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What is the best progressive rate coil spring set for an E30?

Discussion in 'E30 (1984-1993)' started by Brian A, Oct 20, 2008.

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    Brian A

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    I am looking for comparative reviews of progressive rate coil springs for the E30. Particularly, does anyone know of reviews of H&R vs. Eibach vs. BavAuto (vs. other) progressive rate coil springs or have direct comparative experience themselves?

    As of last week, the torrid 12 year relationship I've had with my 1987 325i convertible is no longer monogamous: I bought my second BMW; a 1991 318i. The surprise is that the 318i has a small case Limited-Slip Differential; totally unsurprising is that its suspension is loose just about everywhere.

    I am going to renovate the suspension as a DIY winter project (springs, shocks, sway bars, control arms, tie-rods). I want to set it up to be 90% daily driver, 8% autocross competitor and 2% track rat. Said another way; I don't want to be miserable for the 90% of the time I'm not at 10/10s, but I do want a good autocross set-up.

    I've been researching spring choices. Quite frankly, I've confused myself.

    Which springs are best for my configuration goal? Why do I want to change springs anyway? I've got Bilstein HDs and Eibach 20/16mm adjustable sway bars on my 1987 325ic with stock springs and, quite frankly, seem to do okay in autocross (I'm in 6th place in C class with Golden Gate Chapter). Likewise, the long stock springs swallow the freeway bumps. I don't know what new shorter springs will do for me.

    I would prefer comments from people with actual comparative experience of the various spring options since ride quality is such a subjective issue.
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    granthr

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    Brian:

    I don't know if this will help or not. My 84 318i with the H&R sport springs and bilstein sport shocks is stiffer than the Stock (and original, 74,000 miles) springs and shocks on my 88 M3. On occasion I have hit the bump stops on my 318i on bad Philadelphia city streets, not on the highway though. I don't drive the M3 in Philly!

    Don't forget to take tire and wheel size considerations into this. If you keep 14 inch wheels, it won't be as stiff compared to 15 or 16 inch wheels. I have 15s on my 318i and run 35 psi, I have 16s on my M3 and run 36f, 38r.

    Does Dinan make suspension kits for the E30? I have a Dinan stage II suspension on my E36 and it is flat in the corners, but not as stiff as my 318i. The shocks are adjustable Koni, I am not sure who makes the springs for Dinan.

    This is a tough decision. See if you can get a ride with someone near you.

    GR
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    Brian A

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    Hi Grant,

    Thanks for the input; it's surprising to hear how firm you find the H&Rs compared to your stock M3 set-up. I will keep researching.

    Regarding wheels, I currently intend to keep the 14 inch bottle caps. At a lithe 14 lbs each, there is only an aesthetic issue some people (not me) may have with them. I run 195/65R14s at 33 psi on the street and 43 psi front / 38 psi rear for autocross on my 325ic. I will likely change to 205/60R14 on the 318i next time, although the tires the car came with still have 40k miles of tread left.
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    MGarrison

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    the stock E30 M3 suspension or 325is suspension I think would be the least harsh of most combinations you might consider -

    harshest jaw chatterer - coilovers
    next - koni or bilstein sport shocks with any progressive rate spring (I think the Koni's on their highest setting are stiffer than the bilsteins by a tad).
    then - Bilstein HD shocks w/ prog. rate springs
    then - Bilstein HD's w/ stock springs
    basically stock - Boge's & stock springs

    Depends on your ride quality (or lack thereof) tolerance -

    Looking @ the Dinan site, looks like they have their own springs & bars, using Bilstein or Koni sports. They have adj. rear camber kits for the trailing arms, but others do as well.

    For some auto-x & track capability, I'd probably consider larger swaybars (The Turner Motorsports H&R kit looks like a total package), Bilstein HD shocks for some preservation of ride quality, and springs. If you stuck w/ stock springs, you would preserve more ride quality at the expense of the car's transitional ability. In an auto-x, the stock springs, sitting higher, will make for more lean, and to get through those tight/quick changes in direction, you'll tend to throw more weight around, in a sense. Lowering the car, you lower the center of gravity, and the stiffer springs will be pushing back harder (as it were) against the car's wanting to lean in turns- (I'm sure there's in infinitely better more technical explanation for those handling dynamics, hopefully you know what I mean).

    The setup on my E30 is Eibachs, 22mm Racing Dynamics adj. front swaybar, 19mm old suspension techniques adj. rear bar, RD heim-joint swaybar links, Koni sport shocks, Dinan camber plates, stock offset front upper strut mounts, E30 M3 offset lower control arm bushings, KMac adjustable poly rear trailing arm bushings, Ground Control rear shock mounts, Bavauto front stress bar, and a Hartge rear stress bar, just fyi. The Koni's, even on their softest setting, are still very stiff.

    Eibachs, H&R, Bavauto - can't offer much insight for comparison - I'd guess try and compare specs as best you can, I'd be surprised if there would be huge differences in their overall performance. There's probably something to be said for components that have been tuned to work together. I'd tend to think the greater the amount a spring lowers the car, the stiffer the ride would get - that would be a good question for whoever you talk with.

    If you go to poly rear subframe bushings, expect your in-cabin nvh to increase.

    Post what other suspension options you find -
    spring & swaybar kits I saw taking a quick look around:
    Suspension Techniques
    Dinan
    Racing Dynamics
    H&R & Eibach stuff - Tire Rack, Turner Motorsport, Bimmerworld
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    mooseheadm5

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    I recommend getting a set of track/autox wheels in 15". Run 205s and you will not regret it. Plenty of tire for the street or track (even if you drive like me.) Running 14s on the street with stiffer springs will be easier on you because of the damping provided by the taller tires.
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    MGarrison

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    CRKrieger

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    Why would he want to run taller tires on a 318? It is inherently acceleration-challenged, so the best thing to preserve what little momentum-accumulation it has is to run the 14"s, at least in autox. If he wants to get an extra set of wheels, I would suggest a pretty set for the street and use the OEMs for the track.
    • Member

    Brian A

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    Great lead: I was told that Dinan had ended their supplying of E30s, but it sounds like they are still selling. I'll give them a call or drive down. Their springs are a couple of hundred extra dollars than everyone else though. I'm still hoping someone has compared Eibach vs H&R vs some of the others you listed.

    sway bars are a no-brainer YES, as are shocks (probably Bilstein Sport or may be Dinan/Bilstein.) (or Bilstien HDs if I stay with stock springs).

    The lights are coming on regarding the (theoretical) benefits of lower, stiffer springs. The 318i (2600 lbs) feels noticably lighter than my 325ic (2950 lbs). I like it.

    Ireland seems to have reverted to the 3 position adjustability rather than their "infinitely"
    adjustable style I have heard about in the past. I am wondering if anti-sway bar diameter is an instance where more IS better. Ireland "wins" in that race.

    I am thinking that staying with 14" might be the way to compromise: I can run 33 psi street pressure and pressures in the 40s for the track/autocross. That'll give me a soft(er) compliant ride on the street, but a good contact patch racing. I don't know much about this actually, so need feedback if I am on the wrong track.

    Hey! I got a swagging 138 hp. You got an issue wit' dat? Seriously, I was actually wondering if anyone runs smaller diameter tires at autocross (not sure they exist) to effectively change gearing and lower the body even more. It would look decidedly uncool, but I would take special glee at smoking the 335is and M6s.
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    granthr

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    I think you miss understood what I was trying to say. First, I have not changed the overall diameter of the tires on my car. I went from 195/65-14s to 205/55-15s, basically the same diameter. I am running a 3.91 lsd diff. This is the stock set up.

    For Brian, I was just saying if he runs 195/65-14s he will have a taller sidewall to absorb bumps better, if he is concerned about a harsher ride from the sports suspension. If he were to switch to 205/55-15s he will have a harsher ride. As we all know here the taller the side wall a tire has, the more it absorbs. I was not suggesting he increase the size (diameter) of his tires. I agree that this would degrade the acceleration and would not be beneficial in this case.

    GR
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    Brian A

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    Still searching for spring comparisons for my 318i

    1.) I would dearly love to find a comparison of Dinan vs Eibach vs H&R vs Suspension Techniques vs Racing Dynamics vs etc progressive rate springs. Anything anyone?

    2.) The above list is pretty much in rank order of the alternatives I am considering. Its basically based on my preceptions of performance and marketing rather than any objective input.

    3.) I am going to stay with my 14" bottlecaps, at least initially. The factory recommended pressures posted on the driver door frame are 28 psi front and 30 psi back so these pressures will buffer the stiffer springs when I am just cruising the highway. I have a lot of room to crank up the pressures for autocross.
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    Brian A

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    Ya payz yer money and takes yer chance.

    To close this thread out, I settled on Dinan springs and Dinan Bilstein shocks (a Dinan "Stage 1" suspension package). I go down to Dinan next Friday to pick them up. (I also have a new Dinan engine performance chip waiting there for me too.)

    After talking with several people I talked myself into the price premium to get Dinan's fine tuning of shock/spring interaction. They have a spring/Koni package for an extra $300 that Dinan particularly recommends, but I decided not to go that far since it pushed me over my $2,000 car renovation budget and Bilsteins are sturdier, don't fade on the track and Dinan still feels like they are "good enough" for them to sell. There really is no way to objectively decide between set-ups. Mike Miller was helpful because he had comparative experience.

    I am going to install "plain" Eibach 20mm/16mm adjustable swaybars. Dinan sells swaybars too (bumps it to "Stage 2"), but would be yet another $300 compared to the plain Eibachs. Compromise, compromise.

    Also, somewhere in this great nation is a UPS truck loaded with new control arms, tie-rods, shock mounts, etc etc etc headed toward my house by the end of next week. Total cost so far is $1,905 and I still need to pay to have my M3 off-set control arm bushings mounted, a wheel alignment and who-knows-what. I think I am going over budget (which is already above Kelly Blue Book for the value of the entire car!!)

    z31maniac guest

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    I didn't realize Dinan still made their E30 chip. Although I think you may be disappointed with it. I have one in my car, but it came with the car when I bought it.

    It's been shown on the dyno to be outclassed by the TMS/JC chip, which is then outclassed (by the tune of 10+hp) Mark Dyslvia chip.

    I'll be swapping in 19# injectors and the Mark D chip in the next month or so.
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    Brian A

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    Dinan says they still have a pile of them, at least for the 1991 318i.

    Dinan's assertion is that their chip boosts hp to 150 hp (from stock 138). I'm in California where the hottest gas we got is a tepid 91 octane so that is a factor for me. I put a Dinan chip into my 1987 325i about 10 years ago and easily felt a substantial increase in power/torque.

    The 318i engine is 10.5:1 compression ratio, already needs 91+ octane as stock and does not have knock sensors, so I am surprised that other tuners can push timing/fuel that much more than Dinan without causing pre-detonation. Do you have a link that shows comparative performance curves? I had looked at the Turner/Comforti chip curves before going Dinan and I had thought they were basically the same as the Dinan.

    Regarding the injector change, what improvements are you making to the air intake system to take advantage of any increased fuel delivery volumes?

    150 hp is still pretty anemic, but I can't see how one can wring much more out of it without major surgery.

    z31maniac guest

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    Ooops! I guess I should have paid closer attention to the fact that you have an M42 vs an M20!!!

    On the M20, the stock injectors are literally running out of gas in the upper part of the rev range, which is where the bigger injectors help. Also the stock 14lb are Design II with 1 hole pintle cap vs the 19lb Design III which has a 4 pintle cap for better fuel atomization.

    The throttle body isn't a restriction on the M20 until stroked/hotter cam/headwork/etc, and the AFM is a known bottleneck, but there seems to be some controversy whether a MAF kit is worth the cost, or the M30 AFM actually helps.

    There are a few dyno sheets for the M20 MarkD chip floating around, and if I remember correctly it beat the JC chip by 10+ HP all through the upper rev range and users have reported vastly improved throttle response as well. I'm working on getting a set of injectors today or tomorrow, then will be sending them off to witchhunter for a clean and rebuild.

    Hope to have the injectors and chip in, in the next 2-3 weeks.

    PS, we are stuck with 91 octane here in OK too. :(
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    Brian A

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    The monster breathes ...

    After its major surgery these last few days, my new 1991 318i is back on four wheels. Thanks to all for the advice and morale support.

    http://www.justracing.com/homepage/BrianA

    Next is a wheel alignment and BMW CCA Technical Inspection. ... I registered last night for my first ever high performance driving school: Laguna Seca 16 January.
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    az3579

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    Hmm, is that why you got a non-convertible E30?
    Just admit it. :D


    Looks really nice! Are those 195-60-14 tires?
    • Member

    Brian A

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    One of the reasons. I have wanted to go on a track for a long time, particularly Laguna Seca, and it has been impossible with the convertible.

    Nope. Plain 195/65R14s. I will change to 205/60R14s when the tread is gone on these. I swapped wheels with the convertible since the bottle caps on the 318i were in slightly better shape. The convertible is my mistress.
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    az3579

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    Those don't look nearly as tall as my bottlecap tires before I got rid of them. Mine were 195-65-14 as well but they looked a lot taller than yours...
    http://s200.photobucket.com/albums/...1987 BMW 325e/?action=view&current=before.jpg



    Anyway, how do you like your new setup on the 318?
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    Brian A

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    Hummm. Not sure why. Maybe its that tire shine stuff I slop on them before going to the Monterey Historic Automobile races. That stuff lasts a long time.
    The two front tires are still pointing in two different directions since the car is awaiting an wheel alignment after the surgery. I've taken it out for a couple of blasts, ... er cautious excursions..., and it felt fantastic. Classic Dinan: smoother than before yet little body roll, no dive during hard braking, no bumpsteer, laser guided steering. There is a louder impact noise now when I hit a bump, which I think is from the solid control arm bushings. Don't know yet about understeer/oversteer. I've set the front swaybar to full stiff and the rear to medium; time will tell.
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    az3579

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    I get that too, but I replaced the mounts when I did shocks all around and it is also louder when hitting bumps. Did you replace those? I think that's what's causing it...

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