfect surface. They under steer like crazy. I like my Road Rages on new pavement but on almost every other surface the under steer. If you looking for street tires the Losi Street Meats are not bad and I have actually had good luck with the stock Mini L8ight model tires.
My RC18B is purely a flat surface car. I added some droop-limiting spacers inside each shock, which took out a bit of roll. It wasn't easy as I had to make my own out of some small brass tubing. I put 1.5mm in the front and 2.5mm in the rear. I'm running 3Racing shocks, Driven Production spring retainers, and Associated springs (gold front, blue rear), oh and I'm running for your reference.
But tires make the most difference. I run Tamiya M-grip 60D tires and wheels (with 3Racing touring hex adapters) which give me plenty of steering on carpet but hardly any on asphalt.
how tight is your diffs and are they locked if so this is the problem
My diff's are set just fine. Like I said, I won my races, but I want to turn a little better. My front diff is 1/4 turn out and the rear is just about 1/2 turn out. I changed my front camber to about -1 degree and front toe to 0 and it seems a little better. I also added a DP steering link to tighten it up a bit and it works ok. I may just have to bear with it until I can get new tires.
My diff's are set just fine. Like I said, I won my races, but I want to turn a little better. My front diff is 1/4 turn out and the rear is just about 1/2 turn out. I changed my front camber to about -1 degree and front toe to 0 and it seems a little better. I also added a DP steering link to tighten it up a bit and it works ok. I may just have to bear with it until I can get new tires.
im not sure what mine are but take the diff out and lossen it hold both ends i have mine set so it BARELY slides under a good amount of force they dont slide on take of but are very loose then match them on how hard they are to turn i run foams every where ilove the feel they have try them note they are 10th scale bsr tires.
The stock servo saver is very weak on these cars. I have a B, T, and R. All of them pushed on high traction surfaces no matter what tires I used until I strengthened the stock saver. A good cheap fix is a spare shock spring. Cut a coil off and wrap it around the servo saver, you may have to experiment with the length to get the proper tension.
Try adding some droop to the rear and softer spring and oil in the front. You may also might want to take a look at buying the XXX Main book for Touring Cars. The basics of weight transfer it talks about will help you out.
You push through the turns because your rears have too much grip. If you add some toe in to the rears, you could lose a little rear grip. Alternatively, you could add some weights in the front to make steering inputs more pronounced. You don't have to add a lot; just enough to lessen the amount of push. 4wd cars are notorious for having understeer, so you're always going to have some. If there were a front one way diff available, things would be different..
First of all, running slight toe-out on the front will give you more initial turn in but will give it more push leaving the turn. With as much travel as these shocks have, the droop is crazy.
Set your truck down and compress the suspension, then release it. Now, put your fingers on the 2 front tires and pull the front shock tower up, and notice how much it lifts. This is the droop in the front end. Basically when you get on the throttle the front end is lifting like crazy causing a ton of weight transfer.
SO... what I did was put 3-5 small O-rings (like are included in the shock rebuild kit) under the shock piston to eliminate this. Do keep in mind this can affect your ride height depending on how it's set.
Also, you can run thicker oil or a stiffer spring in the rear. Or, run the rear of the truck sitting higher than the front....
When you get the adjustable turnbuckles, try running 1.5 degrees camber in the front and 1 degree in the rear. I don't know what the stock plastic links set the suspension to.
All of this, plus what everyone else has mentioned with the diff's and steering...
The possibilities are endless......
And MIP does make a front one-way. I ran it in my 18R. Talk about turn-in! I think it'd be decent for medium or low traction surfaces, like asphalt, but on our carpet track it was a bit too much for my liking.
Thank you all for your input. Since I originally posted, I got the adjustable turnbuckles, a DP steering link, and put two coils of a spring around the servo saver. I setup my 18T using Tony Phalen's setup and it is much better now. I will be going to the track tomorrow to see how much better it is in a racing environment. I'll let you all know!
RC18T understeer on asphalt...PLEASE HELP!
