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Thread: Upgrading the Suspension. Need some input.

  1. #1
    Join Date
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    1981 bmw 320i

    Upgrading the Suspension. Need some input.

    I have been doing some reading on what to do about my worn out suspensions parts.
    First off my use of the car is mostly daily driving.
    I do like my cars stiffer with a more planted fee.
    Right now it feels like a unpredictable boat.

    Lowering the car with H&R springs i will need a toe and camber adjust kit from ireland racing in order to correct the negative camber as it will wear the tires out correct?
    I did see where some where flipping there rear sub-frame mounts to help correct the camber issue as well.
    I understand that lowering the car will require the correct height struts.
    This option overall seems like it will add up quickly in time and money.

    The next choice would be to keep stock springs and get sport shocks and struts.
    This way there is no camber issues to deal with.
    I cant imagine the stock 143k springs a in the best shape.
    Will this improve the handling enough i guess is my main concern.

    Would you recommend sway bar on the second option or both?

    I will also replace any worn bushings at the time with eurometric stuff.

  2. #2
    Join Date
    May 2005
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    82 E21
    I too like a tight but not punishing ride. My '81 has Eibach springs and old school Boge Turbo-gas dampers with a rear swaybar and a front upper shock tower bar. It sits lower than stock but not terribly low, handles well and does not really ride too bad. Visually it does not have massive negative camber but I don't have alignment data; no heavy wear on the inner rear tires.

    The Boge TG's were not really designed for lowering springs but were a hugely popular option back in the day. Therefore the front strut inserts are blown (esp. on fast compression) so I am in the process of replacing all the dampers and refreshing all of the suspension bushings while I'm in there.

    Here is what I am in the middle of installing:

    Front

    - Bilstein sports w/existing Eibach's
    - Re-packed front upper strut bearings
    - Meyle control arms
    - Lemforder tie-rods
    - Tinker's Bav-auto style anti-shimmy bushing kit with new OE rubberized washers
    - OE swaybar bushings
    - Eurometric poly steering rack bushings
    - Ireland Engineering Alpina replica lower chassis brace

    Rear

    - Bilstein sports w/existing Eibach's
    - OE upper spring perches and rubber inserts
    - Lemforder trailing arm bushings
    - OE rear swaybar end-link bushings and hardware (bar mounting bushings were fine)
    - Eurometric poly rear subframe bushings or Urethane filled "hard" compound OE bushings...still undecided


    I am not a huge fan of loading my cars up with urethane bushings throughout....a track car would be another story. I think used appropriately a mix of new OE and poly will tighten everything up and address the known failure points while providing a quiet low maintenance platform.

    I have no personal experience with an E21 on H&R springs but on the E30 and E36 platform they are more aggressive than Eibach's. It is too bad the E21 Eibach's are now NLA because I think they are just perfect on my car. It will be very interesting to see how much the Bilstein's tighten things up....hopefully not too far on the harsh side.


    Regarding the stock springs; my old '82 had 227,000 miles on it when I purchased it back in '95 and the springs were fine. It had a set of Sach's dampers installed at that point and the next owner (a friend) finally retired the car due to rust with close to 400k - all on the stock springs. Yours should be just fine as long as there is no major rust.


    MJ

  3. #3
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    Thanks for taking the time to write all of that.
    Some nice info.
    Yeah agree on not going full poly just some key areas i have been reading about.

    I also have euro metrics poly steering rack bushing with lemforder tie rod assembly waiting to go in.
    As mine have way to much play in them at the moment.

    I wish i could find a set of eibachs to buy.
    I am looking at buying a set of H&R springs for a good price along with some new old stock Koni yellow sports for the front.

    I guess as long as there is enough stock adjustment not to cause rear tire wear i would be ok with the H&R springs.

    That's a lot of miles on those springs.
    Not worried about breakage so much.
    The springs in other cars i have worked on tend to sag over time.
    I have installed lowering springs and gained height before.

  4. #4
    Join Date
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    Quote Originally Posted by osburn383 View Post
    Thanks for taking the time to write all of that.
    Some nice info.
    Yeah agree on not going full poly just some key areas i have been reading about.

    I also have euro metrics poly steering rack bushing with lemforder tie rod assembly waiting to go in.
    As mine have way to much play in them at the moment.

    I wish i could find a set of eibachs to buy.
    I am looking at buying a set of H&R springs for a good price along with some new old stock Koni yellow sports for the front.

    I guess as long as there is enough stock adjustment not to cause rear tire wear i would be ok with the H&R springs.

    That's a lot of miles on those springs.
    Not worried about breakage so much.
    The springs in other cars i have worked on tend to sag over time.
    I have installed lowering springs and gained height before.
    Panjo.com, search "BMW e21" NIB eibachs for sale. I've purchased from the seller before with no issues. Hope this helps.

  5. #5
    Join Date
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    1980 BMW 320i E21 M10B18

    Cool

    I was going to get H and R's lowering springs-yet the seller was not into customer service, so I cancelled the order and got Bavarian Auto Sport lowering spring for $200 delivered, the caster camber is fine lowering 1 1/2" all around, no significant to same tire wear due to these lowering springs, plus I installed an Alpina Bar to reduce nose twist, I got this from Bmac-RIP- for $40 and also the rear sway bar from Bruce. I also have installed a rebuilt steering rack 3 yr warranty for $115 delivered to the door, the package was a good 4 to 6 ' in length.. I have Jesters poly control arm bushings, steering rack bushing and front sway bar bushings installed, The control arm bushing stop the 55 mph shimmy--yet a little more bumpy ride-as stock control arm bushings flex more thus absorb more road roughness if you know what I mean.. Go for it-----

    Randy
    Last edited by 320iAman; 08-07-2017 at 10:18 PM.

  6. #6
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    What is the largest OD strut cartridge you can fit in an American 82 320i?
    I read on a couple threads OE is 38mm.

    Most the Bilsteins i see listed are for 45mm id.
    The ones on rock-auto all say 45mm id struts.

    Edited:
    Looks like this thread answered my question.
    https://www.bimmerforums.com/forum/s...truts-to-a-BMW
    320I struts tubes are - 40.13 mm i.d. 457.2 mm deep
    Last edited by osburn383; 08-08-2017 at 03:00 PM.

  7. #7
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    I cannot speak to the exact dimensions, however the Bilstein Sport part numbers I ordered are Front: BIL-34186350 Rear: BIL-24184618.

    I purchased from Turner Motorsport who had the best price at the time and are an authorized dealer. FCP Euro has a selection of Sach's replacements as well as Bilstein and KYB.

    One item of note, Bilstein HD or Sport front inserts have built in bump stops and come with new dust covers so you will not need to replace the OE pieces if they are deteriorated. The rears still utilize the OE pieces....I forgot to order new rear bump stops (pn: 33521118793) for my install and am waiting on delivery. My car has only 115k yet the bump stops both front and rear were completely disintegrated.


    MJ

  8. #8
    Join Date
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    1980 BMW 320i E21 M10B18

    Cool

    More on Strut Tubes, see post #6, ect.

    https://www.bimmerforums.com/forum/s...-Struts-In-E21


    FCP Euro

    BMW Strut Cartridge (320i) Bilstein Sport 34-186350,Fitment: 1977-1983

    Part #: BIL-34186350

    30mm, B8 series monotube strut insert

    https://www.fcpeuro.com/products/bmw...port-34-186350



    Randy
    Last edited by 320iAman; 08-09-2017 at 12:09 AM.

  9. #9
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    Quote Originally Posted by osburn383 View Post
    I have been doing some reading on what to do about my worn out suspensions parts.
    First off my use of the car is mostly daily driving.
    I do like my cars stiffer with a more planted fee.
    Right now it feels like a unpredictable boat.

    Lowering the car with H&R springs i will need a toe and camber adjust kit from ireland racing in order to correct the negative camber as it will wear the tires out correct?
    I did see where some where flipping there rear sub-frame mounts to help correct the camber issue as well.
    I understand that lowering the car will require the correct height struts.
    This option overall seems like it will add up quickly in time and money.

    The next choice would be to keep stock springs and get sport shocks and struts.
    This way there is no camber issues to deal with.
    I cant imagine the stock 143k springs a in the best shape.
    Will this improve the handling enough i guess is my main concern.

    Would you recommend sway bar on the second option or both?

    I will also replace any worn bushings at the time with eurometric stuff.

    Lowering the car does not change the geometry of the suspension until you start slamming things on the ground. you will not have to adjust camber with H&R springs. You also will not need to change the height of the struts. Add bigger sway bars, an Alpina bar, Bilstein shocks, and you will be good to go.

  10. #10
    Join Date
    Nov 2016
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    Calgary Canada
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    1981 BMW 320i E21
    I am also installing Bilstein B6 HD's Front 34-001219, rear 24-006125.
    Need to order rear bump stops (pn: 33521118793) - any suggestions where to order. BMW Canada says 2 weeks from Germany.

    While installing fronts, I plan to replace steering rack bushings - anything else I should do while all apart?

    Suggestions for rear sway bar? I have 81 E21, which does not have rear sway bar.
    Live in Canada but can buy parts in USA and have the parts ship to Montana and pick up on the weekend. Haven't found a reasonable place to buy parts in Canada.

  11. #11
    Join Date
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    Cool

    Quote Originally Posted by George Mac View Post
    I am also installing Bilstein B6 HD's Front 34-001219, rear 24-006125.
    Need to order rear bump stops (pn: 33521118793) - any suggestions where to order. BMW Canada says 2 weeks from Germany.

    While installing fronts, I plan to replace steering rack bushings - anything else I should do while all apart?

    Suggestions for rear sway bar? I have 81 E21, which does not have rear sway bar.
    Live in Canada but can buy parts in USA and have the parts ship to Montana and pick up on the weekend. Haven't found a reasonable place to buy parts in Canada.
    Stock rear sway bar D=16mm is fine, I'm running one it will connect right up, you'll need a sway bar thru-probably someone here has one for sale, plus end link hardware with polyurethane rings--kits for $20 or so,plus two brackets that attach to rear axle carrier and two rubber or poly mount that sway bar pivots thru-held by the brackets..here is a picture from real oem.

    https://www.realoem.com/bmw/enUS/sho...diagId=33_0258

    Randy
    Last edited by 320iAman; 08-11-2017 at 10:21 AM.

  12. #12
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    George Mac,

    I ordered my bump stops through FCP Euro. Their web site said they were in stock ready to ship but I have yet to receive shipping confirmation and will be calling today for an update.

    *Edit* FCP Euro apparently did have the parts in stock and shipped them 1 day after my order - their email notification was lagging the actual shipment.

    It is always a good time to check the outer front control arm ball-joints and tie-rod ball joints for excessive movement before you pull the struts out of the car. There are various methods to check the ball-joints so do a bit of research to determine which method(s) work best for you. The inner tie-rod is a ball in socket arrangement which can get loose over time. With the tie-rod loose from the strut, grab the outer section and with the assembly level with the steering rack push in/out to feel for play. They should have no discernible movement. In my case, I found issues with all of the above and ended up replacing all the parts.

    As 320iAman states, a stock rear bar is a good upgrade. I would not go larger unless matched to an up-sized front bar to keep the handling balanced.


    MJ

    Quote Originally Posted by George Mac View Post
    I am also installing Bilstein B6 HD's Front 34-001219, rear 24-006125.
    Need to order rear bump stops (pn: 33521118793) - any suggestions where to order. BMW Canada says 2 weeks from Germany.

    While installing fronts, I plan to replace steering rack bushings - anything else I should do while all apart?

    Suggestions for rear sway bar? I have 81 E21, which does not have rear sway bar.
    Live in Canada but can buy parts in USA and have the parts ship to Montana and pick up on the weekend. Haven't found a reasonable place to buy parts in Canada.
    Last edited by mjweimer; 08-11-2017 at 09:17 AM. Reason: update

  13. #13
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    I have a complete rear sway bar with mounting brackets and links you can - pm - me.

    Lots of great info here - but if you get lowering springs do not get Bilstein HD shocks you need to run the sport shocks with lowering springs.
    Last edited by OLD MAN; 08-11-2017 at 10:01 AM.

    Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link

  14. #14
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    Quote Originally Posted by OLD MAN View Post
    I have a complete rear sway bar with mounting brackets and links you can - pm - me.

    Lots of great info here - but if you get lowering springs do not get Bilstein HD shocks you need to run the sport shocks with lowering springs.
    What if any bumpstops do you prefer running with the sports?

  15. #15
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    The front Bilstein sports or HDs have a really big OD on the piston shaft so I bought some at a local offroad build supplier. In the rear I run the stock BMW ones and I cut 1/2" off the bottoms, the bigger inside opening end.

    The front external front bump stops I used are for Fox 1.5" od shock shafts and are 1" thick/tall. They are real stiff so I cut down the OD so they would bow out more under a hard hit.

    I can try and take a picture if you would like to see it.
    Last edited by OLD MAN; 08-11-2017 at 08:18 PM.

    Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link

  16. #16
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    Both the Bilstein Sports and HD front strut inserts have appropriate bump stops built into the assembly. They are located within the insert housing at the bottom of the damper assembly since they are an inverted mono-tube design. See diagram here: http://www.bilsteinus.com/uploads/tx...ro_7-10_11.pdf

    The only way to get to them is by disassembling the insert - which I do not recommend unless you really know what you are getting into....


    In the rear I am planning to use the factory bump stop since the Eibach springs don't drop the car too low. If you are using a very aggressive lowering spring/racing spring you could trim or replace with an alternate to avoid issues with the bump stop coming into play too early in the suspension travel and potentially upsetting the suspension tuning via unwanted spring rate change.

    Of course if you are at the point of tuning bump stops you probably already know more about suspension tuning than I ever will...

    Here is an interesting article - not E21 centric but an interesting read nonetheless: http://www.sladeshocktechnology.com/bump-stops.html


    MJ

    Quote Originally Posted by WantingAfunE21 View Post
    What if any bumpstops do you prefer running with the sports?

  17. #17
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    OP- 143K miles for stock springs is nothing unless they are rusty or physically damaged... Good old steel... Unlike any aftermarket springs that collapse after 2 years...

    If you decide to modify, I'd suggest keeping the original springs in case you decide to go back to stock. Original shocks at 143K are junk but a set of new shocks with your original springs and all new bushings/control arms will make a huge difference. Many people are comparing apples and oranges as replacing worn out components with new aftermarket parts. It is not the same as replacing new original parts with new aftermarket parts.

    I know that a new set of Sachs shocks and bushings/control arms will make a huge difference. However, I'd keep in mind that when it comes to suspensions, opinions are subjective. You have to try and see what setup you like the best yourself. By the way, if you are interested, I still have a set of Suspension Techniques swaybars (25/19) I am not planning on using.

    Max

    Max

  18. #18
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    Thanks for all the info everyone.

    I did get some H&R springs. Waiting on them to arrive in the mail.
    Might have to hold off on running them as i cant spend the money on bilstein sports.
    I bought some kyb fronts struts inserts and rear shocks for now.


    I am correct in thinking that the kyb struts and shocks cannot be run on H&R springs due to the potential to bottom out the components?
    Last edited by osburn383; 08-17-2017 at 10:42 PM.

  19. #19
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    Yes, KYB's will not work well with H&R's. You'd need shorter stiffer shocks, such as Bilstein sports.

    Max

  20. #20
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    Quote Originally Posted by mxl556 View Post
    Yes, KYB's will not work well with H&R's. You'd need shorter stiffer shocks, such as Bilstein sports.

    Max
    Ok thanks. I guess i will sit on the H&R springs till i can come up with some bilsteins down the road.

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