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Discussion Starter #1
I'm going to put new shocks in the 2000 M5 I just bought. I'm coming off of 8 years driving an E36 M3 with Koni sport yellow shocks, but I won't be tracking or autocrossing the M5, so I was thinking of going with the Koni FSDs after reading all the postings here. I will have to carry passengers, so I want to stick with stock springs.

Is it still the case that you need to do something in the rear (like cut a half coil) if I don't want the rear end 1/2 inch higher?

Thanks!
 

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You will need to cut the stock coil if you don't want the ride height increased with FSDs and stock springs. Check some other links here as well to see how others have approched the problem. The FSDs are nice, they just raise the rear 1/2 inch (or more). They are much softer than the Koni sports you are used to also--give the PSS9s some serious thought.
 

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I did not cut the springs when fitting the FSDs. The appearance and the ride of the car are perfect IMO. All the consumables were replaced too.
 

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The rear FSDs lowest groove for the lower spring perch is 1/2" higher than the stock shocks or Koni yellows, hence you do end up with an even higher tail than stock.
 

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Has anyone who owns FSDs complained to KONI about this? I can't see a technical reason for it and they may need to fix this.
 

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I just called KONI and talked to someone in technical support. He said that he had no idea why the perch is in a different location, but ride height may not change. I responded that I had talked to some other owners who had complained that it did. Since I'm mid install right now I had a chance to snap some pics and shoot him an email. He said he would talk to Holland about the issue and respond with a solution asap. Pics I sent are attached.

My email:

Not the most scientific of methods, but I'm sure you get the idea. It's 10-5/8" from center of bolt to perch of the stock unit, and about 11-1/4" on the FSD. This is for KONI part #2100-4030.

A couple M5 owners have cut their springs to suit the new perch location. I would prefer a more sensible solution.

Thanks,
Dylan
I'll keep you guys updated.
 

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Discussion Starter #7
Dr. Pooface,
Thanks for getting this elevated at Koni. I'll be very curious what they say.

From my Formula Ford days, I know that if the spring perch is higher, the ride height will be to. We also had this issue with Miatas running stock class autocross. if you didn't use the top notch, you were running lower than stock and were illegal. I had to protest someone at a Divisionals because of this.

I'll stay tuned...
 

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I'm going to put new shocks in the 2000 M5 I just bought. I'm coming off of 8 years driving an E36 M3 with Koni sport yellow shocks, but I won't be tracking or autocrossing the M5, so I was thinking of going with the Koni FSDs after reading all the postings here. I will have to carry passengers, so I want to stick with stock springs.

Is it still the case that you need to do something in the rear (like cut a half coil) if I don't want the rear end 1/2 inch higher?

Thanks!
I would buy the stock shocks,problem solved.The ring taxi coped fine with them 4 passengers up.

I doubt Koni have developed the shock/spring ratings like M gmbh did for 100000miles of testing.

Logical and less hassle.
 

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Dr Pooface, keep us updated as to what Koni figures out about the increase in rear ride height with the FSDs, and/or how to fix it. I installed them, with stock springs, about 6000 miles ago and they have not "settled-in" and the rear is still higher than stock. I guess I'm getting used to it now and I don't notice it as much. I do, however, notice that with the slightly higher and stiffer (rear) that a little of the understeer has been dialed out. So I guess it's not all bad.....
 

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Discussion Starter #10
M5fan: Did you keep the springs stock length? It sounds like you did.
 

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I just called KONI and talked to someone in technical support. He said that he had no idea why the perch is in a different location, but ride height may not change. I responded that I had talked to some other owners who had complained that it did. Since I'm mid install right now I had a chance to snap some pics and shoot him an email. He said he would talk to Holland about the issue and respond with a solution asap. Pics I sent are attached.

I'll keep you guys updated.
It's good that you've escalated this at Koni. The exact issue for Koni is that they need to use the same snap ring slots on the FSD as they do on the Koni Sport (Yellow) damper for the E39. The Koni Sport (Yellow) damper has three snap-ring slots but the FSD only has two. The "missing" slot on the FSD is the lowest one on the Yellow.

For the M5, the lowest slot on the Yellow gives you the exact same ride-height as stock. Because this slot is "missing" from the FSD, you get a higher ride.
 

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Discussion Starter #13
Dr. Pooface:
Did you ever hear from Koni NA?

I just called today and the guy I talked to in tech support (Bob) said that they have 3 guys out with the flu, so maybe that's why you haven't gotten a response yet. Oh, Bob said he thought the lowest spring perch should give standard ride height, but he wasn't sure. I told him that people had measured the perch at over 1/2' higher than a stock strut and his response was very non-committal.

I talked to the performance shop for Koni racing here at Infineon Raceway (Sears Point) and he agreed that Koni should get the ride height perches right. That shop could even machine another groove for the proper spring perch height.

I also thought of adding a set of the Dinan camber plates to the front, which would give me more negative camber and raise the front up about 3/8" so the car would be almost level, but a little higher than stock. Not ideal either, but it's a thought.

Thanks for driving this with Koni. I'll be very interested in what you find out.
 

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I also thought of adding a set of the Dinan camber plates to the front, which would give me more negative camber and raise the front up about 3/8" so the car would be almost level, but a little higher than stock. Not ideal either, but it's a thought.
So this really means that they should add another lower position on the fronts so that you can add camber plates.
 

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Discussion Starter #18
Well, for the rears I got a quote this afternoon of $40 to machine a third ring groove on the FSD rears to get the stock ride height like you can with the sport yellows. This is thorugh Performance Shock, Inc. at Sears Point/Infineon Raceway in Sonoma, CA. They are getting me a quote for the set of 4 FSDs plus the mods to the rears to get proper ride height with stock springs. It sounded like they could come very close to Tire Rack's price for the shocks, then the only extra cost is for the machining.

Seems a very reasonable way to get it right without compromising somewhere or resorting to a torch.
 

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Seems a very reasonable way to get it right without compromising somewhere or resorting to a torch.
+1, as I don't like the idea of making the rear springs shorter on this car. At full extension, the stock springs are just loaded enough to keep them in the car, although Old Ranger and others who have cut 1/2 coil with FSDs don't seem to have any problems. Cutting 1/2 coil will increase the rate, though, which you may or may not want. Machining a third ring, assuming this does not introduce any weakness into the shock body (not a slam dunk, btw, since the valving inside the FSD shock tube is different from the sport yellows), seems to be a better way to keep stock height w/o changing the spring rates.
 

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+1, as I don't like the idea of making the rear springs shorter on this car. At full extension, the stock springs are just loaded enough to keep them in the car, although Old Ranger and others who have cut 1/2 coil with FSDs don't seem to have any problems.
The stock rear springs are about 16.5" uncompressed, so you have to compress then a LOT to get them onto the shocks as the full droop perch to perch distance is around 11.5". They are a LONG way from being loaded just enough...they have a lot of preload. You definitely do not want to open up the top mount without having compressed them first!!! There is a ton of preload to easily cut 1/2 coil or more off them and not have any issue at all. I think there was a lot of misinformation about rear springs in past posts over the years for some reason (most came from speculation as opposed to direct measurements).

Chuck
 
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