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sower
2013.04.12, 05:08 PM
Hey guys. Ok, I'm not too good at setting up a car and could use some help here. I picked up a sweet MR-03 recently that has just about everything you could want. It has the PN double a-arm front, PN Reconfigurable Mount rear, PN lightweight diff, etc.

Well at first I was getting no turn in going into a corner down the straight so I pulled up a nice write up by Brian Ma (Greyscale) and used the same front setup. Huge difference!

Now my problem is that anytime I give the car any throttle the rear end breaks loose immediately. Not only that, but when I come down the straight into the corner - when I let off the throttle the car's rear end just spins around. I'm running at 94mm with a 575gtc but have tried the SC430 with no difference.

For a radio I'm using the EX-1ur too. Can anyone help me out here? Oh, and we're running on a RCP track in my shop and my tires are all Kyosho 20's. Thanks for any help!

chad508
2013.04.12, 05:47 PM
Sounds like a diff problem. Have you oiled the thrust bearing recently? May just be time for a diff rebuild

josyskunk
2013.04.12, 06:39 PM
All Kyosho 20s ? Front and Rear ? I think that is problem. You should try 30 Front

sower
2013.04.12, 07:36 PM
We've had great luck with running 20's all around - are you sure that's the problem?

TheSteve
2013.04.13, 05:46 PM
I'd also recommend trying 30 fronts.

chad508
2013.04.13, 06:33 PM
Wow I didn't even see the 20s all around. I still think you have a diff issue but fir sure need to go 30s if not 40s

color01
2013.04.13, 07:12 PM
I haven't been away for that long. :p

Kyosho 20's in front isn't unworkable but it's not recommended for RCP, the rubber heats up a lot from scrubbing and can cause spin out problems as you mention. That should be the primary cause of your on-throttle issues, just too much front bite. ;) Kyosho 30 (Slicks will bite more, Radials with corner more efficiently) is a good starting point, then there is the full range of PN compounds between 15 and 25 that you can play with once you've got the hang of it.

sower
2013.04.14, 03:39 PM
Well, what I don't understand is how all the guys running 98mm have 20's on the front and they're hooked up. Most of us have had good results with the 20's and before adjusting my front end, I was running the 20's and had no front end grip. Now it's the rear.

I don't know, I will look at the tires and see how that impacts things. Then I'll look at the diff and do a re-build. And it's not just on power where I lose rear grip - it's also when I let off coming down the straight into a corner.

cowboysir
2013.04.14, 05:05 PM
As a possible (maybe unlikely) effect of using 20fronts:

Which body do you use and do you think it's weight distribution might affect how your 20fronts work? Of the 98mm bodies I have the Audi (being the lightest overall in the front) could benefit from using grippier front rubber where the HSV uses 30front and I couldn't use any grippier rubber without oversteering.

Just a thought.

imxlr8ed
2013.04.14, 09:13 PM
New 20s... Better have some real stickiness on that rear! Well worn 20s on the front... Do-able, but I'd run a pretty stiff front end setup. PN tires are a totally different beast, 6s, 10s, 15s on the front can work out real well on some tracks. Once again though, the stiffness and camber would go up as the tire durometer went down.

Never an exact science here, but I'd have to agree with the gang here. 20s all the way around is a tough setup to work.

Right now, I'm on the 30 front, 20 rear setup more than anything else. One of my rides has a set of 40s on the front.

Check that dampener too, if you're running one. Cleaned and lubed disks work wonders sometimes!

blt456
2013.04.14, 10:20 PM
At my track, I experience this issue when I don't true my front tires down enough. Whenever I drive with front tires that are slightly too large, my car will drive as if it has no rear traction. I helped one person yesterday with the same issue as yours and we narrowed the problem down to the front diameter being too large.

Maybe you should try to reduce your front tire diameter. After breaking in the tires, if your car still spins out, try cutting the tires a bit more. If the problem still exists, then you should try a different suspension setup.

color01
2013.04.14, 11:02 PM
Well, what I don't understand is how all the guys running 98mm have 20's on the front and they're hooked up. Most of us have had good results with the 20's and before adjusting my front end, I was running the 20's and had no front end grip. Now it's the rear.

I don't know, I will look at the tires and see how that impacts things. Then I'll look at the diff and do a re-build. And it's not just on power where I lose rear grip - it's also when I let off coming down the straight into a corner.
That usually happens when you have too much front grip lol. Once upon a time I ran an MRCG with Kyosho 20's all around, but it was a tough beast to drive until the rear tires were fully warm. There is no way I'd ever be able to put that setup on an MR02/03.

It's not impossible to use Kyosho 20 fronts, but if the setup won't handle it, it won't handle it. I would stick with 30's to start with, and see if you can add enough rear downforce to make the car understeer like crazy. At that point you could try trued-down 20's, but really, they overheat and wear down so fast I personally don't feel like that is worth the extra grip.

sower
2013.04.15, 09:22 PM
You guys are awesome - thanks so much for the help! I've been playing with different tires and that's definitely a huge part of it. I've also been toning down the sensitivity on the steering on my TX. After working on it, I'm not sure if I want to do the 94mm length though. The last car I ran at 94mm was an AWD and it was awesome because it was heavier. This MR-03 seems to easily get thrown off course.

That brings up another question - is it possible to change the CF base plate to the 98mm and be good for that length, or do I need other parts as well? I have the PN Reconfigurable Mount. Thanks again everyone!!