03-05-2019, 04:33 PM | #1 |
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For the sake of science (and those that are interested....) a few spring and shock dyno's from my OCD collection of trying things out in an effort to find a well balanced track setup that's "streetable" enough to drive the kids to school on the way to a track day at Sebring.
-April 20th, 2019 EDITED to include a cross link to my final setup using stock M3 EDC electronic shocks with DSC Sport completely configurable active suspension controller based off G force. Dyno plots for stock EDC shocks posted in this link as well with an overlay of the stock M2 shocks in the same graphs! DSC Sport , Active System Retro-fit https://f87.bimmerpost.com/forums/sh....php?t=1603360 Roehrig data files available for those that are interested. Start of with springs and the next forthcoming will be dampers.. Stock: Front 218 lb/in (linear) Rear 331-681 with the 2.5-3.5" compressed range of 528 -681 lb/in So the rear springs ARE PROGRESSIVE...flashback to the E36 rear beehive days presumably...this was very interesting to find out.. Ride Frequencies 1.52 Hz Front / 1.58 Hz Rear (using 604.5, 528 - 681 averaged) Dinan: 267/670 lb/in both linear (I should note this kit was from my F80, the Dinan M2 kit has a 750 lb/in Hyperco and helper spring setup, front is the same) Ride Frequencies 1.69 Hz Front / 1.67 Hz Rear BMW M Performance Suspension (KW V3 ish..): 233 / 640 lb/in both linear (consistent with TUV approval in manual) which is a bit of a surprise as KW, who makes BMW MPS uses progressive up front at time. Ride Frequencies 1.58 Hz Front / 1.63 Hz Rear JRZ RS TWO: Came with 450/685 lb/in Eibach ERS 2.25 springs and helpers, Ride Frequencies 2.19 Hz Front / 1.69 Hz Rear (pitch, no "flat ride") Spring MR for above ride frequencies 0.956 / 0.58 front and rear Last edited by jetbill; 03-07-2019 at 03:48 PM.. |
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03-05-2019, 04:36 PM | #2 |
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BMW M Performance Suspension (KW V3 ish..)
Dampers, both front and rear appear to have identical valve characteristics...hence only three settings were dyno'd by the shop here in Tampa, refer to the third image below illustrating nearly identical... For those comparing MPS vs Stock M2 dampers it looks like you could possibly dial in a similar stock damper profile using the MPS?! Front : Compression between 1-3 from full soft or 9-11 from hard. Rebound around 12 -14 from full soft or 6-8 from hard. Rear : Compression around 6 from full soft or 6 from full hard. Rebound between 14-16 from full soft or 4-6 from full hard. This varies a bit as all dampers have 20 clicks of rebound adjustment but front vary between 11-13 (driver vs passenger) and rears vary between 14-16 (driver vs passenger) on compression which drives me a little nuts. BMW recommends from full hard (closed) Street F C6/R9 ; R C6/R12 Track F C4/R7 ; R C4/R10 I've tried both street and track setting (as well as about 100 other variations) at Sebring and both work well, I've tried numerous spring rates with this setup and have finalized at 250/685 lb/in rates replacing the front larger dia spring with a 2.5" Eibach for more Camber adjustment (stock MPS spring interferes with chassis at 3 degrees). GC front plates and Dinan bars , front full stiff rear full soft.
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Last edited by jetbill; 03-07-2019 at 03:51 PM.. |
03-05-2019, 04:40 PM | #6 |
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JRZ RS2 Unfortunately I only have the dyno from 0-2" range for these, but something none-the-less... Front, then rear
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Last edited by jetbill; 03-07-2019 at 03:34 PM.. |
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03-05-2019, 05:05 PM | #8 | |
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03-05-2019, 05:17 PM | #9 |
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The relative position of the kinks in the compression curves between brands are interesting, but KW seem to like a particular value.
Strange that while Ohlins have compression and rebound non-linearities on both front rear rear, Bilstein only have both on the rears |
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03-05-2019, 07:30 PM | #10 |
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Can someone explain how to read these for the non experts...IE Me
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03-06-2019, 12:59 PM | #11 |
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Well, each line of a particular colour represents a damper setting (compression or rebound). The vertical axis is recording the resistance (damping), while the horizontal axis is recording how quickly the damper was being made to compress or extend.
So the rhs side of the horizontal axis is a pothole, bolt down speed bump or really big trackside marker, hit at speed, while the lhs is a fast sweeper of a corner. Noting that damping is proportional to the velocity, you want a damper that lets the suspension absorb the the potholes etc, while resisting roll in corners. All of the above do that in compression on the front, some don't do it in compression on the rear, some do it in rebound, some don't (which is not a bad thing - you want the suspension to recover quickly to be ready for the next bump). Last edited by M Fifty; 04-17-2021 at 02:23 AM.. |
03-07-2019, 11:04 AM | #12 |
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Updated for stock M2 dampers, plethora of spring dyno's (with a bit of a surprise stock fronts are linear but stock rears are clearly progressive) coming in addition to JRZ doubles..
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Last edited by jetbill; 03-07-2019 at 11:31 AM.. |
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04-08-2019, 02:52 PM | #16 |
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Appreciating the effort gone in here testing all these suspension combos 👍🏻
If you were to look at the bilstein dyno what settings would you say would suit more bumpy roads but with performance in mind? I’ve tested various combinations on the road and feel 4f 3r dealt with these types of roads best but it would be interesting to see if the dyno info above correlates to this. I’m not going to lie, I don’t completely understand the plots! |
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04-08-2019, 03:30 PM | #17 | |
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On the rear, I ran from 1 to 3. If I ran the front at 3, I set the rear at 1. If I ran 4 on the front, I'd run the rear at 2. The settings aren't symmetric front and rear. Proper ride height is essential as the bump stops for the PSS10's are very long, the fronts are internal you can see them but the rears you can if you cut the tie wrap and pull the blue boot up. You want min of 1/2" clearance from shock body to bump stop.
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04-08-2019, 04:21 PM | #18 | |
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Again this correlates with what I found on the road. I had to raise the rear on mine slightly as it was bottoming out on the bump stops and causing the rear to bounce which was a bit unnerving at high speeds. What’s your thoughts on shorter bump stops? |
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04-08-2019, 04:24 PM | #19 | ||
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04-09-2019, 01:30 AM | #22 |
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Do you have the files for the JRZ's? The stock dampers leave much to be desired on the M2C...
Coming from an OG M2 with MPS... i really want better. Very much like the fast blow off valve system they have.
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