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08-26-2019, 11:38 AM | #1 |
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backroad / HPDE coilover spring rates
getting ready to order coilovers, anyone wanna comment on front/rear spring rates?
car will get 1M fenders and run 245-255 square 200tw, use is commute once a week, backroads and HPDE, currently I hpde/instruct using a R53 mini. Not sure I will fully convert over to HPDEing the 135i, but I'm building it in case I do leaning towards 400/600 or in that range, using BC or ISC N1 not sure yet car currently has m3 arms, HR springs and koni FSD
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08-26-2019, 01:10 PM | #2 |
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I ran Ohlins R&T with the following rates, similar use as you with 200TW tire. It was a good setup for both street and track.
- Spring Rates Front: Swift 65mm 7in – 336LB - Spring Rates Rear: Swift 60mm 9in – 672LB Shameless plug I am also selling my Ohlins setup as I sold my car, but the others you mentioned I have heard heard good things too. |
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08-26-2019, 02:02 PM | #3 |
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You need to do rear subframe bushings before going crazy with spring rates or you're wasting your time. Go straight to solid aluminum bushings. After that, it'll depend on the dampers. I have JRZ RS2s with 550F and 800R and it's smoother than stock, but other dampers may not be able to handle rates that high.
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08-26-2019, 04:41 PM | #4 |
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I forgot to mention I have subframe inserts from my previous 135i that are going in
not really interested in solid bushings
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08-26-2019, 10:01 PM | #5 |
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Subframe inserts aren't worth much. If you're going to go back there and do some work, at least put something quality in. PowerFlex black bushings are awesome. Subframe bits don't increase NVH and do wonders for everything else.
Spring rates depend highly on what shocks you're using and what they were valved for. Everyone tends to run SUCH soft rates on this car and I'm not totally sure why, as it's heavy, brakes hard and makes a ton of torque. On my KW Clubsports I ran 450/750 and it felt proper. On my new MCS setup I run 700/1000 and it feels incredible. If you're just enjoying some back roads and the occasional track day, just run an out-ouf-the box setup and rock out.
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08-27-2019, 07:01 AM | #6 |
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I've seen out of the box that run everything from stiffer in front to stiffer in back, and ISC sells one with 12k on each end
I think these cars should be softer in front or the understeer will be worse, leaning towards 500/700 right now, the BC coilovers come in very close to this stock if the car becomes my primary track car I would have to set it up for hoosiers and all the issues that come with those
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08-27-2019, 05:06 PM | #8 |
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The ISC dampers really aren't terrible. I think most people's impressions of them come from the garbage springs they supply them with when you don't pony up for the swift's. We have a set of the track valved versions on my wife's 135i with 550/800 eibachs and they work very well. Better options out there, but can't beat them for the price.
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08-27-2019, 06:53 PM | #9 |
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what length/diameter eibachs did you run with yours? anything needed besides the springs? I might just get the track version and suffer a bit until I get the rest of the car sorted, it needs oil cooling bad
I would not even buy coilovers yet but the HR springs with koni fsd and no bumpstops is HORRIBLE
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Driving e82, e72, e85, R53 Gone but not forgotten.. 1974 2002, many various 3s. |
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08-28-2019, 06:13 PM | #10 | |
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09-02-2019, 11:55 AM | #11 |
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On my 128i, we have run both 400/700 and 500/700. (Although actually metric equivalents). It was faster and still very street tolerable on 500/700; for your 135 which is a fair bit heavier and mostly in the front end, I think that spring rate would be a great "dual duty" starting point.
A lot of people do not run enough front camber in these cars and then end up running crazy soft front end spring rates (300-400) to allow them to transfer weight to make them not an understeery pig; if you actually run a reasonable level of camber, the car is far happier with a stiffer front end. -Mark PS - quick photo of the car rolling in the front end on street tires, on a cold day, on a not particularly aggressive corner at autocross. 500 is not too stiff!
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09-02-2019, 08:04 PM | #12 |
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what do you run for camber on your car? I figured I woudl just max out what the plates do, and the m3 arms.
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09-03-2019, 07:46 PM | #13 |
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We ran -3.6 degrees which was the max we could get with both camber plates and lower control arm modification.
-Mark
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09-03-2019, 07:51 PM | #14 |
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that's quite a bit, did you run that on the street too?
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09-04-2019, 09:48 AM | #15 | |
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I don't think anyone has ever argued 500lb/in is too stiff. People have argued, myself included, that 500lb/in (in this example) is generally too stiff relative to a stock-like rear spring rate people run. There are obviously tons of other factors that affect balance in roll: rake, track width differences, sway bars, damping, alignment, etc. For example, the 3-series Hotckiss sways that you put in your 128i increases rear roll rate relatively more than the front... especially so for a 128i that comes with no rear bar at all (non-msport cars). This is something most other people aren't doing since the rear sway is hard to get to. When you look at spring rates in isolation, 500/700 is not neutral handling no matter how you try to slice it. Do you think your spring rates would work all the same on another 128i that didn't put in a rear sway bar? I am not saying you're doing anything wrong by any means. You found a setup that works for you. But, I will point out that running 300lb front springs has nothing to do with people "not running enough camber." Running -3.6* camber might be necessary for you purely because of your setup. Just looking at pictures of your car, and reading your stated spring rates, I can go off on a whole tangent about why you probably have more body roll and more camber loss than my car despite the fact that I run softer front springs and sway bar. I'll spare you though lol... The conversation has already played out in other autocross related threads. Sometimes we have to mod our cars purely because of self-inflicted issues. Last edited by bbnks2; 09-04-2019 at 10:25 AM.. |
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09-04-2019, 02:36 PM | #16 | ||||
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09-05-2019, 02:14 PM | #17 | ||
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Suspension travel and dynamic geometry is just as important as spring rates. OP is using TcKline still? |
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09-05-2019, 03:22 PM | #18 |
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I was running HR springs with koni fsd, terrible combination
just finished installing a set of MeisterR ZetaCRD coilovers, 6kg/mm front 12kg/mm rear I can actually drive the car now, no more rubbing. Max neg in front and rear, 0 toe up front and 1/16 total in rear. It's raining due to hurricane so all I could do is make sure it tracked well and it no longer bottoms out on the road I live on, huge improvement
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You only need two tools in life - WD-40 and Duct Tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.
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09-05-2019, 03:41 PM | #19 | ||
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What are you saying? You run long bumpstops to limit travel? You reengineered the front suspension to gain camber in roll? |
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09-05-2019, 06:23 PM | #20 |
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Since that photo is perhaps not "rolling" enough, how about a series?
I don't really have an axe to grind, but what I don't really understand is why this forum likes to argue so much. I am not the be all end all to driving or car setup, but I am not a hopeless shoe with a few wins under my belt and I tend to surround myself with the best drivers I can find. I post our conclusions in complete transparency, without any agenda, with the goal of helping the community build more faster E82s. This is what made the E36 community great and is in general what almost every other group - S2000s, Miatas, FRS/BRZs, etc are like. If you don't think you need -3.5+ degrees of camber without geometry correction in the front end of a Mac strut BMW, then I am not sure how you are measuring your performance, but I question your data. This car got absolutely, unequivocally, quantifiably faster going from -2.8 to -3.6. It is our opinion that with our bars, at 400/700 the car was oversteery, 500/700 the car was distinctly better and beautifully neutral. That is our opinion and worth only what you are paying for it... nothing. -Mark
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09-06-2019, 12:00 PM | #21 | |||
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Massively different context than stating that "Some people on this forum say 500 lb/in is too stiff and they are wrong." Just pointing that out... not looking to argue. Conversely, other people say that 900lb rear springs is too stiff and that even at 600lbs they have oversteer. That's torque and a heavy right foot. Even with 900lb out back my car squats hard upon acceleration right down onto the bump stops. If bumping up the front spring rate isn't all that scary to people than bumping up the rear spring rate shouldn't be Quote:
Re-engineered suspension geometry? No, more simple than that... A higher front ride height (use coil-overs with independent height adjustment) keeps the suspension geometry moving along a more favorable area of the camber curve. And, a helper spring can be used to redistribute bump/droop travel when using higher spring rates so you don't end up with more compression travel than a bone stock car lol. You're confused why people on this forum like to argue and I'm over here confused on how people who claim to be national level auto-cross drivers don't understand they are using some of the shittiest suspension components offered for the platform Last edited by bbnks2; 09-06-2019 at 02:43 PM.. |
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09-06-2019, 03:06 PM | #22 | |||
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I'd really like you to get technical. Please explain why they are limited in what they can do with those setups. Many, many guys have been very fast using products from those two companies on multiple platforms. Quote:
Pretty easy to google names. What do you claim to be? |
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