Suspension

[Jayson]

Has anybody run H&R coilovers on their m5? Ive seen some older m3's with um, but I'd like to hear about the acual m5. Besides KW are their any other company's making coilovers.


And what other spring/shocks are available.

[03E39M5]

I dont know about this product in particular, but in general, if you dont have you car properly corner-balanced after installing coilovers, you are likely to wind up with WORSE handling than you started with.

[Jayson]

Ive acually done coilovers so I'm prepared, for all kinds of mods. Thanks.

[MIB]

Hey Jayson,

If dollars aren't an issue than there is only one Coilover setup to get.

ACS Damper Force Control (DFC) Electroniacally controlled from inside the cabin.

I have personally been in Hamann7's DFC equipped beast and it is worth every penny.

I'm getting around to getting it. When I start running out of power mods, I will get it for my beast.

This board is a wealth hazzard.

[Jayson]

The DFC is awesome no doubt, but the 7k price tag seems extreme even to me, and I know for the most part once I set it I woun't need to touch it again.

[MIB]

Originally Posted by Jayson

The DFC is awesome no doubt, but the 7k price tag seems extreme even to me, and I know for the most part once I set it I woun't need to touch it again.

Umm No. The inside has three setting.

Sport for normal stock type ride. Intermediate for a Coilover ride, and race track for the ride of your life.

Its the no compromise suspension, for the no compromise beast.

It has nothing to do with corner balancing. Obviously that would be done and you could set and forget.

But the dial inside is great when you are cruising to a restaurant with friends.

Intermediate when you get a surge of blood but the road is a little rough, and Race Track for the Track or smooth hard driving.

The best of all worlds at the flick of a button. It doesn't get any better than that. I witnessed the unbelievable instant transformation at the flick of a switch. You can go from a stock ride to a full race prep.

Its worth the ticket price. IMO.

[Lscman]

I have owned several cars with SA and DA dampers and two cars with cockpit adjustable suspension. The spring rates largely determine firmness and roughness. The proper damper setting keeps the car from bouncing uncontrollably (too little damping) or skipping (too much damping) over bumps. Spring rate & chassis girth will jointly determine what damper settings are appropriate.

I have no doubt that adjusting the dampers makes the car "feel" different. That said, tweaking the damper settings to "soft" can not improve ride much because the car will heave & bounce (like Sanford and son's pickup truck). A car with insufficient damping does not soak up bumps like a luxury car. A comfortable, smooth luxury ride mandates low rate springs combined with a matching, soft damper.

Firming up the damper settings beyond the optimal setting for the spring rate will not improve handling either..it will degrade it. The car will skip over bumps, handle poorly and offer a falsely stiff ride.

From what I can see, the DFC units have highly progressive "compromise" springs, and as such, they can not and do not offer the best of all worlds, unless springs are swapped. DFC uses moderate, progessive rates to please folks who see a mix of cruising and performance. "Compromise is unavoidable" because there is no such thing as a spring that offers everything. "Progressive rate design is unavoidable" because most folks are concerned about looks & want to get rid of the "fender gap". Significant lowering the E39 chassis reduces precious jounce & mandates a very high linear spring rate or a moderate, streetable progressive spring rate to avoid bottoming. Obviously the typical owner prefers the latter, so their $75K saloon doesn't ride like a $10K Ford Focus.

Moderate rate progressive springs do not provide a linear feel or rate, so they are not suitable for serious handling or track. Chassis pitch under braking and cornering instantaneously changes the rate at each corner. For this reason, they offer no predictability and the car will shift uncontrollably between understeer and oversteer at the limit. This results in poor handling. These units are not track springs by any stretch and their adjustable dampers can not transform them into track springs.

There is another problem relating to progressive spring designs that is seldom discussed. A progressive spring requires a progressive damper that is matched thru it's travel from full droop (fully extended) to full jounce (fully compressed). When the spring rate jumps from partial coil bind, the damper rate should follow. With the DFC's adjustable static ride height feature, this is completely impossible. Such damper technology does not exist, so the DFC's will be underdampened as they approach jounce and overdampened during droop. This is not good for handling or ride. The result of this phenomenon is the double adjustable DFC dampers are poorly matched to their progressive springs, compared to certain linear springs and non-adjustable dampers (OEM etc). The dials need active computer control driven by instantaneous ride height!

For all-around use, these units are well-suited to a $75K saloon, but tweaking dials from optimum setting will not change spring characteristics and it will lead to poor suspension control.

You will find that a $1200 Ground Control setup with linear springs in the 450-600lb/in range will blow the DFC's out of the water in any handling comparison.

If you're looking for a mixed-use suspension that provides "good ride" and "good handling", the DFC's are a good choice. If you want optimum handling, you need to choose a good damper with no-compromise linear rate springs....and live with the firm ride.

[Lscman]

Jayson,

It depends what you're looking for in a new suspension. Most aftermarket systems for the E39 are designed just for looks. That is, their goal is to drop the car and still make it ride reasonably smooth. From a performance perspective, there are slim pickin's.

What is your goal?

If you are looking for better handling than stock, just install better dampers and retain your factory springs. Install an adjustable rear Dinan bar or an 18mm Eibach rear bar to reduce understeer. Install a more balanced tire/wheel combo such as 9" or 9-1/2" on front. Install Dinan or K-MAC front strut mounts to dial in a little more neg camber. This setup won't impress slammers, but it'll handle much better than stock.

If you want optimum handling & you're willing ot sacrifice ride quality, you'll need to move to Ground Control or some other solution that offers high rate linear springs.

If you simply want the car lowered with a streetable ride and handling on-par with stock springs, there are many progressive compromise spring systems to choose from including H&R coil overs, KW & DFC. Many folks will notice an improvement in handling after replacing their short-lived factory Boge's.

The H&R 29441 spring is linear, shorter and a higher rate. It will add too much understeer unless the front wheel/tire combo is widened, some neg camber is dialed in on the front and a stronger rear swaybar is used. This front spring has good potential with such a setup. Do NOT install a bigger front swaybar with the 29441's.

[Jayson]

Originally Posted by MIB

Umm No. The inside has three setting.

Sport for normal stock type ride. Intermediate for a Coilover ride, and race track for the ride of your life.

Its the no compromise suspension, for the no compromise beast.

It has nothing to do with corner balancing. Obviously that would be done and you could set and forget.

But the dial inside is great when you are cruising to a restaurant with friends.

Intermediate when you get a surge of blood but the road is a little rough, and Race Track for the Track or smooth hard driving.

The best of all worlds at the flick of a button. It doesn't get any better than that. I witnessed the unbelievable instant transformation at the flick of a switch. You can go from a stock ride to a full race prep.

Its worth the ticket price. IMO.

I knew all that, and thats what I mean, I'd put it on one and prob never really use the other 2.

[Jayson]

Alright guys perhaps I should add this little blurb.

I know everything thats been written above. Ive had hands on experience with a verity of setups.

I was really simply looking for first hand experience of the above systems. And choices that are out there, that I may not be aware of, then I can check them out for my self and go from there.


I know forums typically fall in love with about 2 things then every car becomes the same, so I look for choices hoping that some have chossen the "non typical" route.

The more choices and the more hands on storys the better, all this tech stuff I know.

PS I will never ever use G.C.

[Jayson]

Ok WTF, why is this now in the otf???? I think a moderater has a problem with me.