When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
On the S it's not an option you want to skip, being both lower and firmer rates. I'd have to check but I think the sway bars are different with PASM too. Edit - true only for the Boxster, not the Cayman.
Brandon's car had PASM. I chatted with him on his setup after 2022 Nats.
PASM was avallable on the base 987.1 Cayman. However, there's a catch: in the US (maybe everywhere?) it was optioned only along with the 6-sp trans. (All S cars got the 6-sp anyway.)
I'm very weight conscious. The 6-sp is 100lbs heavier, so it was a no-go for me. The lower CG height would be an advantage, but I'm not worried about stiffness of the springs. I got stiff taken care of.
Well, in your particular example I think it would be covered by 13.2.A which allows gauge modifications. I guess I'm not knowledgeable enough about SCCA history to know all the sticky situations. I vaguely recall something about radio deletes and blanking panels from many years ago.
PASM was avallable on the base 987.1 Cayman. However, there's a catch: in the US (maybe everywhere?) it was optioned only along with the 6-sp trans. (All S cars got the 6-sp anyway.)
I'm very weight conscious. The 6-sp is 100lbs heavier, so it was a no-go for me. The lower CG height would be an advantage, but I'm not worried about stiffness of the springs. I got stiff taken care of.
From what I can tell from looking at US order guides, code P04 package is 6 speed AND PASM. Code 475 PASM was standalone but seemingly incredibly rare.
I know I'm probably missing something, but this should allow for Ohlins with stock top hats and springs ?
You can use any brand you want as long as it is only 2-way adjustable and meets other length and fitment requirements and there's a fitment for the car, or one can be fabricated. Basically they have to be the same geometry, bumpstop engagement length, etc. I preferred Penske in the past because they let, er actually require, you to tell them what you want, i.e. specify forces and speeds, etc. (They will also do the best they can with a less specific use case.)
I'm going Bilstein this time because 1) cheaper initial cost, 2) once figured out I almost never change the adjustments except for rain in any case, and 3, this lower initial outlay leaves money over for revalves (if needed) and 4) the entire Bilstein catalog of motorsports internal parts is available for use.
I have good news and bad news regarding my CS Cayman.
First the bad: I received a set of Bilstein B6 struts from FCP Euro. I was praying that they would not be a crimped assembly and they are not. (I was 99% sure. FCP couldn't tell me.) However, they are also not the standard 46mm piston used in most of the motorsport products. They are 36mm pistons with a very odd-sized 11mm shaft. There are apparently only two pistons in this size, linear and COB (Compression-
Only Bypass) and very few other parts. I will find out for sure how these struts are valved tomorrow after they are dynoed.
The good: I took one front and one rear to my shock guy and he said that, yes, he can take it apart and that he works on these all the time. He can revalve them and probably make them do what I want. He also says I won't like what I see when he does the dyno, but he is, in general terms, a fan of the COB piston. (He thinks that's what is inside these and that they will be fairly digressive.) He showed me a whole shelf of similar Bilsteins for different fitments.
If the forces these produce are anywhere near what I think I need for the (bumpstop) spring rates I'll be using then I'll go with them as-is until after Bristol. In the mean time I'll work on bumpstops, front bar settings, alignment and tire pressures to get the car into the window of competitiveness.
Thanks for the update, very interesting and good of you to document the hurdles for others who may follow your lead. Regarding the bar, I thought you were going with a rear rather than the front?
Thanks for the update, very interesting and good of you to document the hurdles for others who may follow your lead. Regarding the bar, I thought you were going with a rear rather than the front?
I had a discussion with BMacIL (on this forum) and he set me straight, given the handling characteristics of the car at this point and where I'm going with it, as to which end needs a stiffer and tunable bar.
1. All else stock except for tires/wheels, the present bumpstops have given the car a perfect autocross slightly-oversteer balance that I like. This was just unplanned pure luck but is just a waypoint on the path. However, there's a continuing issue with spinning the inside rear tire on acceleration off a corner due to no LSD.
2. I wish to move up one durometer step in bumpstops and the math says that will push the car further into oversteer. (There are very limited choices available with big jumps in between... I can't mix my own rubber.)
3. A stiffer rear bar will pull weight off the inside rear tire, aggravating the no-LSD problem, as well as push it further into oversteer. A stiffer front bar will tend to keep weight on the inside rear tire. Being able to choose how stiff will allow a tunable movement of the balance back toward understeer.
You're in an area of the tuning curve where the ***** start to do things that would normally be unexpected. Depending on what all your bump stops are doing, a stiffer rear bar might not make the car tend more towards oversteer, if it keeps it from burying the rear stopper and going asymptotic.
I wouldn't pretend to know what bars you should mess with at this point. You're well on your way to making a car that makes time on the clock in autocross but doesn't do much else. It's what I would call a typical SCCA build, and It's why I don't think bump stops should be allowed to be changed in street. If someone casually wanted to autocross they would have to be way in the weeds to play with a setup similar to this. DPS on this board installed a set of off the shelf coil overs, front and rear adjustable bars, and headers on his AS cayman, and it's giving me a run for my money in a stock GT4. Bolt on stuff is way cheaper and easier for most people than trying to build an ST type car that runs in street class through loop holes, and using completely the wrong tuning levers. You would spend more money paying someone else to develop a cobbled street setup for you than a set of coil overs and everyone playing on a level field.
I would think at a minimum you would need to try both sway bars (obviously one at a time) to see what they are really going to do for you. In general if the car is even close to balanced, you tune the end of the car that's having a problem. Throwing a bunch of bar at the front of the car to help the rear may work or it may not... but if you throw the front bar on and end up too pushy, you can always crank up the rear damper finish the perfect pushy loose SCCA street class style build.
You're in an area of the tuning curve where the ***** start to do things that would normally be unexpected. Depending on what all your bump stops are doing, a stiffer rear bar might not make the car tend more towards oversteer, if it keeps it from burying the rear stopper and going asymptotic.
I wouldn't pretend to know what bars you should mess with at this point. You're well on your way to making a car that makes time on the clock in autocross but doesn't do much else. It's what I would call a typical SCCA build, and It's why I don't think bump stops should be allowed to be changed in street. If someone casually wanted to autocross they would have to be way in the weeds to play with a setup similar to this. DPS on this board installed a set of off the shelf coil overs, front and rear adjustable bars, and headers on his AS cayman, and it's giving me a run for my money in a stock GT4. Bolt on stuff is way cheaper and easier for most people than trying to build an ST type car that runs in street class through loop holes, and using completely the wrong tuning levers. You would spend more money paying someone else to develop a cobbled street setup for you than a set of coil overs and everyone playing on a level field.
I would think at a minimum you would need to try both sway bars (obviously one at a time) to see what they are really going to do for you. In general if the car is even close to balanced, you tune the end of the car that's having a problem. Throwing a bunch of bar at the front of the car to help the rear may work or it may not... but if you throw the front bar on and end up too pushy, you can always crank up the rear damper finish the perfect pushy loose SCCA street class style build.
The 2022 BS winning Cayman had a mild front bar upgrade and that was done specifically to mitigate open diff issues. Since there's room to increase rear roll stiffness without hurting inside tire loading via stops, the front bar seems like the logical play to control the balance.
You're in an area of the tuning curve where the ***** start to do things that would normally be unexpected. Depending on what all your bump stops are doing, a stiffer rear bar might not make the car tend more towards oversteer, if it keeps it from burying the rear stopper and going asymptotic.
I wouldn't pretend to know what bars you should mess with at this point. You're well on your way to making a car that makes time on the clock in autocross but doesn't do much else. It's what I would call a typical SCCA build, and It's why I don't think bump stops should be allowed to be changed in street. If someone casually wanted to autocross they would have to be way in the weeds to play with a setup similar to this. DPS on this board installed a set of off the shelf coil overs, front and rear adjustable bars, and headers on his AS cayman, and it's giving me a run for my money in a stock GT4. Bolt on stuff is way cheaper and easier for most people than trying to build an ST type car that runs in street class through loop holes, and using completely the wrong tuning levers. You would spend more money paying someone else to develop a cobbled street setup for you than a set of coil overs and everyone playing on a level field.
I would think at a minimum you would need to try both sway bars (obviously one at a time) to see what they are really going to do for you. In general if the car is even close to balanced, you tune the end of the car that's having a problem. Throwing a bunch of bar at the front of the car to help the rear may work or it may not... but if you throw the front bar on and end up too pushy, you can always crank up the rear damper finish the perfect pushy loose SCCA street class style build.
I look at it this way:
The first iteration of bumpstops on stock struts produced a very drivable car, both on the road and at the autocross, that's capable of trophying at a Tour or Nats, IMHO, RIGHT NOW (with the right driver... probably not me) for about $250 in parts. No aftermarket front bar, no upgraded struts, no revalved shocks. If I'm right, this makes the Cayman a competitive but significantly cheaper alternative to a used ND2 and much cheaper than a new ND3. (2 people in my region already sold their ND2s and bought ND3's.) All thanks to that loop-hole.
The second iteration in work now is looking like a modest increase in stiffness over iteration one, still with off-the-shelf bumpstops, and adds an adjustable bar and $1200 in struts, basically equivalent to what many run in CS now in an ND2 with their tailored aftermarket bumpstops, front bars and Koni yellows. We will see how it turns out, but I fail to see anything particularly weird or unusual about the setup I'm creating. It will still be much less stiff than what is run in ST*. Other than what seem to be kind of wonky damping curves provided by Bilstein in the B6, which are apparently intended to make sure the new owner feels a big difference so they know they got something for their money. It looks like the B6 rear damping at least fixes the crazy Porsche rear compression damping that degrades the ride over sharp bumps.
The expense of iteration 2 is still a drop in the bucket compared to ST*, both in terms of money and knowledge required.
edit: the B6 damping curves may actually be intended for people who want to track their otherwise stock car. It probably works decently well on a smooth race track and may somewhat improve the ride on the street. Generally they have more damping than I need with iteration 2 bumpstops.
edit 2: By the way, the bumpstops that come with the B6, and the B6 strut itself, are legal in Street according to my measurements, in case anyone was wondering.
05-13-2024, 07:48 PM
