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View Full Version : DIY MR-03 Antisway Setup


Digitalis West
2010.04.03, 11:25 PM
I thought my MR-03 would benefit from a front antisway bar. When the front of the car was stiff enough to have the balance I wanted, the car would bounce down the track. Thinking about it, I noticed the different way the spring end of the A-arms move. When the suspension compresses evenly, going over a bump, the ends of the A-arms move together. When the car tips in roll, the arms move in opposition.

I thought putting a spring between the A-arms would add roll stiffness without affecting the spring rate much. I bent up a spring I had and bolted it through the holes in my PN A-arms. I had to mill down the head of the screw I used to clear the springs.

The picture is clearer than my description. Please excuse the RCP fuzz... this it post race.

It works! I can now run a much softer front spring without traction rolling or having too much steering. For me, this makes the car faster and more consistent to drive on bumpy RCP.

There is still some tuning to do. I need to find a way to bend the springs more consistently and I need a wider variety of springs. It takes a lot of manual adjusting to get the spring right. The red springs I am using are a little too stiff.... but it works well enough to make my novice driving much much more consistent.

color01
2010.04.04, 03:50 PM
Very interesting. Geometrically not perfect but very simple and clever. :)

I think that with a little bit of modification, PN Racing's MR-02 anti-roll bar should also fit the MR-03 as the kingpin spacing and offset geometry haven't changed relative to the MR-02. That would be a slightly more plug-and-play solution and would require less hand-tuning each time you wanted to replace the bar.

Again, nice work!

EMU
2010.04.04, 08:46 PM
I like the idea, and think that there is too much bounce in the front end when I have it sprung well for the corners... I am going to try something similar, and see how it feels. Although I dont want to use a spring, but want to connect the inner upper arms when using soft springs on the RR long kingpins...

When the car corners, it should use the opposite sides spring as well as the one in its side to apply force on the outside wheel... Maybe part of an FRP t-plate between two washers, with an elongated hole for the screws to allow a little movement, but stiff enough to give anti roll...

Digitalis West
2010.04.04, 08:58 PM
There is no binding or hitting of the coils even when the suspension moves to the extreme limits. I also checked the suspension movement without the main springs installed and there is very little effect on the suspension loading from the antisway spring. The geometric compromises seemed better to me than potential binding or slop from trying to adapt an MR-02 setup... and I had the parts. But yeah, there is some development required to be sure. I will post an update if I figure out anything that works particularly well.