A couple of strut questions

[xcastaway]

I think I know the answer to this first question, but making sure. I'm about to replace my front Bilstein Hds with a set of Sachs struts, after ruining one of my Bilsteins hitting a curb that shouldn't have been in the middle of a hundred foot wide gas station driveway. My bad, I wasn't expecting it to be there, and my windshield was filthy. The question is: will the strut retaining nuts for the Bilsteins, that hold the struts into the strut housings work to secure the Sachs properly? I tossed the stock retaining nuts when I installed the Billies. I'm pretty sure they will, but I prefer asking dumb questions to making stupid mistakes. I don't have the proper tool to fit these nuts, I used a bf pair of channel locks to install them.

Second, and the more important question is: I have H&R sport springs, and I just bought some spiffy new Magnetti Marelli bump stops and gaiters for the struts. These are the correct Sachs for sport suspensions. Should I use the full bump stops, or, as I've heard mentioned, should they be cut down, and if so, where? I'd rather not experiment and have to do this several times to get it right. I'm guessing I should use the full stops, but checking to see what others have done and experienced. The Bilsteins bottomed out a lot using only their internal bump stops, I was considering adding external stops when I made that moot by tagging that curb.

Thanks.

[moroza]

If the struts are designed for E34, their fitment to the retaining nut is identical. EDIT: my mistake, this is apparently incorrect. See below.

Which Sachs are these? With 312 254, I was advised by Sachs tech support to use full-height bumpstops regardless of their internal assist spring. I used Sport-suspension 65mm bumpstops 31331138814 (Rein AVZ0277P) without trimming. My front springs are 25mm lower than stock and marginally stiffer. According to my spring chart, on your 525iTM, H&R should sit right around the same height, for a rim gap (15") of 562-567mm. Can you verify? As your springs are quite a bit stiffer than mine which work great with this setup, I reckon yours will too. But contact Sachs to verify.

[xcastaway]

I'm just uncertain if those retaining nuts have a different upper inner surface that conforms to the top of the Bilstein, and might not to the Sachs. Probably not, but I've had stranger things happen. Trying to make sure there won't be any issues before taking it all apart and having that for a problem. I used the nut that came with the HDs.


The struts are the Sachs-312-393 set I picked up from you. The bump stops are 31331140140, which is what realoem calls for on mine.

I have 16's on the car, with approximately the same rim to fender gap of around 570mm. So about a 25mm drop from the springs. With mine, it was closer to a 5 or 6 inch drop, given how high it was riding before. I was gonna end up erring on the side of caution, and using the full stops, if I didn't hear a compelling opinion to cut them down. I probably should have checked with Sachs, and will, but I've read a number of threads where people used cut down stops, and thought it worth checking to see if anyone recommended it and why.

Not going to get to it until whenever my right arm recovers from that adventure with the pilot bearing I recently had. I may put my new hatch glass in first. I was shocked, all the bulbs in the chmsl work! Only 3 were working, sometimes, on the 3rd brake light I currently have installed.

[cirrusblau]

For the retaining nut, no, the Bilstein's diameter will be too large for the Sachs struts. You shouldn't have thrown away your original one. That's why Bilstein includes it with the strut because you can't use the OE nut with their strut.

[xcastaway]

Thanks, cirrusblau, that's the reason I asked the question rather than finding out the hard way by disassembling it and discovering it wasn't gonna work. The outer diameter of the struts is going to be the same, it's just the inner upper surface where it meets the top of the strut that could be different and prevent these from working with the Sachs struts. I didn't check to see if there was a difference between them years ago when I installed the Bilsteins. I'm painfully aware I should not have tossed the stock retainers, given what a PITA it's gonna be to have to pull a pair of them from the junkyard. It took a 3 ft long pipe wrench to convince my original ones to come off, but I'm convinced they had been there the full 180k miles the car had on it at that time. Hopeful that I can pick up a pair at the junkyard that aren't quite so difficult to remove, since they are asking nearly $50 each for new ones.

[xcastaway]

I've located some clear pictures of the inner surface of the stock 31 32 1 129 196 retaining collars, but I can't find any for the Bilstein retainer. It would be greatly appreciated if someone could post a photo of the inner surface of one they have laying around, so I can put this particular issue of mine to rest. I doubt they made them differently for HD's or the sport shocks, so either should do. I'm trying to avoid another boneyard trip in the rain. Thanks!

[moroza]

Huh, I stand corrected. But unless that hole is bigger than the entire strut body, or there are other dimensional differences, it should still work. 312 393 are stock-esque Sachs shocks for V2 mounts, otherwise identical to the 312 254 that I'm using (which are for V3). Where did you see that they're designed for Sport suspensions?

Pulling them off a junkyard car shouldn't be hard. I've released several E34, E32, and related (E30...) front springs in junkyard cars without spring compressors. Simply stand back, or better yet lean over the other side of the car, and remove the big nut on top. There'll be a moderate pop when it lets go, not as severe as you might think. Then with some grunts and swears, the spring can be fished out and then the nut removed easily. The springs might even be able to stay in place if you can maneuver a pipewrench in between the spring coils, and the nut through the spring helix and out below the strut mount (still attached to the body).

Also a correction regarding bumpstops: sedan base and sport 31331124449 85mm, wagon 31331140140 89mm, sedan EDC 31331133513, wagon sport and sedan MTech or M-Sport 31331138814 65mm (Rein AVZ0277P), early MTech? and M5? (unclear) 31332226674. I used the 814 65mm ones without trimming. I vaguely recall holding several brand new ones and finding that these were a bit stiffer than the 140.

Due to an unrelated shipping screwup, I might be heading back up to P-town within the week. If so, there's a good rear seat bottom for you coming with.

[xcastaway]

Still haven't located a picture that shows the inside of the Bilstein retainer, but photos of the struts themselves show a concave portion at the base of the strut center rod, whereas the Sachs are flat. I'm not at all familiar enough with the struts and retainers to know whether that will make a difference. I don't think so, but hate to tear into things based upon I don't think so or probably not. The B4's retainers are flat inside and would work, but they don't have that concave bit that the B6s do, according to the photos I've found. I'm guessing that the retainers will do just fine for holding the Sachs into place. I believe that the center hole will be a bit larger where it fits around that raised portion that the pictures I've found show, which shouldn't affect anything, afaik.

I've released a few struts in the yards w/o compressors as well, from as far away from them as I could get. I have a real healthy respect for the power of springs after being pinned by my bicep to the ground by an Opel GT's transverse leaf spring. Tore my arm up getting it out of that predicament. The problem I had with removing the retainers on mine was that I needed two people hanging on to the strut housings while I jumped up and down on the end of that 3 foot pipe wrench. They were firmly installed! It probably wouldn't be as big an issue with the struts still attached to the car, but this has not been my year for doing mechanical things, with simple things proving nearly impossible more than once. And, I think the retainers I have will most likely work, I've just been trying my best to confirm that first.

I wish I had known there was such a range of bump stop lengths before I bought these, 24 mm is quite a bit of difference. I still think I should err by leaving them alone for now, since I don't know enough at this point to know what the effect is going to be. None of the vehicles I've worked on before had struts, and the bump stops were completely destroyed on this one before I stuck the Bilsteins on. Trial by error, I guess.

Wonderful, re: the rear seat. I'll have to convince my sunroof to open up again, so I can clean out my rear drains that constantly clog with pine needles before installing it. It only goes thru the first part of opening before it jams up some phantom somewhere, though it worked fine this spring. I'm afraid of breaking something if I try to force it open with the allen wrench.

Copied from Amazon ad for 312 393

This product fits this position on your 1992 BMW 525i:

Front



Notes: INSERT~E34 BODY - ALL w/SPORT SUSPENSION (w/LEVELING SUSPENSION) - ALL w/SPORT SUSPENSION (w/o LEVELING SUSPENSION) - ALL w/STANDARD SUSPENSION (w/LEVELING SUSPENSION) - ALL w/STANDARD SUSPENSION (w/o LEVELING SUSPENSION)~E34 BODY - ALL w/M-TECHNIC

[xcastaway]

I thought I'd update this post so anyone with these questions in the future will have the answers they need.

Not sure how I never heard of the 65mm bump stops in the 9 years of mostly lurking here, but they are a much better solution to shorter stops than trimming the 89mm ones would have been. Wish I'd known about them before having to buy a set of each.

Regarding the Bilstein retainers, it's a yes but no answer. Yes, they might have just maybe worked, but would have just barely held them with about an eighth inch bit of aluminum around the edge. I would not have felt confident in them. Fortunately, I went to the boneyard first and rescued a pair of the stock retainers to be sure. Glad there were 2 e34s there, as I had to get one from each, since the other 2 were impossible to break loose with the bf pair of channel locks I had with me.

The Sachs seem to ride a bit better, and didn't bottom out in the 10 mile trip to return the spring compressors. It was mashing itself constantly with the blown strut, time will tell how these work out. And, since I was considering adding external bump stops to the Billies before I munched one, I discovered that would not have worked due to the large diameter of the shaft.

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