Front air spring strut replacement
 

Hi all! My X5 4.8is has a little problem with the front air spring strut. If it sits overnight, the right side front will drop around 4mm lower than left side, if it sits for 2 days, the right front side will drop even lower. I think the right side air spring is leaking very slowly. Now I am planning to replace both side air sping strut. I know it is DIYable and I have already had the manual for replacing front air spring strut. Only twe things confuse me, one is how to remove the front wheel arch and how to use the center ping of the strut to mark the poisition. Thanks for help!

Hi Roger.
I just did it on my 2005 4.8is last week end.

I know that BMW says to remove the wheel arch (liner), but I didn't. After the strut is unbolted from the knuckle and the sway bar unbolted, I removed 2 of the 3 top nuts then slowly the 3rd one with one arm while holding the strut in the wheel well. When loose, I slowly lowered the strut until it was supported on the suspension arm. I found that having a small piece of 2X4 wood over the suspension arm was easier and left more slack for manipulating the air hose. I then slowly unscrew the fitting until I could hear air going out, and let it bleed until empty.

For the centering pin, it will fit in only one way, so the strut will go back at the same position as it was before.

Also, take a marker and outline each of the three nuts that hold the strut in on the top... One of my new struts came without the alignment pin on the top. If I hadn't marked it, I would of had to guess where it went.
This was one of the easiest strut replacements I've ever done...

Thanks a lot for help!

Turbo Bimmer, do you mean just release the all screws on the wheel arch liner and there will be enough space to loose/tighten the air connection to the strut by lowering the strut? What do mean by 'having a small piece of 2X4 wood over the suspension arm was easier and left more slack for manipulating the air hose'? Can you explain more on this part? Thanks a lot!

I see there are two black stuff on the top of the strut. Can anyone tell me which one is the center pin?

Can anyone help?

From the picture, it looks like the centering pin is the one on the right (cone shape). Your strut will go back at exactly the same place because of that pin, so don't remove or break it.

About the liner, I didn't even loosen it. There is about 3-4 inches of air hose coming out of the liner to the strut. That was enough for me to lower the strut about that (3-4'') to be able to unscrew the fitting. Since the air hose is short (with the liner in place) you cannot let the strut hang or drop by itself because you will put tension on the hose and kink it. That's why the strut needs to be supported at all time as long as the hose is not disconnected. Since holding the strut with one hand while removing the hose fitting with the other hand is not easy (strut is a bit heavy), I put the bottom of the strut on the suspension arm so it holds by itself. The 2X4 piece of wood was inserted between the bottom of the strut and the suspension arm to lift the strut a little bit and make more slack to the air hose (may be not required in your case).

If you are not comfortable working on the strut while it is up in the wheel well, then you will have to remove completly the liner, and unclip the small bracket holding the air hose to the body to give you more slack.

Something that you need to keep in mind, you must already know, but just in case, is to keep things clean and not kink the air hose.
Before unscrewing the air fitting, take a rag and wipe the hose, fitting and surroundings to remove any sand and dirt. You don 't want debris in the treads or in the system.

Yep, the cone shaped thing is the alignment pin. I'd still take a sharpie and mark those three bolts in the picture.

I didn't touch the wheel well liner. I used a floor jack under the rotor to move the strut up and down as needed after unbolting. The air hose is hard to get to but it can be done pretty easily. If you use a floor jack, just be careful that you don't bend the backing plate behind the rotor. I got just the tip of the jack pad under the rotor and that worked great.

Please be safe and also use jackstands. They're cheap insurance.

Yea I Don't do anything without jack stands and a wheel chuck.... Nice Shelby!

Thanks but I wish. It's just a 68 fastback wannabe Shelby. :D

It's still Bad-Ass :thumbup:

Completely understood! Thanks, pal!

Hi Trubo, one more thing. Did you replace all the nuts and screws? Accroding to the BMW's manual, all the nuts on the top to hold the struts (total 6) and the screws and nuts that hold the wheel (total 4 each) must be replaced. Is it necessary? Thanks!

BMW Air Suspension Parts & Kits - Arnott Industries

No, I reused the same nuts and bolts. For the bottom ones, just inspect them to make sure they are not damaged or overly corroded.
When I removed those lower bolts on my E46, one bolt had its center section with a smaller diameter due to rust! So I replaced them. But on my X5, they were like new.

Thanks a lot!

Hi Fitzuni, thanks for your info. In HK, I can get brand new genuine BMW front air struts for USD530 each side (the whole with air spring and the strut). I found that Arnott does not ship the whole strut overseas, but only the air spring that needs to be assembled, the price is USD640 for both left and right excluding shipping (I believe shipping cost close to US$200 or even higher). Therefore, I will choose local genuine parts. Just wonder which one is better in quality between genuine BMW air strut and Arnott made air strut?

Just to let you know, I ordered the air spring only from Arnott, and it is an easy job to replace, and if your shock absorber is good, it is cheaper to replace the air spring only.
You just need to be carefull when you insert the new air spring on the strut and make sure that you use a silicone grease for sealing and ease the sliding of the spring over the 2 rubber o-rings, and push with a slight L-R-L-R movement to move the air spring to the bottom of the seat.

Thanks for your explanation! I just bought the both sides brand new genuine air struts for USD1,060. The price is OK compare to Arnott USD600 + USD110 for shipping at eBay (just USD300 more but with struts).

Very interesting, I found that my front air bags held very well in recent weeks. After overnight (over 10 hours) sitting in garage, both front left and right air bag hold pretty well. One thing I found that, after overnight sitting, both front left and right drop a little bit but not noticable, I guess maybe only 5mm. Is it normal or it just leaking very very slowly? What is your suggestion? Should I still go changing both front left and right air struts or just hold until significant leakage found?

Hi Turbo_Bimmer, I am trying to install Arnott's fron right air spring only and as I look at the spring, I'm a bit confused as to why the metal head of the air spring is fixed while the original one has a rotating head. Also, did you have problems with the air connection line? Thanks!

Hi, the metal head of the Arnott's spring can rotate like the OE one. It's because they are new that they don't rotate as easily as the BMW ones. Grab it with one arm and you should be able to rotate the upper portion, and position it correctly vs the strut.

The air inlet on the Arnott's unit is not drilled at an angle like the BMW one. Instead of pointing down at 45°, it is horizontal which makes the connection of the hose harder. I don't know why they did it like that though.
Also, the fitting on the Arnott's spring was not compatible with the tube. I had to remove the fitting from the BMW spring and install it to the Arnott's spring.
On my truck, the hose was barely long enough to connect to the newly positionned fitting, but it worked.

Keep in mind that temps decrease overnight, and lower temps equals less air volume. (~1 psi for every 10 degrees cooling) Leave the car a few days, and if it keeps dropping, you have a leak. Otherwise, just chalk it up to normal air expansion/contraction with temp change.

You could spray the bags with some soapy water and see if they bubble up anywhere. One may be leaking and the system will compensate by lowering the other one. It's usually the left one that starts leaking first. Remeber if you find one that is leaking, the rest aren't far behind.

If you determine that they are leaking, change them before you get the dreaded air suspesion inactive message. It will save you $$ and a lot of headache

It seems that, in general, all of the airbags are reaching their end of life in these vehicles...