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Old 09-30-2016, 12:41 PM   #1
So Live
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e34 535i custom coil over diy

Since I couldn't find a lot of info on this and a lot of what I did find wasn't helpful or correct, I decided that I would document how I went about building my custom coils for my 1991 535i.

The idea was to get the car considerably lower and still retain decent ride quality, not build a race car.

Front set up:

e30 front strut mounts, due to the geometry of the front strut mounting area. Different shocks may allow e34 mounts. No strut tower drilling was required, these fit like they are supposed to be there.
Shortened front strut tubes 2.75" and removed stock spring perches (more on this later).
Upper spring perches from the Allstar Racing ALL61461 kit worked ok but required some machining to fit under the e30 mounts without interference.

Front CO Parts:
KYB AGX Toyota MR2 Rear P/N: 765016
Hypercoil Springs 8" 350lb P/N: HYP188B0350
CO nuts P/N: ALL64180
CO Sleeves 5" P/N: ALL64160

Lessons learned:
-2.75" is too much to shorten the tubes. I would recommend more like 1.75", due to spring adjuster nut to tire interference and the fact that I needed to add a 1" spacer under the springs because the car was too low with adjusters all the way up.
-I read somewhere that the e34 strut tubes were the same diameter as e30 tubes which is why I used the MR2 shocks (they seem to be gaining popularity in the e30 world). This is not the case on my 535. The e34 tubes are larger, so I turned some custom bushings to center the struts in the tubes and locate them vertically so the top nut properly retains the strut.
-The struts needed to be ground down a little bit to fit inside the e30 upper mounts (well documented on e30's)
-Also had to turn the ID of the coilover adjusters because the OD of the tubes is (shockingly) larger than the e30's...
-Also cut the adjusters down length wise to fit between the factory spring perch weld and the strut retaining nut.

Otherwise this was pretty straight forward.





Strut locators:


Rear setup:
Rear CO Parts:
KYB AGX Nissan 240SX Rear P/N: 741017
Hypercoil Springs 6" 400lb P/N: HYP186B0400
CO Sleeve Kit 7" P/N: ALL64141

OEM upper mounts.
Custom (super low stack height) upper spring perches
Custom bushings and washers to locate the shocks in the trailing arms
Chopped the CO adjuster sleeves to fit better, also turned the ends to fit over the spring perches that are on the shocks.
These perches are removable but my CO sleeves were too large ID and I didn't feel like making more parts.
Custom UHMW Poly spring pads

While the 240SX uses larger lower eyelet bolts than the e34, the ID of the eyelet is smaller than the sleeves BMW used to locate the lowers IN the trailing arms so these bushings needed stepped and separate from the "washers". I also didn't have the 240 washers so I machined some big beefy ones. Setting it up this way puts the adjuster on the wheel side which in hindsight may not be preferred, there are no clearance issues though. This also keeps the left side adjuster away from the exhaust which may be a good thing.





I can provide rough drawings and dimensions on all the parts I made if anyone thinks they will be useful. I will not make parts for people, too many projects and not enough time.

Complimentary turning photo:


2 cars worth of coilovers later:



Will add photos of both ends installed and ride height once wheel spacers arrive.

Cheers,
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-Chris
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