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I am about to tweak my suspension a little and I have been doing a ton of reading for the past few days and have a few questions:
Current Setup: Techart CO's (Bilstein PSS9's with Techart Springs), DSC module. Ride Heights (from the fender arch) F: 26 1/4 Inches R: 26 1/2 inches Mileage: 40K Daily Driver, with thoughts of track time, but would be very limited
1. GMG Sways - will be using softest front and mid rear settings. I am worried about binding. What have you guys done with the bushings? Added grease fittings? If so, what technique did you use? Drop the sway clamps and re-grease? What type of lubricant works best with the GMG bushings?
2. Drop Links - Bilstein has newer style links with a bend in them. The aftermarket links seem straight. With some catastrophic failures of links and CO's, am I better staying with the Bilstein links? Worried about noise as well (not NVH).
3. Bump Steer Tie Rod ends - I have not verified, but I have to believe with the ride heights my steering geometry has been changed. Does anyone use a bump steer kit and if so, any recommendations on who's to use (or maybe who's to avoid)? Currently looking at Rennline.
4. Related to 3, I have a vibration I feel at high speeds. Last time I had the wheels off, I noticed the inner tie rods had play in them. I will be replacing them with Porsche parts. I am wondering if the possible geometry changes contributed to the wear.
5. Rear drop links - probably tarret. I don't see anything negative about this. Anyone have any other experiences?
6. Transmission mount inserts from function first, either the 70 or the 80 durometer options. Any experience or opinions on this or which stiffness would be best. More concerned about NVH from the trans mounts
7. Engine Mounts - URO S4. I have been up and down and around on these options, with everything from semi solid mounts, genione RS4 mounts, Function first's filled stock mounts. I know this one may be the most varied response/usage, but since it is part of what I am doing I have added it for any commentary
There are other options, especially in the rear (dog bones, tie rods, etc) but I think this will be it for this go around.
Over all I am very happy with the way the car handles, but the rear end bounces around too much, and while I have been conscientious about not plowing the front end and using the throttle to whip the rear around, I would like to have less movement back there. The DSC did wonders to remove some of the "bounce" in extreme maneuvering, I want to take that to the next level with the above changes.
As you'll find with most people, all I can do is comment on what I've done.
I'm running:
GMG Springs, stock dampers
GT2RS rear sway, stock bushings, no extra lube
GT3 LCAs up front (-2.1 camber)
Torque Solutions Street trans mount insert
Rennline Tuneable Semi Solid engine mounts (running Medium bushings)
DSC module
To help answer your questions, as you can see I'm not running custom drop links/dog bones. I've not found the need as I can dial in the alignment I want without adding these to the mix. Some say they're necessary, I don't see the need and neither does my alignment guy.
The urethane trans insert definitely adds a little NVH, but not so much that it's annoying. TBH I like the small amount of additional engine noise I can hear now.
The engine mounts added no noticeable NVH, but made a huge difference to how the car feels - the engine no longer slops around when the weight of the car shifts. One of my favourite mods for sure.
The other bits do what you'd expect, dialling out understeer (sway), dialling in more contact up front when cornering (LCAs), and smoothing it all out while keeping it flat in hard cornering (DSC).
An ex GT3 owner took my car for a hoon on the track recently and must have said "it turns in really well" about 15 times. I took that as validation that my perception of how the car now handles as being vastly improved is correct
Same here, I can only comment on what I'm doing. I'm also right in the middle of suspension research and have decided on the following options. Not trying to take away from the OPs original ask on his options but please let me know what you think about this. My car is a built/forged 997, so plenty of power but needs help with this kind of power in the turns. I also track it 5 to 6 times a year but also drive it a couple times a week, weather permitting. I'm in the advanced run groups and notice myself getting caught pretty fast in the turns by GT3s, RSs, etc. My current suspension is stock but I have Techart lowering springs, new DSC module and adjustable tow links already:
Planned suspension mods:
KW V3 Coilovers
Billet Drop Links for front and rear
Sway Bar front and rear with bushings
Front monoball camber plates
I'm widening my front track for better stability and turn in like the GT3, this requires the following additional parts:
Front and Rear lower control arm kits
Front Axle Spacers kit
GT3 lower arm conversion kit
Control arm shim kit
Litronic brackets
If I was looking to do what you're about to, I'd reach out to TPC and/or Tarett - they'll be able to give guidance on the best approach as well as supply the parts.
If you're wanting to daily as well as track, the TPC/DSC Tractive Suspension is probably your best bet.
The right answer depends upon what you are trying to accomplish.
Spirited street driving / canyon carving / occasional track day -- start with the DSC module and a more aggressive alignment. For the latter many people (including me) go with the GT3 LCA kit from Tarret. Also, the GT2 rear sway bar helps. Finally, rear toe links and locking plate from Tarret -- our cars are very sensitive to rear toe settings. Similar to NZskater I am running -1.9 front and -1.7 rear camber. Assuming Bilstein B8's are ever available again in our lifetime, they are a great option with lowering springs.
Track focused car -- go coilovers, corner balancing, polyurethane bushings, camber plates, super aggressive alignment, etc.....will handle great but ride like a rock.
Money is no object -- the full monty from TPC Racing including Tractive dampers (a cool $6-8k for the dampers alone). You will get the best of both worlds.
I am about to tweak my suspension a little and I have been doing a ton of reading for the past few days and have a few questions:
Current Setup: Techart CO's (Bilstein PSS9's with Techart Springs), DSC module. Ride Heights (from the fender arch) F: 26 1/4 Inches R: 26 1/2 inches Mileage: 40K Daily Driver, with thoughts of track time, but would be very limited
1. GMG Sways - will be using softest front and mid rear settings. I am worried about binding. What have you guys done with the bushings? Added grease fittings? If so, what technique did you use? Drop the sway clamps and re-grease? What type of lubricant works best with the GMG bushings? Sways should be the last thing you change on the car IMO. Are you keeping the PSS9's?
2. Drop Links - Bilstein has newer style links with a bend in them. The aftermarket links seem straight. With some catastrophic failures of links and CO's, am I better staying with the Bilstein links? Worried about noise as well (not NVH). End links can flex or bend, what you want to focus on is if you will adjust their length. Adding rigidity to anything will increase NVH.
3. Bump Steer Tie Rod ends - I have not verified, but I have to believe with the ride heights my steering geometry has been changed. Does anyone use a bump steer kit and if so, any recommendations on who's to use (or maybe who's to avoid)? Currently looking at Rennline. This depends on how low your total ride height has been or will be lowered. If you get coilovers with height adjustability you wont have that issue. If you stay with the tech art springs you will need to get a bump steer kit. None are particularly superior to another.
4. Related to 3, I have a vibration I feel at high speeds. Last time I had the wheels off, I noticed the inner tie rods had play in them. I will be replacing them with Porsche parts. I am wondering if the possible geometry changes contributed to the wear. Geometry changes wont wear things out in general. However If you use lowering springs but not a shorter damper you can increase wear to the damper as it has reduced stroke length and the forces needed to activate the piston are not the same as if it were at its designed OE rest position.
5. Rear drop links - probably tarret. I don't see anything negative about this. Anyone have any other experiences? For light or no track use there probably isn't an appreciable benefit. For normal or even spirited driving... mayybe... but still nothing which will be noticed by the but dyno.
6. Transmission mount inserts from function first, either the 70 or the 80 durometer options. Any experience or opinions on this or which stiffness would be best. More concerned about NVH from the trans mounts If concerned about NVH do not add rigidity. Any increase from OEM will add NVH and how much NVH is tolerable is very subjective.
7. Engine Mounts - URO S4. I have been up and down and around on these options, with everything from semi solid mounts, genione RS4 mounts, Function first's filled stock mounts. I know this one may be the most varied response/usage, but since it is part of what I am doing I have added it for any commentary For light or no track use there really is not anything to be gained, again nothing that will be felt by you, maybe more NVH if anything.
There are other options, especially in the rear (dog bones, tie rods, etc) but I think this will be it for this go around.
Over all I am very happy with the way the car handles, but the rear end bounces around too much, and while I have been conscientious about not plowing the front end and using the throttle to whip the rear around, I would like to have less movement back there. The DSC did wonders to remove some of the "bounce" in extreme maneuvering, I want to take that to the next level with the above changes.
Any and all commentary will be appreciated.
TIA,
Ed
The bouncing around in the rear is due to the tech art springs and the poor OE dampers. (I have tech art lowering springs on my car thanks to the previous owner, and I hate them) The DSC module will only get so far as you're running the dampers more to try and accommodate the total ride frequency per wheel. The DSC or our semi active suspension is not fast enough to truly be precognitive of the road. So you're getting a really good reactionary system which has some intelligence to it. That comes to you in the form of how often the damper "switches" profiles internally. Meaning it has 2 modes a "normal" and a "performance" mode and obviously either one is not a one size fits all. So the real value in the DSC is how to apply a performance profile to the dampers without them switching or changing modes and reducing their effectiveness.
A better matched spring/damper combo in addition to a bigger rear sway will reduce/ eliminate the "bounce" you feel in the rear. Aside from all of this as others have said you should be more clear on your goals, from what I can tell you are mainly worried about NVH. However without additional information it is hard for anyone to recommend something or give feed back to what you think you might want to do to the car.
Thanks for the feedback. The CO's are actually Bilstein PASM compatible dampers, not OE. Do I still have an issue?
As far as goals, this will be mainly for street, so too much NVH is not desirable, but being more connected to the car and the drivetrain to the suspension is. So no solid motor mounts and probably the least amount of metal to metal links. I already have spherical bearing camber plates and the change in NVH was quite minimal. This was done to get rid of the spring binding on the stock uppers, that boing sound when turning in parking lots.
The GMG adjustable sways should go a long way to eliminate understeer and body roll. Additionally I want to minimize bump steer and make sure the new sways are connected the best way. So knowing any experiences with various bump steer tie rods and rear drop links would be great to hear.
I also want to make sure I choose the right front sway drops since I have seen a bunch of posts about curved links from Bilstein, destroyed links and even one nasty one of a cracked drop link mount on a PSS9 due to an install issue. I actually found my CO drop links installed backward from all the reading I had done, though I saw another post about the drop links being installed differently on the passenger and driver side (on Olin CO's though). Just want to be careful.
I thought our OE dampers are in essence PSS9's... Either way they won't do well with the tech art springs. There are a couple approaches to dialing in suspension. Big Bar Soft Springs, has been one approach gaining momentum in road racing. Ultimately you would want to get a matched springs / damper combo. Elephant Racing has a good damper package and a tool to help you dial in what your setup will look like. I am currently debating between them and ohlins r&t.
Roughly speaking (I am assuming a .95MR front and rear) Elephant Racing seems to target a 1.75hz front ride frequency with a 250lb spring and a 1.925hz rear ride frequency with a 500lb spring and falls in line with at least one primary train of thought online as to how you want to setup a 911. A benefit from this setup is that there is a 16% delta between front rear frequencies which provides flat ride (911's typically have some naturally built in due to where the engine is) but some people would argue that adds to the responsiveness/comfort/driver confidence. Another benefit is after ~2hz ride frequency things start to become very uncomfortable as that is where most race cars end up vs 1.5-1.9hz for a "sporty" road car.
No idea on the dampers, I am relatively new to Porsche. I was under the impression the CO's were upgrades to the stock suspension, including the obvious springs and the dampers, and while Tech Art is on the Springs, Bilstein is etched into the CO body, but I don't know about the dampers for sure. All of this was on the car when I purchased it 1 1/2 years ago. I did some looking and saw that the TechArt springs are/were manufactured by Eibach, but I could not find information about spring rates. I will need that information to compare to your numbers above.
I have read about changing out the springs, so that is an option, and I have had the fronts out a couple of times, so I am comfortable with the work. I have to be conscious of cost, so while getting something like the Tractive suspension would seem to be one of the more attractive options, I cannot justify the cost.
The track is stock on the car.
I like your numbers based approach at analyzing spring options. Now I just need to find out what the heck is on the car already. The springs are blue (the eibach techarts I have seen pictures of are white, but that may just be production run differences) and there is a part number on them. I will have to see if that leads me anywhere. It does not look like the CO's are available from TechArt any more (although now I am doubting whether these are just TechArt springs on Bilstein Damptronic PSS9 CO's).
The right answer depends upon what you are trying to accomplish.
Spirited street driving / canyon carving / occasional track day -- start with the DSC module and a more aggressive alignment. For the latter many people (including me) go with the GT3 LCA kit from Tarret. Also, the GT2 rear sway bar helps. Finally, rear toe links and locking plate from Tarret -- our cars are very sensitive to rear toe settings. Similar to NZskater I am running -1.9 front and -1.7 rear camber. Assuming Bilstein B8's are ever available again in our lifetime, they are a great option with lowering springs.
Track focused car -- go coilovers, corner balancing, polyurethane bushings, camber plates, super aggressive alignment, etc.....will handle great but ride like a rock.
Money is no object -- the full monty from TPC Racing including Tractive dampers (a cool $6-8k for the dampers alone). You will get the best of both worlds.
Great breakdown...as a new P car owner that really was quite informative....greatly appreciated.
Tech art springs are indeed made by Eibach. If I remember correctly TA mentioned somewhere that they are ~30% stiffer than stock. Take that as you will, but in my own looking there is not a particular targeted approach by anyone that I have seen. It's mainly "this worked this one time with this one person so it might work for you"
Eibach's rates:
*Note they are progressive
F
168/300 in/lbs
I'm new to all things P car and just bought my 997.1 TT three months ago so take this for what it is worth. Just bought new forged HRE P101 wheels which beyond looking way cool should help with rotational mass and Michelin SC2 tires which of course are the biggest difference makers in handling so that should help the cause. I am installing 993RS motor mounts and have heard great things about them but haven't yet driven the car so can't comment. Also having H&R springs installed with a trade secret alignment by AutoQuest MotorSports in Ft. Myers which should really help. I would like to install the Bilstein shocks when they become available again. And though I kind of like the hyper activity of the bounce at speed in sport mode I am considering installing DSC as it is so widely praised.
I am going to need some more information (mainly about the CO's on the car) and some time to digest all of this.
Ed
Sorry the weekend got away from me. I do not like that link you pasted. It has ok info but I do not agree with some of it. I have a different site which walks you through what is what in those formula, another thing to remember is even with higher frequencies you can still have some comfort /compliance with well matched dampers. You would want a nice digressive piston / damper profile and IMO you would want a monotube which allows you to get away with low-ish gas charges. That lets the design of the valving do its job as with lower gas charges it takes less initial force to begin to actuate the piston/damper. The other main advantage with a monotube is that it does not experience a lot of cavitation. All dampers will have some cross talk until you spend big boy dollars and get an external reservoir.
10-25-2018, 02:36 PM
Suspension Upgrade Questions
