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Old 08-27-2020, 02:24 PM   #1
redblockpowered
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Default Koni damping rates for 740/940

I asked Koni for these and they gave them to me, so I'm sharing them here because I figure they may be useful to others. The measurement points seem a little strange to me for comparative purposes but probably still have some utility. The rep also told me this is at full soft, and the rebound adjustment is up to 100% more than listed.

8641 1246sport (front strut insert)
Tested @ .33m/sec
Compression – 700N
Rebound – 1300N

Tested @ .13m/sec
Compression – 500N
Rebound – 580N

30 1479sport (rear shock)
Tested @ .33m/sec
Compression – 650N
Rebound – 2100N

Tested @ .13m/sec
Compression – 380N
Rebound – 110N
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Old 08-27-2020, 02:34 PM   #2
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For the record, I asked Bilstein for similar information on their B6 stuff for the 940 and was told it was proprietary information. If you have it I'd love to know.
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Old 08-27-2020, 03:14 PM   #3
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If you mean it seems strange that front and rear are tested at different velocities, I agree. They will be mounted on the same vehicle and in theory, will hit the same bump, thus, see the same compression velocity.
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Old 08-27-2020, 03:42 PM   #4
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If you mean it seems strange that front and rear are tested at different velocities, I agree. They will be mounted on the same vehicle and in theory, will hit the same bump, thus, see the same compression velocity.
Low speed and high speed values are much more informative than a single value at a high velocity. It gives much more insight into how much dampening there is under different circumstances

That's why there are 4-way adjustable shocks which allow you to tune the high speed and low speed characteristics independently.
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Old 08-27-2020, 03:45 PM   #5
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I appreciated getting multiple data points but the thing that I was referring to was the use of the .13 and .33 m/sec which doesn't directly compare to the usual (to me, a layman) .05 m/sec figures. Perhaps that's just a Bilstein thing.
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Old 08-27-2020, 03:52 PM   #6
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Wow, now I actually have specs for what I've had in the car for the last 8 years. lol

Thanks!
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Old 08-27-2020, 03:55 PM   #7
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Quote:
Originally Posted by blkaplan View Post
Low speed and high speed values are much more informative than a single value at a high velocity. It gives much more insight into how much dampening there is under different circumstances

That's why there are 4-way adjustable shocks which allow you to tune the high speed and low speed characteristics independently.
I see that now. I didn't notice both of those values were for each damper. I was thinking they were testing the fronts at one velocity and the rears at a lower velocity. That's what happens when I have 4 different websites open at the same time.
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Old 08-27-2020, 04:17 PM   #8
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edit: nvm.
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Old 08-27-2020, 04:21 PM   #9
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edit: nvm.
Not necessarily. I would bet the damper velocity on my independent suspension BMW or Mustang GT is nearly identical, front and rear.
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Old 08-27-2020, 04:42 PM   #10
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I also emailed KYB tech support (since that's what is on the car now) and they told me:

The 365053 (GR2 strut) is 110/45 and KG5565 (Gas-a-just rear shock) is 150/55. This is measured at .3 meters per second with a kilo of force.

Neat.
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Old 08-28-2020, 05:44 PM   #11
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Originally Posted by redblockpowered View Post
I also emailed KYB tech support (since that's what is on the car now) and they told me:

The 365053 (GR2 strut) is 110/45 and KG5565 (Gas-a-just rear shock) is 150/55. This is measured at .3 meters per second with a kilo of force.

Neat.
This puts the damping ratio in my car (at this speed) at a decidedly unsporty 30% front and 37% rear, or 34%/42% with stock sedan spring rates. Worth noting that the front is a stock replacement strut while the rear is a "performance upgrade". Advertised at 25% stiffer.
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Old 08-28-2020, 05:48 PM   #12
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Quote:
Originally Posted by redblockpowered View Post
This puts the damping ratio in my car (at this speed) at a decidedly unsporty 30% front and 37% rear, or 34%/42% with stock sedan spring rates. Worth noting that the front is a stock replacement strut while the rear is a "performance upgrade". Advertised at 25% stiffer.
Are you taking into account the MR for the rear shock and the rear spring not being equal to each other and also not 1?
Woops, just realized for 7/9 series. Question still stands though
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Old 08-28-2020, 05:55 PM   #13
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Are you taking into account the MR for the rear shock and the rear spring not being equal to each other and also not 1?
Woops, just realized for 7/9 series. Question still stands though
Yes, I am! I measured the distance to the shock, the wheel centerline, and the spring from the center of the front trailing arm bolt where it pivots. Admittedly not terribly precise, but certainly close enough to be crazy far off (or really much more than a little far off)
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Old 09-04-2020, 04:11 PM   #14
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Of course, I'm still not terribly sure how to pair my spring/damper rates, so if any of you nerds could help with that I'd appreciate it.

Messaged a few more manufacturers who sell shocks and struts for 940s but didn't get any response (yet). Very curious about the rates on the off the shelf Bilstein HD as well as the Gaz adjustable dampers that seem to be popular overseas. I know the HDs have a reputation for being soft on 240s and stiff on 940s so it would be interesting to see how they compare.
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Old 09-04-2020, 05:03 PM   #15
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Did I miss where you posted your spring rates?
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Old 09-04-2020, 06:34 PM   #16
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Did I miss where you posted your spring rates?
It's in the thread for my car. Wheel rates according to my math are 169/174 lbs/in front/rear. Feels like it could use more up front but that is beside the point (at least, beside the point of learning how to match spring/damper rates)
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Old 09-04-2020, 08:49 PM   #17
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It varies according to the use.
I'm not a pro at this, but I know what works on some stuff. And for those rates, bilstein hd or koni adjustable will be great. But yes, you need more spring in my opinion. 225# front at least.
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Old 09-05-2020, 08:15 AM   #18
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I know the HDs have a reputation for being soft on 240s and stiff on 940s so it would be interesting to see how they compare.
I don't have but a single data point, but it tells me this latter "belief" is wrong. I had a 92 745T which had stock wagon springs all around and Bils HD. The damn thing was the best damped and road gripping 7/9 series I've ever driven. It did Forest Service gravel roads with ease (stock height for clearance) and also handled brilliantly on paved roads. IMO, Bilstein got the damping rates spot on for the 7/9 Wagon.
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Old 09-06-2020, 07:04 PM   #19
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I don't have but a single data point, but it tells me this latter "belief" is wrong. I had a 92 745T which had stock wagon springs all around and Bils HD. The damn thing was the best damped and road gripping 7/9 series I've ever driven. It did Forest Service gravel roads with ease (stock height for clearance) and also handled brilliantly on paved roads. IMO, Bilstein got the damping rates spot on for the 7/9 Wagon.
Perhaps this is skewed by too many Bilstein owners who over-lower their cars on soft spring rates.
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Old 09-07-2020, 01:45 PM   #20
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Perhaps this is skewed by too many Bilstein owners who over-lower their cars on soft spring rates.
This,

Also Bilsteins can get water down in the cylinder and it hydrolocks the damper creating a horrible ride.
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Old 09-07-2020, 02:54 PM   #21
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This,

Also Bilsteins can get water down in the cylinder and it hydrolocks the damper creating a horrible ride.
And Konis do not have this problem, then? The adjustability certainly has some appeal to me but realistically once it's set the way I want it'll probably end up staying there. Would be nice to get both on a shock dyno for comparison.
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Old 09-08-2020, 10:14 AM   #22
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I had Billy HDs and TME sport springs on my old 744t and currently have Koni sports on my 945 with TME springs in front and 150 lb/in eibachs in the back. Neither car was/is slammed. Bilsteins were always crashy and too stiff for my liking.

I'm enjoying the Konis much more, better compromise for stiffness and seem to be a better match for mildly upgraded springs. Prior to the Konis the wagon had the TME springs with new OE turbo gas shocks front and rear. Personally, for a DD, I think TME or some mild sport spring and some fresh OE (german made) gas struts/shocks is the best all around combo for a DD. Konis are great for a weekend car that does some occasional commuting. That's just me though.
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Old 09-08-2020, 10:33 AM   #23
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And Konis do not have this problem, then? The adjustability certainly has some appeal to me but realistically once it's set the way I want it'll probably end up staying there. Would be nice to get both on a shock dyno for comparison.
No, they don't. It's not an inverted strut. There's no cavity to get filled with water.
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Old 09-08-2020, 10:56 AM   #24
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I have heard of that but never seen it. Volvo struts are open at the bottom, maybe Z struts or others that are sealed collect more water. Or they failed to grease the sliders, no boots, etc.
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Old 09-08-2020, 11:15 AM   #25
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I have heard of that but never seen it. Volvo struts are open at the bottom, maybe Z struts or others that are sealed collect more water. Or they failed to grease the sliders, no boots, etc.
I know Billys 740 had that problem and we couldn't figure out why the suspension was so stiff.

I think towery had that problem too.

It's common if you are running coilovers and can't fit the factory Bilstein dust boot.
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