frustrated
 

I built one of the tracks that is one the www.xmodsrc.com web site. I cleaned out my garage and have it set up out there. The floor of the garage is real smooth concrete. At first i was running my XMOD rwd. I had heard that the AWD slowed it down and that is messed up the turning radius, so I never got it. When i was running the RWD on the course and it was awesome whipping around the U-turns ( I could go around them at full speed almost), but I had problems with the regular turns. It would spin out everytime unless i compleatly laid off the gas. So i broke down and went out and got the AWD. As far as speed goes it's awesome. If anything its faster because its not spinning comeing off the line. I can take the regular turns fine (a little bit of under stearing), but i can't take the U-turns anymore. I've tried all differn't tires, springs and tie rods. I've taken it apart many times and i can't understand how the turning radius is different. With rwd with out any spinning it was about 2.5-4 feet (depending on set up), with awd its about 5 feet. I can't understand it. Its frustrating because all i want to do is race around my track and i can't. If you can help please reply.

Ummm........try Hard springs all around. That helps me make really sharp turns around corners at really high speeds.

Ok I have been working on a homemade chassis and I have been looking at the parts very closely and today I noticed something.

As I was looking at the tierod and front knuckles and just moving it back and forth (AWD diff installed) I noticed the diff was moving back and forth, the axles press on the diff and move it alot, I laughed and thought great one more little problem.
I did not have the center shaft or front pinion gear in there so I could not tell how much it would bind up and at this point it is not important to me.

There is diffenently something off set on the front end that could be scrubbing the steering.(along with the tierod tab hitting the diff)
I will worry about that later I'm to far into making my third chassis version.

Check it out on yours to see if yours is the same.

B.C. I know you made a course, did you have any problems with U-turns useing AWD?

Yes, I did notice I had to slow down for the U turns with the AWD. I built the track after I installed the AWD in my outside car, so I'm not sure how the 2WD runs it. My outside 2WD car is a 6 cell, so that wouldn't be much of a comparison. If you want to increase oversteer, stick soft springs in the front, that will help it turn. I was also on blacktop, so it may be a little different for you.

try a stock differential in back. the ball differential doesnt let the wheels spin independently causing it to have a smaller turn radius

try putting hard slicks in the back, soft up front... then you might be able to just whip around U turns, as apposed to actually go aroound the turn...

thanks for all the tips. the last thing I tried was hard treds in the back and soft slicks up front. I'll put the stock differential back on and see what happens. If anyone else has any ideas please reply.

You might have better results if you were to slide the U-turns. Maybe try locking the rear diff, Hard springs in the rear, med-soft up front, hard tyres in the rear and softer ones up front. This should make your car more prone to oversteer. Maybe also try the gear diff. in the front.. that way when you go around a corner one front wheel should start spinning taking power away from the other slowing the front down, if you have locked rear diff it should have full power and power the rear sideways over the front.

I hope that makes sense, it works in my head but I dont know how it will work for you.

that might work but it might not. im not a genius but it could cause it to push the car through the turn instead of it turning at all.

I have had the same problem too. The reason is that now there is another dynamic added to the front wheels. Same thing as torque steer in full size front wheel drive cars. Try this as an experiment, go full speed in a big open area. Then turn with the throttle applied. No do the same thing accelerate to full speed but then let off the gas completely, wait a second, and then try to turn. With no throttle applied I guarantee that your car will tunr in half of the distance. to get around those U-turns, you are going to need to apply the brake to slide the rear, and then reapply throttle to slide through