I enjoy sharing thoughts here but consider that what I share is based on my research, building my car, and now add to that working for a great pro touring suspension company. When I designed my suspension I intended to make a presence at autocross events with a car built on a budget. I drive it everyday, but I'm pretty serious about going around corners as fast as I can. In time you'll see even more changes to the suspension as I get out to more events and hone my driving skills. I wanted to throw this in as if to say what I might suggest is because of the way I drive my car and may not fit everyone's build. On the other hand, my philosophy is if you're gonna build it, you'd just as well set it up so that it does well when you do go to the track. Even if you only occasionally see track time, at least you know your car is better than your driving skills and not boring because your skills are beyond what the car can deliver.
Chevy- We have done it this way in the shop before with coilovers. To avoid clearance issues between the shock and bolt heads we'd recommend running the bolts down through control arm with the nuts on the bottom, you may even need to use button head bolts. Not sure on the UMI arms you just have to be sure you have decent clearance between the bolts and the shock body. It would be easy enough to mock it up with your current hardware and if there's any issues a quick run to the hardware store could get you different style bolts.
Steve- Isn't it great how things evolve? At first we experiment and work with what we have, then in time companies take the ball and run with it developing something even better.
I thought of doing the B body swap when I first put my car together but after researching things decided against it. At the time the Hotchkis arms to fix the camber curve seemed spendy and to get a better camber curve is duplicatable with stock spindles and tall ball joints. Keep in mind too the steering arms are intended for,
and in position for, a B body car, which is completely different than a G body. The way the car turns and how all the suspension and steering components react to hard cornering will be different too. Consider this, if GM could have used the same parts on each car they would have to cut costs, but instead they spent plenty of $ developing suspension components matched to each individual car. B body or 2nd gen Camaro taller spindles adapted to a G body was a good idea in theory but not necessarily the
optimum set up for traversing the cones. My opinion is it worked until something better was developed. How much of a better time will either suspension choice translate to at the track? Probably no one really knows, you'd have to have two identical cars except the front suspension set up and have the same driver go beat on both of them to really know.
Bump steer can be felt the most under full lock steering, like pulling into a parking space. It's when the tires are not pointed in the same direction to manage the different curve radius' the tires travel around corners. When bump steer is high as they fight each other trying to travel different paths the steering will bump back and forth. You don't really feel it as much while driving the car but it's there to some degree. As the suspension articulates the steering linkage becomes "shorter" or "longer" and changes the alignment. You will see this accentuated if you slam the car and the tie rods point upwards as they head to the spindle, which is to say extreme lowering a car alone isn't the answer to better cornering. Basically said, in a racing situation you want to set things up so that everything remains in a manageable range so that all parts work in harmony to get around the curve. Changing the caster setting for the positive on G bodies and getting the camber curve towards the negative all play factors too. I don't know much about those Hotchkis arms and what they changed in geometry settings but my understanding they were designed specifically to help with the bump steer that the taller GM spindles caused.
More aggressive caster adds to more aggressive handling in most cases but changes the way the car feels for normal driving. We recommend generally that caster be initially set around 5 deg positive and you can add more as you tune your individual set up. The combination of our upper and lower control arms comes in about 4 degrees positive on their own and the alignment will add more.
You're on the right track with wanting to swap in coilovers, it's so much easier to make adjustments with the suspension all intact rather than tearing it all apart again and again to get the optimum spring in there. Now that I've been driving the car for almost 2 years and have raced it a bit I'm leaning towards the convenience of the coilovers too. The biggest advantage you'll see from swapping over is better spring rates and compression/rebound adjustability, added to that the ability to tune things on the fly. The control arms themselves positively affect the geometry more than a coilover will, and adding the AFX spindle with the custom relocated steering arms adds even more benefit. Hopes that answers your question.
Speedtech makes a "Chicane" bracket kit that converts a regular chassis to accept true coilovers with standard (non hybrid) coilover springs. We sell them for all the cars we make parts for EXCEPT the G body, see here...
http://www.speedtechperformance.com...duct_id=12/category_id=23/mode=prod/prd12.htm The biggest factor is that G bodies are a little behind the popularity curve in the pro touring world compared to the more common Camaros and such. I asked the boss again today about it and his response is we need to see more G body demand. By far we sell less G body stuff compared to the other cars, I think most modified G bodies are going straight real fast instead of chasing cones. When I'm ready to pull the trigger I will be bugging them more and suggest my car is the guinea pig to develop the brackets for the G body. Having you guys speak up (and buy more parts
) will help put the pressure on to add those coilover brackets to the line up.
