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      09-15-2015, 11:54 AM   #23
x.shell
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Quote:
Originally Posted by BC_Garrett View Post
I could offer some suggestions but I'd be slightly biased for obvious reasons. I will say that we (BC Racing) do offer custom setups at no additional charge. This includes damper lengths, spring rates, spring lengths, valving etc....So besides the rates and valving we have determined to be a great balance for these cars based on our testing overseas along with on a number of cars here in the states our customers can spec out a kit in a anyway they like.

In being completely fair I think the best way to do this is to just give you as much information as possible to allow yourself to make an informed decision on your own rather than fall for a sales pitch and have it be something that isn't quite what you want. As I said if you have any specific questions please let me know and i'll try and give you as honest of an answer to it as possible



To be honest I don't have very much first hand experience with those units. I'd have to check later but from memory the factory front spring is about 185lbs, so 300% increase would bring it just over 550lbs (or almost 10kg). If this is correct i'm not sure if I would agree with the statement that its "just as comfortable". There really just isn't a way to use a much higher spring rate and create a damper to control those oscillations without a change in cabin sensation.

While some of us may not mind the ride quality at this rate- its far from a OEM feel. What many people find very comfortable is an overall soft ride, one that "soaks" up all the small bumps in the road without very much sensation being transferred into chassis. Swapping to anything in the ballpark of 9-10kg will not feel like that at all...a LOT more is transferred and can be felt by the drivers and passengers of the car. That being said this is a lot closer to where you would want to be for maximum performance out of your car on street tires.

As I mentioned before your entire setup is always going to be a balance filled with compromises...many of us may be willing to give up comfort (soft) for performance or vice versa but regardless you need to figure out what you would be comfortable with. I've seen people get upset by how stiff their lowering springs are and people who think their custom coilovers are not stiff enough (solely speaking on driver feel on the street). I would like to add that people should not get bouncy (improperly valved setup or damaged/blown setup) confused with stiff or firm, and by no means do I want to push people away from stiffer setups (relative to factory)..they just factually do change how the car feels.

Also, as a rule it's probably better that most who are not familiar with setting up a cars suspension avoid 3 and 4 way adjustable setups. Not because they are inferior in anyway but because it is simply overkill, and they are just wasting money if they never plan to really mess with it and just have a shop toss it on at whatever it came set to from the factory. Having 3 or even 4 way suspension is great at the track, giving drivers the ability to adjust high and low speed settings allow you to truly fine tune your car for the conditions/track you are driving in. When these adjustments are not fully understood by the driver they usually will simply not adjust it and will not have any significant increase in performance or feel over well built single or 2way adjustable setup.
Thank you Garrett for trying to be as unbiased in your post as possible. I agree with you on the sentiment that 10k is WAY too stiff for the front. I have experience with 10k Swift springs on a CKS kit and it was almost unbearable after a while. I eventually bought a set of 6k Swifts and it alleviated much of the stiffness. But I would go even further in saying that a 4k or 5k linear spring would work well with the BC Racing coilover.

It's important to note that BC Racing coilovers have a different methodology in dialing in ride height. Most coilover kits have a threaded shock body that lowers/raises the perch to get the determined ride height. The downside to this is that as you lower the perch, you are also subtracting from the shock travel (compression).

The way BC Racing (and Ohlins RT) coilovers dial in ride height is to lower the entire shock body into the carrier while the perch is set to a predetermined preload. The plus side to this set up is that you can lower the car to extreme amount while still retaining the full shock travel. The potential down-side of this set up is that you get less "droop" (especially if you use high rated springs on the front). Not "drop", "droop". In laymen's terms, droop is how much the wheel will hang when the suspension has no load on it, or decompression or rebound amount. Droop might not seem important, but it actually is when you're driving on the street (or rally racing for that matter). If you don't have enough droop, the car might fly over bumps as opposed to roll over them (literally, your wheel will be airborne. See attached pic of M3 GTR hitting curb vs Subaru STI rally car below). A good amount of droop will give you more traction on bumpy roads.

In my experience, putting a 10k spring on this kind of suspension set up pretty much eliminates all usable droop because you have to lower the preload really far down the carrier to achieve a lowered ride-height. So it's imperative that you get a reasonable spring rate; unless you only care about racing on a smooth track. To me, reasonable is 4k - 6k on the front and BC should have no problems valving their dampers to match that rate.

The point is that all suspension (even OEM) is a collection of compromises. But someone who is knowledgable can minimize the compromises and get closer to what they desire out of their suspension.

I'm sorry if my response is cobbled together poorly; I need coffee. If I confused anyone, please ask and I'll try to clarify with more elegance next time.






Last edited by x.shell; 09-15-2015 at 12:29 PM..
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