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What are the diameters of the stock anti-roll bars?
By the way, adjustable shocks are NOT active suspension. Active suspension means having the ability to move the wheels, including lifting them, under computer control.
What are the diameters of the stock anti-roll bars?
By the way, adjustable shocks are NOT active suspension. Active suspension means having the ability to move the wheels, including lifting them, under computer control.
I don't believe your statement is accurate. Active suspension adjusts the internal valving of a shock based on road conditions.
What you're discribing sounds like PDCC. Where the sway bars are mechanically loaded to level off the car when hard cornering.
Didn't realize I would have to drop the front subframe, but I guess it makes sense.
Question though - I don't think I will need an alignment afterwards. As long as the new bars going in are not preloaded (which should be the case if the car is static), why would I need one? The one DIY said I would.
Can anyone provide more advice, particularly around the torque values? Thanks.
Jimbo, manual or computer adjustable shock absorbers are not active suspensions. Some call them adaptive suspensions, but as I stated, an active suspension can extend or retract a wheel as needed. No such suspension is currently in production, but the Infiniti Q45 did offer a low-frequency active suspension in the Nineties. Lotus and Bose, yes the audio company, have built prototypes of such suspensions.
The Lotus design used hydraulic rams in place of springs and shocks at each corner. A network of sensors read the road surface and moved the wheels to minimize impacts to the body. Imagine the car seeing a three0inch high bump approaching and as each wheel hit the bump, retracting the wheel at precisely the correct rate to make the bump invisible.
To demonstrate the capability of the Bose system, it was installed on a Lexus LS400 that could, in a parking lot stunt, leap over a 4x4 at 30 mph with both its front and rear wheels. Try that with adjustable shocks!
Jimbo, manual or computer adjustable shock absorbers are not active suspensions. Some call them adaptive suspensions, but as I stated, an active suspension can extend or retract a wheel as needed. No such suspension is currently in production, but the Infiniti Q45 did offer a low-frequency active suspension in the Nineties. Lotus and Bose, yes the audio company, have built prototypes of such suspensions.
The Lotus design used hydraulic rams in place of springs and shocks at each corner. A network of sensors read the road surface and moved the wheels to minimize impacts to the body. Imagine the car seeing a three0inch high bump approaching and as each wheel hit the bump, retracting the wheel at precisely the correct rate to make the bump invisible.
To demonstrate the capability of the Bose system, it was installed on a Lexus LS400 that could, in a parking lot stunt, leap over a 4x4 at 30 mph with both its front and rear wheels. Try that with adjustable shocks!
While i do value your reasoning and your time to explain it. I believe that the OP is refering to the application of active suspension on the 991 platform. Porsche is calling it Porsche active suspension management. Who am I to argue the fundamentals of why they are calling it as such at this point. Pdcc does lower and raise the height though. So it seems that its a hybrid of sorts with both options.
Didn't realize I would have to drop the front subframe, but I guess it makes sense.
Question though - I don't think I will need an alignment afterwards. As long as the new bars going in are not preloaded (which should be the case if the car is static), why would I need one? The one DIY said I would.
Can anyone provide more advice, particularly around the torque values? Thanks.
I believe you will need a realignment. Simply because lowering the car naturally flares the wheels out but if you already realigned the car when you lowered it than it should be fine. One thing Ive seen meantioned is the drop links. You will definitely need the spasm drop links to get the proper sway bar preload. Adjustables are fine two but require an experienced tech to preload them properly.
I have nothing against PASM. My 991.2 has it and it works well, but it's simply an adaptive shock absorber system. Porsche calling it active suspension is just overheated marketing hype.
PDCC is simply a roll mitigation system and can't lift individual wheels at will. The combination of PASM and PDCC together has about ten percent of the capability of a true active system.
Here's a link to a video that shows what the Bose active suspension could do:
- Yes I had the car aligned when lowered, just changing sways now
- I too thought the sway bar end links would be different between normal suspension and PASM, but the parts catalogue on listed one part number for both. So I assumed I could use my existing links
- I don't have PDCC, so these are conventional sways
- Yes I had the car aligned when lowered, just changing sways now
- I too thought the sway bar end links would be different between normal suspension and PASM, but the parts catalogue on listed one part number for both. So I assumed I could use my existing links
- I don't have PDCC, so these are conventional sways
Sounds like you have everything covered than.
Let us know how you like the results. A base car with a lowered suspension, swaybars and a LSD would be a hoot to drive daily or on the track. If Porsche offered it this way I believe many people would never move on to the S version. Next step is LSD.
Tried to install the rear bar last night, and chickened out when I realized I would have to loosen and move the rear lower wishbone. I was worried that it would affect my alignment, and I didn't know what torque spec to retighten to.
The former I think I can get around, the latter I can guess (118 ft-lbs ish from other similar bolts) but I'd like to know for sure. Can anyone help?
Finally got these in yesterday. For the rear I did have have to undo the lower control arm bolt (and buy a new bolt), but otherwise that was a snap.
The front was MUCH more involved. Had to drop the entire subframe. Bought $65 in bolts alone (ones that could not be reused). I got through it, but was not for the faint of heart. It's like a snakes nest under there with the steering, coolant lines, etc. Ith was the first time I had separated a ball joint - that was a fun pop!
Still haven't gotten to test it out fully, but I think I can feel a difference. Here are the updated measurements:
Stock front sway bar - 27mm,
SPASM - 28.3mm
Rear stock 24mm
SPASM 26 mm
So not a drastic change, but again noticeable. However for the effort involved you might want to go straight to a GT3 front, which I think is 30-31ish mm. I didn't do that because it would have required a custom rear bar and new drop links all around, which added about $1000 to the project.
I'll report back on further driving results, but I am happy that I can now say I've effectively retro-fitted (or duplicated) the SPASM suspension. Car feels great!
02-26-2017, 07:36 PM
