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      03-05-2019, 04:33 PM   #1
jetbill
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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
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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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      03-05-2019, 04:37 PM   #3
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Bilstein PSS10

Bilstein PSS10
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      03-05-2019, 04:38 PM   #4
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KW Clubsport

KW Clubsport
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      03-05-2019, 04:39 PM   #5
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Ohlins Road And Track

Ohlins Road And Track
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      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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      03-05-2019, 04:55 PM   #7
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Stock M2 Dampers

Stock M2 Dampers (Front and Rear)
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      03-05-2019, 05:05 PM   #8
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Quote:
Originally Posted by jetbill View Post
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..Roehrig data files available for those that are interested.


BMW M Performance Suspension (KW V3 ish..)

Springs, both front and rear are linear with average rates of 233 lb/in front and 640 lb/in rear.
Useful to know.
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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).

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      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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      03-07-2019, 03:18 PM   #13
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Quote:
Originally Posted by jetbill View Post
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..
This is an awesome post and very cool to see. Now if only I could figure out how to interpret it to set up my KW V3 for max comfort on the street
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      04-08-2019, 12:27 PM   #14
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Start with the damper settings Jetbill suggests in the 2nd post.

I'm going to be trying them on my MPS this coming weekend...
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      04-08-2019, 02:17 PM   #15
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Excellent post, thank you!
Does anyone know the H&R spring rates?
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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 👍🏻

Quote:
Originally Posted by jetbill View Post
Bilstein PSS10
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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Quote:
Originally Posted by Daleb View Post
Appreciating the effort gone in here testing all these suspension combos 👍🏻

Quote:
Originally Posted by jetbill View Post
Bilstein PSS10
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!
I ran the front PSS10 front between 3 to 7, staying closer to 3-5. The dampers don't jack down much in the range up to 10 in/sec which is good but I don't have data at higher speeds and the rebound profile hasn't blown off yet by 10 in/sec so I think on bigger bumps you'll get more jacking down on the front.

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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Quote:
Originally Posted by jetbill View Post
I ran the front PSS10 front between 3 to 7, staying closer to 3-5. The dampers don't jack down much in the range up to 10 in/sec which is good but I don't have data at higher speeds and the rebound profile hasn't blown off yet by 10 in/sec so I think on bigger bumps you'll get more jacking down on the front.

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.
Thanks for the detailed response. I’ll soften the rear off one more click to go 4/2 then I’ll try 5/3 to see how they feel.

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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Quote:
Originally Posted by Daleb View Post
Quote:
Originally Posted by jetbill View Post
I ran the front PSS10 front between 3 to 7, staying closer to 3-5. The dampers don't jack down much in the range up to 10 in/sec which is good but I don't have data at higher speeds and the rebound profile hasn't blown off yet by 10 in/sec so I think on bigger bumps you'll get more jacking down on the front.

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.
Thanks for the detailed response. I’ll soften the rear off one more click to go 4/2 then I’ll try 5/3 to see how they feel.

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?
I trimmed the rears 1/2"
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      04-08-2019, 04:43 PM   #20
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Quote:
Originally Posted by jetbill View Post
I trimmed the rears 1/2"
Thanks 👍🏻
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      04-08-2019, 05:10 PM   #21
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Quote:
Originally Posted by Daleb View Post
Quote:
Originally Posted by jetbill View Post
I trimmed the rears 1/2"
Thanks 👍🏻
No problemo sir. Instead of cutting you could just raise ride height of course
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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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