killacam

i'm looking to lower my car but i'm conflicted on which route to go. i like the simplicity of the bilstein b12, no need to ever adjust dampening or rebound and a set ride height. i was also looking into the ohlins road and track coilovers. it looks like the best bang for your buck coilover system around $2.2k. full ride and height adjustability.

i'm looking for reviews from anyone that's had the bilstein b12 or ohlins coilovers installed on their car. i dont track my car, i just want it lower for street driving. i had coilovers on my past car and never changed any settings on it. i set it to full soft and the ride height i liked and left it alone. what i'm looking for is a nice stance, comfort, and reliability. right now i'm leaning towards the bilstein b12 because its $1k cheaper but i dont know if it'll be low enough. they use eibach pro kit springs.

if i buy either suspension, what other parts would i need to get my alignment right? thank you in advance.

Tj40

So my 2c would be - from your description (no track want comfortable street use) - go with the Bilstein/Eibachs


Lowering on Eibach/Bilstein - plenty of pictures on threads here to give you an idea of the drop, a lot of people say the Eibach's ride better/a bit softer than stock but plenty of data out there. You might give a little of this back with the stiffer shocks vs. stock though.


The R&T have height adjusters on the shock bodes so you can get the drop you want. This also means spring preload is adjustable independently - but from you comment above I don't this this will be a big consideration. But you should be able to dial in exactly the drop you want.


However the R&T have significantly stiffer springs,
Stock 997.1 is 152/245 Front/rear
R&T is 342/685 Front/Rear - more than double stock rates


Eibach don't quote spring rates - I did find one posting were someone said they got numbers from an Eibach tech plus they are progressive, i.e.have a softer starting rate with a firmer secondary rate - so the best I can quote there is
Front 108 - 194 initial/final
Rear 296 - 513 initial/final


So the fronts are arguably a little softer than stock to start which explains a lot of comments about the ride you get with the Eibachs.


Hope this helps........

motopix

If I didn't have PASM, I'd probably go with the Ohlins. Unless Ohlins does PASM and I had PASM, then I'd probably spend the same money and buy B16s and a DSC module.


^ excuse the sentence. I'm tired.

killacam

thank you tj40 for the detailed reply. right now i'm leaning towards the bilstein b12's. besides bilsteins, what other shocks are available for 997's? I was considering h&r springs, which would give me the drop i'm looking for, with new shocks.

Appraiser

TJ40, thanks for posting the specs.

Is that 997.1 Stock 152/245 standard suspension, sport or PASM suspension?

Tj40

For anyone with mild OCD all your questions answered in the attached.........enjoy!!


My caveat is there that there are two sets of Data for Eibach, that's because the original posting where I found the data quoted numbers in both units- but the conversion's didn't jive so I've given both sets of data here. Given people say these are softer than stock I'd believe the numbers quote above.


Also 'progressive' springs typically seem to only have two rates, initial softer rate and firmer final rate, what percentage of the travel is taken up with each rate will affect perceived ride quality and roll on the car - I have no data on how this varies with manufacturer.

Appraiser

TJ, Aces! I love the data - I'm surprised how low sprung the beginning of the PSS9 kit is - lots of breath there for the rear to ramp up. I imagine they would get more complains of a softer ride than the B12 kit, no? They share a similar f/r ratio with the R&T kit as well (198% & 200%) which is approximately 40 basis points over factory for a C2 like mine. I wonder if this is to take into consideration larger/heavier rear rubber - like seen with the GT3/RS models which tend to support 186-263%.

German888

Wow! Great resource. Thanks for pulling this data together. Just intalled BC Racing coilovers on my base C2. Still to much snow for testing but based on the numbers I'm coming unglued with anticipation as to how they will perform.

Tj40

Thanks guys, wrt the low starting rates on the PSS9 depending on how much deflection is in the spring at this ratio there may be effectively none left by the time the kit is installed and sat on the ground - a bit like a 'helper' spring in a coilover that is there just to keep the spring in tension.


That's the unknown with progressive springs, if 50% of the spring is wound at that rate it's going to ride very differently than if only 25% is wound at the lower rate. You cag get a feel by looking at the springs - the lower rate coils are the closer wound section - from this I assume that Eibach has a bigger % at the lower rate than H&R and this is 'possibly' why they feel softer to most users on the forums.


Glad you like the data! Cheers


TJ

swoardrider

Boy oh boy this is a tough question to answer. I've owned five vehicles with Bilstein shocks, one vehicle with 2-way adjustable Ohlins race shocks, and a motorcycle with Ohlins shocks. Both companie's suspensions have pluses and minuses.
With Ohlins, the magic is really in there valving, and ability for their dampers to control very high spring rates. This allows the user to run higher spring rates and softer shock settings, for comfort, or high spring rates and stiffer shock settings for some of the best handling money can buy.
Bilstein (consumer stuff) tend to be the best bang for the buck, and offer amazing damping for the price up to 80% of the capability of the vehicle, while providing a decent ride. Until you get into their full blown race stuff, which then, is comperable to most of the Ohlins stuff.
So from my experience I would bet money that the Bilstein b12 would be a more comfortable ride due to it's valving and spring rates for the street, and the Ohlins would perform better on the track and be stiffer but more compliant.
If you could choose a soft spring rate with the Ohlins struts, that would be the ultimate street set up. I'm just not sure if they offer different spring rates with the R&T stuff, which is designed for some decent track duty, hence stiffer spring rates.