[mlifxs]

I like Mil.spec's recommendation, and especially his comment of 'good starting point for a DD and you can go from there'. If you're mainly a DD, it is possible to overshoot beyond your preferences.

My 328i is the first car I've ever modded and I used to think that people who modded cars were, well, frankly NUTS. So, deciding to go nuts myself, and striving to keep the wife on board, I tried to keep the expenditures low and learn some things as I experimented.

Today, I have something akin to a "budget b12 kit". I bought bmw performance dampers with low miles, used, for $250, and Dinan linear springs new for $200. I suspect the b12 kit is better and worth the price for new, but my setup is a strong improvement over the zsp. Linear springs (also on the b12) are delightful. Before installing, remove your front sway bar to see how stock springs behave, then install the linear springs and notice the improvement in predictability (then put the front sway back ) I'm not saying you should go my route, just saying I think my setup is close, therefore thumbs up to the b12.

I have M3 control arms front and rear. The fronts will be the most noticeable and you can find the oem TRW kit for just over $300. The rears make a difference but omitting them is a good corner to cut.

I also did the subframe inserts. It's a cheap, low risk mod with noticeable results. I say zero chance of regrets. Maybe it doesn't achieve the full effect of upgrading the entire bushing, but you won't have any complaints about NVH or spending too much time under your car.

Though not low budget, lightweight wheels are good. To keep the price down and for more fitment flexibility, wait until your tires wear out. Also, consider a square set up. I did, and the result is a much more neutral feel. Michelin PSS are well worth their price. Why did I wait so long to try them?

With the above and a few other small inexpensive tweaks, my car is greatly improved from showroom new. With 130k+ miles, it's delightful to drive fast with very little compromise - and still feels like an affordable luxury car.

[cpie168]

Thanks for your input mlifxs. What are the advantages of linear springs vs non-linear ones? If I already have ZSP springs, is it worth the extra to get a set of linear ones as replacement?

[ashmostro]

Originally Posted by DrRobert

The Dinan RUSM will help reduce rear up-and-down bounce when hitting a bump while going straight (assuming your springs and dampers are well matched). The subframe bushings (or inserts) will reduce rear end side-to-side wiggle you get when hitting a bump while turning. Two different kinds of rear end instability on this platform IME, with 2 different fixes.

One million percent agree with this, as well as the followup regarding the lever effect on the subframe with stiffer rear springs.

Most of the handling issues with this platform is in the bushings, period. I'd do arms and bushings all around before touching the springs, dampers, or sways, if on a budget.

[avocet]

I have bilstein hd's(essentially the same damper as the b12 kit) with my sport springs. IMO it is a perfect match. Give this a read: http://blog.**********s.com/linear-r...best-4-street/

Huh guess I can't link the article regarding linear vs progressive. Google the subject and you will find a ton in info.

Originally Posted by cpie168

Thanks for your input mlifxs. What are the advantages of linear springs vs non-linear ones? If I already have ZSP springs, is it worth the extra to get a set of linear ones as replacement?

[mlifxs]

Originally Posted by cpie168

Thanks for your input mlifxs. What are the advantages of linear springs vs non-linear ones? If I already have ZSP springs, is it worth the extra to get a set of linear ones as replacement?

IMO linear springs give a more predictable feel, as the spring rate is consistent throughout travel, whereas progressives begin with a softer rate and roll a little at first as weight transfers.

downside to linear is you feel the full spring rate, even at low speed, even in a straight line. So, more steering wheel and suspension feedback over rough surfaces. Progressives will smooth much of this out.

Is it worth it for you? I don't know. For me, only if the dampers can handle the spring rate. I'd rather do the install when I'm changing dampers in order to not double the labor.

[ashmostro]

Great answer

[DrRobert]

Originally Posted by ashmostro

Most of the handling issues with this platform is in the bushings, period. I'd do arms and bushings all around before touching the springs, dampers, or sways, if on a budget.

Which bushings besides subframe are you referring to?

[cpie168]

Thanks for the explanation mlifxs. So in summary, would it be correct to say linear springs would be the better choice for someone who favors better handling than ride comfort, and progressive spring for the other way around?

[ashmostro]

Originally Posted by DrRobert

Which bushings besides subframe are you referring to?

Good question. I poorly phrased my comment. Essentially the point of doing the M3 arms is to get the better bushings from them. Yeah you get a bit more camber up front which is nice but the big change is going from the squishy and frankly horrific liquid filled crap our RFT-equipped cars come with to ones where deflection is measured in millimeters rather than centimeters.

It's possible to just buy the M3 arm bushings and press out-in but way easier to just replace the arms.

I also highly recommend delrin subframe bushings if you are going with a really high rear spring rate. I wish I had gone that route instead of M3 style (I'm running 800# rear springs).

[ashmostro]

Originally Posted by cpie168

Thanks for the explanation mlifxs. So in summary, would it be correct to say linear springs would be the better choice for someone who favors better handling than ride comfort, and progressive spring for the other way around?

I know this wasn't directed at me but I'll add in my shillings.

Not necessarily. I think the question you want to answer to inform that decision is how hard you intend to push your car, literally. Are you going to be pulling 1 G consistently and doing a lot of lateral transitions (e.g. track driving)? If yes, then linear (and stiff) is what you need. If you're into "performance" but that means spirited canyon carving at 7/10s you can probably get away with progressives and enjoy their comparative comfort the rest of the time.

All of this also assumes we are talking about really high rate linear springs. If you're not then the comparison has even less meaning and linear springs can be just as comfortable cruising down the highway as mlifxs so aptly put it.

[cpie168]

Thanks for your input ashmostro. For me, I don't track the car and it is my dd, so my focus would be on ride comfort. I want the car to ride better than the jarring sports suspension, but handles with less lean when it goes into corners. In that case, based on your input, I think it should be fine keeping my sport package springs and just go with an upgrade for the shocks, either Bilstein B6 or Koni FSD.

[ashmostro]

From what I've heard, FSD's can give inconsistent behavior and don't really live up to the reputation they earn on paper. If you simply want to upgrade shocks then in the Koni lineup the Yellows would be a better choice.

Have you considered the BMW performance suspension option? I personally have no experience with them but have read quite a few positive reviews here.

[cpie168]

My understanding of the Koni Yellow is that they offer stiffer damping which is good for handling but bad for ride comfort. That is a compromise I am unwilling to make. As for the BMW Performance suspension, I would assume they're somewhat more expensive than the aftermarket options, which means they will be out of my budget...

[ashmostro]

Sport damping doesn't necessarily equate to ride discomfort. It can even improve on it by better low-frequency control and high-frequency blowoff. I'll let others who have run yellows or FSD's comment on this more specifically.

For example my JRZ-based suspension with springs 3-4x stiffer than stock is in many ways more comfortable than stock sport suspension.

[cpie168]

What is JRZ?

[ashmostro]

Just a brand. High end race-oriented suspension. Only brought it up to make my point. It's not likely something you want to consider for your application ;-)

I use the RS1 line which is the most street oriented of their products. http://www.jrzsuspension.com/products/rs-line/rs1.html

[DrRobert]

I had the FSDs and did not like them, but in my case the main reason for that is that they were the wrong choice to pair with the BMWPS springs I installed at the same time - my mistake. I have since replaced the FSDs with Koni yellows, which IME is a perfect match for the BMWPS springs. However, I did not feel like I gave up any ride comfort going from the FSDs to the yellows. The FSDs are made to match with stock or sport package BMW springs - lots of feedback available on them by searching - lots of folks love them but many complain of inconsistency like ashmostro said. Not sure how the yellows pair with OEM springs.

[DrRobert]

Originally Posted by MIL.SPEC

With the new 18" ARC-8 rims and the PSS with 235's in the front and 265's, I am taking on ramps and off ramps at similar speeds to what I was doing in the Evo (not that I was pushing the Evo). But the confidence with the B12 kit and better rubber is pretty darn good for a luxury car. Car handles great even without an LSD.

Any issues running that size tire on your 335? I'm thinking of bumping it up a notch to those sizes, but with Bridgestone RE11s on OEM rims.

[ashmostro]

Shouldn't be an issue. I run 245/275 on 19s but will be going down 10mm each to address excessive OD.

[DrRobert]

Are those tire widths OK with my rims too (18" 287s, 8" front and 8.5" rear)? They came with 225s/255s on them.

[ashmostro]

Should be. Check out tire racks spec sheets they will tell you allowable rim width ranges for every tire in every size!

[cpie168]

Thanks again ashmostro and DrRob. I'll do a search for Koni FSD to find out more.

Have a good one!