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Thread: Suspension options for lowering the E39 Touring

  1. #1
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    Suspension options for lowering the E39 Touring

    I am no expert on the various options available to lower the tourings but I figure it would be a great thread to have for a resource as I see so many questions about lowering the tourings. I know I had trouble finding info at first.

    There seems to be 2 variants of suspensions on these cars. SLS (self leveling suspension) which uses a sensor and airbags to adjust the height for the given load on the car in the rear only. Then there is also the standard style with a spring and shock. The shock and spring are not combined into a single assembly either.

    To lower the standard suspension car that has the spring/shock, you can either get lowering springs or coilovers. I know H&R makes the lowering springs and perhaps someone else could add to the list.

    I also know that KW & ST make coilovers for our cars. It seems that ST is just a much cheaper version of the KW's.

    Hopefully someone else can come along provide additional information about available options. I have read that you can get adjustable end links for the SLS cars and/or bend the sensor arm that is used to adjust he height in order to trick the car into lowering the rear.

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    You beat me to the punch starting this thread!

    I have a 2002 with sport package and SLS. I've definitely had a hard time figuring out my suspension options. Right now I'm riding on 11 year old 100k mile hardware, so it's wallowing a bit. I'm not as concerned with just lowering it as I am with tightening it up in general. I'd love to make it a little sportier than it came from the factory. Would love to hear about what others have done.

    I did recently purchase a set of lowering links (http://loweringlinks.net/Home_Page.php). They work exactly as advertised and are easy to install. The factory links they replaced are made of rubber, so whatever is used to replace them doesn't need to be very robust.

    Now that I've solved the rear ride height problem, I need to address the rest of the suspension. From what I've read, people seem to be fairly happy with BC racing, ST & KW coilovers. Right now I'm leaning towards ST, but would love to hear from anyone with experience with any of these.
    Last edited by gonzilla; 12-02-2012 at 11:09 AM.
    Mike
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    Just how low can the rear drop with those links? I've been wondering what the limitations are before I pull the trigger on a setup.

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    I am trying to figure something out in the rear suspension.

    I am putting my own rear coilover kit together and am now getting ready to get the shocks. But I am running into something odd.

    I measured the distance from the eyebolt hole to the collar of the output shaft where the top mount sits. On the stock shock when it is out of the car, the dimension is 16 1/2" (picture below). My car is lowered about 3" and I took the same measurement while in the car at the static dropped height and it was 15 1/8". How could the shock only be compressed 1 3/8" when dropped 3"?! It doesn't even make sense to me. I would imagine the shock drops that much just under the weight of the car when you set it back down.



    I certainly don't want to get expensive shocks made without figuring all this out. Does it make sense that when a shock is mounted at a 45 degree angle and the car is dropped 3" that the shock will only be compressed about half that? And furthermore, when a shock is installed and you set the car back down on the ground, shouldn't the shock also compress some under it's own load or is the suspension designed so that when the car is at static height, you are at the fully extended shock height?


    Is the shock only compressed a little b/c it's at a 45 degree angle? I am no engineer so not sure about that. Here is an image of the rear suspension. The spring sits on top of that large round plate with the hole in it.

    Last edited by RVAE34; 12-03-2012 at 08:29 PM.

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    Just a heads up that I am currently working with Fortune Auto to put together a coilover option for our tourings. I am currently running their M5 front setup but since they only currently offer the M5 kit, I am having to put the rear setup together. The best part about Fortune's design is that when you lower the car in the front, you aren't compressing the shock spring the lower you go. The whole assembly threads into the mounting portion at the bottom so the ride quality is the same whether 2" above stock height or slammed all the way to the ground Unfortunately with BMW, the rear is a separate shock/spring so this could never be the case for the rears. Luckily their focus is on the shocks themselves and they a phenominal job with the valving etc.

    I will update once the kit is complete in my car and then will get pricing and distribution info.

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    Quote Originally Posted by FerM3 View Post

    ST is lower quality with only 5 year warranty. They put worse quality internal. aka: not as good as a real KW.
    I'd have to disagree with you on the ST's. I don't own a set of ST's but if you call KW they will tell you that all the internals are the same as your KW V1's (street comforts) including the springs, except for the non-stainless bodies.

    If the ST's were available when I bought my BC I would have gone with them because I live in CA where it never really rains.

    I have the BC's and I'm happy but I need to fix other issues like upgrading my bushings throughout the car to get the car tip top.

    I would recommend the BC's to anyone but without the pillow top mounts unless they really want camber adjustment.

    "If everyone thought the same when it came to modding there would be no thinking"

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    I tend to take anything a vendor says with a grain of salt..

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    Quote Originally Posted by CLKFAN View Post
    I'd have to disagree with you on the ST's. I don't own a set of ST's but if you call KW they will tell you that all the internals are the same as your KW V1's (street comforts) including the springs, except for the non-stainless bodies.

    If the ST's were available when I bought my BC I would have gone with them because I live in CA where it never really rains.

    I have the BC's and I'm happy but I need to fix other issues like upgrading my bushings throughout the car to get the car tip top.

    I would recommend the BC's to anyone but without the pillow top mounts unless they really want camber adjustment.
    KW has V1, V2, and Street comfort for our tourings.

    My street comforts retail at $2100, They have a 286 spring rate front and rear with dampening control. ST's ARE lower quality. A shock body doesnt cut the cost in half, putting in a lesser quality internal structure does.

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    Quote Originally Posted by FerM3 View Post
    KW has V1, V2, and Street comfort for our tourings.

    My street comforts retail at $2100, They have a 286 spring rate front and rear with dampening control. ST's ARE lower quality. A shock body doesnt cut the cost in half, putting in a lesser quality internal structure does.

    My mistake, I thought there was only v1 v2 v3 for our cars and that you were calling your v1 streets but in fact they are diff model. The v1 is the identical set up as the St's except for the shock bodies. Thanks for the clarification.

    "If everyone thought the same when it came to modding there would be no thinking"

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    Quote Originally Posted by RVAE34 View Post
    Does it make sense that when a shock is mounted at a 45 degree angle and the car is dropped 3" that the shock will only be compressed about half that?
    Uh-oh! Sounds like somebody's going to have to review all that trigonometry he slept through in high school ...

    C.R. Krieger #53302

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    That stuff makes my brain hurt and my ears bleed. I will leave that to those that are a lot smarter than I am

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    Quote Originally Posted by RVAE34 View Post
    That stuff makes my brain hurt and my ears bleed. I will leave that to those that are a lot smarter than I am
    Then it's gonna be real expensive getting the right size shocks made for it.

    C.R. Krieger #53302

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    Not too bad actually. They won't be anymore to have done than if I was buying them off the shelf. I just don't want to buy two sets if the measurements aren't right

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    Quote Originally Posted by RVAE34 View Post
    I am trying to figure something out in the rear suspension.

    I am putting my own rear coilover kit together and am now getting ready to get the shocks. But I am running into something odd.

    I measured the distance from the eyebolt hole to the collar of the output shaft where the top mount sits. On the stock shock when it is out of the car, the dimension is 16 1/2" (picture below). My car is lowered about 3" and I took the same measurement while in the car at the static dropped height and it was 15 1/8". How could the shock only be compressed 1 3/8" when dropped 3"?! It doesn't even make sense to me. I would imagine the shock drops that much just under the weight of the car when you set it back down.



    I certainly don't want to get expensive shocks made without figuring all this out. Does it make sense that when a shock is mounted at a 45 degree angle and the car is dropped 3" that the shock will only be compressed about half that? And furthermore, when a shock is installed and you set the car back down on the ground, shouldn't the shock also compress some under it's own load or is the suspension designed so that when the car is at static height, you are at the fully extended shock height?


    Is the shock only compressed a little b/c it's at a 45 degree angle? I am no engineer so not sure about that. Here is an image of the rear suspension. The spring sits on top of that large round plate with the hole in it.

    Well, not to toot my own horn, but I am an engineer and the short answer is yes...but the angle is not 45 degrees.
    I did a little trigonometry and without boring you with the details...
    if the shock length is 16.5 in the extended position and at a 45 degree angle, that means both horizontal and vertical span of the shock is 11.67 inches.
    If we assume that the horizontal span does not change as the shock compresses (it does, but to a far smaller extent than the vertical span), then the new angle for a 15.125 inch long shock and a horizontal span of 11.67 inches is 50.5 degrees. The new vertical span is 9.62 inches. So there you can see that the shock compressed by 1.375 inches and the vertical span decreased by 2.05 inches.

    All it would take is for the shock to be at an original angle of 43 degrees (instead of 45) for you to get a 3 inch difference in the vertical span for a 1.375 inch difference on the hypotenuse.

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    Quote Originally Posted by CLKFAN View Post
    The v1 is the identical set up as the St's except for the shock bodies.
    Sorry but thats not the only difference. Search the subject and educate yourself.

    Quote Originally Posted by vavet View Post
    Well, not to toot my own horn, but I am an engineer and the short answer is yes...but the angle is not 45 degrees.
    I did a little trigonometry and without boring you with the details...
    if the shock length is 16.5 in the extended position and at a 45 degree angle, that means both horizontal and vertical span of the shock is 11.67 inches.
    If we assume that the horizontal span does not change as the shock compresses (it does, but to a far smaller extent than the vertical span), then the new angle for a 15.125 inch long shock and a horizontal span of 11.67 inches is 50.5 degrees. The new vertical span is 9.62 inches. So there you can see that the shock compressed by 1.375 inches and the vertical span decreased by 2.05 inches.

    All it would take is for the shock to be at an original angle of 43 degrees (instead of 45) for you to get a 3 inch difference in the vertical span for a 1.375 inch difference on the hypotenuse.
    Last edited by FerM3; 12-05-2012 at 05:00 PM. Reason: Automerged Doublepost

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    Quote Originally Posted by FerM3 View Post
    Sorry but thats not the only difference. Search the subject and educate yourself.




    I called the manufacturer (KW 800-445-3767) directly a while ago regarding the ST's and V1's and this is what they told me. And since I just read your reply I called again just now to confirm what I was told months ago. I spoke to Brenden.

    So then are you saying that they lied to me again and you're right?

    I think you need to call them yourself so that you can get the information from the actual manufacturer and not by hearsay on the forums. I'm not trying to create any friction because I'm not that kind of forum member at all but I just want to you to know that what you are telling people is not correct and since this is a informational forum I think the readers should be aware of the facts and not hearsay. Call them before you reply to this, thanks.
    Last edited by CLKFAN; 12-05-2012 at 05:17 PM.

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    Will do. Thanks for the number

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    Quote Originally Posted by FerM3 View Post
    Will do. Thanks for the number
    Anxious to hear what they tell you.
    Mike
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    Quote Originally Posted by vavet View Post
    Well, not to toot my own horn, but I am an engineer and the short answer is yes...but the angle is not 45 degrees.
    I did a little trigonometry and without boring you with the details...
    if the shock length is 16.5 in the extended position and at a 45 degree angle, that means both horizontal and vertical span of the shock is 11.67 inches.
    If we assume that the horizontal span does not change as the shock compresses (it does, but to a far smaller extent than the vertical span), then the new angle for a 15.125 inch long shock and a horizontal span of 11.67 inches is 50.5 degrees. The new vertical span is 9.62 inches. So there you can see that the shock compressed by 1.375 inches and the vertical span decreased by 2.05 inches.

    All it would take is for the shock to be at an original angle of 43 degrees (instead of 45) for you to get a 3 inch difference in the vertical span for a 1.375 inch difference on the hypotenuse.
    Outstanding reply! Thank you.

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    Quote Originally Posted by CLKFAN

    I'd have to disagree with you on the ST's. I don't own a set of ST's but if you call KW they will tell you that all the internals are the same as your KW V1's (street comforts) including the springs, except for the non-stainless bodies.

    If the ST's were available when I bought my BC I would have gone with them because I live in CA where it never really rains.

    I have the BC's and I'm happy but I need to fix other issues like upgrading my bushings throughout the car to get the car tip top.

    I would recommend the BC's to anyone but without the pillow top mounts unless they really want camber adjustment.
    CLK - can you elaborate some on the BCs? I've found lots of BC kudos for the sedan non-SLS versions but A. No good review of a touring setup, and B. its unclear if they have an SLS specific version? Nothing I've found on web says explicitly but admit I haven't called them direct yet...

    The competition for me is STs most likely... Although I could go as far as KW V2 to get some adjustability.

    Lastly as an aside its a bit irritating that the KW and similar coil over setups charge the exact same amount for the sedans as for a touring SLS version (aka with no rear springs required or provided). Yeah yeah I know... "R&D costs are the big factor so materials don't matter!" But hey wait somebody just said "ST must be shittier than KW because they are cheaper"... Seems contradictory... ;^>
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    Quote Originally Posted by geargrinder View Post
    CLK - can you elaborate some on the BCs? I've found lots of BC kudos for the sedan non-SLS versions but A. No good review of a touring setup, and B. its unclear if they have an SLS specific version? Nothing I've found on web says explicitly but admit I haven't called them direct yet...

    Actually just sent both Megan and Bc a email asking them if they have a SLS and non SLS version for the tourings

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    permission to post pix?












    this one wrecked my tape measure lol



    Quote Originally Posted by geargrinder View Post
    CLK - can you elaborate some on the BCs? I've found lots of BC kudos for the sedan non-SLS versions but A. No good review of a touring setup, and B. its unclear if they have an SLS specific version? Nothing I've found on web says explicitly but admit I haven't called them direct yet...

    The competition for me is STs most likely... Although I could go as far as KW V2 to get some adjustability.

    Lastly as an aside its a bit irritating that the KW and similar coil over setups charge the exact same amount for the sedans as for a touring SLS version (aka with no rear springs required or provided). Yeah yeah I know... "R&D costs are the big factor so materials don't matter!" But hey wait somebody just said "ST must be shittier than KW because they are cheaper"... Seems contradictory... ;^>
    Quote Originally Posted by whterice View Post
    Actually just sent both Megan and Bc a email asking them if they have a SLS and non SLS version for the tourings

    http://www.ecstuning.com/BMW-E39-525.../Coilovers/ST/
    Last edited by FerM3; 12-06-2012 at 03:12 AM. Reason: Automerged Doublepost

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    Quote Originally Posted by geargrinder View Post
    CLK - can you elaborate some on the BCs? I've found lots of BC kudos for the sedan non-SLS versions but A. No good review of a touring setup, and B. its unclear if they have an SLS specific version? Nothing I've found on web says explicitly but admit I haven't called them direct yet...

    The competition for me is STs most likely... Although I could go as far as KW V2 to get some adjustability.

    Lastly as an aside its a bit irritating that the KW and similar coil over setups charge the exact same amount for the sedans as for a touring SLS version (aka with no rear springs required or provided). Yeah yeah I know... "R&D costs are the big factor so materials don't matter!" But hey wait somebody just said "ST must be shittier than KW because they are cheaper"... Seems contradictory... ;^>

    Regarding the BC's for the touring, you have to go directly to BC Racing and not a vendor in order to get a front set of coilovers only. I got mine for about $575 shipped. They do not have a rear shock application so I would recommend either Bilstein sports or factory sport rear shocks. And to lower the rear end you have two options which is to buy the adjustable links or have the rear height adjusted through the ECU.

    Regarding BC review on my touring, I would recommend them but without the pillow-ball mounts unless you absolutely need the camber adjustment. Reason why is because the pillow-ball mounts will give you a sharp road feel that can become annoying to the average driver who is not on a race track that is perfectly smooth so if you opt for the setup without them and just a regular top hat that is rubber bushing-ed like the OEM set up and most other coilovers on the market where you have to use your OEM top hats you will have a smoother ride. The BC's are a nice product and have a lot of adjustability to suit anyone's needs. But if the ST's were on the market when I bought my BC's I probably would have gone with the ST's because they come with a 5 year warranty and also come with rear shocks. I would not mind a preset shock from KW/Koni because they have their stuff together and I have always been a Koni advocate for all my cars so I'm a bit biased.

    Regarding ST's and KW, The ST's are the same as the KW V1's, the only difference is that the shock bodies are not stainless like the KW's. I called and was able to confirm this with KW twice for good measure. If I were you I would go with the ST's since it's a complete set with rear shocks but if you want to be able to adjust your dampening go with BC's for the money but you only get front shocks or you can go with one set up that has not been mentioned and that's the FK Silverline ( http://www.ecstuning.com/BMW-E39-540...ers/ES1844184/ ) setup that actually comes with rear shocks as well and links just like KW. The FK's have adjustable front struts and adjustable rear shocks but the rear shocks can only be adjusted by removing them just like the ones that come with the KW V2's and V3's. And it's a Koni product just like KW and ST.

    Hope I was able to answer your questions and provide some insight.
    Last edited by CLKFAN; 12-07-2012 at 12:28 AM.

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    Wow!! Must all be in the valving then as those shocks are longer than my Bilsteins.. Very interesting.

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    BC doesnt make a kit for the touring. I wouldnt buy suspension that wasnt designed for our added weight in the rear.

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