09-15-2015, 11:54 AM | #23 | |
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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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09-15-2015, 12:51 PM | #24 | |
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For me personally depending on the piston design used in the damper to control it or where you set the damper I personally find 8-10kg under the front of these cars very streetable for a daily setup...but that is my own preference. I couldn't agree more with how all of this is a compromise and the best setup is one you pick out yourself making an informed decision. To be honest that's the entire reason I joined and now started posting was to try and help put the info out there and help the members make more informed buying decisions (regardless if its our products or someone else). I think the word we are looking for is "sag". You don't hear this term as much in reference to cars but anyone familiar with motorcycle setups will instantly know what it is. When using a singular linear spring the distance the wheel could drop back down before the wheel lifts off the ground would be the same as the amount of sag the setup has- or the distance the cars weight compresses the spring. For illustration purposes we can average and round the weight of the front corner of f82 to around 950lbs. so if you were to use a 10kg spring (560lbs) the car would sag about 1.7 inches. (again I say roughly because there is number of other factors that should be considered if we were trying to get a 100% accurate number). So this 1.7 inches would be distance the tire/suspension could droop back down before the wheel raised off the ground if we went over a bump. Simply lowering your spring rate to gain more droop is yet again another compromise and not something that always makes sense. A helper spring could be utilized to give more suspension droop in a setup that doesn't naturally have much (higher spring rates)....but I also wouldn't just add helpers to all setups as this add length to your spring setup which then takes away from wheel and tire backspacing (you can't run as big of a tire on factory fender car). We also use helper springs a lot here for rwd setups built for drag racing. There is a number of worlds fastest (for a given chassis) street car setups we've build where helper springs are utilized for more travel. When rwd drag cars launch and get large amounts of weight transfer the extra travel down allows the front wheels to stay in contact with the ground (completely or more depending on the car) giving the driver more control allowing them to maintain steering control where it would otherwise be lost. Companies who offer setups without independent preload and height adjustments usually add helper springs to their setup to maintain preload (and eliminate noise and other issues associated with drooping the spring to change ride height). I agree rebound/droop is very important, but having a TON isn't always necessary and can sometimes have a negative impact overall. Again it can't be stressed enough, there is no "best" without a context, and even then its very subjective. The best racing suspension is not going to be fun for the street or even work well (since it was setup for lighter car with more mechanical grip)...and the best street suspension will just bottom out all over the track in a full race car. |
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09-15-2015, 01:04 PM | #25 | |
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One small note to point out about helper springs and coilover kits. All the coilover kits that come with helper springs are in the upper range of each respective company's product line (way out of OP's budget). Until you get to the track coilover with camber plates, you'll mostly see the conical spring that utilizes the OEM tophat. For kits like the KW V3, this is it's biggest downfall IMO. Having a loose front spring always seemed ghetto to me; reminds me of back in my JDM days when we used to just cut springs in the backyard. To me personally, the compromise in suspension is mostly in my disappearing cash; all out or nothing. ![]() |
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09-15-2015, 01:32 PM | #26 | |
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(you have forgive me I deal with and we make products for just about every type of car on the road...keeping up with all of the companies and recalling off hand how all of our competitors build their setups compared to ours for hundreds of applications proves to be difficult to keep up with. You are right and most of the ones for this application are in the higher price tiers with the exception of ours in a custom setup)
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09-15-2015, 01:39 PM | #27 | |
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Ohlins / JRZ Bilstein PSS10 / Clubsports and Budget setup is Swift + aftermarket shocks I've always ran my secondary option (blisteins) but lately I've been feeling little lazy (older?) and don't want to deal with rubbing fenders, scraping front lip, and want to just run a sub 500 dollar swift setup on my new f82 shocks until they seem blown, then probably set it up to PSS10 / JRZ in 2-3 years; also leaves some funds for exhaust to get rid of the lawnmower sound - but I digress. Great thread.. much better than some hella slammed bagged flush yo thread ![]() I ran eibach sportlines in the "jdm" days - I learned 12 years ago the hard way...... |
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09-15-2015, 01:45 PM | #28 |
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09-15-2015, 01:45 PM | #29 | |
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So funny because Eibach did an advertisement photoshoot with my car to promote their coilovers for the Integra; I didn't have Eibachs. |
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09-15-2015, 01:48 PM | #30 | |
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09-15-2015, 02:26 PM | #31 | |
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Anyway, I was thinking about what was being said about droop/sag. Correct me if I'm wrong but wouldn't a car with more droop require stronger swaybars to counteract the body roll? For instance my Jeep has 14" (travel) coilovers on the front and 12" coilovers on the rear. The majority of the travel on both the front and the rear is on the rebound side rather than the compression side. The Jeep has no swaybars at all and on the street going around corners, the body roll is extremely pronounced. Lastly I have a quick question, I've been looking for the answer in the suspension and tires/wheels threads but haven't found it yet: Are coilovers required to fit the wider tires (e.g. 265 front / 305 rear)?
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09-15-2015, 02:35 PM | #32 | |
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As far as needing coilovers to fit wider tires... who told you that malarkey? If anything some coilover kits will actually rub the tire if you go with a wider wheel/tire. The best way to fit a wider tire is to get a more aggressive offset on the wheels. And there are plenty of threads that go over that topic. |
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09-15-2015, 02:54 PM | #33 |
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Nobody. It was true for my old car, I just couldn't find anything about it for the M3/M4 -- probably because, like you indicated, it isn't an issue. However, absence of information is not the same thing as validation so I asked to be sure. Thanks!
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09-15-2015, 02:57 PM | #34 | |
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Very good information in that article. As far as coilovers vs wheel/tire size. You are SORTA correct, how correct you are depends on the car we are talking about and options it came with. For these cars it is possible to gain a little bit of space (but not a ton) other Strut based cars can gain a ton of space. As a rule most factory strut based cars come with a spring perch that starts ABOVE the tire, this means that the spring does not have any impact on your backspacing. Switching to coilovers can many time bring the spring down to the same height and so you'd then lose backspacing. Sometimes if your spring doesn't come into play messing with things MORE space can be gained as some aftermarket dampers are smaller in physical diameter than OEM so you gain just a tad more backspacing as a result of changing the dampers. In a case that doesn't apply here but does on many other strut based cars...when you have camber adjustments at both the top of the strut (camber plate) and at the bottom usually via a slotted top bolt (eccentric bolt) you can add as much camber as possible via the top of the strut then pull it back out at the bottom resulting is a similar alignment but with a ton of added backspacing (you basically be putting the suspension at a greater angle). Offset is the location of the mounting surface of the wheel. If your goal is nothing other than to get a bigger tire without permanently modifying the car then the options like I mentioned which all have to do with aftermarket suspension could allow for sometimes as much 1 inch larger wheel. Weather or not you should do this or it's the best option for you is a whole other discussion. |
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09-15-2015, 03:00 PM | #35 |
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Top 3 solutions for daily usage are:
JRZ Touring Bilstein PSS10 B16 KW V3 In that order respectively. We have the Clubsport 2 Way Adjustable on our shop car now and that is definitely way too much for the street. We've installed all of the products listed in our facility and experienced the ride and performance each brand offers. Feel free to PM us for more information on each set up ![]()
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09-15-2015, 03:01 PM | #36 | |
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If you plan to order suspension in the future you should ensure the wheels specs you want to order will work with change in clearance the new suspension will provide to avoid a possible headache in the future. If you don't plan to change it out then order whatever you want. |
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09-15-2015, 03:52 PM | #37 | |
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09-15-2015, 04:17 PM | #38 |
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I'll confirm and post the exact amount of change if people are interested. I don't recall how much or see it in my notes from the original development of this kit so i'll have to go measure it...but I do recall there being a tiny bit more room on this application. (I don't want to post a guess or incorrect information)
You should also keep in mind there is a number of other variables that can come into play. Ride height and diameter wheel also play a factor on this. Also currently swift does not make a spring in the default length of our M4 kit. All orders that are upgraded to swift springs need to either utilize a slightly shorter or slightly longer spring. I could make suggestions as to which I would do but if you wanted a custom kit like many of our customers do, it would be better to speak to PSI as they have messed with this or contact me directly with any questions about your car and the spring rates you'd like to use. (I wouldn't for example go shorter spring if you are going with a spring rate closer to OEM). If you wanted a more definitive blanket answer, as long as your are not super slammed our default BR kit should offer a tiny bit more clearance at the shock body (backspacing, but don't expect this to be a ton of extra space ) and since the kit is offered with camber plates (currently only for 3bolt cars but 5bolt would be available soon) more front spacing can be gained by the addition of a little bit of camber. Last edited by BC_Garrett; 09-15-2015 at 04:23 PM.. |
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11-24-2015, 10:55 AM | #39 | |
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11-24-2015, 10:58 AM | #40 | ||
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Based on previous experience, I can definitely see Ohlins R/T taking over as the best coilovers for street use.
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11-24-2015, 11:12 AM | #41 |
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11-24-2015, 11:37 AM | #42 | |
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06-07-2017, 02:27 PM | #44 |
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which one would you recommend for street use after you guys tried different setups? Thanks
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