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Thread: Front strut mount removal

  1. #1
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    Front strut mount removal

    Has anyone recently replaced their front struts/strut mounts? I completely removed the front struts so i can swap them out w/ bilsteins/new springs however, im not sure of the correct tools needed to remove the strut mount from the actual piston rod? there's a 27 mm nut on the bottom, and the bolt (13mm i believe) to the piston rod sits directly ontop. i got some go-thru sockets to see if they would work but aren't big enough to fit the bottom nut.

    70675545980__25F6DF1C-AE0E-42D1-8BE7-A4948D3291E6.jpeg


    Having a hell of a time finding this special tool that the repair manual references as well. Anyone ran into this same issue? http://3.133.101.21/E24/PICS/D/PIC31/2031048.jpg
    Attached Images Attached Images

  2. #2
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    The top bolt is actually the strut shaft. In the sets that I have replaced, I used a deep socket that had a hex head top that I secured with an wrench and a 1/4" drive extension with appropriate socket. Turned the outer socket on the nut holding the shaft still.
    I also have used an electric impact wrench/socket just on the outer nut and it spun off just like a wheel nut. There appears to be just enough drag on the shaft to let that work.
    Be careful, the spring is still usually compressed some even off the car. You do not want those parts flying around your garage or face. Spring compressor will keep the pressure down.

    Sent from my Moto Z (2) using Tapatalk

  3. #3
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    I'm not sure what your skill level is, and I definitely don't want to throw any shade, so this is just editorial food for thought.

    You could just drag them over to your mechanic late in the afternoon...a little cash gets a lot of things done around here. I've done a lot of strut springs myself over the years, but I still outsource stuff if it's dangerous, time-consuming or requires expensive tools I don't have the space for.

    I'd avoid the cheap claw-type compressors, they're difficult to work with and somewhat more dangerous. I never really feel safe with a loaded spring compressor. These springs store a tremendous amount of power.

    If you get one of the large spring compressors at a rental shop, hopefully a bench mount type, there's usually enough space between the spring coils for a vice-grip pliers to clamp onto the strut piston rod, underneath the strut upper bearing. Once the nut is loose, remove the vice grips and slide the compressor & spring off. Of course, the piston rod will likely be damaged with this technique, so don't expect to reuse it later on. I'm assuming you're just swapping everything out.
    Save the manuals!
    '08 128i 6MT, '86 635CSi 5MT (B32, Motronic 1.3, WBO2, G265, 18# FW, 3.46 torsen)
    Past projects:
    '96 318iS, sold 4/23 '90 535iM, RIP 1/23 '90 535iA RIP 6/22 '91 318i, sold 7/19 '97 M3 sedan, sold 11/18 '85 735i, RIP 2/18 '92 325iC, sold 7/16 '91 318iS, sold 6/16 '84 745i, sold 10/14 '82 633CSi, traded 9/12 '90 325i, RIP '87 325 sold '89 525i, traded '87 325iS, RIP

  4. #4
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    You said change struts/springs. I assume you mean just struts as the springs should not need replacing unless you are swapping for other springs to change stance or ride quality.

    In the future, you should loosen the gland nut at the base of the housing while still on the car. You can fit a pipe wrench between the spring coils to get it started so when the housing is totally out like you have, you can unscrew it by hand instead of loading the whole thing in a vice to get it loose.

    The 27 (24?) mm nut of course is removed ONLY after the spring is compressed. Since you are changing struts, you can grab the strut shaft with a vice grip to hold it in place and then remove the nut in your photo. Keep track of the order of things, washers bearing covers etc.

    The spring hat and pads are usually a mess so perhaps purchase before you start. The strut bearing probably ok to reuse unless original. Not sure the cost. These things for newer cars are cheap, for older cars well,......

    Clean the strut housing including the flange, if you look close, there are drain holes in it that are always clogged. This is how the flange rusts out.
    Last edited by RSheiman; 05-31-2023 at 09:12 AM.
    Rob E3

  5. #5
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    I'm not sure of the exact size you need, but this is the type of socket, made by Schwaben Tools, that gets the job done:

    https://www.ecstuning.com/b-schwaben-parts/strut-nut-socket-24mm/003046sch01a-05/

    Last edited by LarryM; 06-05-2023 at 07:25 PM.

  6. #6
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    I made a socket as you will need by welding a socket to an old wrench. the reason being some struts have a recess for an Allen wrench which allows you to break the nut loose without the shaft spinning. The other alternative is to use an impact wrench which will spin the nut off. You will remove the strut housing with the spring in place. Contrary to what Desktop Dave said, I have never had a problem with a "claw" type spring compressor. Cheap at Harbor Freight or rent from Auto Zone etc. What I am suggesting is the same principal as the one from Schwabben Tools and if you can weld will cost only a few dollars, maybe $10 or so if you have to pay for welding
    Last edited by Bert Poliakoff; 06-05-2023 at 09:27 PM.
    81 Euro undergoing total nut and bolt restoration
    pictures at: flickr.com/photos/bertsphotos

  7. #7
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    I'll clarify my position, since Bert called me out, LOL. I use the claw type compressors myself, they're OK for the job at hand, but ONLY if you've had a competent teacher. It's easy enough to pick up good tips on YouTube, but I've seen a few horrific "tips" from "mechanics" that might lead someone astray. You'll see scary stuff like ropes, zip-ties, using the car's weight to compress mounted springs, etc.

    The claw type is absolutely the cheapest way to do a suspension upgrade, but it's not ideal for beginners since it's pretty easy to misuse the tool. Overloading one clamp is pretty easy, a casting flaw could ruin your day, getting the right angles with the clamps is hard, the claws are usually the wrong size for the coils, the tooling is always in the way, stuff like that.

    I can also claim the dubious distinction of breaking a claw-type HF compressor. The threaded shaft stripped an internal bolt inside one of the clamps. I'm usually pretty careful with tools, it was well maintained & freshly greased up. HF was actually pretty decent about it, gave me a full refund as a discount on a newer unit.

    Either way, doing the work yourself is always worthwhile...as long as nobody gets hurt.
    Last edited by DesktopDave; 06-06-2023 at 02:11 PM.
    Save the manuals!
    '08 128i 6MT, '86 635CSi 5MT (B32, Motronic 1.3, WBO2, G265, 18# FW, 3.46 torsen)
    Past projects:
    '96 318iS, sold 4/23 '90 535iM, RIP 1/23 '90 535iA RIP 6/22 '91 318i, sold 7/19 '97 M3 sedan, sold 11/18 '85 735i, RIP 2/18 '92 325iC, sold 7/16 '91 318iS, sold 6/16 '84 745i, sold 10/14 '82 633CSi, traded 9/12 '90 325i, RIP '87 325 sold '89 525i, traded '87 325iS, RIP

  8. #8
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    ^^^^ Good response. I have also had one strip the threads
    81 Euro undergoing total nut and bolt restoration
    pictures at: flickr.com/photos/bertsphotos

  9. #9
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    I appreciate all the help and insight - im definitely not a pro ive just been fiddling around with this 6er for a few years. definitely willing to take some guidance whenever i can get it

    *UPDATE*

    I was able to easily get the bottom nut off with an impact wrench once i had the springs compressed. IDK why i was making this a bigger deal than it needed to be.. I was not going crazy though, the outer nut was definitely not a 24mm lol i had to use a 1 1/16 deep socket which fit perfect.

    i have the springs/strut mount removed so im ready to remove the old strut insert, but im not sure how to remove the strut insert retaining nut (#31321117376) Search SiteSearch 31321117376 - 31321117376 - Threaded Ring (31-32-1-117-376) (ecstuning.com).

    Im assuming a gland nut wrench would work? but those arent in stock in most stores. I got a 7$ "pin spanner wrench' from harbor freight, but there's no way to get enough torque behind this thing to do anything. I was tempted to throw a pipe wrench on there, but would assume thats going to do some damage..

    Any suggestions?

    im replacing the control arm/sway bar bushings while i try to figure this out lol it never stops

  10. #10
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    I used a large channel lock style pliers. Be some what careful, thin tube and fine threads. If installing Bilstein's, drain out excess oil from the tube. Stock and most others call for some oil in the tubes for heat dissipation, Bili's do not call for it.

    Sent from my Moto Z (2) using Tapatalk

  11. #11
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    i went ahead and used an old 36 inch pipe wrench i had - made short work of it


    now i just need to figure out what going on w/ the top nut and i will have these ready to go.

    RealOEM shows it being an M18 lock nut, so i got a strut socket set off of amazon that contains M 18 - 24, and the M24 socket IS NOT big enough.

    im able to get the nut torqued down to a certain point, but then the piston rod just spins with it of course. I was thinking of getting it torqued down as much as possible then releasing the springs a bit to see if that helps? Really dont want to have to counter hold the piston rod with a vice/pliers like everyone tells you not to do hahaha

    I may just see if i can find an M24 lock nut at Ace that i could swap out? Im not sure why these top nuts are so much bigger than everything ive found online for reference... super confused. I just dont have a go-thru socket big enough to fit.. i found some disel fuel injector sockets that could work in theory

  12. #12
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    Glad you got the retaining nut off the top of the piston rod. I've had trouble tightening them up even once it's loaded up, since the strut rod will still spin.

    I was totally on the wrong page here, forgot about the strut tube retaining collar/nut that Bilstein uses to hold the strut insert into our E24's old school strut tubes.

    Bilstein uses a large skinny pin drive collar to retain the strut inside the BMW tube. You can't re-use the BMW part since Bilstein's monotube struts have that hilariously thick piston rod. In the past I've used a drift or screwdriver to tap the collar nut onto the strut tube, maybe with a little touch of blue locktite, they really don't need to be on there with a lot of torque. I seem to recall that Bilstein makes a special pin wrench tool to snug it up. I think this is the correct one:
    https://www.ecstuning.com/b-bilstein...nch/tms189771/
    You'd think they'd include one in the box, but I suppose they mainly deal with professionals rather than us amateur shadetree mechanic types.

    I hate to bring this up...but if you're lowering the car, did you shorten up the internal bump stops before installing the strut insert? I'm not sure if that's required based on your setup. Follow the Bilstein directions, post up if you're confused.

    I wish I'd have found this earlier...this thread has a complete Bilstein installation on an E28.
    Save the manuals!
    '08 128i 6MT, '86 635CSi 5MT (B32, Motronic 1.3, WBO2, G265, 18# FW, 3.46 torsen)
    Past projects:
    '96 318iS, sold 4/23 '90 535iM, RIP 1/23 '90 535iA RIP 6/22 '91 318i, sold 7/19 '97 M3 sedan, sold 11/18 '85 735i, RIP 2/18 '92 325iC, sold 7/16 '91 318iS, sold 6/16 '84 745i, sold 10/14 '82 633CSi, traded 9/12 '90 325i, RIP '87 325 sold '89 525i, traded '87 325iS, RIP

  13. #13
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    I do that gland/collar nut final tightening when installed, car not weight bearing. As I think I mentioned, pipe wrench will fit between the spring coils. No need to tighten that much as Dave says. I also put copper grease on each insert so the next owner says thank you when they replace the insert...or curses me for the mess.
    Rob E3

  14. #14
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    I learned my lesson 100% there - im going to loosen/tighten that gland collar with the strut housing on the car (was almost my entire problem if im being honest)

    1 last question to the group here... any suggestions on how to accurately preload the suspension once im finished? This was something i knew was going to be a challenge for a 1st timer. Ive seen a lot of suggestions online, but wanting to make sure i dont cause any additional problems.

    The most simple way would be to just use a jack/jack stand on the control arms im guessing, but wondering if there's another method that might work better on a e24? I just would hate to do all this work to find out im out of alignment

  15. #15
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    That's a good question for those of us without a full car lift. I used to do what you mentioned but I got a set of low profile ramps and am able to get under the car and tighten up everything.

    You pre-load to avoid torque on all the rubber bits, meaning if you tighten with no load, the control arms are not held in the final position that they will be in when the car is on the ground. Car down, arms rotate but bushings stay where they were when tightened and under all that strain.

    I have never re-aligned the car after strut placement as long as everything else was left untouched.

    The lock nut can on the top of the strut, easiest to do a final tightening once on the car. The weight compresses everything down so their is no fighting the spring's pushing against the nut from below so the nut has to fight the spring and in doing so, the strut shaft spins with it. Once on the car, the spring and hat are pressed down, the strut shaft rises up and you are only fighting the lock part of the lock nut.
    Last edited by RSheiman; 06-19-2023 at 07:18 AM.
    Rob E3

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