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A little excerpt that illustrates the oversteer I was dealing with at first before I disconnected the rear sway.
That's a heck of a save right there and at that speed ! Do you feel like you are hitting the bump stop on the rear or front ? This probably be tuned out with stiffer springs.
Hmm, good question but I didn't feel any obvious bottoming out. I'll start with an adjustable front sway, that should be enough to get the car more neutral.
let me try a little mind exercise, This corner is an uphill , under throttle sweeper. if my mechanical skills are correct, you are effectively loading the driver side wheels , especially the rear one since you are under throttle. with soft oem springs and a disconnected sway bar, the rear inside wheel is unloaded and your open diff wants to transfer the power to the right rear wheel. With grip, this would create an understeer situation for a moment that would even out as you are tracking out but in your case, the rear becomes unstable. So basically you are running out of rear mechanical grip. Theoretically, you should increase the spring rate ratio to the front. ( meaning decrease spring rate in rear or increase spring rate in the front). A stiffer front sway bar might help a little in that sense but I doubt it will be enough without unbalancing the suspension too much.
How does the car react on turn 3 and what about turn 4 ?
A simple solution would be to source a lsd and stop worrying about rear traction when balancing the car suspension.
Yes, I'll be doing LSD over the winter, that's on my ever growing list of things to address during the off season. But beforehand I do have a VIR weekend coming up, so the upgraded sway will have to do.
With the rear sway connected the rear was washing out in just about every corner, so I wasn't able to put any power down out of the corners. In slower corners I was able to catch it, not so much in fast sweepers. With rear sway disconnected the snap oversteer was gone but the rear did bounce around a lot, so in faster corners like 9 and 10 the car would never settle down and grip was reduced, but at least it wasn't trying to kill me. My laps towards the end of the day were still about 5-6 seconds off pace. It's all good, it's time behind the wheel and an opportunity to learn the car and get comfortable with it.
Hmm, good question but I didn't feel any obvious bottoming out. I'll start with an adjustable front sway, that should be enough to get the car more neutral.
Be interesting to see how it goes with just a front bar, I don't know about 350's specifically but not all RWD cars have to have a rear bar in order to handle well.
I got the Megan Racing front bar installed. It's only maybe 1mm thicker than stock, but it's 3 lbs lighter and it has addition stiffer mounting holes. I went ahead and set it to stiff and reinstalled the stock rear sway bar. If I get too much push I can change the front setup to medium at the track pretty easily.
Yeah, the stiffer the suspension the less need for sway bars. Some race cars with stiff coilovers can run without sway bars altogether. But for a stock soft suspension this is at least a bandaid.
I also reinstalled the race mirror using some better brackets. These weren't cheap, but they allow the mirror to sit higher, closer to the windshield and further away from my head.
Back from a weekend at VIR. Overall the car did well with no mechanical issues whatsoever. The stiff front sway bar did help to keep snap over steer in check. I learned pretty much what I expected. First, open diff has got to go asap. Basically I was not able to power out of any of the sharper corners without spinning the inside tire and doing 60 MPH burnouts. Fun for the drivers behind me, not so good for lap times or the longevity of the hoosiers. It was an exercise in patience applying throttle around turn 1 and the oak tree. Second, the stock suspension is way too soft and bouncy. Every little bump in the tarmac results in loss of traction. I discovered bumps I never knew existed. So coilovers are also on my winter project list.
It was busy with between 40 and 60 cars in each group, hard to get a clean lap in. The best time I got all weekend was a 2:22 lap, which is ok I guess for a car with stock engine, stock suspension, open diff and stock brakes. I can feel the potential though, there is plenty of power in the straights and with a bit more camber and grip the lap times will fall quickly.
Made some headlight covers from cheapo ebay headlights. Decided to include some lighting, so built in a small LED units. Significant weight reduction vs. stock HID units.
I do need to pick coil-overs to install over the winter. While I'd love to do spec Z KW suspension, I'm not about to plop down $3K for a track car. I'm thinking something in a $1k range, so I narrowed my choices to either ISR Pro series coilovers or Megan Racing track series coilovers. Both have 14k/12k spring rates, both are dampening adjustable with true rear setup, but Megans are $1k while IRSs are $800. Is there any reason to spend $200 more on the Megans?
Most of your cheaper kits your are gonna have problems with the dampers blowing. Cheapest i would consider using would be bc racing. One nice thing about bc is you can buy a single replacement damper if one does blow and not have to buy a full kit or wait on sending out the dampers for revalving.
Don't know if you can get them in the US but MCA make a kit for the 350, in my experience they are excellent. One thing that most of us do with a track car is to try to save money on suspension which is not a good idea, value for money of course but real track suspension makes the car more fun to drive and improves lap times. It's a good investment.
While I agree in principle, I'm trying to find some happy medium. I had full blown KW V3 suspension on the Audi and while it was a great handling package it did run north of $3k and was a bit of an overkill and the dual adjustments were a bit too much for me, I could drive myself crazy trying to fine tune them just right, probably not the greatest choice for someone with OCD :P I think single adjustment is all I'm willing to handle for now...
I know everyone has their favorites and I do appreciate your feedback. Right now I'd like to concentrate more on specs than brands, I'm wondering what people with square tire setups are running in terms of spring rates. I've seen rates between 5k and 15k with some setups being pretty close (like the ones I listed at 14k front 12k rear) and some being way softer in the back (12k front, 7k rear or so). So with the square setup am I ok going with stiffer rear springs or am I gonna end up with way too much oversteer? Those running stiff setups, are you still running sway bars and if so what kind?
If you run true style coilover setup the rear spring rate needs to be much lower than the front, If running OE style coilovers then usually 2-3k lower than fronts.
The idea behind getting a good kit is that you get the right springs and correctly valved shocks, plug and play. From what you are saying this seems to be the way to go for you, OCD problem eliminated.
Personally I don't think any damper package under $1000 is worth it. You are better off saving the next thousand going with something like Ohlins DFV. Fwiw I run anywhere from 20-22k up front and 9-11k in back on a true style Penske set-up.
I can be convinced to spend more for something that worth it. Unlike the Audi where I had just a few options, the number of choices here is overwhelming. From what I saw so far, most square setups are running much lower springs rates in the rear than in the front. You're talking about 20k/10k (with full aero + power), the KW club sport coilovers that spec Z runs appear to be 855/455 or around 14k/8k (no aero or power adders). That sounds like the area I need to be in. I'm not planning to run aero right now but I probably will do something in the not too distant future. I'm also not planning to add power anytime soon. So I probably need to be closer to the spec setup.
rustyschopshop mentioned that true style coilovers need lower rear rates than oe style, however the club sports are oe style and still have much lower rear rates. Also, just looking at available kits I'm not seeing any direct correlation between coilover style and spring rate ratios front to back, so I'm not sure if that tracks?
Ohlins looks like a decent setup, however the DFV option of switching between road mode and track mode is not really useful for me, since this is purely a track vehicle. While I like the simplicity I think I'd prefer to have a real damping adjustment. I think I misunderstood the description, it does have a 25 step adjustment, so n/m...
The MCA race primes look good, translate to around $1700, which is not horrible, with 12 step adjustment and the spring rates 16k/7k, but I am not sure about buying a product with no US support.
Total $305 and I can sell the stock hid units for more than that, plus save some weight in the process.
For off-road use only since no turn signals and no real headlights (unless I connect the blue strobes to the turn signals lol)
Very useful. I didn't realize the stock setup rear spring rates are actually higher than front, explains a lot about how car is behaving right now (oversteer, rear tire lift) and puts to bed my worries about stiffer suspension making this worse. Most aftermarket setups stiffen the front rates by a lot more than the rear. For example KW club sport setup rated at 855 front vs 317 stock and 455 rear vs 427 stock, which raises the front stiffness by 172%, but rear only by 7%. Still not quite clear on the the advantage of using true coilover rears vs. stock spring location, there doesn't seem to be much going for it?
