Installing Billy SP on my E30, have not seen this before!

[alen]

Hi all,

after purchasing a set of Bilstein SPs from a member here years ago, I finally got around to installing them this weekend after my stock set up blew up. I planned to also install Lowtec springs I bought some time ago.

My car is a 1985 318i, which I believed had a 45mm housing. So, as I started to dismantle the front struts, I hit a few snags, mainly getting the tie rod end out, and then getting the gland nut off the strut housing. However, after a second pair of hands, I declared victory. Or so I thought...

The shock I took out is a KYB PN 363044 Excel-G, pictures below. It has a large gland nut that has an inside thread and threads onto my strut housing, which has an external thread! Pictures below:













Here is where things get really interesting.


Almost pushed the strut inside the housing.




What you're seeing is the Bilstein SP shock with its gland nut interfering with the shock body. They are sitting side by side and I have no other hardware to tie them together. It appears that the Bilstein shock is for the 51mm housing with the internal thread, so that the external thread on the Bilstein can go in.

However, the two shocks PNs are:



Per my web search, the Bilstein appears to be the PN for my car with the 45mm housing. However, I just don't know how to install the shock.

Is this normal?

[PNWDan]

Not sure but I do believe earlier cars had different strut tubes as you state. Someone may be able to confirm this. I think you'll need to swap out to run those billys. They sure look like the larger ones to me.

[acolella76]

That's crazy, I don't think I've ever seen an OEM strut housing with external threads like that. I guess your best bet would be to call Bilstein and tell them that you need a different gland nut, they are pretty helpful people.

[jlevie]

You certainly have the wrong gland nuts and may have the wrong shocks. Look up the Bilstein part number for YOUR car and compare that to what you have.

[alen]

I checked everywhere. The PN on the Bilstein shock body corresponds to my year car on Bilstein website and everywhere else.

Their replacement in kind (non SP and non HD), black housing strut looks and has the same gland nut as my KYB shock. But on the same page, their SP and HD have the gland nut that looks like the one I have on my Bilstein SP shock. Intriguing..

[mr ilia]

Cant you make original oem gland nut work with the billies?

[acolella76]

Cant you make original oem gland nut work with the billies?

Nope. Thanks to Bilstein's silly inverted strut design, the shaft is much larger than the opening in the OEM gland nut.

[Northern]

Definitely the wrong glad nut, possibly strut insert too (will be obvious if it doesn't fit inside the housing)

First instinct would be to pick up some used 51mm housings if the insert is wrong, or open up the old gland nut to fit the billy sport.

[alen]

Nope. Thanks to Bilstein's silly inverted strut design, the shaft is much larger than the opening in the OEM gland nut.

Right on the money.

Definitely the wrong glad nut, possibly strut insert too (will be obvious if it doesn't fit inside the housing)

First instinct would be to pick up some used 51mm housings if the insert is wrong, or open up the old gland nut to fit the billy sport.

Strut insert appears exactly correct for this housing.
I thought the same thing about making the opening bigger but I would have to compromise a good amount of the gland nut Integrity.

[Northern]

I personally feel that the gland nut only experiences forces during rebound, and not nearly to the extent the bottom of the housing would see during compression. If it were my car, I would do it, but I'm not going to tell someone what is safe and what is not.

[Northern]

I do know that it cost me a lot of money to get 2 gland nuts shipped to me from bilstein. Ended up being about $70 plus UPS border and brokerage fees, so like $120 or so.

[einstein57]

Nope. Thanks to Bilstein's silly inverted strut design, the shaft is much larger than the opening in the OEM gland nut.

Reduced un-sprung mass is silly?

[acolella76]

Reduced un-sprung mass is silly?

I take it you've never had to take apart a Bilstein. Also, the shock weighs more. So yeah you have less unsprung mass but you have more mass in total. They're clunky and dumb and I don't like them.

[JGood]

You have the correct 45mm inserts, but you have 51mm gland nuts. Call Bilstein, they will sell you the correct 45mm gland nuts. I ordered one last year, it was $22.

Although if it were me, I'd probably just open up the hole in the old ones you had. If it's just regular steel you could run a bead of weld around the outside where the threaded portion meets the lip, to add a little strength.

[einstein57]

I've taken apart and modified several sets. People spend big bucks on things like aluminum control arms, titanium lug nuts, and race wheels to reduce un-sprung mass. Makes the car drive smoother and your shocks work less. The only additional mass would be the aluminum end cap and the thin yellow sleeve. But the piston shaft is thinner than a conventional twin tube so that would offset some of that minimal weight increase.

As far as importance

Rotating >Un-sprung> Sprung

I'm not sure how you'd quantify clunky and dumb.