Follow up to "Need Emergency Help" post

[Neveragain55]

I wound up taking the stock, lower coil spring perch plate to a machine shop where the machinist is either going to basically make a washer that would slip on top of the perch plate that came with the Bilstein shock that's to small to accommodate the larger M6 spring or make a whole new perch plate that will accommodate the spring.

Turner Motorsports, Pelican, and some BMW dealers all sell the M6 top rear shock mount so I'm ok there.

The only last piece to this puzzle is the upper & lower coil spring pads (or cushions).

I've searched like crazy everywhere for the BMW OEM spring pads that would fit rear M6 springs, and I can't seem to find them anywhere.

At this point I'll accept any pad as long as the diameter is correct which is 4 inches. (measuring the springs diameter from the middle points of the spring wire)

Does anybody have any idea who would sell 4 inch diameter spring pads, preferably with the cut-out pocket for the end of the coil to rest into?

See the picture.

If not any 4 inch diameter flat pad will do.

Thanks guys.......

[MinneapM635]

The part number for my rear spring lower perch rubber is 33521117504

Available at fcpeuro and i assume other retailers as well like pelican

https://www.fcpeuro.com/products/bmw-sp ... 3521117504

[Neveragain55]

Thanks,

Are your spring roughly 4 to 4.5 inches in diameter as well?

I know it sounds silly as a question but part numbers don't do anything for me with this build due to the fact that everything is "not" stock.

I found a machine shop that will make the (what amounts to basically large washers) for the lower perch plate to accommodate the new "larger" springs, and I found a BMW specialty car restoration shop working on the top mount for me.

Once I source the pads I'll be home free...........

Thanks again for the reply...

[Brucey]

you will find that the ID of the spring perch shoulder is different between the two perches and if this is not corrected your 'big washer' solution isn't going to work because the spring and the rubber pad won't be located centrally.

BMW only supply the correct spring perch with the relevant Bilstein shock; they never have listed the spring perch as a separate item, so there is no separate part number.

However your Bilstein distributor should be able to supply the correct perch part because that is the one that is supplied with the correct M6 rear shocks. Had you ordered those instead of conventional 'sports' shocks then you would have got the correct spring perch with your shocks.

If you still have your old bilstein shocks you should be able to knock the perches off them and re-use them. In the UK such perches are usually badly corroded in the tube section but this is easy to weld repair if needs be.

I don't know WFT the guy that sold you those shocks was thinking of, BTW.

'eny fule kno' that M6/M635 rear springs are a different size to other E24/E28 springs.....

cheers

[Neveragain55]

Brucey,

Once again your 100% right…….with most of the things you said in your reply.

The “larger washerâ€

[Brucey]

OK I understand how you have ended up where you are.

I think that Bilstein deserve to be torn a new one too because they should have that spare part. Their statement that the perch is welded to an original M6 (bilstein) shock is of course 100% bovine excrement too.

What I am struggling with is why you are persevering with the M6 springs; the sport shocks have five perch adjustment points and you can fit a load of other springs in there (including the original ones, or other E28 sport springs) and get the ride height that you want.

The M6 springs are only a little stiffer than the stock springs and the damping rates are a bit different in the M635 spec rear shocks as I understand it.

One part you have not mentioned is the bump stop; I would suggest that you buy the BMW bumpstop as fitted to the M6/M635 models, which is slightly shorter than the standard bumpstop fitted to E24 Bilstein HDs etc. Under no circumstances should you fit the rear shocks with no bumpstops or knackered bumpstops!

Still it sounds like you are on the home straight now....

good luck

cheers

[Neveragain55]

Thanks Brucey,

Every time I enter a post in this forum I learn something new, and after your question about why I didn't go with a different shock I've learned something new about these Bilstein shocks.

When I was going through all of this drama last week, I did notice all of the various slots on the lower end of the rear shock and the clip where the perch plate sits.

I thought to myself: "I wonder why there are several other grooves, and I wonder if they are there for you to move the clip around to get various heights"......

How do I spell stupid...."Neveragain55"

I feel like such an idiot, really, and I guess that answers your question as to why I was so stuck on the M6 springs.

I was told by not only the folks at Bavarian, but many others that there were "NO" other springs and there was "NO" other way to get the 0.75 drop I wanted without using the M6 springs.

Plus I had spent all freaking day installing the front shocks & springs and there was no way I was going to rip it all apart, send back springs, and start all over again with a completely different set of springs, so my mind was stuck on making what I had work.

So I did what I always do, what I do best.....crash through several brick walls until I get what I want and get the job done.

I really wish you were my neighbor so you could have come over and bopped me on the head to set me straight.

Regarding the bump stops, I did call Bilstein about that and they told me that the sport shocks I have that came with the blue accordion-like top cover negated the use of bump stops because they're built into the shocks, but I do have bump stops for the rear.

They are the bump stops designed for the original suspension set up that Bavarian sent me so I was just going to use them.

I hope that I don't need a different set because the springs are 0.75"" shorter?

Anyway, thanks for all the advice Brucey, and thanks for the lesson, much appreciated.

I have attached a picture of the shocks I bought.

[Ralph in Socal]

Have you inquired about the shock set-up for an e23? Just an idea as e23s are heavier and may use larger springs. Good luck.

Ralph

[Brucey]

re bumpstops and boots

Fronts;

Bilstein front inserts have a bumpstop built into them, hidden inside (which ideally needs to be trimmed or replaced with a different one if the ride height is different from that intended for that shock). So if you are lowering about 0.75" the sport insert should be OK as it comes. The blue thing is nothing to do with bumpstops, except that with the boge inserts, you do need an external bumpstop and that also locates a shroud. You can't use the boge style shroud with bilsteins

a) because there is nothing to attach it to and
b) it isn't good enough anyway.

With bilstein front inserts you need full boots that are in perfect condition; nothing else will do. If you don't have the boots in perfect condition, the shock bushings will get water in them and the shock will fail.

Rears;

With Bilstein rear shocks you need the BMW OEM shroud piece and the bumpstop upon which it locates. The correct bumpstop part for use with 0.75" lower springs is the bumpstop that comes with an M635, which is part #11 here

http://2009.bmwfans.info/parts/catalog/ ... ing_strut/

i.e. BMW 33 52 2 225 023

This is similar to the standard bumpstop but it is shorter. You can trim the stock bumpstop down but if you do it won't locate on the shocks shaft or the shroud correctly, depending on which end you trim.

The shroud is the same piece as with standard Boge shocks.

cheers

[Neveragain55]

Understood.........

If I'm reading your last post correctly, your telling me that basically I can leave the front end alone just as I have it because the 0.75" drop won't drastically or negatively affect the shock/spring/bump stop relationship?

I basically took the old front strut out of the strut housing, and I put the new one in per the Bilstein directions without adding any internal or external bump stops, boots or anything.

I didn't trim anything either, I just slipped the strut in the housing per the Bilstein instructions, compressed the outer spring, slipped the top mount on and tightened the nut to hold it all together, and installed everything back together with the blue boot (that was already affixed to the strut).

By the way that part of the job went great and everything went back together with no problems at all.

I'm not sure if that lower, clear, plastic ring (that came with the new Bilstein's) is supposed to be affixed to anything as right row it just sits in the lowest groove of the blue, accordion-style boot.

I take it that the lower end of the boot is meant to be left alone in order for it to move freely up & down.

If that lower, clear, plastic ring is supposed to slip over something or be permanently attached to the lower cylindrical nut (for example) that screws into the strut housing please let me know. (the Bilstein directions were not clear on this)

Regarding the rear (if I'm reading your reply correctly) I should at the very minimum either trim the original equipment bump stops 0.75", or use the bump stops that you suggested that were meant for the M5/M6 set-up?

If I have read & understood you correctly with everything please get back to me as I greatly respect your opinion in these matters.

I can't begin to thank you enough for all of you help with this, and It's extremely all appreciated.

Thanks Brucey.......

[Brucey]

at the front if you had boge inserts before, there would most likely have been about half a cupful of ATF inside the leg. If present this needs to be drained out before you install Bilsteins, because it

a) doesn't do any good (it is there for heat transfer with boge, which cannot work with Bilstein) and
b) the oil will rot the bilstein bumpstops (which are in the base of the strut insert).

The plastic ring is (I think) meant to fit in or near the groove that exists between the top of the leg and the big nut that secures the insert. You can usually (with difficulty) slip it over the top of the nut if you want to. I think if you leave it on the chromed part of the shaft, it will foul something when the suspension is on full bump. The boot locates over it snugly, of course, and the slots allow the air to get in and out as the suspension moves, hopefully without letting water in.

I think the 'sport' front bumpstops will be the right length for a 0.75" lowering.

At the rear I'd suggest you get the M635/M6 bumpstops, because trimming the stock ones will most likely leave the bumpstops the wrong shape or loose on the shaft; because they support the shroud, they can't be loose on the shaft and work properly IMHO.

If you just use stock rear bumpstops with a 0.75" drop, you may find the ride gets a bit jiggly; the bumpstops start fairly early in the stroke on these cars.

cheers

[Neveragain55]

Got it.....

I actually did drain & clean the strut support housings before I slipped the new struts in so I'm all set there. This is where having the cleaning OCD really helps...

I'll revisit that clear plastic piece to make sure it's where it needs to be.

I'll also definitely use the correct M6 bump stops to be sure there's no problems.

Thanks again Brucey........