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Hello. I've convinced myself that it's time to upgrade my suspension (currently all stock components) and need to make some decisions. I've read many of the suspension posts here with interest but I thought I'd simply ask for some direct advice so here goes. Thanks for taking the time to read and reply.

Background: I've got an 02 w/ 74K miles. No real problems to-date. Have tracked the car pretty hard the past 3 years and am an instructor for BMW and PCA driver schools. Mods include Stoptech front BBK (many thanks to Dave Z), Dinan CAI, exhaust and differential, UUC short shift kit, Rogue tranny mounts, as well as competition tires and wheels for track days. I drive hard on the track but am usually pretty tame on the street. It's my daily driver and I don't need any traffic tickets.

I've investigated Dinan, GC, and H&R. Liked the handling of a GC setup on an E46 a lot but unsure how much would translate to the E39. Thinking about a set of GC coilovers with a Dinan rear sway bar and possibly strut tower braces. I don't want a washboard suspension but I'd like to reduce the amount of roll in corners I get at speed. Also experiencing significant track tire wear on the outer edge of the fronts and assume this is due to less than optimum camber.

Question: I know there is a significant personal preference factor that eliminates a universal right answer but I'd appreciate any comments from those of you with experience in this area. Do you think this is probably a good setup? Are there other manufacturers I should consider? Is corner weighting a necessary part of the installation process or just nice to do?

Thanks again
 

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MariettaM5 said:
Hello. I've convinced myself that it's time to upgrade my suspension (currently all stock components) and need to make some decisions. I've read many of the suspension posts here with interest but I thought I'd simply ask for some direct advice so here goes. Thanks for taking the time to read and reply.

Background: I've got an 02 w/ 74K miles. No real problems to-date. Have tracked the car pretty hard the past 3 years and am an instructor for BMW and PCA driver schools. Mods include Stoptech front BBK (many thanks to Dave Z), Dinan CAI, exhaust and differential, UUC short shift kit, Rogue tranny mounts, as well as competition tires and wheels for track days. I drive hard on the track but am usually pretty tame on the street. It's my daily driver and I don't need any traffic tickets.

I've investigated Dinan, GC, and H&R. Liked the handling of a GC setup on an E46 a lot but unsure how much would translate to the E39. Thinking about a set of GC coilovers with a Dinan rear sway bar and possibly strut tower braces. I don't want a washboard suspension but I'd like to reduce the amount of roll in corners I get at speed. Also experiencing significant track tire wear on the outer edge of the fronts and assume this is due to less than optimum camber.

Question: I know there is a significant personal preference factor that eliminates a universal right answer but I'd appreciate any comments from those of you with experience in this area. Do you think this is probably a good setup? Are there other manufacturers I should consider? Is corner weighting a necessary part of the installation process or just nice to do?

Thanks again
Based on the above, I think you would want the GC coilovers, camber plates and a Dinan sway bar. I say that being extremely satisfied with my Dinan Stage 3, but for corner wighting and tracking the car, I think GC. My $.02
Regards,
Jerry
 

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i also have dinan stage 3 with front and rear strut braces, and run r tires on the track, running in the instructor group with the bmw cca. I've been quite pleased with the dinan suspension. It certainly is not an all out track suspension, but personally, i would not want it firmer on the street. I track the car maybe 10 days out of the year, which leaves 355 days of street use. If the m5 was not my daily driver, i'd probably be more aggressive, but honestly, if i were building a track car, it wouldn;t be a big sedan! (although it is a lot of fun to track this car!).
Mike
 

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GC coilover with Dinan adjustable swaybar and BeastPower brackets would be my choice. From what I've read, the GC suspension isn't any stiffer than Dinan Stg. 3, yet has the adjustability of a coilover setup.

Also, the strut tower braces aren't necessary. The M5 has already proven to be structurally very stiff, and the braces will have minimal minimal affect, if any.

Travis
 

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M5Kid said:
Also, the strut tower braces aren't necessary. The M5 has already proven to be structurally very stiff, and the braces will have minimal minimal affect, if any.

Travis
Jeff at Dinan mountain view did tell me that had some effect for a car that sees track time. He had told me they've seen a few e39's, with track use that have broken spot welds in the package shelf and behind the dash area, most likely from track use. They were all cars that were tracked pretty consistantly and used R compound tires, so he recommended them to me as a preventative measure, not something i would necessarily feel.

I did give GC some thought, but was unable to get any real info from them. At the time, it seemed that they just wanted to sell their 350/315 set up, which i had driven, and seemed a bit more 'bouncy' than the dinan set up. Personally, i'm not going to tune/adjust anything, i just want to get to the track and go. I really don't even like swapping tires and brake pads (but do, for now, just to save the street equipment).
Mike
 

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I considered GC last Fall when I decided to upgrade my suspension, but ultimately went the Dinan route. I went through a similar thought process as mottati describes in terms of wanting to set the car up for occasional track days, and preserving a decent street ride. Also, only a handful of owners had installed GC on their cars, and I didn't want to be one of the pioneers. If you look at M3 boards, you'll find tons of feedback from serious track rats on the pros / cons various GC spring rates, along with recommendations regarding numerous other tweaks and settings. There's no comparable pool of information for the M5, and I personally do not bring a lot of suspension tuning experience to the table. Plus, if the main benefit of GC was being able to spec a relatively high spring rate, again, I didn't want to go there with this car. Hopefully, I'll eventually have the experience, time and money to justify a track car. In the meantime, the M5 must pull double-duty.

In terms of performance, it came down to the adjustable front camber on the GC versus -1.5 fixed with Dinan. In the end, I was willing to accept this trade-off given my objectives. I tracked twice last season with the new suspension and didn't see excessive wear on the shoulders of the street tires I was running then. I know lscman doesn't like the fixed plates because they reduce jounce slightly, but so far that hasn't been an issue for me or anyone else as far as I can tell. I can understand why the GC adjustable plates would be a better technical solution, but I'm not trying to squeeze out those last few secs/lap just yet.

I don't think there's a right / wrong choice on this -- only the best choice given the owner's individual objectives.
 

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I say the bilstein pss9 for due to the ability to custom tailor ride height and suspention firmness via a 9 postition knob, plus it can be had under 2g's unlike the others (1800)
 

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Mike,

I remember you saying that a while back, interesting stuff. If driven hard enough, a lot of the stock components on this car will fail. Something to keep in mind when modifying a car such as the M5 for track use. By upgrading the brakes and suspension, you are just moving the weak link somewhere else. You and I both agree with the proper setup (i.e. Dinan stg. 3, Stoptechs, R-compounds) the M5 will do quite well, however.

It comes down to what the owner wants to do, what they are willing to sacrifice, and how much money they want to bring to this game.

Travis
 

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I put the H&R coilovers on my car last November. Ground control made the camber plates IMHO they are the best out there for our cars. As for tracking the car man it handles well, so much better than stock. And the ride height it lowers quite a bit, of course its adjustable. Now for the street version as long as you do not mind stiff this is a good set up. I believe the front spring rates are like 600 or 650. I would have to look to confirm. After putting on about 3000 miles and 4 months. I think the springs are a little to stiff for the street. Its like driving a Kart. I don't mind it but my wife won't hardly ride in it.

Boz
 

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Jayson said:
I say the bilstein pss9 for due to the ability to custom tailor ride height and suspention firmness via a 9 postition knob, plus it can be had under 2g's unlike the others (1800)
Do you know if these (or any of the coilovers, for that matter) are relatively easy to adjust at the rears? In other words, where is the adjustment. With koni's, it's on the top of the strut, which is essentially impossible to adjust on the e39 rear. I've seen some that have it on the body of the shock/strut, so you could actually access the adjustment. That is part of my problem with the coil overs on the e39, you really are not going to do much adjustment with any regularity, at least at the rear, unless i'm missing something.

With the e46, GC kit, you can easily get to the rear shock mount thru the trunk to adjust the shocks.
Mike
 

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Boz M5 said:
I put the H&R coilovers on my car last November. Now for the street version as long as you do not mind stiff this is a good set up. I believe the front spring rates are like 600 or 650. I would have to look to confirm. After putting on about 3000 miles and 4 months. I think the springs are a little to stiff for the street. Its like driving a Kart. I don't mind it but my wife won't hardly ride in it.
I agree Boz. I have recently added the H&R Coilovers and they are fairly stiff. Wife and the 15 month old seem to think they are too harsh.

Going to Willow Springs this weekend with BMW CCA, so we'll see how they do on the track, I imagine they will be ideally suited for that environment.

I like the handling, lack of body roll. Just a bit stiff, but hoping I will get used to them.
 

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mottati said:
Do you know if these (or any of the coilovers, for that matter) are relatively easy to adjust at the rears? In other words, where is the adjustment. With koni's, it's on the top of the strut, which is essentially impossible to adjust on the e39 rear. I've seen some that have it on the body of the shock/strut, so you could actually access the adjustment. That is part of my problem with the coil overs on the e39, you really are not going to do much adjustment with any regularity, at least at the rear, unless i'm missing something.

With the e46, GC kit, you can easily get to the rear shock mount thru the trunk to adjust the shocks.
Mike
The 9 adjustment knob is on teh bottom, so you may have to lift the car (a simple jack)...But pretty easy, or you could just slid under the car, not as easy as say the coilovers on my other car where you slid your arm through the wheel and turn it but still much better than removing the deck.

Then of course height adjustment is via the spring perch.
 

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i'm taking my car in tomorrow to have the GC coilovers installed to replace my Dinan III. GC now offers a track/school spring alternative with quoted 440#/in front springs and probably 400 #/in rear -- which are now sitting in the garage

i'm a little concerned with what appears to be limited front suspension travel and was hoping for more than the 2 degrees max front camber

i'll have a report of the roadworthiness of this setup next week and the first track outing a week later

if you're going to regularly track the car, i think GC (with the Dinan rear sway bar) is the way to go for a) linear springs and b) adjustable front camber. on the other hand, GC is supposed to offer adjustable camber plates now that will work with the Dinan suspension (i'm not sure how the current pricing adds up for GC plus Dinan bar vs Dinan + GC camber). you really need as much front camber as you can get to save on tires and rotation, not to mention grip

i think the front strut bar is worthwhile long-term insurrance running big R-compound tires on the front with higher spring rates on track
 

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By the way the bilsteins are linear springs as well, not progressive as apposed to the other coilover options.
 

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Does anyone have the Bilsteins? These seem to be a superior product to the GC.
 

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Discussion Starter #17
As expected, lots of good info; thanks everyone. I've ridden in an M5 w/ Dinan Stg II and another w/ the H&R’s but that was before I had much track experience so my only judgment was ride quality. At that time, the Dinan setup seemed better. The GC seems to be between Dinan and H&R in terms of ride stiffness and provides more adjustability (camber, ride height) so that seems the way for me to go.

Stever mentioned limited travel. Is that something that varies significantly between these setups?

Also, does the buyer specify spring rates at time of purchase? I don’t have any idea how to make that decision.

Thanks again.
 

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MariettaM5 said:
Also, does the buyer specify spring rates at time of purchase? I don’t have any idea how to make that decision.
Slippery slope! Slippery slope! Welcome to the Dark Side of suspension modification, Big D!

If I were to do it all over again, I'd forego the KWs and do the GC + Dinan sway setup. I like the linear spring rates, and adjustable front camber, altho' I'd need help spec'ing which spring rates to use.

I'd suggest getting Rick (Lscman) to offer his counsel on likely spring rates to suit your intended uses.

I'm jealous, man. It's been so long since I've had track time (Mid-OH last summer) that I think I've forgotten what it's like....

p.s. I'll be back in ATL 4/18-4/22; maybe we could squeeze in a lunch that week?

-Dave
 

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i'll be interested to hear how the 440/400s work, keep us posted.

Question, why does everybody suggest the dinan rear bar, isn't the eibach similar or larger. How about the front bar, dinan now has one, as does eibach?
Mike
 

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Falb said:
Does anyone have the Bilsteins? These seem to be a superior product to the GC.
From the picture posted here a few weeks ago (from a 540 application), they use helper springs on the front struts, and as a result the spring perch sits fairly low on the strut body. If you plan on using oversized front wheels and tires (e.g., the original post here mentioned competition wheels & tires), clearance is going to be a big issue. This is what an OEM rear wheel with a Dunlop 265 SSR tire looks like up against a Dinan/JRZ strut (using a 3mm spacer):

 
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