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Thread: "Casper": BF10108 - '90 535i 5MT in Sterlingsilber Metallic/Silbergrau

  1. #1
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    "Casper": BF10108 - '90 535i 5MT in Sterlingsilber Metallic/Silbergrau

    Long overdue, the thread for my silver sedan "Casper": a '90 535i 5MT in Sterlingsilber Metallic over Silbergrau.

    21A9CB0B-BD17-4F13-A2BA-738BBE07C378_1_105_c.jpeg

    [Spring 2021 Autocross On Track with Bridge City Autosports at Oregon Raceway Park.]

    I purchased this car in Monterey, CA in May of 2015 with 105,137 mi. The original intention was to have an engine donor for an E28 project, with a drivable extra car in the interim. Since then, needs have changed and the car is still in one piece. I've done thousands of miles of road trips in comfort and style (the Portland<->SF route maybe a dozen times) and a bunch of autocross, bringing the car up to ~145k mi.

    After purchase I decided to drive the car for a bit and began with necessary repairs. This was a classic case of deferred maintenance on an overall fairly solid chassis. On early model E34s with IKHR I, there is no cabin air filter. As a result, the AC condenser core accumulates exterior grit that is sucked in through the blower motor. My A/C was dead and the blower noisy, so I pulled the cover to inspect.

    C2DEDCD1-7081-429E-8E6C-65B10A479FD0_1_105_c.jpeg

    I cleaned and lubricated the blower assembly (still going strong seven years later!) and then pulled the condenser core after determining that the A/C system was completely empty.

    C068BB85-F560-4475-9755-D5D60137CD39_1_105_c.jpeg

    With the discovery of corrosion on the lower fins, I proceeded to my local independent mechanic for a new core, expansion valve, and A/C charge.

    Around this time, I discovered that the brake system was completely full of sludge. Over to my indie BMW specialist, where we completely replaced the brake calipers with refurbs, flushed the lines thoroughly, and replaced the ABS modulator which was also full of sludge. I believe that I got the last NOS E34 ABS modulator in the world. They also sold me a full set of 2-piece BBS Style 42s for a very good price, to replace the kinda ugly and unsalvageably bent 5-spokes from the PO. We also did complete fluids and replaced the front control arms.

    985B63CB-D6F6-45FF-89AB-CC562269734F_1_105_c.jpeg

    Soon after, I also had my local mechanic replace the springs, shocks, struts, and sway bars: Eibach Pro Kit for springs, Koni Yellows, and Racing Dynamics (North America) adjustable sway bars. Then took it out with my brother to a BMA CCA car control clinic.

    IMG_6039-0002.jpg


    --- snip ---
    Last edited by dschneider; 03-18-2022 at 07:00 PM. Reason: grammar

  2. #2
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    '90 535i, '91 M5
    Who needs a truck anyways?

    D4E0B090-19A7-444B-8AD9-DB353573A520_1_105_c.jpeg

    Every single item pictured was packed in or on Casper when I moved out of the dorms at my school. One of those 633 mi. drives from OR<->CA, accomplished with confidence and aplomb on the interstate. 85 mph for 10 hours straight, fully laden, demonstrates the Autobahn-oriented engineering. And shows off a previously-repaired cooling system!

    Nothing interesting to report on this car for the next few years. I drove it through the rest of college and continued with normal maintenance. Had the rear subframe fully refreshed and the diff re-sealed. Discovered a leak in the fuel system at one point and had the filters replaced and the valves adjusted. All shop work, mix of West Bay Bavarian for experience-required items, Bill Arnold for a few things, Matrix Integrated when I was up in Portland, and my local indie for basic stuff. I didn't even have a flat driveway at the time, so couldn't do anything mechanical.

    F980361E-E738-4154-8A93-D14197B1B802_1_105_c.jpeg

    The most exciting repair was this fuel leak.

    Then last year started autocrossing the car with Portland-based Bridge City Autosports. As an independent, non-SCCA autocross club, we have a very diverse membership and attract all eras, makes, and models. At Oregon Raceway Park, we set up some cone obstacles on the racetrack for a higher-speed "track-cross" event, and I was tailed by a Ferrari 488 GTB.

    937733C4-A7A1-409F-8CAB-C1E3FF256D29_1_105_c.jpeg

    [Staging for start at ORP. We follow SCCA rules, so the relatively mild suspension mods put me into a highly modified street class, which puts me in a very fast superclass.]

    At this event, I placed 34/65 in raw times at 133.3s. The fastest "normal" cars (we had a LeGrand MK18, a '70s era tube frame race car, out with us) were a track prepped 2018 Audi TT-RS with aero and a couple forced induction Miatas running ~120s, and around ~130s were things like a modern Focus RS. Overall pretty respectable for a 30 year-old, 3500lb sedan.
    Last edited by dschneider; 04-08-2022 at 02:57 AM.

  3. #3
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    Last summer the car developed a very unpleasant driveline noise and mild vibration. Interestingly, the noise appeared under braking but disappeared under acceleration. Diagnosis: a failed center support bearing on the driveshaft caused the vibration, while a piece of gravel resting on top of the trans tunnel heat shield (between the exhaust and the driveshaft) was rolling around and colliding with the driveshaft.

    IMG_3583.jpg

    Driveshafts are NLA from BMW, so I sourced a replacement from Driveline Services of Portland (driveshafts.com), a local distributor and servicer for Powertrain Industries. The first unit arrived with a manufacturing defect in the transmission output shaft receiver and Driveline Services was very responsive in acquiring a replacement and handling the RMA.

    IMG_3590.jpg

    Since dropping the driveshaft requires dropping the exhaust, I had a fun time removing the rusted exhaust connector bolts. Replaced them with brand-new high grade units. At this time I also replaced the steering end links, center/drag link, pitman arm, and both control arms (I upgraded to E31 aluminum/spherical units).

    IMG_3394.jpg
    Last edited by dschneider; 03-19-2022 at 04:16 PM.

  4. #4
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    Last month I performed some electrical repair. The cluster was acting up: the odometer/trip reset button stopped working, then shortly after that the odometer would stay permanently illuminated and the trip counter stayed at 0 even when driving around.

    I fully documented the repair procedure in a dedicated thread, since I couldn't find a really good guide anywhere else: https://www.bimmerforums.com/forum/s...ure&p=30789008

    Summary pics, before and after of the Check Control and Odometer/Trip Reset switches on the cluster main board:

    IMG_3795.jpgIMG_3808.jpg

  5. #5
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    Looking forward to seeing more on this car and the M5! Great work as always!

  6. #6
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    Suspension got some work a while back. Camber/caster adjustable strut tops from K-MAC were on sale so I picked up a set. Sadly, did not come with the correct hardware for my strut tops. E34 had too many types of strut top sizes, apparently. It's not just the thread sizes, the length of the strut top also varies: mine were too long. Had a local shop turn a set of top spacers for me on short notice, blew out the sale price savings.

    IMG_4002.jpg

    Ultimately, I do not recommend the K-MAC adjustable strut tops. The primary issue is not due to the strut tops themselves, but the design of the E34 front suspension. There is simply not enough space between the factory spring and the strut tower. The picture shows maximum negative camber achieved before interference. It's negligible.

    The second issue is that the camber plus caster adjustment is absolutely a pain. The plates are just loose and sandwich clamp. You have to take reference measurements against the mounting studs in order to get them even. The caster adjustment is also of dubious value in the E34 geometry, in large part because the clearance to the strut tower is circular so adding (negative) caster decreases (negative) camber.

    The third thing I don't like is that the K-MAC units are a pillow ball bushing. I'd prefer a needle bearing, like the factory units.

    Additionally, there are disadvantages to strut top camber adjustments, because they impact your kingpin angle (the axis between the strut top pivot and the strut bottom pivot). But that's not unique to the K-MAC units.

    If you want more negative camber on the front, you have to get coilovers to reduce the front spring diameter and allow more movement before interference with the strut tower wall. Any decent set of coils will come with adjustable strut tops, and most of them are graduated so you can dial in even negative camber on both sides without needing an alignment rack.

    So I agonized over manufacturers and got some coilovers.

    IMG_4001.jpg

    I ultimately chose FEAL suspension. It was down to them or CEIKA, an Eastern European brand that seems to be basically the high end of Taiwanese manufactured units. The reasons I chose FEAL were entirely in rebuildability: they will factory rebuild their coils for a very reasonable rate and offer upgrade rebuilds to add functionality. They're also domestic US for manufacturing, assembly, and support.

    I ordered a set of 441+ with Swift springs at 8k/6k, needle bearing top hats, adjustable bump stops, and a few accessories: ~$2200 US. Took around six weeks from time of order to delivery, which is pretty solid.

    Unfortunately, there appears to be a slight fitment issue on the rears. The bottom mount is a tiny bit under-sized, leading to slop where the strut bottom bushing's stud is supposed to clamp into the cup on the hub housing. I cross-checked Koni Yellow and Bilstein B8 units I had on hand, and they measure out to 22.05mm diameter for the stud. The FEAL studs are only 22.75mm. That makes a big difference in having a close fit in the cup, which is where the suspension load is actually carried. The M14 shoulder bolt (which fits very nicely on the FEALs) is mostly a retainer, it's not intended to carry a shear load from the strut bottom. We're talking like 15 degrees of slop when you wiggle the strut in the cup, where OE and other aftermarket units have basically zero. I've reached out to FEAL about this and hope we can correct their reference specs.

    Another small question mark during the ordering procedure is the option for 55mm front strut housings. As far as I can tell, no E34 front struts were ever 55mm diameter. I wonder who/what spec'd for 55mm that made it into their reference specs for these. Someone please correct me if I am wrong, but both my V1 struts on the 535i and V2 struts on the 525iT are 50mm, and the strut retainer cap part number interchanges across all E34s.

    Fit and finish is stellar on the FEAL units. I will report back once install is completed.
    '90 535i: MegaSquirt (DIYPnP), AFM delete, wideband https://www.bimmerforums.com/forum/s...rau&p=30789010
    '91 M5: Rust-bucket engine donor waiting for space in... https://www.bimmerforums.com/forum/s...n-Alpinewei%DF
    '95 525iT: M50 with a blown motor, prepping to accept the S38

  7. #7
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    Quote Originally Posted by dschneider View Post
    Ultimately, I do not recommend the K-MAC adjustable strut tops. The primary issue is not due to the strut tops themselves, but the design of the E34 front suspension. There is simply not enough space between the factory spring and the strut tower. The picture shows maximum negative camber achieved before interference. It's negligible.

    The second issue is that the camber plus caster adjustment is absolutely a pain. The plates are just loose and sandwich clamp. You have to take reference measurements against the mounting studs in order to get them even. The caster adjustment is also of dubious value in the E34 geometry, in large part because the clearance to the strut tower is circular so adding (negative) caster decreases (negative) camber.
    Wish you'd have asked first, we've beaten the dead horse on E34 suspension configs for years. If you drove hard enough or long enough you'd also notice the K-MAC plates mushrooming. To get all the adjustments they advertise without a huge stack height, they use awfully thin hardware without sufficient support close enough to the single load point.

    Quote Originally Posted by dschneider View Post
    Additionally, there are disadvantages to strut top camber adjustments, because they impact your kingpin angle (the axis between the strut top pivot and the strut bottom pivot). But that's not unique to the K-MAC units.
    It's bad in theory but tends to be good in practice. When you're driving fast you don't actually use that much steering lock, so the increased SAI improves self-centering and to a lesser extent, increases steering feedback. You don't see the worst of the camber loss that SAI causes.

    As a side note, for the same reason caster really isn't that useful for camber gain as a function of steering lock - it's the same deal, it just increases self-centering and forces a tiny bit more load to the inside front tire (helps until you start taking load off the inside rear).

    Quote Originally Posted by dschneider View Post
    Any decent set of coils will come with adjustable strut tops, and most of them are graduated so you can dial in even negative camber on both sides without needing an alignment rack.
    Doing this without an alignment rack will fuck your tires. The E34 gains several degrees of toe in when you knock a few degrees of camber into the top hat. Even stock alignment specs only ask for ~0.25 toe in at most.

    Quote Originally Posted by dschneider View Post
    I ultimately chose FEAL suspension. It was down to them or CEIKA, an Eastern European brand that seems to be basically the high end of Taiwanese manufactured units. The reasons I chose FEAL were entirely in rebuildability: they will factory rebuild their coils for a very reasonable rate and offer upgrade rebuilds to add functionality. They're also domestic US for manufacturing, assembly, and support.
    Again, wish you had asked. I've run Feal on two cars before and we have another E34 on them now (bought because cheap), the damping profile is simply not as good as even basic BC coilovers. I found it hard to fully dial out bump harshness and porpoising from the Feal dampers whereas BC's and Fortune Auto can at least do a tradeoff (no harshness but a little oscillation, or vice versa). At $2200 you could have bought KW V2's which are a WAY nicer damper and need very little mucking with from the box.

  8. #8
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    Quote Originally Posted by circuit.heart View Post
    Wish you'd have asked first, we've beaten the dead horse on E34 suspension configs for years. If you drove hard enough or long enough you'd also notice the K-MAC plates mushrooming. To get all the adjustments they advertise without a huge stack height, they use awfully thin hardware without sufficient support close enough to the single load point.
    I try to do my due diligence by searching instead of asking and didn't see particularly compelling critiques. It is, indeed, hard to sort the wheat from the chaff. I have since determined that you actually know what you're talking about, and appreciate your feedback.

    Quote Originally Posted by circuit.heart View Post
    It's bad in theory but tends to be good in practice. When you're driving fast you don't actually use that much steering lock, so the increased SAI improves self-centering and to a lesser extent, increases steering feedback. You don't see the worst of the camber loss that SAI causes.
    I'm mostly doing autocross currently and end up using a fair amount of lock on courses laid out primarily for Miatas, but of course it ends up being lower speed where as you note, less impact. Obligatory: this is the wrong chassis for this application and I do not expect to ever be "competitive".

    Quote Originally Posted by circuit.heart View Post
    As a side note, for the same reason caster really isn't that useful for camber gain as a function of steering lock - it's the same deal, it just increases self-centering and forces a tiny bit more load to the inside front tire (helps until you start taking load off the inside rear).
    So I've found. There's enough caster in the stock geometry, no need to meddle with it.

    Quote Originally Posted by circuit.heart View Post
    Doing this without an alignment rack will fuck your tires. The E34 gains several degrees of toe in when you knock a few degrees of camber into the top hat. Even stock alignment specs only ask for ~0.25 toe in at most.
    Is the steering end link really that far out of plane with the control arms? Or is is the fact that the control arm ends are not in the same plane themselves? Damn virtual lower pivot strikes again. A constant source of complications. I align after mucking with it anyways, but the degrees of freedom in the geometry just don't add up to that much change in my mental model.

    Quote Originally Posted by circuit.heart View Post
    Again, wish you had asked. I've run Feal on two cars before and we have another E34 on them now (bought because cheap), the damping profile is simply not as good as even basic BC coilovers. I found it hard to fully dial out bump harshness and porpoising from the Feal dampers whereas BC's and Fortune Auto can at least do a tradeoff (no harshness but a little oscillation, or vice versa). At $2200 you could have bought KW V2's which are a WAY nicer damper and need very little mucking with from the box.
    Interesting. I'd love it if KW actually listed them as available in their catalog (same for Fortune). Determining what aftermarket manufacturers actually sell parts for E34s is a painful exercise. Why do they make it difficult to receive my money? Must I track down a reseller by phone to enquire about every part they might conceivably supply?

    Inability to balance harshness with oscillation/porpoising indicates that the compression and rebound are not balanced. Were you running the single-adjustment variety? In that case I wouldn't be too surprised. Or are the curves fundamentally incompatible, so that adjusting them separately only lets you get one velocity region right while messing up the rest of the speed-damping ratios? That might be a bit harder to fix.


    I'll see how it goes once they're on. So far I am pleased with my interactions with Feal. They've responded to my concerns by revising the rear lower mount sizing and shipping me replacement parts. The fact that they have a shock dyno on site and use it to QC their units, as well as their engineering being on-site, and offering rebuild and custom valving indicates to me that I can get what I need from them if it's not right out of the box.


    In the big picture, this car is a bit of a test mule for modifications to the M5 wagon. I'm strongly considering the value of air springs for that car, at least for the rear, which is a whole other can of worms. However, I may simply choose coilovers, and may even transfer these. So this is a valuable experience.
    '90 535i: MegaSquirt (DIYPnP), AFM delete, wideband https://www.bimmerforums.com/forum/s...rau&p=30789010
    '91 M5: Rust-bucket engine donor waiting for space in... https://www.bimmerforums.com/forum/s...n-Alpinewei%DF
    '95 525iT: M50 with a blown motor, prepping to accept the S38

  9. #9
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    Quote Originally Posted by dschneider View Post
    I'm mostly doing autocross currently and end up using a fair amount of lock on courses laid out primarily for Miatas, but of course it ends up being lower speed where as you note, less impact. Obligatory: this is the wrong chassis for this application and I do not expect to ever be "competitive".
    For AutoX I would say caster and SAI actually matter much more... but at the same time, if it's a tight enough corner the E34 needs to be driven tail-out to rotate the long sausage body around the cones faster. You wind up reducing steering lock in that process.

    Quote Originally Posted by dschneider View Post
    Is the steering end link really that far out of plane with the control arms? Or is is the fact that the control arm ends are not in the same plane themselves? Damn virtual lower pivot strikes again. A constant source of complications. I align after mucking with it anyways, but the degrees of freedom in the geometry just don't add up to that much change in my mental model.
    The tierod attaches significantly higher than the ball joints on the steering arm, that's all it takes. Nothing to do with the dual-pivot geometry in this case.

    Quote Originally Posted by dschneider View Post
    Interesting. I'd love it if KW actually listed them as available in their catalog (same for Fortune). Determining what aftermarket manufacturers actually sell parts for E34s is a painful exercise.
    First result on google for "KW E34". No need to bother with manufacturer catalogs when search indexing will tell you pretty well what's actually existent.

    Quote Originally Posted by dschneider View Post
    Inability to balance harshness with oscillation/porpoising indicates that the compression and rebound are not balanced. Were you running the single-adjustment variety? In that case I wouldn't be too surprised. Or are the curves fundamentally incompatible, so that adjusting them separately only lets you get one velocity region right while messing up the rest of the speed-damping ratios? That might be a bit harder to fix.
    I haven't tried Feal doubles - Feal singles were the garbage, I'm pretty sure compression was fundamentally too stiff so if you tweaked rebound to match up, everything was too stiff, and if you turned down rebound to keep tires on the ground, comp/rebound were mismatched.

    Quote Originally Posted by dschneider View Post
    I'll see how it goes once they're on. So far I am pleased with my interactions with Feal. They've responded to my concerns by revising the rear lower mount sizing and shipping me replacement parts. The fact that they have a shock dyno on site and use it to QC their units, as well as their engineering being on-site, and offering rebuild and custom valving indicates to me that I can get what I need from them if it's not right out of the box.
    I've gotten custom valved coilovers from Feal, BC, and Fortune, none of them were really that good on the first try. It's to be expected that if you want perfect valving you need to take the Round 1, get data off the car and then submit that back to them for a Round 2.

  10. #10
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    Quote Originally Posted by circuit.heart View Post
    For AutoX I would say caster and SAI actually matter much more... but at the same time, if it's a tight enough corner the E34 needs to be driven tail-out to rotate the long sausage body around the cones faster. You wind up reducing steering lock in that process.
    Yep, that's what I've found. When I'm really in the groove, putting down the fastest times, I'm rotating the car basically an entire corner early. At least, that's the feeling I'm aiming for. It's definitely tricky with an open rear end, but sourcing a limited slip unit has proven challenging and expensive. Expensive to the point that I can get an OS Giken, Quaife, or WaveTrac core for the price of an original LSD.

    Quote Originally Posted by circuit.heart View Post
    The tierod attaches significantly higher than the ball joints on the steering arm, that's all it takes. Nothing to do with the dual-pivot geometry in this case.
    Ah, right. As negative camber increases, having the tierod pivot higher than the lower arm plane causes toe-in to increase.

    Quote Originally Posted by circuit.heart View Post
    First result on google for "KW E34". No need to bother with manufacturer catalogs when search indexing will tell you pretty well what's actually existent.
    Noted. I'll keep that in mind for future cars where I want less fiddling.

    Quote Originally Posted by circuit.heart View Post
    I haven't tried Feal doubles - Feal singles were the garbage, I'm pretty sure compression was fundamentally too stiff so if you tweaked rebound to match up, everything was too stiff, and if you turned down rebound to keep tires on the ground, comp/rebound were mismatched.
    After driving on just the rears for a while, that's my conclusion. The compression curve is too far "ahead" of the rebound curve, so dialing in appropriate compression damping results in inadequate rebound, while increasing rebound damping to eliminate porpoising results in a very harsh ride.

    Quote Originally Posted by circuit.heart View Post
    I've gotten custom valved coilovers from Feal, BC, and Fortune, none of them were really that good on the first try. It's to be expected that if you want perfect valving you need to take the Round 1, get data off the car and then submit that back to them for a Round 2.
    Yep, that's something I anticipated going into this. I expect that I'll upgrade to two-way adjustable over the winter off-season, which should provide the level of control that I need without re-valving.
    '90 535i: MegaSquirt (DIYPnP), AFM delete, wideband https://www.bimmerforums.com/forum/s...rau&p=30789010
    '91 M5: Rust-bucket engine donor waiting for space in... https://www.bimmerforums.com/forum/s...n-Alpinewei%DF
    '95 525iT: M50 with a blown motor, prepping to accept the S38

  11. #11
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    '90 535i, '91 M5

    Rear Coilover Install Success and Driveline Maintenance Woes

    Project update.

    Communication with FEAL was prompt and professional. They machined new rear bottom mount inserts based on my measurements and had them shipped out fairly quickly, enabling me to complete the rear install. New parts were easy to fit and precisely machined. Working with their service rep was pleasant and professional.

    Dropping the rear ride height considerably enabled me to pick up a bit of the dynamic negative camber in the arms and help plant the rear end a bit better. Had the car out to Oregon Raceway Park for a bit of mixed AX on-track and light track time. The front end still ploughed, but I was able to get a lot of fun laps in. The rear heights were merely measured equivalent on each side. I'll corner weight the car when the fronts are on.

    IMG_4094.jpg

    [View from the grid. ORP's gorgeous, if remote, location offers a beautiful view of the west face of Mt. Hood on clear days.]

    While installing the rear coils, I wanted to also take the opportunity to replace the rear axles and wheel bearings, chasing the perception of significant driveline lash and performing preventive maintenance on 30 year-old wear items. However, I encountered a couple significant setbacks. The first problem was the axles. Not willing to spend ~$600/ea on BMW original units, I decided to try out auto parts store specials. The wheel bearings, National Wheel Bearing 513180, are perfectly fine. The axles, Import Direct BM8002, are not. The size and fitment is correct, the quality of the CV joints is adequate. They didn't come with grease cups/plates, which was the first disappointment. The second was the abominable fit in the splines between the CV spiders and the axle shaft. Significant play on all connections. This is supposed to be a loctite-and-press fit, with zero play, yet I was able to wiggle the whole unit from the ends. The CVs themselves were nice and tight, nothing wrong there, but the axle spline was unusably sloppy. I kept them in the box and put the original axles back on.



    [Slop on axle-CV fit of Import Direct parts. Original equipment is a tight press fit.]

    The second problem I encountered was that I couldn't source the rear stub axle bolt's press-in retaining ring from any supplier in the entire US. I didn't realize that this was a single-use part when planning the project (it doesn't indicate in the parts diagrams or the Bentley manual), and also didn't expect that it would be quite so difficult to remove. For future reference: this is a very firm press-in retaining "clip" made of thick stamped sheet metal. You may not be able to remove it non-destructively. I couldn't pull it out from the edges.

    Unable to source replacements at the time, and having determined that the current wheel bearings were still smooth and moist, I gave up and reassembled. I'll be back under there to refresh the CV axles (I'll just clean and rebuild the originals over the winter), so I'll consider doing the wheel bearings at that time. When I do, I think I'll be able to pull the retaining piece out by drilling and tapping a couple holes in the flat face, and then using a couple bolts through a bar brace to pull it out.
    '90 535i: MegaSquirt (DIYPnP), AFM delete, wideband https://www.bimmerforums.com/forum/s...rau&p=30789010
    '91 M5: Rust-bucket engine donor waiting for space in... https://www.bimmerforums.com/forum/s...n-Alpinewei%DF
    '95 525iT: M50 with a blown motor, prepping to accept the S38

  12. #12
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    '90 535i, '91 M5

    Front Coilover Fab and Install

    So after getting the rears on, it took a while to wrangle the fabrication necessary to fit the fronts. During this time, I just drove on the rears and got a couple really enjoyable events in with them. Slight improvement to handling, but without fully tuning the whole setup I've been reserving final judgement.

    The fronts are a weld-in fitment. It's pretty simple:

    E34 Feal Coilover Front Install.jpg

    Just cut and weld the new coil over bottom mount into the factory strut retaining tube. In order to facilitate this, I borrowed a friend's shop and we welded up a set of simple alignment brackets for each side, to ensure that the sway bar mounts ended up in the right place. The fit between the coilover bottom mount and the strut retaining tube is a tight, slightly tapered press fit, so getting the whole thing aligned vertically (to prevent unintended camber and caster deviations) is not too difficult.

    I then sent the parts out to a local fabricator who I trust to do structural TIG welds on suspension components. Here's the result:

    IMG_4425.jpg

    There was some difficulty in fully pressing one of the inserts, causing one of the sides to be a few mm higher than the other. I don't think that this will be an issue, and I can always add an adjustable length sway bar link to one side to compensate.

    At this point, I was finally ready for reassembly and installation. I sourced a new set of front wheel hubs with integral bearings (grr) from FCPEuro, since they're an install-once item (pulling them off frequently leaves behind one of the bearing races). Note: there are two sizes of ABS ring depending on your chassis. I believe that this corresponds to the strut version, but am not certain. Consult the parts catalog to ensure you have the right size hub ABS ring. The FCPEuro kit comes with new hubs (with integral bearings), rear dust ring, and outside dust cap.

    I also sourced a new set of braided stainless brake lines (Condor Speed Shop), bump steer correction spacers (AKG Motorsports), and a complete set of E31 brakes (Craigslist! complete with pretty-new rotors and pads). Reassembly of the strut modules was straightforward. I cleaned and painted the fabricated parts, then cleaned the stub axles and pressed on the new hubs. I skipped the "splash guard" (which has to go on before the hub) because of the increased brake rotor diameter and different caliper size: although the E31 units fit without interfering, I anticipate bigger brakes in the future and didn't want to have to destructively remove the splash guard/dust/heat shield at that time.

    I added the stainless brake lines and then installed the front strut modules in the car. This was where I met a major disappointment. The bump steer spacers from AKG are unusable. The alignment slot is undersized and at the wrong angle. One of the bolt holes is misaligned. The parts cannot be installed as-delivered, and apparently this is normal. It's as if they didn't even test fitment before ordering a manufacturing batch. This is simply unacceptable. A picture is worth a thousand words, so here's a short video that demonstrates the fitment.



    So I skipped the unusable parts and banged out the rest of the install. At around stock/previous ride height, the lower spring perch sits right around the level of the tire. With M-System wheels (17x8, ET20 square) rocking thicc 255/40 Kumho Ecsta V730s, there isn't enough clearance to the tire sidewall to reduce ride height (without increasing preload), so I need to order a selection of shims to make it fit. I've maxed out the negative camber adjustment at the strut top, which isn't a whole lot (I'll provide a measurement when I corner balance and align things properly).

    Next update after corner balancing. I have a friend with a set of scales, just need to coordinate the time (and wait for him to recover from the bug).
    '90 535i: MegaSquirt (DIYPnP), AFM delete, wideband https://www.bimmerforums.com/forum/s...rau&p=30789010
    '91 M5: Rust-bucket engine donor waiting for space in... https://www.bimmerforums.com/forum/s...n-Alpinewei%DF
    '95 525iT: M50 with a blown motor, prepping to accept the S38

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