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      02-08-2018, 01:27 AM   #1
S18adeli
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Best Coilovers for track: Z4M Coupe. Ground Control or JRZ?

I'm looking for the most appropriate coilover kit for my Z4M Coupe that is designated for track driving. It's rarely driven on the street and if it is, its usually on canyons or spirited drives. Ride comfort and noise are not considerations. Just looking for optimal performance.

I've read many threads comparing various coilovers for the Z4M Coupe however I was curious to hear opinions of comparison between the Ground Control (GC) and JRZ coilovers ideally from those that have experience with both.

OR comment if you believe another brand is better for the track and why, also how it compares to the above mentioned brands...

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      02-08-2018, 05:55 PM   #2
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There are 4 tiers of suspension products for the BMW market.

The upper echelon, the pro-sumer level, consumer brands, and the budget product. I can best relate this with photography equipment.

On the top end, you have the brands like Leica and Hasselblad. These are medium to large format sensors. Some are worth as much as a used luxury car. They serve a single purpose only most of the time, and have a very niche appeal. But there's no disputing that they make the BEST equipment in the world.

On the pro-sumer side, you have the Canon and Nikon DSLRs. They do what they do fantastically well, and even have a few markets cornered. They're far more versatile, relatively affordable, but still require a fair investment. Lots of aftermarket support for these, like flashes, filters, triggers, ring lights, etc. You can do a lot, and the upper end of their product range can even compete and rival with the upper echelon photography equipment.

Then on the consumer side, you have the likes of Sony and Olympus and Panasonic. Now, don't get me wrong. They have a lot of photography products that are fantastic. Sony's mirrorless digital cameras are even considered solid competitors to the pro-sumer grade Nikon and Canon DSLRs. But at this point you're buying from companies that don't really concentrate on making only cameras. You're buying from companies that makes printers. TVs. Speakers. Medical equipment. So on and so forth. And again, don't get me wrong. Even Nikon and Canon makes products in this range to compete.

And then you have your budget stuff. Cameras that are basically disposable from brands you've never heard of. Like a Seuny. Or Yonglong. Or Digigear. On paper the product reads fantastic, like 200,000 megapixel, 1 Mil X digital zoom, shoot up to 20,000 shots without recharging, build in 5 billion lumen flash...etc. The cost to replace the battery and for the price of a new high speed UHDSDXCWXYZ card is higher than the camera itself, but anyone will tell you that photography is all about the framing of subject and controlling of light, so in the hands of a world class photographer the images still turns out as stunning as something shot with a Hasselblad.

If you're not a camera buff, there's probably a similar analogy in there for just about any market there is. Bicycles. Jetskies. Cars. Computer cases. Laptops. Et cetera, et cetera.

But back to suspensions for BMWs.

The top end stuff, are most likely going to be Öhlins, JRZ, MCS, Motons. There's a couple of smaller, one-off brands built by a small handful of elves that does fantastic work on track that can't seem to scale to a larger sales capacity. These are typically favored by racers with big budget, they don't tend to function exceptionally well for street, but there are exceptions (Öhlin's ROAD and track kit works well on street). Typically they specializes in building fantastic dampers with voodoo/magic based valving that does sh*t to your car's weight transfer like you wouldn't believe.

Then just below that you have a few brands like Hanchey, AST, and TC Kline that are just full of people who know their sh*t when it comes to tuning a suspension, and built excellent products that won't cost you the price of your car and a left testicle for something that works 99% of the time to get you well within 1/100th of a second to the guys on the leaderboard with unlimited budget. Their top end, three way adjustable with nitrogen remote reservoir shocks are just as good, sometimes better, than the bottom end bump and rebound adjustable shocks from the likes of Öhlin, JRZ, Moton, etc. These will also typically include some of the ancillaries that are required to install your suspension, like shock-mounts, camber plates, and god forbid, SPRINGS that goes with the coil over.

After that, you have a very crowded consumer field, with a wide range of quality and offering. Again, in this bracket, you have companies like GroundControl, KW, Bilstein, H&R, Eibach, Koni, and a few that I probably have let slip my mind and if any of my buddies are reading this, will likely give me sh*t over the next time I see them, all competing for the largest slice of the pie. Unlike the upper echelon companies, these guys make suspension for EVERYONE. From simple springs, or simple shock and spring set, all the way up to racing kits with fully 3 way adjustable remote reservoir stuff. And their top end stuff is quite good, and can be expensive, but you'll always run across racers that run MCS or Motons that piss you off, because you know you're probably just as good a driver, but they almost always seem to be about 2/10th of a second a lap faster than you. You'd want to blame the equipment, but you really can't.

Then the rest of the field is populated by smaller players, budget brands, or companies that are well known with OTHER marques that are constantly trying to fight for the bottom half of the cost to value market. These guys don't necessarily have bad products, it's just that they're either unknown within the community, or source their products from a third party and rebrand, or reuse parts bin products to save cost, or heck, have to compete with more features for less buck just because they're small. ANYONE will tell you that a great driver can drive on these budget suspensions just as fast as you can drive with a set of JRZs on your car, but that doesn't mean they're as good.

Having said all that.

It doesn't mean that, say, a KW Clubsport isn't as good as whatever AST makes. Or a GC kit isn't as premium as a JRZ. There's a lot of product cross over, and in the end of the day, you get what you paid for, and you have to truly do your due diligence and understand that you ARE paying for what you need, but not paying for what you want. So for a guy who's looking to convert a stripped race car in Modified class for BMW CCA CR, getting a set of Megan Racing rebound adjustable coil-over is going to get him NOWHERE (on the podium, or near it. I mean, he'll still be able to go SOMEWHERE). Or a guy just looking to cruise the blvd., with stretched tires on 22s, occasionally "carving" some mountain roads? MCS 3 way with Swift Springs and remote reservoir isn't going to do him (or her) any more good than that same Megan Racing coil-over IMO.

But I'm sure you know all that. So I'm going to tell you this. I've had GC's Track School kit on my MZ4 Coupe. I liked it. A lot. But now that I'm riding on KW Clubsports I can tell you that the GC kit has some quality issues and they couldn't get the rear dampers quite right. I don't have JRZs on my MZ4 Coupe, but have driven and ridden with a few friends who have them on their BMW CCA CR cars, and JRZ is LEGIT, especially on track. You pay more for the premium dampers, but you get every cent you put in back in the quality and amount of control you have in your chassis. Every. Single. Cent.

But I wouldn't tolerate that E36 with JRZ that I drove back from Laguna Seca on a daily basis. No way. Especially not when you have to rebuild it annually since driving it on street basically destroys the valving. Since you said the Z4M Coupe is going to be primarily be used for track, I would think the JRZ would be a better choice than the GroundControl. Unless you're working with Jay personally to have a race only kit build using customized 3 way Remote Konis and Swift/Hyperco/Whatever float your boat springs, then at that point it's a toss up, because I have met Jay and seen him give seminars on suspension tuning, dude knows what he's talking about.

But I digress.
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      02-08-2018, 11:52 PM   #3
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I will not pretend to be as qualified as some forum members, however I do recall hearing that JRZ coilovers are not as top-of-the-line as they used to be? Something about new component suppliers, etc? Anyone know information to the contrary?

The shop I frequent recommends Ohlins R&T for most cars that aren't a dedicated competitor, however the Z4M platform is not supported by Ohlins.

A friend runs MCS 3-way on his enduro Z4M and has a history of successful track builds on BMW platforms. They are SOLID and used by a few folks on the forums here as well.

I personally have KW Clubsports on my car, a bit noisy (cranky) but absolutely zero complaints when it comes to on-track or canyon performance. The car hooks!

Regardless of brand, the most important thing is that you have the suspension and alignment set up properly. When lowered down to track height >2" the stock geometry becomes compromised folks have sought out modified or aftermarket control arms to gain back the proper balance.
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      02-09-2018, 02:14 AM   #4
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There is no Ohlins kit for the e86/85. Never has been, most probably never will be. Maybe if you chuck a tonne of cash at them they will custom make one for you, but that's been tried before too with Nill result.

Def what Hack says is true, you get what you pay for.
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      02-10-2018, 01:06 AM   #5
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Check out Fat Cat Motorsports in Redwood City - I have a setup from Shaikh and it's exceptionally good maximizing grip at the track while also improving on OEM damper comfort on the street.

He bases his setups on Bilstein monotube dampers and custom valves them for the application, taking into account what your track car weighs, if you have aero, and also offer a digressive high speed bump setup (KBO aka Kerb Blow Off) that helps settle the car on big hits.

If you go with MCS / JRZ, you should still spend the time and money on either custom valving for your application or testing enough to find optimal adjuster settings - an off the shelf "overdamped in rebound" setup will feel sporty but may actually decrease ultimate grip.
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      02-10-2018, 04:23 AM   #6
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I actually live close to the MCS shop and these guys are first class, I will be updating next year to their 2 way which will run you about 4,500 with all the extras. The nice part about them is every set is custom built to your specs.
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      03-27-2018, 08:11 PM   #7
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So what did you end up getting, you never replied to your own thread
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      03-27-2018, 10:02 PM   #8
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Really.
And after all the effort Hack put into it.
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      03-31-2018, 12:20 AM   #9
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Agreed on lack of response being shady...

I’m eyeing a complete refresh of all suspension components in a few months. I think my decision for coilovers is first choice JRZ 2 Way kit from Apex. Looks like a killer setup.
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      03-31-2018, 04:57 PM   #10
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A really good write-up from Hack. Wish someone knocked his wisdom in my head before I bought my coilovers. But regardless I will be changing mine eventually.
I don't plan on getting track setup but you still need something nice for a weekend fun car.
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      04-03-2018, 09:08 AM   #11
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Nice write up Hack - I too have contemplated finding the 'best' coilovers for my non-M Z4, and it's just a mixed bag.

I know folks (my brother in fact) who have top end coil over units and have had nothing but quality issues, or the requisite yearly rebuild needed as par for the course. Yes, they feel great at the track and absorb the harshness on the street as well.

I'm running the cheap of the cheap: BC Racing BR. I drive the snot out of the car at the track and haven't really felt like the shock/spring setup has held me back any. Keep in mind I spend quite a bit of time 'tuning' pre/post each session, including trying different compression/rebound settings front to back, and different springs.

I'm a believer that when you spend time and set up your "cheap" shocks properly, they won't be as big a drawback as you may think. The great thing about these is - knock on wood - quite a few sessions and street driving later, no rebuilds needed, no leaks, and still rocking.

My next progression would be KW V3s if I were to move up, but it's hard to justify the cost/benefit at this point.

If you are a hardcore racer, then top-tier as Hack mentioned will probably net you a few tenths? Who knows without back to back comparisons.
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      04-26-2018, 02:46 AM   #12
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I completely suck at doing pre-post adjustments.. but maybe i just suck overall at it. Pre-session, i am always in that much of a rush that i am lucky if i make the brief. Then after the session i chuck my board shorts on and get going as soon as possible as my "leave pass" would expire shortly. (those with young kids prob know what i am talking about here)

during the sessions i am pretty much just driving.

Have been taking a few notes, and it does help...

Probably doesn't help i can't plan a pissup in a brewery, with my schedule, only know about a day or 2 max before the day that i get to know if i can go or not. I guess if you do the same track/config all the time that might be different, but i find that my local track always changes its track config, and i don't get out there enough to be able to have a sheet with different settings (alex's advise ) for each config of track. ... I guess this quote below REALLY does apply to me.

"son!!, your lucky to even be here!"

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Last edited by Vanne; 04-26-2018 at 02:55 AM..
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      05-01-2018, 02:40 AM   #13
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In Europe the brand probably considered as the best for shocks is Intrax, most would say they are superior to kW, ohlins, nitron etc.
What is nice when buying from them is that the shocks and springs are done for your car, so your car weight and any savings in unsprung weights over OEM plus wheel size info are provided to them and shocks are valved accordingly.
Bear in mind that your unsprung setup weight could be at least 9kg per wheel less than OEM, if you have any sort of lightweight wheel/brake option then you really don't want any off the shelf kit that has been valved for the OEM 224 and steel calipers imo, it will at best put your adjustment range out.

Last edited by MOTK; 05-01-2018 at 03:34 AM..
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      07-18-2018, 03:07 PM   #14
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Great write-up by The Hack as usual

If I could offer a very simple suggestion: I think the Bilstein PSS10 setup is the best system for the money.

The PSS10 kit is about $2000 IIRC.
Then I'd get Vorshlag camber plates $435.
And some linear springs in 60mm ID $320.
So for about $2800 you have a suspension that is pretty unbeatable for the money.

I run this kit on my Z4M roadster and I love it. I have 525f/650r spring rates.
I also have a PSS9 kit on my E36 M3 street/track/instructing car, same rates.
I also have custom Ohlins that I built on my E36 M3 race car.
And I have MCS 2way remotes on my other E36 M3 race car.

So while the Bilstein PSS9/10 is not 100% as good as the MCS or Ohlins, they are 9/10 as good. They can handle high spring rates if you desire, and they last forever. I had an E46 M3 with PSS9s that had 90k miles on them, and still handled well and had no leaks. Bilsteins are some of the most well built suspensions on the market. You can't go wrong with this kit.
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      09-20-2018, 08:36 PM   #15
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I've used both JRZ RS Pro & Ground Control.. Obviously JRZ wins haha BUT Ground Control does quite a good job. I have a set with just 2 track days on it and about 400 miles (from and to the track). If anyone's interested shoot me a PM.

Z4M Race setup. Red shocks, Race camber plates, Race rear shock mounts, 600/660 springs, Thrust bearings for the front, nylon spring cones for the back, bump stops, OEM BMW rear shock dust boots (put them on myself as they aren't included.
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      09-23-2018, 12:15 AM   #16
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Just some fun fact, Öhlins uses Eibach springs because Eibach are the best at getting maximum spring travel in relation to the total length of spring.
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