Slow Car Fast
January 18, 2011 - Since I had the welder out and the front wheels off, the obvious thing to do is to add a front sway bar.
The car needs more roll stiffness, and I've been looking at how to add a front bar for a while. Of course, I'm trying to use a Miata part because I have a huge collection of them.
I built a couple of plates with studs in them and welded that to the bottom of the frame rail. I considered simply installing some rivnuts, but the sway bar mounts see quite a bit of load and I can see myself ripping them out of the frame. So I have a nice solid mount instead.
The geometry would have worked better if the bar was on top of the frame rail instead of underneath, but the packaging would simply not allow that. Even if I could cut a big enough hole in the panel above the rail, there isn't enough room for the bar to go between the engine and radiator. We'll see how it works. On a short drive, the car did feel more settled. Too much traffic to try out the handling balance. I'm still dialing in the spring rates so I'm not sure exactly what the sway bar sizes will be yet. This one's off a 2004 Mazdaspeed turbo Miata. Why? Because that's what I had on hand! If I want a softer bar, I can use a non-turbo version. If I want an adjustable bar, I can use one of the Flyin' Miata ones.
And yes, I have an idea for a rear bar. We'll see if it will package.
entry 536 - tags: sway bar, handling
January 5, 2014 - The MG's seen some action.
First, I took it to the track again. I finally got the chance to see how it handled at the limit without the big fireballs. The answer? Not that well, really. The car was oversteering badly, feeling like an arrow flying backwards. On the sweeper, it was actively trying to kill me constantly. The steering still had the wobble in it I didn't want. I tried adjusting the rear suspension pickup points (based on something I came across in Mark Donohue's "Unfair Advantage", of all things) and it helped a bit. But it was still twitchy and difficult to even drive on the interstate without the car exhibiting roll steer.
But I noticed something. The front tires were worn as if I had significant toe in. Lots and lots of it. So I checked, and sure enough. The toe was way out. I fixed that and all of a sudden the car was much better. The odd roll behavior went away and the steering dead spot disappeared. All of that chasing around, and it was just a bad alignment. Which is odd, given that it's been aligned before...
I also took the car out to a Corvette autocross, which they found fairly entertaining. Unfortunately, I simply didn't have enough tire to deal with the torque of the engine on a first-gear course and finished 4th overall if memory serves. Still, it was a fun day.
So it's mostly a driver right now. There are still some things that need to be sorted - in particular a vibration from the transmission leaning up against the tunnel under load and the bad reverse selection - but those don't stop me from driving it. That steering problem really took the fun out of it. That's been sorted!
entry 648 - tags: track, steering, handling, autocross