Snap oversteer/understeer

[whitess]

I've heard these terms mentioned a lot, but I don't know what they are and what causes them. Any help would be appreciated.
Thanks,
Larry.

[XcYZ]

Usually they are implying that the car goes instantly loose or tight with little or no warning. Some of the things that could cause that are a cut tire, suspension bottoming out, or the chassis bottoming out on the ground.

[Mean 69]

The late model Mustang guys use this phrase a lot. If you are familiar with the rear suspension design, you'll note that it is a triangulated four link setup, not unlike that used on the earlier A bodies and some other cars/kits. In this example, they are describing what happens when the system "uses up" the available compliance of the suspension bushings, and the result is a virtual metal to metal bind. When this happens, the car looses rear grip due to the immediate change in suspension bind, and the rear of the car comes around, right now. Having had a couple of these cars, it is a very real condition, not terribly friendly, pretty much impossible to recover from.

I have never heard of snap understeer, though I am guessing that it too could/does exist, I think the most likely scenario would be when something on the front binds up hard, and causes the front end to abruptly wash out.

Mark

[whitess]

Thanks all, that helps a lot.
Larry.

[Marcus SC&C]

Hey Larry! On your SS the main problem is the convergence angles of the upper arms in the rear. With stock Squish-O-Matic bushings and the U channel arms it`s not too pronounced because the front end will push bigtime before the rear ever gets ugly. Although it WILL bite you if you`ve got serious horsepower and get it sideways! I good friend put his big block `87 Cutlass into a bridge abutment like that. It`s aggrivated by low compliance bushings and box section arms with little or no torsional flex. We`ve had good luck with Currie Currectrac arms with their Johnny joints. It`s not the ultimate solution but they work very well within the constraints of the original suspension. As you know (and I know Mark will agree with me here!) a better solution is a 3 link like the one we`ve been testing and running in our G-5 car for 3 years or so now. Of course that kind of thing is a lot more pricey... Mark SC&C

[McssGmachine]

I hate to jack this thread, but do you have any updates on the 3-link Marcus?

Thanks