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Thread: Suspension questions for 98 1.9L

  1. #1
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    Suspension questions for 98 1.9L

    I daily drive my Z3 1.9L 5 speed in the summer. I'm tight around 73k on it, and probably due soon for a suspension refresh. I don't have any big issues at the moment. I do notice that the front end lifts on acceleration some, but otherwise it tracks straight. I am assuming that all suspension components are factory original.

    1) What all should I be looking to replace? Control arms/bushings, subframe bushings, diff bushings, etc

    2) For shocks/Struts, on a daily driven car, what would be preferred? I see KYB, Sachs, and Koni as options in my price range, and may even have bought the Sachs rears already.
    2a) Can I mix and match brands or is that frowned upon? Like KYB front with Sachs rear.
    2b) Can I just do the rears now, or is it best to do them all at the same time? Would there be any negatives?

    3) I have a 3.45 small Case LSD here that needs a rebuild. Where would be the cheapest place to get parts for this, and would I benefit from swapping it in for my Open Diff 3.45? If not, is there a how-to for replacing the fluid in the differ and with what type? Any other fluids to do?

    4) Is there an upgrade for the swaybars that is available from other cars that I could pull and use? Would it help any?

    Thanks.
    Last edited by jimmyfloyd; 04-24-2018 at 12:23 PM.
    1998 Z3 1.9L Dinan Stage 3.

  2. #2
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    Quote Originally Posted by jimmyfloyd View Post
    I daily drive my Z3 1.9L 5 speed in the summer. I'm tight around 73k on it, and probably due soon for a suspension refresh. I don't have any big issues at the moment. I do notice that the front end lifts on acceleration some, but otherwise it tracks straight. I am assuming that all suspension components are factory original.

    1) What all should I be looking to replace? Control arms/bushings, subframe bushings, diff bushings, etc

    2) For shocks/Struts, on a daily driven car, what would be preferred? I see KYB, Sachs, and Koni as options in my price range, and may even have bought the Sachs rears already.
    2a) Can I mix and match brands or is that frowned upon? Like KYB front with Sachs rear.
    2b) Can I just do the rears now, or is it best to do them all at the same time? Would there be any negatives?

    3) I have a 3.45 small Case LSD here that needs a rebuild. Where would be the cheapest place to get parts for this, and would I benefit from swapping it in for my Open Diff 3.45? If not, is there a how-to for replacing the fluid in the differ and with what type? Any other fluids to do?

    Thanks.
    1.) It's never bad to replace all of the semi solid mounts/bushings.
    2.) Bilstein B6~ Bilstein B12. That's what I have and it handles bump like a champ.
    It is not advisable to mix dampers and springs of different brand because you never know
    its static rebound and compression settings let alone the dynamic ones (.e.g. during fast cornering).

    What you could do is put a stiffer damper from the same brand as front (less travel) in the rear like I did with stiffer springs for a
    more neutral feel. I have sport suspension from BMW (which is Bilstein) so I put Z3M dampers in the rear with slightly higher spring rate.
    Again, this isn't advisable if you don't know what you are doing.

    3.) I live in Japan, and the most popular option is Cusco 1.5 way for diff rebuild.
    OEM Open diffs are garbage; go to a shop that does proper backlash setups.

  3. #3
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    Quote Originally Posted by kyrix1st View Post
    Bilstein B6~ Bilstein B12. That's what I have and it handles bump like a champ.
    Are the roads in Japan smooth? A stiff suspension on smooth roads works great. I can guarantee that the roads in Rochester, NY are no better than what we have in northwest New Jersey. Bilstein sports with lowered HR springs nearly rattled the fillings out of my teeth after I drove it home from Florida, where I had purchased it. Stock springs with Koni Sports work great on the rough roads around here.
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  4. #4
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    Quote Originally Posted by jimmyfloyd View Post
    ... I see KYB, Sachs, and Koni as options in my price range, and may even have bought the Sachs rears already.
    2a) Can I mix and match brands or is that frowned upon? Like KYB front with Sachs rear.
    2b) Can I just do the rears now, or is it best to do them all at the same time? Would there be any negatives?... .
    The KYB and Sachs are equivalent. I got KYB because they were cheaper and people said they were smooth and lasted longer than my OE Sachs, which were unpleasant at 30,000 miles.

    OK to mix front and rear. No harm in doing rears alone, but you may notice the rear is stiffer than front.

    If Koni is truly in your price range, they are better than KYB or Sachs. They can be acceptably smooth if the cheapest model is bought and set to soft. I would have gotten Koni but I thought their struts were inserts that required cutting up the OE Sachs to install. I think that only applied to the M suspension.
    Last edited by Vintage42; 04-24-2018 at 07:54 PM.
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  5. #5
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    Quote Originally Posted by rasmuw View Post
    Are the roads in Japan smooth? A stiff suspension on smooth roads works great. I can guarantee that the roads in Rochester, NY are no better than what we have in northwest New Jersey. Bilstein sports with lowered HR springs nearly rattled the fillings out of my teeth after I drove it home from Florida, where I had purchased it. Stock springs with Koni Sports work great on the rough roads around here.
    Ah, NY roads are indeed crap. My rental low mileage Mini cooper S already had crap hub wheel bearing.

    Kyoto has some undulations here and there, but PSS9 with Swift linear springs (F 14kg/mm & R 16kg/mm) worked pretty well on my E36 M3 except for really hard bumps.

  6. #6
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    Nobody benefits from swapping an LSD to an open diff... LSD is the upgrade option

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  7. #7
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    Quote Originally Posted by kyrix1st View Post
    ... Bilstein B6~ Bilstein B12. That's what I have and it handles bump like a champ...
    Those are very different struts/shocks. Which do you have, and what does handling bumps like a champ mean? Many people find that their Bilsteins are too stiff.
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  8. #8
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    Quote Originally Posted by Vintage42 View Post
    Those are very different struts/shocks. Which do you have, and what does handling bumps like a champ mean? Many people find that their Bilsteins are too stiff.
    I have B12. B6 is slightly more compliant.

  9. #9
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    Quote Originally Posted by BimmerBreaker View Post
    Nobody benefits from swapping an LSD to an open diff... LSD is the upgrade option
    Ok, I should clarify. THe car has an Open Diff in it currently. I have purchased a 3.45 LSD from another 97 Z3 that needs a rebuild. The question is should I stick with the Open Diff or attempt/pay to rebuild the LSD and swap it in. I am not sure it is worth the expense/effort.

    Quote Originally Posted by Vintage42 View Post
    The KYB and Sachs are equivalent. I got KYB because they were cheaper and people said they were smooth and lasted longer than my OE Sachs, which were unpleasant at 30,000 miles.

    OK to mix front and rear. No harm in doing rears alone, but you may notice the rear is stiffer than front.

    If Koni is truly in your price range, they are better than KYB or Sachs. They can be acceptably smooth if the cheapest model is bought and set to soft. I would have gotten Koni but I thought their struts were inserts that required cutting up the OE Sachs to install. I think that only applied to the M suspension.
    I checked and I bought KYB Rears already, probably because they are cheaper. The car will remain on the stock springs for now, so I am really just looking for stock or slightly better handling.

    As for which bushings I should replace, is there a list of them or an order that I should replace them in. only have 74k on it.
    1998 Z3 1.9L Dinan Stage 3.

  10. #10
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    Here are pictures of the 3.45 LSD I have out of the 97 Z3 and the number on it. It was drained of fluid when I got it, and the two axles spun opposite like an open diff, which led me to believe it needs a rebuild.
    Attached Images Attached Images
    Last edited by jimmyfloyd; 05-01-2018 at 02:53 PM.
    1998 Z3 1.9L Dinan Stage 3.

  11. #11
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    Quote Originally Posted by kyrix1st View Post
    I have B12. B6 is slightly more compliant.
    I think B12 must be rock hard, and B6 should be close to OE. If B6 is only slightly more compliant than B12, I would conclude that it is not very comfortable.
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  12. #12
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    Quote Originally Posted by jimmyfloyd View Post
    Here are pictures of the 3.45 LSD I have out of the 97 Z3 and the number on it. It was drained of fluid when I got it, and the two axles spun opposite like an open diff, which led me to believe it needs a rebuild.
    Depends how you tested it.
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  13. #13
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    I had B8s and they were brutal. I'm running koni s/a and love the ride now

  14. #14
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    Quote Originally Posted by 328 Power 04 View Post
    Depends how you tested it.

    Can you elaborate on how I should test it? It was off the car, and I turned the input if I recall. I can go try again in a bit.
    1998 Z3 1.9L Dinan Stage 3.

  15. #15
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    Quote Originally Posted by z3forlife View Post
    I had B8s and they were brutal. I'm running koni s/a and love the ride now
    Yeah, I'm starting to understand why I got this Bilstein/H&R setup so cheap used...

    Luckily roads near me are ok for the most part but any time I'm down town it's awful... I think I'll recommend against Bilstein from here on out lol

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  16. #16
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    Ok, Thinking I'm just going to grab the KYBs to match the rears I have. Seem like a decent stock replacement, and the B8 setup I was considering sounds like it will be too harsh. Our roads suck currently.

    While looking for strut mounts for the front, I ran across this kit: https://www.ecstuning.com/b-assemble...3329061945kt9/ on ECS Tuning. Can anyone shed some light on why I would not want to get that for a Daily Driver 1.9L 72k mile suspension refresh? Seems like it has everything I would need. Are the brands ok?
    1998 Z3 1.9L Dinan Stage 3.

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