[ashmostro]

So I'm collecting all the parts for my upcoming suspension transformation and the only bit left is the coil setup, which means I need to decide now if I want to convert to an M3 lower rear camber arm or not. I'm not convinced that the few pounds of unsprung mass are going to be that noticed by an ordinary schmoe like me, but I figured I'd ask the question before committing to a purchase.

I'm leaning towards the Ground Control Street/tour kit for my mostly DD, but some track purpose 335is.

As for my purchased suspension/drivetrain mods:
- Quaife LSD
- Powerflex Subframe bushings
- Megan Upper camber, trailing, and toe arms
- M3 front control and tension arms
- Eibach sways(f+r)

So, I ask you- do I really *need* the M3 lower camber arms since the bushings are in the chassis and knuckle? Is the different lower shock mount that much of a difference in the real world? I'm thinking I don't want to pay $400 for the last 10th of performance, but if we're talking a 50% improvement for little to no ride quality degradation I'll consider it.

Thanks folks.

[CJ421]

The weight difference with the M3 camber arms is attractive but is not by itself worth the upgrade cost. Another difference comes from how the damper is connected to the arm; the standard camber arms have the damper sitting in a rubber saddle, whereas the M3 versions have the damper solidly connected. This allows the damper to react quicker and eliminates some of the rear slop our cars are known for.

That said I don't know how to quantify the difference with the M3 camber arms. Like the rest of the M3 suspension parts, the difference is incremental for a not-so-incremental price (though, many M3 parts together are quite noticeable). Some people like myself will chase after this incremental difference ...I do it with just about everything I get into, like speakers, computers &c. My car is fully converted to M3 suspension parts and them some, without regret.

P.S. ride quality is a confused term; the M3 parts don't directly affect ride quality. Here are three things we can change that directly affect it:
-Dampers
-Spring rate
-Tires

[ashmostro]

Thanks for posting man.

Agreed ride quality is misunderstood, but I'm not sure I fall into that category Frankly, I wonder if the rubber mount actually helps with some of the small-bump impact with minimal downside since the lower perch isn't used to "locate" the suspesion like the rest of the bushings are. Since I'm not hardcore racing I feel like this is sort of equivalent to choosing street camber plates that use high durometer rubber mounts up top (GC).

Thoughts on that? I'm still open to the M3 lower arms but not yet sold on the cost/benefit.

[The HACK]

"Real-world" advantage? Ask yourself this question. How often do you go to the track, and how well can you drive your car. Answer both questions truthfully and you'll maybe get some real answers.

[ashmostro]

Like yours?

[The HACK]

Yes, like mine.

If you failed to read between the lines, I'm going to give you this nugget of wisdom. The E9X chassis is far more capable than just about 99.95% of the drivers can extract out of it on the road. Heck with my 10+ years of high performance driving experience on the track, put a set of slicks on the car and some decent brakes and the car itself is probably still far more capable than what I can wring from it.

The god's honest truth is, if you're not extracting the last bit of performance already from a chassis from a driver's perspective, there are little to no real world performance to be gained from the M3 lower control arms. In fact, all you are doing, is increasing the rate at which your tires wear without actually being able to take advantage of the REASON why you're increasing your tire wear.

So, again, in terms of real world advantage? You must ask yourself this. How often are you going to take the car to the track, and as a driver, are you already capable of extracting every bit of performance out of the car. If the answer is neither, then it offers zero tangible real world benefit. If the answer is "I go at least a dozen day a year and I've been doing this for the last 10 years" then yeah. That added camber will give you some REAL handling edge when it comes to going around the track FAST.

But judging from your answer to my question, I already know the answer.

[ashmostro]

I just didn't appreciate your tone. Based on your further response I think that's just how you communicate.

Obviously, the fact that I'm asking the question (and in particular, the way I phrased it) should suggest that I'm not naive to the competence of my car's chassis. If you want to be a cynic, that's your thing man- not mine. Peace.

[cvc 22349a]

As 'cj421' mentioned the m3 lower camber arm eliminates the bottom rubber shock mount eliminating deflection at that mount thereby increasing the increasing damper reaction time to suspension movement.
Personally I don't have them on my car and could only quantify the benefit as feel.
GC does sell them with their street/school suspension cheaper than you could buy them separately. Perhaps they're the folks to ask.

[ashmostro]

I talked to GC yesterday in fact. Of course they are going to try to upsell so I came here to get unbiased and hopefully experienced opinions.

Anyway, I'm probably going to stick with the steel/rubber lowers in interest of some NVH and bump compliance. Same reason I'm going with street camber plates instead of pure pillowballs.

[CJ421]

Originally Posted by ashmostro

Thanks for posting man.

Agreed ride quality is misunderstood, but I'm not sure I fall into that category Frankly, I wonder if the rubber mount actually helps with some of the small-bump impact with minimal downside since the lower perch isn't used to "locate" the suspesion like the rest of the bushings are. Since I'm not hardcore racing I feel like this is sort of equivalent to choosing street camber plates that use high durometer rubber mounts up top (GC).

Thoughts on that? I'm still open to the M3 lower arms but not yet sold on the cost/benefit.

You're welcome. I apologize if you felt I roped you into the category.
Personally, I'd spend money on the M3 lower camber link before I spent money on any other M3 part back there (aside from the subframe bushings). The M3 camber link forces the damper/spring to control the movement. The rear of the car is always going to move more than necessary with the rubber saddle in the stock camber link. BMW probably designed it that way to make the car feel cushier on the street, but a good damper with a sensible compression stroke will invalidate that reasoning. Again we're talking incremental upgrades ...it's been so long since I got my M3 camber arms in, I don't remember what it was like without them. I couldn't honestly tell you spending $40 let alone $400 is worth it.

P.S. Consider replacing the rear shock mounts with something stiffer than stock. The stock one is soft enough that it'll move before the damper starts moving. That's a pretty inexpensive upgrade, IIRC.

Originally Posted by The HACK

"Real-world" advantage? Ask yourself this question. How often do you go to the track, and how well can you drive your car. Answer both questions truthfully and you'll maybe get some real answers.

HACK - I appreciate your knowledge as much as the next person. Regardless of intention, your tone comes across as dismissive.
You might have added your own info about the M3 camber arm so the OP has something else to factor into their decision. Instead you asked a loaded question that you probably wouldn't have accepted an answer to anyway: how well they drive the car.
As I said, dismissive.

[ashmostro]

Originally Posted by CJ421

You're welcome. I apologize if you felt I roped you into the category.
Personally, I'd spend money on the M3 lower camber link before I spent money on any other M3 part back there (aside from the subframe bushings). The M3 camber link forces the damper/spring to control the movement. The rear of the car is always going to move more than necessary with the rubber saddle in the stock camber link. BMW probably designed it that way to make the car feel cushier on the street, but a good damper with a sensible compression stroke will render that argument meaningless. Again we're talking incremental upgrades ...it's been so long since I got my M3 camber arms in, I don't remember what it was like without them.

P.S. Consider replacing the rear shock mounts with something stiffer than stock. The stock one is soft enough that it'll move before the damper starts moving.

No worries, I wasn't offended or anything. Appreciate any constructive input regardless of position on the matter.

The GC coils use their own high durometer upper mounts. Only the lower mount is reused. The other option for a hard lower mount is Turner's m3-style conversion part. http://www.turnermotorsport.com/p-20...m-e82-e9x.aspx

I'll consider all three options but I'm thinking it's either the mount conversion, or stick with stock. I still can't justify the $400 cost for the arms for a few semi-sprung pounds saved. I'm no Alonso.

[CJ421]

Oh, I just remembered, you could replace the bushings on the stock camber arm with Powerflex ones:
http://powerflexusa.com/E9X3Series06.aspx
I haven't seen anyone do that, but it'd be less money for sure. Something to do later on perhaps, after you have time with the parts you're getting.

Either way, good luck, your setup looks great and you're going to have a blast.

[ashmostro]

Aren't those upper mounts?

Anyway, I'd be hesitant to do urethane lower mounts because those will likely make noise. Powerflex is great for fixed bushing use, IMO. When you expose them to the elements with a part that articulates I think they get noisy once the lubrication has washed off.

[CJ421]

#14 and #15 look like they go on the camber arms. I wish I could share some experience with these parts. I've seen a few people use Powerflex with good success but nothing for this particular application. Someone has to be the guinea pig.

Did you order your dampers/springs yet?

[ashmostro]

yeah 14 and 15 are for the arms but they actually go into the chassis and hub. The arms don't "hold" the bushings on the rear, which makes the swap that much easier.

Didn't buy the coils yet... this will probably be a birthday present to MEE Leaning towards the standard mount setup but got a few more things to think about, namely if I buy the turner mounts GC will do an M3 style rear shock at the same price, so that would leave me more conveniently open to the option of an arm upgrade in the future if I want it.

Thanks for your help man! We should meet up sometime. Wife's got family in Pittsburgh and we go to Philly a few times a year.

[cvc 22349a]

I read somewhere those turner lower shock mounts will cause increased nvh. They didn't sound so great for a street driven car.

[ashmostro]

Yeah I did some research and read that too, although I don't really understand why they would make more NVH than the M3 lower link setup, unless you are using metal race leeves on the shock instead of a polyflex material. Maybe that's why.

[cvc 22349a]

Pls post a review if you try them