Story by David S. Wallens • Photography by Tom Suddard
Does more money equal better results?
Yes. No. Maybe.
More likely, the answer is the usual: It depends.
Take a suspension setup. Today’s market offers the full range of options, from simple, comfortable upgrades to hardcore,…
Great article! I would have liked to see the impact on lap times too.
And jeez, what ever happened to the days when you could take your bone stock BMW to track days without worry of everything breaking. Carbon residue? Clutch slip? Bad rod bearings? James spent an age to find a good clean example of a 335i and still had to spend *thousands* to get it track-ready.
Is there a major typo in the spring rates for the first kit? Based on the others, it should probably be about 319 for the front springs - unless there was a drastic change in handling that wasn't acknowledged.
The testing was a little messy here. Camber changes (and did the toe get reset?), big swings in spring rate - the main thing that changes with more expensive suspension is the quality of the damping but too many variables were changed to evaluate that. Two sets of the shocks were adjustable but weren't actually adjusted. I understand there were time limitations but I'm not sure any real conclusions can be drawn. We've done similar testing and if the data is too noisy, it gets thrown out.
When the less-expensive suspension is MaxPeedingRods, then yes 
In reply to Keith Tanner :
They wanted to test it accordingly to Koni setup that does not have ability to change the suspension height, however, it is not important cause we still having very understandable picture of what does what and lowering them won`t change results, especially, if we are not presented with lap times
A 6 MPH difference between setup 1 and 2? That's a good bit higher than I'd have guessed.
But was that due to the new springs and shocks or the extra 2.6 degrees of front camber? We have no idea. How many laps, and was that the maximum speed recorded or an average of X laps?
GRM usually tries pretty hard to do real testing, but this is not very well done.
Does the first kit come with marshmallows for front springs? What is happening there?
Bimmerworld doesn't list a spring rate for the Pro-Kit for this chassis. Neither does Eibach, just a "lowering range". The Bimmerworld description does say they're "proprietary" spring rates, so I guess we're not supposed to know.
Keith Tanner said:Bimmerworld doesn't list a spring rate for the Pro-Kit for this chassis. Neither does Eibach, just a "lowering range". The Bimmerworld description does say they're "proprietary" spring rates, so I guess we're not supposed to know.
I'm guessing because Eibach, they are progressive and that number is the initial rate, but it quickly reaches 300+lbs with minimal loading
They don't look progressive to my eyes.
Good point.
I am shocked upon further googling, that those are almost the same as the stock sport rates (145/460). Those both just seem very soft for a car of that size.
Keith Tanner said:But was that due to the new springs and shocks or the extra 2.6 degrees of front camber? We have no idea. How many laps, and was that the maximum speed recorded or an average of X laps?
GRM usually tries pretty hard to do real testing, but this is not very well done.
I am with Keith here sorry. Also all the money in the world is nothing if you don't spend the time to actually get your fancy suspension dialed in. The number of very expensive builds running around on 4 way adjustables with everything set the middle is laughable large. Your better off buying a non adjustable package that has been fully developed that you can learn to drive on in a predictable manner and spend time on really getting your alignement dialed in.
Big thanks to Quantum Speed Works. They have saved my HPDE weekends 3 times. Friendly, fast, and super experienced.
Keith Tanner said:Bimmerworld doesn't list a spring rate for the Pro-Kit for this chassis. Neither does Eibach, just a "lowering range". The Bimmerworld description does say they're "proprietary" spring rates, so I guess we're not supposed to know.
That instantly pegs them as hardparker components in my mind.
Pete. (l33t FS) said:Keith Tanner said:Bimmerworld doesn't list a spring rate for the Pro-Kit for this chassis. Neither does Eibach, just a "lowering range". The Bimmerworld description does say they're "proprietary" spring rates, so I guess we're not supposed to know.
That instantly pegs them as hardparker components in my mind.
Right? I was trying to order a cam for an LS engine once, called this specialty LS component manufacturer who was prominent in the SpeedGT world back in the day, they were trying to sell me on their SpeedGT cam but refused to give me anything about advance, lift, duration, etc as it was all "proprietary." Called a few engine tuners in CFL and they all refused to tune a cammed car unless they knew those specs.
Anyways - in champcar, we've had better success with Koni STR.R shocks/struts than the more expensive and adjustable yellows. Combined with the same Eibach springs. For some reason the cheaper damper combo allows the car to roll into turns better and way more predictable.
Bluebayou22 said:Big thanks to Quantum Speed Works. They have saved my HPDE weekends 3 times. Friendly, fast, and super experienced.
Heck of a thread bump "New Reader"
I know it's a zombie bump, but think there are some things that could use clearing up.
1) Pro-kits are not 'hard parker', but rather a mild drop on mildly increased spring rates for typical sporting street user. Always have been, always will be. Not sure how or why anybody would be surprised by this. On the E90, it turns out to be basically just an aftermarket way to get the sought after ZSP suspension on non-ZSP cars.
2) Just because they aren't published, so that people who don't understand them can't misuse or misrepresent them across the internet, doesn't mean the spring rates aren't available. Eibach is more than willing to provide spring rates to anybody who understands enough to ask. Yes, they are linear on this chassis, despite them generally being known as being progressive rate products.
3) Speaking of people misunderstanding spring rates, there is nothing wrong with the Pro-Kit rates. Considering some of the off-base comments even in this thread of above average enthusiasts and even suspension professionals, I really can't blame anybody for not advertising rates on their general public street products which cover a wide range of cars whose rates and ratios cannot be directly compared. These particular cars have a front motion ratio of ~.955 and a ridiculous rear of .567. This is why the stockish stuff runs rear spring rates ~3x higher than front, to get appropriate wheel rates at each end for a 'flat ride' type f/r ratio. So stock is something like 1.2Hz front and 1.3 Hz rear. Pro-kit is more like 1.3Hz front and 1.4Hz rear. For reasons, as the rates go up, the ratio is not maintained. As the ride frequency approaches 2Hz, the most typically run closer to 2x higher rear than front. And as it gets up into 'race car' territory, generally get more like the MCS rates with 2.7Hz front and 2.1Hz rear. The subframe and suspension design on these cars doesn't do well with spring rates high enough to provide actual 'racing' wheel rates and ride frequencies at the rear of the car.
4) The ISC rates are actually the ones here with the jacked up spring rates. Looking at like 2.45Hz front and 1.33 Hz rear. That's barely stiffer than stock in the rear, actually softer vs ZSP, but on the soft side of race-car-stiff up front. The only excuse I would accept there is that the article accidentally swapped rates in the table. Otherwise those rates are trash.
DirtyBird222 said:Pete. (l33t FS) said:Keith Tanner said:Bimmerworld doesn't list a spring rate for the Pro-Kit for this chassis. Neither does Eibach, just a "lowering range". The Bimmerworld description does say they're "proprietary" spring rates, so I guess we're not supposed to know.
That instantly pegs them as hardparker components in my mind.
Right? I was trying to order a cam for an LS engine once, called this specialty LS component manufacturer who was prominent in the SpeedGT world back in the day, they were trying to sell me on their SpeedGT cam but refused to give me anything about advance, lift, duration, etc as it was all "proprietary." Called a few engine tuners in CFL and they all refused to tune a cammed car unless they knew those specs.
Anyways - in champcar, we've had better success with Koni STR.R shocks/struts than the more expensive and adjustable yellows. Combined with the same Eibach springs. For some reason the cheaper damper combo allows the car to roll into turns better and way more predictable.
That's interesting about the STR.T (think "street" with no vowels). In the Miata application, I believe they've valved like a Sport set to full soft so they should act the same. That may not be the case for other chassis.
Driven5, I understand enough to ask. But I don't take a suspension vendor seriously if they don't publish basic specs like spring rate.
In reply to Keith Tanner :
That is the confusing thing to me - Eibach told people what the rates were for older RX-7s instead of being all coy and "it's a secret."
Maybe something has changed in the past 30 years.
There are few comparison tests like this out there with technical data, was very much excited to read. So I'd like to say thanks for putting it out there. I'm sure that was a lot of time wrenching. But , as an engineer I agree with other comments that controlling one variable at a time, including setting up the suspension properly, and collecting more data would be worthwhile to understand the true delta between kits. The conclusion was predictable Maybe we could be lucky enough for GRM to do a round 2 follow up?
Makes me feel more comfortable knowing my BC racing Coilovers at $1200 are safe for track use, just a bonus to add some speed. My build and progression as a driver (32 days across 10 tracks) doesn't need an MCS kit, but that's what I plan go to when I finally start wheel to wheel racing.
I see I can't get to the entire article unless I have GRM+ or I'm a magazine subscriber. But I am a magazine subscriber, and have been for well over a decade. Does this mean this is an article that is exactly the same in a paper edition, and I can't see it for 160 some days because I can look at it on paper, or are shenanigans going on here? I know this may not be totally the appropriate place to ask, but I'm here, so I'm asking if any of you guys know. I don't get to be on here often (obviously) so I'm unsure of what is going on. Thanks if anyone can help. PS-I have a 335i that I bought with BC adjustables already on it and i remember reading about the Bimmerworld car, so this particularly interests me.
Would love to see the full laptimes.
wearymicrobe said:Keith Tanner said:But was that due to the new springs and shocks or the extra 2.6 degrees of front camber? We have no idea. How many laps, and was that the maximum speed recorded or an average of X laps?
GRM usually tries pretty hard to do real testing, but this is not very well done.
I am with Keith here sorry. Also all the money in the world is nothing if you don't spend the time to actually get your fancy suspension dialed in. The number of very expensive builds running around on 4 way adjustables with everything set the middle is laughable large. Your better off buying a non adjustable package that has been fully developed that you can learn to drive on in a predictable manner and spend time on really getting your alignement dialed in.
I feel personally attacked. Apologize.
I firmly believe that a LOT of the additional speed on (all) McStrut cars comes from adding camber more than anything else when you swap to coilovers. Very few people try to add camber without putting (usually crappy) coilovers on first.
My 2019 GTI with camber plates, Koni Special Actives, STOCK SPRINGS, and bigger F/R sway bars has entered the esses at 122mph and maintained 118 up until T9 (where you need to breath off to maintain the line for T10).
This is only on some 245 wide V730s also.
You'll need to log in to post.
