allen_skillicorn

Curious what changed in your setup?

Vette's have factory adjustable ride heights, but I don't see you changing the rake much, if any.

Camber is adjustable, but would you really dial back some negative camber on street tires?

Maybe a little more rear toe-in.

Going from R's to street tires there should be less body roll, so soften the sway bar? Well, maybe run the front stiffer to help put down power?

I could see playing with rebound to not overload the lower grip streets.

I'm guessing the biggest 'setup' change would be changing tire pressures, but every tire has different construction and pressure demands.

If I'm mistaken, please let know. I hear a lot talk about setups in stock/street, but I'm curious of the details.

PedalFaster

Instead of pinching it between the jam nuts, just sit it on top of the spring perch -- that's standard procedure for high-end shocks (and what I did) on the S2000. Depending on how the stock shocks' diameter compares to your new shocks', you may have to bore out the perch (if the stock shocks are smaller) or fabricate an adapter (if the stock shocks are larger -- unlikely).



Odds are very good that an off-the-shelf high-end shock won't be legal for Street competition, since they're generally optimized for lowered ride heights and thus have shorter than stock lengths. The two builders I linked to above will build you struts matching the stock dimensions if you bring enough money; I'm not sure if MCS will or not.

sjfehr

Will a cut-off OEM perch sit flush if I just drop it on without reinforcement? I worry about the distribution of stress deforming it, and am concerned about it shifting. I sent ANZE an email, and contacted Bilstein again about B6(HD), which are non adjustable but if they're valved/tuned properly from the factory to what I would have adjusted a DA to, adjustability is almost moot, and $3k cheaper.

knfeparty

I was pretty sure MCS offered factory perch versions. They're all that's used at the nationals level. Are they just not available for your car?

edfishjr

Not sure why P-car folks would be interested, but here goes. Car oversteered badly on street tires and couldn't get power down. All changes were based on attempting to increase stability (to withstand too-fast hands) increase rear grip/power-down and eliminate mid-corner oversteer.

Reduced rake to zero. Yep, zero. Nada. I basically set the car as low as it would go, front and back. Adjusted from there only as necessary to get corner-weighting good. The net effect is very close to zero rake.
Kept camber as before: max negative front (sides are not equal) and about 1.3 degrees rear.
Kept shock settings almost as before: I dropped front rebound by 1 click and rear rebound by 1/2 click on Koni 3013s, with front being about mid-range and rear very low.
Increased front toe-out about 50%. (I carry a jack and set the toe out before each event, then restore to zero for travel.)
Decreased rear toe-in from .3 deg to .2 deg per wheel. (IIRC) (Felt I had relied on too much rear toe to stabilize the car with R-comps.
Got a bigger front anti-sway bar and eventually set it full stiff.

The result is a very balanced car that is easily adjusted mid-sweeper and will push if you turn the wheel too fast for the speed and will oversteer only with excessive power. (In this respect it may be very similar to a modern Carrera.) Fine tune at the event with tire pressures, which I run approximately at stock levels, i.e. lower than most people seem to. The thought is to get good transient response with the stiff front sway and front toe-out and maximise mechanical grip with low pressures. I'm on 275/295 18" Rivals.

I had the car at a PCA track day (TGPR) Two different instructors (one a 986S racer with 996 motor and the other a National Cert 996C4S instructor) rode with me and were both amazed at the way the car "just goes where you point it!". (I run zero front toe and equal shock rebound front and rear at the track.)

Edit: If you conclude that the car maybe wasn't that well setup for R-comps, I will not necessarily disagree. It seemed good to me, but R-comps cover up a multitude of minor sins which may have been revealed by the switch to street tires.

sjfehr

We're car nuts, of course we're interested! What tires are you using? Do you have trouble putting power down on them?

PedalFaster

The only cars listed as having stock spring-compatible perches available from MCS are the BMW 1M, the E92 M3, and the Scion / Subaru twins.

I imagine that, if you're patient enough and willing to provide both some stock struts and a big enough check, MCS would be willing to build custom perches for you as well. I imagine it would be quicker and cheaper to do it yourself, though.

edfishjr

B.F.Goodrich Rivals.

I think it puts down power pretty well now, though surface dependent. I lost this weekend to a very good S2000 driver who I'd beaten handily 3 events in a row at other sites. The surface was low-grip and gravelly. Under those conditions, the Vette isn't much more than a plus-size Miata.

On a really clean asphalt surface it approaches how it put power down with R-comps. I've been warned that this will not be the case at Nationals with Rivals on OPR-tainted concrete. I will consider a last-minute change to RS3's after Wilmingtons' concrete.

Me at Atlanta Tour:

sjfehr

Anything's possible with enough time & money. Lex @ MCS emailed me today and let me know they don't have a non-remote double-adjustable setup for the Boxster/Cayman, and confirmed they don't do OEM perches for these Porsches. Which, with my not-unlimited budget, leaves hacking up my struts Han Solo-style for koni inserts or mounting Bilstein B6s. Bilstein won't send me dyno plots to help with my decision, I'm going to talk to Kevin @ allshocks.com some more about the Bilstein option. I can always revalve the Bilsteins, I suppose, it's just not very convenient to fine-tune.

I'm still waiting for AZNE to respond with their recommendations.

allen_skillicorn

Appreciate the reply! We dodge pylons, of course we are a little odd! I still haven't had a chance to drive my 996 in anger yet. Should have the clutch, rms, and IMS done early next week. Stone stock for now.

sjfehr

I compiled a list of all PASM parts required for a complete SCCA-legal I475 option package retrofit to a 987.2S: excluding dampers, labor and dealer charge for PIWIS programming, an SCCA-legal PASM retofit to get PASM springs will run about $3k. Which is actually not bad, considering what I was willing to fork out to buy a car that already had PASM, had such actually cars existed on the used market in the wild... If I can source the sensors & control unit used and bring that cost down, I'm going to do this. The wiring harness is $133, but I'd separate out just the PASM portion of it to retrofit and discard the rest vice tearing out the existing wiring. (Or, for $133 for a special OEM part, it might actually already be just PASM.)

Q. (Since PASM B6 are "only" $800 more than non-PASM B6...) What happens to PASM shocks if they're unplugged? Do they fail to full hard or full soft? If I'm going to the trouble of retrofitting PASM, it sure would be nice to actually be able to run soft on the street.

Audii-Dudii

Unfortunately, I can't answer your question (other than to say that a warning light on the dash lights up whenever a shock is unplugged), but I do have a set of BNIB Bilstein B6 PASM shocks that I am willing to sell. I bought them to install on my '06 CS, but then blew up the engine shortly afterward and as my future with the car after I finish swapping in a used engine is undecided, I think I'll stand on the 15k-old OEM PASM shocks that are already installed on it. Drop me a note if you're interested. (I also have the set of 95k-old OEM PASM shocks I removed from the car that I'll sell inexpensively if you need to harvest a set of PASM spring perches for a custom shock setup or take advantage of the SCCA's shock rule and install some non-PASM shock inserts in the PASM housings so you can run the stuffer springs after you've installed the rest of the PASM system to make it a legal option swap on your car.)

And congratulations on the car acquisition! I know you've been researching/planning its purchase for some time now ... any photos to share?

P.S.: I have two sets of 18x8.5/18x10 Street Class-legal wheels that I'm also willing to sell -- OZ Alleggerita and Champion RG5 -- because even if I do end up keeping the car, I won't be autocrossing it or taking it to any more DEs. Once burned, twice shy and all...

XPC5

PASM shocks default to full hard when unplugged. As far as building stock perches for MCS etc, Vorshlag has done many similar perch setups, just takes maybe $100-200 per corner.

sjfehr

Lex says the issue with Boxster/Cayman non-remote MCS is that the exhaust is too close to the rear strut and cooks the canister. I wonder how it would work with MCS up front and tuned B6 in the rear? Options, options, options

edfishjr

seems like that would be mostly a radiant heating problem. solve by wrapping components with gold foil.