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Z4 suspension mods

Discussion in 'E85 Z4 (2002-2008)' started by scottstradley, Nov 18, 2011.

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    scottstradley

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    '06 Z4 3.0 - like recommendations on what you've found beneficial for suspension upgrades/strut brace/sway bars/etc that reduce the wallowing when going thru multiple quick curves, yet aren't race track type mods.
    The ride of my Z is ok, not looking for lot stiffer, just want to eliminate the lean and pogo type affect in curve transitions.

    Looked thru threads, roadfly archive, etc and didn't see much other than arguments over strut brace lol.
    Dinan stage 1 reviews show it to be aggressive/harsher ride. Anyone done anything that helped theirs?
    Love the car, but do I have to go to a boxster to correct it? :)
    thanks
    Scott
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    MGarrison

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    Hmmm... if your shock absorbers are damping properly, there shouldn't be any pogo-anything. Assuming you're steering smoothly through the turn, that is, and not loading/unloading the suspension by not holding the steering wheel steady as you drive through a turn. And, assuming the stock shocks are well matched to your springs and not worn out. Guessing that, based on typical average mileage/yr., you might be at approximately 60k, I wouldn't typically expect your shocks to be worn out at that mileage, but, anything's possible, including them having worn partially enough to perhaps be the cause of what you're experiencing.

    A more specific understanding of exactly what the car is doing vs. what ideally you want or expect it to do is needed for 3rd party remote armchair analysis. Wallowing is a bit general, for terminology. Since you mention curves, it begins to sound perhaps as if you're talking about your car's transitional response in back and forth turns.

    Strut braces, by connecting the front &/or rear shock towers, should reduce a bit of body flex/shocktower deflection that might be experienced when turning. The car may feel 'tighter' and turn-in/steering response likely would feel more immediate. Might be more noticeable in a convertible. Might improve your transitional response feel when changing directions. Don't know if it would do anything for suspension bounce/pogo-ing/wallowing, but kinda doubt it.

    Stiffer/lowering springs can have a similar affect for turning, and, more-so than swaybars, control the amount of body-roll a car will have. The trade-off can be in the ride-quality area, depending on what springs are chosen. Progressive rate springs, particularly for street-driven cars, can help to ameliorate the typical degradation in ride quality from lowering springs. Swaybars also limit roll: http://en.wikipedia.org/wiki/Sway_bar &/or http://auto.howstuffworks.com/question432.htm

    Shock absorbers obviously help to damp & control the motion of the springs, and can assist with controlling the rate of body-roll (which can also help transitional response). Again, ride-quality can be one of the main trade-offs here.

    Depending on what you want to accomplish, & how far you want to go (or spend), there's a whole variety of options to consider.

    Can't say I recall any review of a Dinan package for a Z4, but, typically, most reviewers I recall reading seem to comment on how well Dinan-packaged cars handle without compromising the ride-quality to an unacceptable level. Stiffer, yes, but most comments seem to say the ride-quality moves towards harshness on the bigger bumps. Dinan might be pricey, relatively speaking, but they seem to be well designed comprehensive packages. It would be best to get some feedback from someone experienced _with_ a Dinan Z4 for some accurate insight - &, I'm assuming Dinan _has_ a Z4 package/components.

    Of course, there are LOTS of options, and you'd likely find more specific input from what all folks have tried/used in any Z4-specific message forums. Expect that, typically, the more you do, and the more compliance you remove from the car (urethane vs. stock rubber bushings in various places, for instance, plus anything else already mentioned, plus any other suspension-related options), the harsher your ride quality is going to be... and, the more-responsive your car's handling will become.

    Keep in mind I ain't no race-car suspension expert, my discussion here is pretty general, and defer-able to any expert who wants to get more specific about it, make sure you read-up on suspension design and component purpose/function so you can make well-informed decisions before you start throwing money at things. You'll be best able to make optimal choices the more you know. (Yeah, I know... very profound, right? ;-))

    (aaaand... yet again... had I not copied/pasted this reply to the clipboard and wordpad BEFORE hitting Post Reply, I would have lost it in its entirety, due to being logged out while writing the reply. Just FYI to anyone writing posts of any length on these forums/boards: You CAN be logged out WITH NO NOTIFICATION while crafting a reply, and if you hit ANY button (Post Reply, etc.), you're thrown to the login page, and hitting your browser's back button WILL NOT take you back to where you were, your reply WILL BE LOST. SAVE YOUR POST(s) by copying/pasting BEFORE hitting a button or you may LOSE IT ENTIRELY, particularly if your reply is of any length that took longer than a few minutes to write. I don't know about you, but if I lose a long reply, I'm unlikely to take the effort to re-write it. Spare yourself the frustration, don't forget.)
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    scottstradley

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    Thanks for great reply. The pogo'ing/wallowing is related to comparison to same set of roads/curves I experienced in Z3. It had strut brace and Koni's. Strut was there when purchased at 72k, at 80k I put on Koni sports on it, and the car was tight, and it handled beautifully - the change with Koni's was stunning. Love the Z4 compared to Z3 overall, but no comparison in handling - sadly. The Z3 blew it away. You're totally accurate in the transition respone is poor. My suspension isn't worn out, but with current experience may put the Koni's on it pretty soon. But prefer to get feedback for recommendations on what to do.

    I've looked for Dinan feedback. and many say it's too harsh a ride for daily use. With the runflats on Z4, take the reading with hmmmm, will this make it far too stiff for daily use. If didn't have runflats, would put Koni's on immediately and expect similar results.
    Thoughts?
    thanks
    Scott
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    MGarrison

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    I don't have anything that uses runflats, so I don't have experience with them. You might search the forums here, I know someplace Satch had a comment about some new or recent particular runflat that was supposed to be better than the earlier ones. But, yeah, I'd tend to think going for Koni sports with the runflats might tend to make for a pretty stiff ride. The Koni sports I have on my E30 with lowering springs is a very stiff ride, annoyingly so if I run around much on the mediocre-quality streets here in town, and potholes are a suspension crash/slam. I play dodge-the-road-imperfection all the time if driving that car on the street, and that's with the shocks in the softest setting. I wonder if Koni has their FSD's for the Z4.... In the meantime, front and maybe rear strut braces might help improve your transitions without costing a fortune, and being easily removed.

    I think the Z4 chassis is stiffer than the Z3, so I would guess what you've experienced from your Z3/Z4 comparison is just how much of a difference the shocks and brace can make, particularly on the less-stiff earlier chassis design. Spring rates and BMW's intent for feel/handling between the two series might be much different though, that's one area that might not be apples-to-apples when comparing the relative difference from shocks & strut braces.
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    Satch SoSoCalifortified

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    As for Dinan, remember that his suspension is sometimes LESS stiff than OEM, particularly in the E46 M3. I know they DID build a nifty Z4, because Dave Haueter wrote it up for Roundel, so maybe they still have parts. But I also know that the market for Z4 aftermarket bits is puny because the people who buy Z4s tend to think they cars are already perfect. . . which is why Dinan didn't bother to put the Z4 M roadster exhaust system into production (damn! Damn! Damn!).

    I agree with Bruddah G: stay away from stiffer or shorter springs, go with bigger anti-sway bars and good shocks. I'd add a strut brace as a last resort, since it's mostly cosmetic and the car is already ridiculously stiff.

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