The last drift event of the season was Saturday.I need to improve the car so its at the level I've gotten to driving, so I finally made a big change suspension wise to the car over the past week. As I've progressed my skills drifting and moving into tandem and more multi car situations on track I've been suffering from a lack of forward bite, or traction to accelerate. All the lowering of the car changes the instant Center of the rear suspension and does bad things for traction. I installed the anti squat rear control arms from a 560SL. This involved making a custom sway bar with heim joints for the upper link to the hub carriers to use with my custom twin linked rear sway bar setup. I also machined custom subframe bushings and control arm bushings from delrin (actually UHMW-PE or ultra high molecular weight polyethylene and basically the same as delrin) rod I got at grainger.
The reason I've waited so long to try this was that I can't use my dual caliper set up on these control arms. Having a hydraulic handbrake is pretty important so it is actually set up temporarily with the foot brake only controlling the front brakes and the handbrake on the rear brakes. I don't really like this setup because in emergency evasion situations you have to grab the handbrake as well or have a greater risk of locking up the fronts and hitting a spinning car you are following. I will address that shortly.
The rear subframe bushings are just stepped bushings that replace the soft rubber upper donut between the top of the subframe and the car. It fits very snuggly on the 22mm tube that comes out of the bottom of the chassis and has a tapered step that fits nice and snug in the 45.5 mm hole on the top of the subframe. I made it 4 mm thicker than the original which lowers the subframe slightly and changes the roll center a bit. I'd like more, but flex discs won't tolerate too much missalignment I assume so I was conservative.
The control arm bushings are the same material and happen to have the same I.D. at 22 mm but have the center steel tube of the original rubber bushings pressed in. I used a couple pieces of tubing and sockets to press the centers out of the rubber bushing and used a really gnarly wire brush cup on an angle grinder to remove that bonded rubber. Definitely a pain in the ass but not as much as machining all new correct sized tubes to use in the bushings. They are 41.8 mm or so O.D.
The sway bar is actually the upper control arm in the anti squat setup. I made a twin, linked together sway bar set up quite a while back I can't remember if I posted about that or not on this thread. The shape of the anti squat sway bar and the conventional sway bar the r107 chassis has is not quite the same, so to use the same setup and also eliminate the rubber bushing that the sway bar/control arm attaches to the hub carrier I just cut the ends off another stock sway bar and welded grade 8 5/8" fine thread bolts on to the stumps and used 5/8 chromoly rod ends which put the attachment point in exactly the right place with a spacer to move it out to the correct location to clear everything.
The great thing about the way this setup worked is that the rear control arm mount/sway bar mount just bolts to the bottom of the car in a clamshell mount, flat on the bottom of the frame rail. It's directly underneath the spot the original bracket was that holds the original sway bar, in the framerail in a cut out. So I was able to use the space above it to hold the second sway bar in it's stock location which is up in the frame rail in its cut out, and put the new sway bar in it stock location below in the same bolt holes. So now I can simply use washers to lower the mount which increases antisquat of the suspension and increases forward bite.
The car responded incredibly well. It feels like a completely different car with these changes made. It definitely took a little while to figure it out, I was feeling a lack of grip and was spinning out. I was driving it the same as I did before with a lot of abrupt on and off throttle, basically full throttle to half throttle. The car never seem to be upset by it before but it didn't have the anti squat to load/unload the tire under power. When I realized the car actually was making more grip under high throttle I could then just slowly lift off when I had to and keep more traction. After figuring that out and adjusting my driving it was great. I was having trouble closing up on cars I was following before the changes and it's so much better now. I actually dropped the sway bar/control arm mount down about 4 washers or 3/8" half way through the day to see if there was a noticable difference on the second set of the same tires and there was.
I would have to guess the stiffend bushings and subframe bushings had a pretty good effect on the way that the car felt and behaved stability wise. Body roll was significantly reduced. The snap of the body rolling over in transition was much better and easier to predict.
This does mean great things but it may end my drift development on this car as it's still a rusty mess in places. Granted I've bashed it in a couple times but that is kinda less important. I want a car that will look decent and has a clean racecar type interior. It needs to be fully caged to take it to the next level with me. A r107 is a much shorter wheelbase and Will change directions easier and quicker. I have a rust free 450SL chassis and engine that I bought already stripped. It may end up getting built this winter with all the stuff I've learned from the SLC. We'll see about that.
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