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      10-03-2019, 11:18 PM   #1
Ultimatemj
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How often are you "bottoming out"...aka bouncing hard off bump stops?

Recently moved from E46 M3 to E92 M3 w/Fortune510 10k/14k, and I'm surprised how often I "bottom out".

From what I can tell the Fortune 510 "ride height adjustment" has no impact on shock travel, as the body and spring is adjusted as an assembly...BUT if run "slammed" I'm wondering if the geometry is "compromised". Meaning the shock may still have plenty of travel but the control arms "run out of range of motion" and "bottom out" (against?) with less travel than designed.

I tried searching with no luck. Where can I find information about "min ride height that maintains full travel"?

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      10-04-2019, 03:36 PM   #2
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From my experience, with spacers the shocks bottom out earlier also.

That is why I removed them, don‘t like spacers.
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      10-05-2019, 09:27 AM   #3
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How would spacers bottom out the suspension sooner if the wheels/tires arenít rubbing?
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      10-05-2019, 01:18 PM   #4
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Well the spacers would technically add more leverage the wheel has on the suspension. No?
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      10-05-2019, 02:36 PM   #5
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Exactly!
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      10-05-2019, 10:12 PM   #6
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Quote:
spacers would technically add more leverage the wheel has on the suspension. No?
Yes...and I am running 15f/12r but I'm also running 10k (560lb) front springs...which my gut is telling me are "too stiff", but I'm "bottoming out"
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      10-06-2019, 01:58 PM   #7
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A proper suspension shouldn't bottom out abruptly. I have only experienced that with lowering springs on factory dampers
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      10-07-2019, 09:30 AM   #8
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Quote:
Originally Posted by slicer View Post
A proper suspension shouldn't bottom out abruptly. I have only experienced that with lowering springs on factory dampers
That is my expectation as well, but my car is also setup very low. So I'm not sure if the ride height is the issue...or? Wondering what to evaluate first...

Any insights would be appreciated
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      10-29-2019, 01:54 PM   #9
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Put the car in the air and checked out the install...

Both were slightly misadjusted...meaning the spring perch was used to adjust ride height, but justb 1/2". I reset the spring preload (per the instruction manual) and adjusted ride height via the threaded body adjustment (back to the height it was prior to adding preload).

Actually improved the ride, but still bottoming This has to mean the damper is not "absorbing" anything.

Current thought is both front dampers need rebuilt
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      11-29-2019, 01:27 PM   #10
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as someone who has been involved with a few race teams on the shock tuning side, the bmw m3 has very little compression available before the shock starts to engage the bump stops. I ended up trimming the factory bumpstops by .380 and my ride improved a ton on my coilovers and i was only running 350 pound springs in the front.
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      11-29-2019, 06:03 PM   #11
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You mentioned you are on 510s, what dampening adjustments are you on?
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      12-01-2019, 08:30 AM   #12
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did you properly preload it before installing the fortune auto?
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      12-01-2019, 02:20 PM   #13
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I had the similar version in Broadway Static flavor and experienced bottoming out and bump steer (the worst) often. I was quite low and upgraded to 16k F and 20k R Swift springs and still experienced this. Just think they aren't the best coilovers for anything but show. Wish I had went the Ohlins route. Good luck!
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      12-01-2019, 02:49 PM   #14
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UPDATE - The front dampers were in fact not damping (at any setting) and I was banging off the bump stops.

Fortune Auto's warranty policy is explicitly "non-transferable", but they "worked with me" and I now have a new set of FA500 w/ 8k front and 11k rear on the car!

Rides great!
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      12-09-2019, 08:54 PM   #15
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Quote:
Originally Posted by Willem3 View Post
From my experience, with spacers the shocks bottom out earlier also.

That is why I removed them, don't like spacers.
Wrong. You're talking about the tire rubbing the fender which is NOT what OP is asking about. He's referring specifically to the shock completely bottoming out onto the bump stop because of abrupt upwards travel because of a pot hole or something.
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      12-11-2019, 03:33 PM   #16
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Quote:
Originally Posted by AWDBooSTIn90 View Post
Well the spacers would technically add more leverage the wheel has on the suspension. No?
That is what I mean, not the fenders of course...
More leverage means more force on the shock absorbers.
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      12-11-2019, 03:51 PM   #17
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I still donít see how spacers can make a meaningful difference in bottoming out the struts.
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      12-11-2019, 06:25 PM   #18
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Quote:
Originally Posted by wyatth View Post
I still donít see how spacers can make a meaningful difference in bottoming out the struts.
I have to agree with you. Never had that issue.
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      12-12-2019, 02:11 PM   #19
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Maybe someone else can help explain?

Has to to with wheel travel versus shock travel, something like this: óO vs -O

I can notice the difference with spacers, suspension feels softer with 10/15mm spacers.
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      12-12-2019, 10:39 PM   #20
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Never.
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      12-13-2019, 05:33 AM   #21
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Quote:
Originally Posted by Willem3 View Post
Maybe someone else can help explain?

Has to to with wheel travel versus shock travel, something like this: óO vs -O

I can notice the difference with spacers, suspension feels softer with 10/15mm spacers.
What you're referring to is that adding spacers increases the motion ratio (i.e. leverage is appropriate term as you used...the effective moment arm from the centerline of the wheel to the spring axis is increased). Hence spacers reduce the wheel rate which you were thinking could more easily bottom a strut -- that is correct in thinking, but the change isn't large so it's not likely to be a source of a bottoming problem in most cases.
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      12-13-2019, 09:35 AM   #22
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Yes that is what I ment, thanks voor the explanation.

With 10mm front and 15mm rear spacers I can definitely notice the softer suspension and hitting the bumpstops much easier, when driving hard it feels like the shocks are worn and too soft.

I can understand this is not the case on this problem here, effect is to minimal as you say.
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