Dallas J

iTrader: (1)

Ive managed to procratinate on ordering a front lower control arm inner bushing and now after about 60 runs on Hankook Z214 C71s I have a corded annulus on the outer edge. Static camber is 2.8*, and the suspension has changed from:

Bilstein/GTworx - stock front sway bar / hotchkiss rear @ full stiff
Bilstein/GTworx - Whiteline FSB / Hotchkiss rear @ full stiff
AMR 10k/12k coils - Whiteline FSB / Hotchkiss rear @ various positions

Tire pressures fall off dramatically around 38psi up front and I ran normally 33psi cold and let it rise up to 35 or 36 psi (depending on how hot I could get the tires). I'm very methodical with setup and generally like making one change at a time but this time I'm doing a few things all at once.

The camber change I make is partially dependent on an assumption of how much camber is being lost through bushing deflection. If more than a degree is assumed then 2.8-3* may be OK to stay with for now.

New changes will be 12k/16k rate change, Front LCA inner bushings, TRE Max Lock diff, rear diff bushings, and fresh v710s in 245s (For local stuff since the Portland lot is nasty abrasive).

So, how much camber am I loosing to the stock LCA inner bushing???

madmax199

iTrader: (20)

I wouldn't think that much camber get loss from the inner bushing alone, what's really detrimental is the dynamic toe change that result from deflection of that worned bushing.

However, since you are cording your outer edges, a lack of roll stiffness and static camber compensation play the main role in your tire wear. Get the roll in check and you will have less camber loss chewing your outer edges. More static camber compensation could help too but at a cost(decreased braking, exit traction etc). Another thing that's your friend (if your class permit) is caster, you'll actually gain camber in a dynamic state allowing the same temperature spread and tire wear with less static camber compensation.

Dallas J

iTrader: (1)

Thanks, I have a pretty good feel for suspension setup from a couple years doing FSAE suspension but its a little hard to guess at how much that bushing is moving. Guess I need to do a little modeling and FEA to get a good guess.

Good point about the toe change, hadn't thought about that aspect. Even though I race with static toe out, I could losing all that with the stock bushing. I do have the bushing on the way and new springs to jump +2k/+4k f/r respectively, and I have a the WL FSB so I shouldn't have to worry about front stiffness.

One thing that was brought to my attention was the fact that my co-driver which is pretty quick but still new may be turning more when understeering mid corner. This only increases the shoulder scrub. Im pretty good at un-steering when I'm understeering from years of Tom Katzian (local Evo school instructor) riding with me but I don't think the co-driver really knows that.

So changes Ive made, New V710s, Front lower control arm bushings, 12k/16k springs, and TRE diff. I guess I'll see the difference in 2 weeks at the next event.

03whitegsr

iTrader: (8)

The stock bushings don't have a ton of rubber in them. The front bushing only has about 1/8" thickness of rubber surrounding inner steel sleeve. That's the only place you'd really lose camber.

The rear bushing has probably 3/8" to 1/2" of rubber and as mentioned any movement there would lead to a change in toe more then anything else.

I had 10k/14k rates on the stock swaybars and found the car to work a lot better with closer to 4* static camber in the front. At 2.5ish I was killing the outsides of the tires.