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Discussion Starter #1 (Edited by Moderator)
Happy new year guys!!

Just picked up my first M-car (’01 M5, thread here), so naturally I’m getting ready to let the wrenches fly. Gonna fix a few known items on my car and would love to upgrade the suspension as one of the first big projects.

After countless searches on the topic, I’ve found… stuff. Much of it is old and opinions vary on what the best setups are. I’ll leave the “what else should I replace while I’m in there” to other threads (like this one), but thought I’d compile what I found out about coilovers & shock/spring combos specifically. I haven’t seen anything comprehensive for the E39 so this is my attempt. Would love it if others filled in any missing info and please correct anything that aint right!


Executive summary

Coilover camp – loves adjustability and firmness (because racecar). Doesn’t hurt that a budget coilover kit costs the same as shocks & springs. Some that daily their car or want a softer ride need to pop for a kit with adjustable damping and should carefully read reviews to find which kit will be the best choice, paying close attention to spring rates and damping adjustment range.

Spring & shock camp – has SO/kids/parents/etc. that need to enjoy the car too. Commutes. Lives where roads suck. Doesn’t care about adjustability, wants to set it & forget it.


More about coilovers

Pros
  • Adjustability – don’t like your ride height? Break out the spanner instead of redoing your entire suspension to get the look and/or driving dynamics you want
  • Coilover kits can be had for the same price as or even less than aftermarket shock & spring setups (+/-$1k)
  • ePeen (is that still a thing?)
Cons
  • Owners of some kits report a harsh ride. Depends entirely on your preference as many consider this to be a benefit.
  • People seem to have higher failure rates with coilovers than nonadjustable shock & spring setups. Source 1, Source 2, Source 3, Source 4. Its most likely because…
    [*]o Stiffer setups transmit more vibration & impact to suspension (and chassis) components. Shocks, springs and mounts all take more abuse.
    [*]Shocks tend to blow faster because of the above and because of cheaper components used in some kits (hard to beat a Bilstein monotube).
    [*]Coilovers are more complicated. Threaded sleeves can corrode, adjustment knobs can seize or stop working.​
  • Front inner tire clearance. Helper springs found on most kits require a spacer for even stock 245 width tires. One exception is Ground Control’s kit with notches cut out of the spring perches specifically to address this and allow up to 275 tires up front. Is this also true of the BC kit? I’ve heard yes but would like confirmation before adding it here.
  • Some report clunking, rattles and popping. Source 1, Source 2 (Dinan Youtube vid). Some have improved these issues with roller bearings (See: Koyo bearings)

Popular coilover kits


  • DGR ($850) - Height & damping adjustable, front camber plates included. Impressions & pics
  • BC BR ($900) – Height & damping adjustable, front camber plates included. Giant BC thread
  • ST X ($900) – height adjustable only. Similar to KW v1s, except they have a galvanized body (less corrosion resistant). Impressions & pics
  • Bilstein PSS ($1,000) - height adjustable only. Pics / Impressions
  • (NO LONGER AVAILABLE)Fortune Auto ($1,350) - Height & damping adjustable, front camber plates included. Pics & Impressions
  • H&R ($1,500) – height adjustable only. There are two versions that are the same price, clubsport and street performance. Impressions & pics
  • KW v1 ($1,700) – height adjustable only. Stainless body. Still looking for good threads & pics of KW setups since KW and V1/V2/V3 aren't searchable
  • Ground Control ($1,900) – Height & damping adjustable (uses Koni shocks), camber plates included and four levels of spring rates & matched dampers are available. Impressions & pics
  • Bilstein PSS9 ($2,000) – Some say… this is the kit to get if you like the stock suspension (full soft setting is a close match). The damping adjustment knob is on the bottom of the rear shock making for easy adjustments & fine tuning. Impressions & pics
  • KW v2 ($2,200) – Height & damping adjustable. Impressions
  • KW v3 ($2,800) – Primo gear with a primo price. Separately adjustable height, damping and rebound (3-way adjustable). Impressions

More about shocks & springs

Pros
  • Balanced ride – fairly easy to get a great ride that is stock or firmer and very streetable
  • Cost effective
  • The choice of discriminating old guys®
Cons
  • Not adjustable – you might have to experiment with different combinations of shocks & springs to get the ride height, road feel and handling you want (hint: do more research)
  • Not cheap. Despite all the additional gear you get with coilovers, you have to pay nearly as much for 4 shocks & 4 springs.
  • Not many options. Basically just the three below, besides a couple other spring options (Vogtland, Eibach).
Popular shock & spring setups


  • Stock springs & Bilstein B6 (HD) ($600) – Cheaper alternative to OE shocks. Impressions
  • Intrax springs & Bilstein B8 ($950) – Springs need to be sourced from Evolve in the US. Impressions & pics / more pics
  • Dinan springs & Koni adjustables ($1,000) – Impressions & pics
  • OE ($1,200+) – for those that want BMW parts on their BMW, here’s a great thread by Tiauguinho: Install / pics


FAQ


Q: What else do I need to buy to install with my new springs/shocks or coilovers?

A: It depends on the kit, but generally you will need to either buy or reuse top mounts. It’s a good idea to buy new replacements for any stock parts that have rubber bushings or bearings in them as they will wear over time. Any kit that includes front camber plates will not need top mounts as these replace the factory parts. Also remember to buy new lock nuts (if they’re not included with your kit) as they are one-time use only!

Q: I want to run a square wheel setup – 4 stock rear 18x9.5” wheels with 275/35-18 tires all around, or an aftermarket equivalent, without spacers. Which suspension options will work for me?
A: Ground Control coilovers. Remember to specify “Yes, add 3mm extra for fat tires” when ordering. I believe all spring/shock combos will work but this should be confirmed by someone with one of these setups first. If you’re willing to run a 3mm or larger spacer in the front pretty much any kit will work without additional modification.

Q: Which brands have the best customer service?
A: YMMV of course, but in the US at least I have heard positive reports about Bilstein, Fortune Auto and Ground Control. On the other end of the spectrum, KW requires you to send in faulty parts before they send replacements which for obvious reasons is a PITA. Oh and what a coincidence, I can’t find an official link to KW’s warranty terms or return policy for US customers, so I’ll link to this instead. Link to KW UK returns page, showing that you must send in faulty parts to be inspected before they’ll replace them. Link to Bilstein warranty info. Link to Bilstein rebuilding and revalving services.



…Is that it? :dunno:

Comments welcome!
 

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You can refer to my suspension rebuild thread. I went with Fortune Auto 500 series coilovers. Did a complete suspension overhaul that includes replacing all of the control arms, sway bar links, front sway bar bushings, tie rods, centre drag link, idler and pitman arm. Similarly, in the rear I went with Thayer Motorsport adjustable toe and camber control arms, sway bar links, sway bar bushings, Beast power brackets, integral links, a used 50k mi lower swing control ams, new ball joints, new diff bushings, new subframe bushings, and the rear subframe was also reinforced too.

http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/476129-auaq-s-m5-operation-suspension-overhaul-fortune-auto-500-thayer-motorsport.html
 

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Nice post!

I am a pretty big fan of GC because they use Koni's, instead of a generic Taiwanese shock like most of the budget options (DGR, BC, Fortune, K-Sport, Etc). There isn't anything wrong with any of these kits, they are great for a street car, but you get what you pay for when it comes to materials and manufacturing.

I've also installed and driven regularly on a set of Bilstein PSS and they are great for the money IMO.
 

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Great post
 

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Discussion Starter #6
Thanks for the input guys :M5thumbs:. Fortune Auto, GC and B6 info added.

Hope I'm not misstating that Bilstein B6 = HD. If so let me know and I'll adjust. Would also love a link to good pics of that setup.
 

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Fortune Auto is actually made here and hand assembled in VA. They have great customer service too. I know few guys running these coilovers and are extremely happy with it.
 

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The dampers are made in Taiwan, they are assembled in Richmond. They do seem to have better domestic support than any other similar brand.
 

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Nice summary SLE.
I paid a couple hundy more for my BC BR to get 10/8K Swift springs but I love the ride and adjustability. Extenders on the rears means you can adjust damping without pulling the entire rear shelf out. I have a 4mm spacer on rear 295s and 5mm on front 275s.
 

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Nice compilation.

I went with ST mainly for price and how they ride, doesn't hurt knowing its from KW too.
They don't ride hard at all.


Sent from your face
 

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Great post. Personally, I don't see the reason for putting "coilovers" (OE is actually a Coilover, just not adjustable) on a luxury boat like the e39, but to each their own. The car really handles at a high limit with OE, or Koni/Dinan. I cant imagine pushing the car to such a limit, that Id need rebound/compression adjustability.

I suspect most use the adjustable kits mainly for height and not actual performance (im still not convinced KW's offer any real perforance increase, and I know the BC's offer zero, as well) Although this is just from experimenting with suspension tuning on the E46 M3.
 

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[*]Ground Control ($1,900) – Height & damping adjustable (uses Koni shocks), camber plates included and four levels of spring rates & matched dampers are available.
A bit more on Ground Control... Many years ago John, aka jaj, helped GC work out the details of the higher clearance design. What GC did was build a strut housing with a relief on the tire facing side and installed Koni damper parts within it. It's easily spotted by its red paint. Through working with jaj, they realized that the collar needed to be trimmed in height also (all covered by his threads on the subject).

Hence when you order their kit, you either specify the standard version (yellow Koni strut version) or the higher clearance version (red, relieved tube with Koni internals). The latter allows 9.5/275s, ET22, up front with no 3mm spacer needed (note for people new to the M5, to do this requires a 3mm spacer with either stock or Koni struts).

You can also work with them to achieve whatever spring rates you need/desire, not just the recommended pairings. Board members have helped them tune recommended offerings over the years (mainly going to a longer and higher rate rear spring compared to the early days). Brian, aka Redshift, was the first GC install on an M5 ages back and suffered some teething pains with spring rates being too soft and rear spring being too short, but that was (yikes) almost 12 years back now. :)

This is a great thread here collecting board knowledge on this subject. Good job!

Regards,
Chuck

Some early finagling with GC spring rates and such along with track reviews, etc, can be found by threads/posts by: jaj, Redshift, drallen, and stever (and I'm sure many others, but these guys were pioneers sorting things out).
 

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I'm planning for a refresh right now, and finding it a little hard to puzzle out which of these options will work with the squared 275 approach (OEM rears with spacer at front). Perhaps any of the collective insight on this could be incorporated here?
 

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I dumped the H&R's for the Bilstein PSS9's which do the trick for me. I don't recall what H&R's I had but they were advertised for the street. They were too harsh and the beast rode like a skateboard IMO. H&R were very cool, however, and refunded my complete outlay.

Pat Arnold
 

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My input - though I'm certainly not an expert I've used both coilovers and spring/shock combos on multiple vehicles.

I disagree with the above statement that coilovers will ride more stiffly than spring/shock setups. Not saying it's never true but I feel it's important to remember that a coilover suspension can ride like stock if you spec the components correctly and spend the time to adjust the dampers right. When I got my M5 it was wearing the H&R front springs and stock shocks; I found the ride to be stiff, with a lot of slap on expansion joints etc, even after swapping the 19" aftermarket wheels on the car for stock wheels. I also then swapped to the stock springs; the ride was nicer but had too much float.

I then went to Ground Control coilovers and got what I wanted - the ride mimics the stock comfort level but the whole chassis is much more controlled in its movements. This was true of two other cars I ran in the past - my 1997 M3, and a Nissan I used to play with. I confess after using Ground Control on these different vehicles I can't imagine buying another product in the future unless the company really changes for the worse.

I can't speak to durability; my gut instinct is that a coilover WOULD have issues before spring/struts, just because coilovers are a more complicated item that will by necessity be more prone to failure. Every car I myself have put coilovers on has been my weekend/evening/toy car, and not my daily driver, so I never subjected them to frequent hard use. YMMV.

One final point - Ground Control's efforts to tailor things to the needs of the front of the M5 are well-documented. I ordered the clearanced version for my car in mid-2014 and I only want to mention that the housings on my front struts from them are NOT red, they're black. I don't know if they decided to start coating them all black or if it was just a few but I had a conversation with GC about it and they assured me they're the clearanced units (and it's obvious when you look at them too).

EDIT: I just looked at the link referencing GC in the OP and found that it's my post! After running the GC setup on my M5 for almost a year and a half I haven't changed my opinion. It's an outstanding product and the company will work with you to get you the setup that works for you.

My $.02.
 

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I agree that the consensus of coilovers giving one a harsh ride than stock/OEM is rightly incorrect. You can still retain much of the stock ride quality but have a better control or handling characteristics of a car which the stock can't provide much. It's just a game of experimenting with different spring rates and with the shock's adjustability (from soft to hard or vice versa) you can attain any kind of ride quality and be satisfied with it. Before I decided to go with Fortune Auto I was contemplating the idea of getting Ground Control after doing a little bit of research here and there, and after reading a lot of great reviews, but after I heard about FA and talking with RVAE34, knowing they are not far away from me, known for great customer service, great quality products, reasonably priced, I ended up going with them. After the install I was initially happy with the ride quality and the new handling of the car, but I had just one minor issue. Had to revise the rear spring rates as it was too soft for the M5 with heavy rear end since it would bottom out too easily. Upgraded from 5K to 7K spring rates in the rear and it's now perfect. FA were helpful, great, and quick enough to ship out the new springs the same day after I had talked to one of their technical support rep and got it the next day. And at no cost at all!!! So far I'm loving the ride and have nothing bad to say about 'em.

Just thought of pointing out for those might be interested in FA or for those who have never heard of them before. :)
 

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Discussion Starter #18
Ride quality is very subjective so I always love hearing first hand accounts. It's not too difficult to parse several accounts and compare that back to the specs as they seem to verify each other. IE Pat Arnold's experience is similar to others' reports of the H&R kit being harsh. That also jives with the specs.... I don't know them offhand, but probably high spring rates and non-adjustable damping. So if you want race-car firm, you should look into H&Rs, but if not you should probably look elsewhere.

One question for the group (and this shows my skepticism with coilovers in general), but I imagine suspension travel has a big impact on ride quality. Yeah you can crank your damping way soft (on a kit that offers that of course), but if you only have 2" of travel you're going to be riding on bumpstops a lot. Does anyone have any more insight there? Maybe the obvious answer is that you can run coilovers and retain a softer ride, but to do so you need to stay close to stock height.
@JWMich - I'll add an FAQ with some of that info that's a great question.
 

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Ride quality is very subjective so I always love hearing first hand accounts. It's not too difficult to parse several accounts and compare that back to the specs as they seem to verify each other. IE Pat Arnold's experience is similar to others' reports of the H&R kit being harsh. That also jives with the specs.... I don't know them offhand, but probably high spring rates and non-adjustable damping. So if you want race-car firm, you should look into H&Rs, but if not you should probably look elsewhere.

One question for the group (and this shows my skepticism with coilovers in general), but I imagine suspension travel has a big impact on ride quality. Yeah you can crank your damping way soft (on a kit that offers that of course), but if you only have 2" of travel you're going to be riding on bumpstops a lot. Does anyone have any more insight there? Maybe the obvious answer is that you can run coilovers and retain a softer ride, but to do so you need to stay close to stock height.

<!-- BEGIN TEMPLATE: dbtech_usertag_mention --> @JWMich <!-- END TEMPLATE: dbtech_usertag_mention --> - I'll add an FAQ with some of that info that's a great question.
Coilovers (good ones anyway) typically have shortened or inverted dampers that are meant for use with lowered vehicles. It also helps if you don't lower excessively - the "slammed" look doesn't do anyone any favors. I can state that my car rides well and stays off the bumpstops - and I'm another that felt the H&R were harsh. The GC setup I'm running uses relatively soft springs (though IIRC they're still 3x the spring rate of stock) but the dampers are paired with them; the whole thing works extremely well together.

I'm not completely sure why it all works so well, all I know is that it does. I had custom GC and Koni on my S13, full-on GC on my E36 M3 and now my M5. They work.

Let me throw one more thing into the equation - my wife was happy to ride in the M3 and likes the M5 even more, both with GCs. She never wanted to ride in other cars I modded with strut/spring combos... she complained about the ride being rough. Again, YMMV and yes, ride quality is very subjective :D
 

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Bilstein B8 (Sprint Damper)

Intrax Springs

Job done.

Can of worms opening :..........................



Coilovers : On an E39 M5....mmmh...Each to their own...but with full leather and wood in a 4 door saloon (Sedan) I am not too sure, oh and I run way over 600 BHP on my one too.

911 GT2 RS ...yes coilovers are great I am sure, and the stock setup is pretty good.
 
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