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Been tracking a Boxster for over a decade. Recently purchased a 2010 Cayman S with JRZ suspension. Super stiff ride with current settings. Anyway, only had one track event in it so far.
First session out, was surprised by how quickly the back end stepped out when driving aggressively. At the suggestion of a couple, I disconnected one end of the rear sway bar. In my opinion it GREATLY improved handling of the car.
Prolly already some threads on this but I couldn't find them. Many others of you do this? Thoughts and opinions? Thx!
Been tracking a Boxster for over a decade. Recently purchased a 2010 Cayman S with JRZ suspension. Super stiff ride with current settings. Anyway, only had one track event in it so far.
First session out, was surprised by how quickly the back end stepped out when driving aggressively. At the suggestion of a couple, I disconnected one end of the rear sway bar. In my opinion it GREATLY improved handling of the car.
This is an unusual fix for a handling problem for this platform so there is something else going on. Do you have an open diff? What are your alignment settings? What do you mean by “super stiff ride”? When does the back step out? Corner entry? Corner exit? Is the oversteer induced by hitting curbs? How does the car behave under braking?
The car was set up at a race shop (the same one I use) by prior owner. No open diff. Max camber on alignment. Don't know what specific settings are on the JRZs, but as mentioned above, very stiff settings.
Back would step out very quickly when hitting gas after an apex, and when entering sharp turns.
As Trygve says, disconnecting sway bar is common for Boxsters, which was the reason for that suggestion. The guy who originally set up the car (he is also one of our best drivers) also took it out for a session and also felt that the back end was rather squirrely before the bar was disconnected.
With it disconnected, the car rotation is much more predictable and controllable.
Sounds like either something in the setup or in the components choice was mismatched. That said, it is not uncommon on earlier Porsches to disconnect the rear bar when the car is sprung very stiffly.
where is it stepping out in a corner (entry, mid, exit) and is it happening on slow or fast corners more?
The rear stepping out can be a feature, not a bug, if it’s used to get rotation on corner entry and you have the confidence to do so. Do you know how advanced the prior driver was? If it’s stepping out on corner exit them there are some other things I’d adjust first, before going without bar, like stiffening the front bar, adding rear toe in, adding taking out some front rebound, etc.
this is of course assuming that the springs are reasonable, like 700-800#. I know one car that has much stiffer springs and almost no bar, but that’s bucking conventional wisdom a bit. Do you know what your spring rates are?
The car was set up at a race shop (the same one I use) by prior owner. No open diff. Max camber on alignment. Don't know what specific settings are on the JRZs, but as mentioned above, very stiff settings.
Back would step out very quickly when hitting gas after an apex, and when entering sharp turns.
As Trygve says, disconnecting sway bar is common for Boxsters, which was the reason for that suggestion. The guy who originally set up the car (he is also one of our best drivers) also took it out for a session and also felt that the back end was rather squirrely before the bar was disconnected.
With it disconnected, the car rotation is much more predictable and controllable.
The corner entry and exit oversteer can have a lot of reasons so you have to eliminate the different culprits. Also, your platform is very different from the way a Spec Boxster with their open diff would be set-up. Here is what I would check:
- Check and note your rear sway bar setting before you disconnected it. Make sure your rear sway bar is installed correctly and does not bind under shock compression.
- You also want to make sure that there is no pre-load on the sway bar when it is connected (I would check this swat bar stuff first)
- I would run a full sweep of your shock adjustments and note where you are on compression and rebound on all corners. (I would check this stuff second)
- Check and note your shock can pressures (I would do this third)
- Check and note your front sway bar settings
- Check and note your front and rear spring stiffness
- Check your latest alignment spec and note front and rear camber and toe (if you are referring to max camber, what does that mean? I used to run 4.5 deg front and 3.5 deg rear on a car like yours but I doubt you would be running that)
I would recommend you look at how the SPC or H class Caymans set-up and how they run their cars. Obviously, the car is currently slowing you down in terms of confidence on corner entry and power application on corner exit and that's not a typical behavior for this platform, so it can be fixed. Just need to take inventory of what you have and take it from there.
I would try putting an adjustable sway bar on the rear before eliminating it all together. Having an adjustable one will also you allow to fine-tune the balance of the car from track to track.
The components in the JRZ kit alter the platform stiffness, chassis balance and other aspects of the response to driver inputs.
It's not uncommon to make this kind of change (removal of the rear bar) to reduce rear roll stiffness and allow more compliance that was originally reduced by the uprated springs.
If the car behaves better, and as you expect it, keep driving.
If you want to retain adjustability, reduce the spring rate in the rear and size the rear bar down to duplicate the balanced chassis platform with the middle adjustment of the new, lighter rear bar.
There is no silver bullet kit or combination of parts that suites drivers with a wide variety of speed and amplitude of control inputs. You have to test and tune to find the balance that works for you, in my experience.
__________________ -Peter Krause www.peterkrause.net www.gofasternow.com
"Combining the Art and Science of Driving Fast!"
Specializing in Professional, Private Driver Performance Evaluation and Optimization
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In addition to all the excellent suggestions here, also look at:
1. Ride height
- cars that are slammed may run out of damper travel and engage the [rear] bump stops, which suddenly increases the effective spring rate, often resulting in snap oversteer
- low cars without bump steer correction can have dynamic toe out
2. Rake re. roll coupling - excessive rake can make the bum quite free.
IMHO your first job is to look at spring rates front:rear because this defines the fundamental grip balance of the car. And then alignment. And then compile a list of all the suggestions here and work through it.
You could set up a Cayman (spring rate, alignment, rake, dampers) to run without a rear sway bar and there are very smart people who don't believe in rear sway bars... but anecdotally I have yet to see a Cayman race car (SPC, H, GTB, Clubsport) without a rear bar.
This is great stuff, guys! Just what I am looking for... different ideas and opinions. Trying to figure out if I should be driving the car differently, or if I should be making setup changes, or both!
A review of your setup is probably a good idea. Another thought - whenever you have a non-stock suspension setup, you are at the mercy of whomever put the stuff on the car, that they did it correctly. In addition to jdistefa's suggestion about the bump stops, it's worth taking a look to make sure no parts are hitting one another, or the chassis. Notably that joints aren't being put into a binding state during normal range of motion. Stuff like that'll screw up handling in a hurry (and also break things). I've seen some stuff over the years on cars that were set up by shops, that really surprised me.
Last edited by stownsen914; 03-05-2023 at 10:54 AM.
Yeah, I've seen some pretty messed up installs on all sorts of stuff. The setup on this car was done by our best race shop, so I have confidence that it was done right. Even so, worth looking into the issues mentioned above to verify.
03-03-2023, 11:19 PM
Disconnect rear sway bar - 2010 Cayman S
