XRAY - Model racing cars

I'm currently using the 2mm swaybar in the front as part of my setup, but I'm still having trouble with keeping the rear end planted at mid corner. If I don't true the tires before every run, or I use a different body, or make any slight change to the setup, it makes the rear end inconsistent. I've also found that with the correct preparationi I have great traction if corner entry is perfect, but if I'm a little off line the rear breaks loose abruptly.

My question is this. Will a front sway bar that is too stiff, when mated to the very rigid XRC chassis, with a maximum wheelbase, keep the rear end from rolling and digging in for traction? My car is also significantly lighter than the stock FK.

I understand the dynamics as to how a less stiff front sway bar should decrease rear traction by increasing front traction, but I'm thinking my setup is an extreme circumstance where the opposite is true because the rear end is too light to fight against the front anti roll bars force on the rigid chassis (basically the car is kept flat, except for front to rear & vice-versa weight transitions).

My other thought is that it might help if I increase the weight over the rear by decreasing the wheelbase.

My front end setup currently allows me to gain A LOT of time on corner entry and a little more on exit, so I'd like to keep it the same as much as possible. I've tested changing the springs, oil, shock position, tire compounds and toe-in for the rear, but have been unable to stabilize it unless I do a complete alignment check and true the tires before each run. And even then it seems if the track grip lessens even slightly, my rear tires abruptly loose traction mid corner.

One good thing of note is that it has allowed me to get a little better at making quicker throttle changes to compensate when the rear breaks loose and I've also learned a new knack for "drifting" on mid traction carpet (not kidding either).

I've never run much on carpet, but as a rule I try to set the car up without the sway bar. The use of a 2mm bar suggests to me that the car may be a little undersprung.

There could be a great deal of things going on with your set-up, but after the springs I'd look at maybe slowing the body roll by changing to a thicker oil or less holes.

To me this sounds like "push-push-snap oversteer"??

teamgp

have tried an lighter sway bar? What could be happening is that your front is too planted and are twisting in the rear enough to pick up a rear wheel. I believe XRay has 2, 1.5 and 1mm sway bar. I usually try the extremes first and then adjust from their. You may find that 1mm still give you what you want but also keeps the rear in-line and planted.

I am just speculating since I don't know your entire setup

so your saying the car is great until you hit a slippery spot or try to carry too much speed mid corner.

well just to brain storm with you, i'd look to fix the "too much speed mid corner" because there isn't a ton you can do about the slippery spots. I know you mentioned there wasn't much body roll, but there will always be some, and what roll there is can be slowed down. I usually find that if the car is sketchy I can make it more consistant by slowing the body roll. This may create other problems, but it's not a bad place to start. It's all about compromises.

Lets go through some more head work:

if your running so much sway bar and a really stiff spring in the front, why not try softening that stuff up and go with a harder shore tire up front?

"my rear tires abruptly loose traction mid corner" There has got to be something pretty radical happening to cause a neutral car to abruptly oversteer in the middle of the corner. You've seen the car run, are there any other clues she may be giving you that your glossing over?
this is fun_
push

a few thing i see that differ from my set, up which is race proven for oval or touring, first i woul dget rid of those tires, racers at my lhs have used them before and they have proven to be very inconsistant, go with a trc pink or magenta, secondly, move your rear shocks to position 3, also move your steering tie-rods to postion 2 in both locations, you will find steering will be smoother, and will have less tendancy to over steer mid corner, i know this sounds like alot of changes but hey it works for me so maybe you couls use some of it, all i know is that those tires realy arn't very good and are very inconsistant, ie, they spin out alot! i also run zero anti dive and anti squat, ie i run them in the lower holes.try all or some of this and see if it helps let me know if it did, so i can make a note of this in my set up note book.

sound like the rear end can't load the tyres. Either too soft at the back or your are running to much negative camber. Could try putting the camber links on the lower outer holes of the shock tower. Forgive me If this has already been suggested I only read the top post

change the rear camber to -2 and run 2mm of droop measured at the end of the rear arm not under the hub carrier.

that will make the the back end more stable

It cured mine

Guys I am a bit surprised nobody stated the obvious here. He changed to a different style body and wing!

TeamGP seems you have found a great setup in concert with a Mazda 6 body. When you change bodies however you also change the aerodynamics and I think this is what is causing your "problem". The car is fine IF you run a Mazda 6. If you run the Parma Alfa however you will need to adjust the setup to suit the body. It may well be that this will never be as good as with the Mazda 6, or it may even be better.

Seems to me you have two choices: (1) develop a setup (using the suggestions made by the others above) that will work for the Parma Alfa, or (2) get a new Mazda 6 and make sure you put the body holes and wing in the exact same positions as on your old Mazda 6 (yes, even where the body is mounted will make a noticeable difference in handling!).