Strut time. Recommendations? Sachs, Bilstein, Monroe?

[josiahg52]

Originally Posted by Diesel Spectre

Bimmerworld…
This

Awesome! This thread was worth posting for me. It's giving me options I hadn't considered.

Monroe OE Spectrum
Koni FSD, now called Special ACTIVE
Bilstein B4
Bilstein B6 (w/taller top mounts for rear)
the venerable Sachs

Poly bushings for front

Lesjöfors springs

I'm going to price out each of the strut options and see what I'm looking at.

[robinasu]

Originally Posted by josiahg52

Awesome! This thread was worth posting for me. It's giving me options I hadn't considered.

Monroe OE Spectrum
Koni FSD, now called Special ACTIVE
Bilstein B4
Bilstein B6 (w/taller top mounts for rear)
the venerable Sachs

Poly bushings for front

Lesjöfors springs

I'm going to price out each of the strut options and see what I'm looking at.

Keep in mind that certain options come with shorter shocks in the rear. For example, if you have the air springs in the back, the vehicle has shorter rear shocks and the rear shock mount is essentially a plate. Here is the upper mount, which is ~3 inched taller:



It's kind of confusing when searching for the right part number(s). I know air suspension uses the low upper rear mounts. It's easy to check, so I recommend all do that before buying after market shocks. I'm not sure what "3rd seat only" uses - might depend on sport or non-sport options. I suspect "3rd seat" and "air suspension" use the low.

To lower the vehicle with air suspension you will need the need the rear tall mounts if you want to use the B8's, but it's unclear if the air spring "spring constant" will be ok at the lower pressure to enable the lower ride height and one would probably need to re-calibrate the air spring ride height sensors. You can buy spring kits / perches to replace the air springs.

[Diesel Spectre]

Yes, robiasu is correct so be careful. The B6s that I have are not made in a short version for a car with 3rd row seating or air springs in the rear so I would need the taller rear mounts to run them because I have a 3rd row. If you don’t (have a 3rd row or rear airbags) you already have the correct top mounts in the rear for the B6s. Incidentally, the fsds (special active konis) also are not made in a “shorter” version for my 3rd row setup but are for the standard “taller” mount.
(standard setup)tall mounts + tall(er) shocks=OK/good=short mounts + short(er) shocks(rear airbag setup)
Short shocks+tall mounts & tall shocks + short mounts = bad.
Don’t let this nonsense confuse you. Figure out what you have (real OEM) by vin and stick with parts that cross to those OEM numbers. If there’s a need to do something “off label”, like robinasu (and soon myself) have done, you can wade into the minutiae.
I’m glad to actually be able to contribute instead of just asking for help like I usually do.

[josiahg52]

I have the base suspension, no third row.

[robinasu]

I was thinking last night about the extra X5M bump stops I bought when I was collecting parts for my recent suspension work. I wound up not using them because the opportunity to use a lift came up quickly and honestly forgot why I bought them. I remembered last night. On the non-M E70 the strut / rear shock isolator foam donuts are compressed by the lower dust cover and the upper washer as you torque the nut on the shock piston. The lower dust cover is made by moulding the plastic dust cover to a washer like the top washer.

The M version front upper strut mount doesn't use the foam isolators and relies on rubber isolation in the upper mount, only. Because of this there are no washers in the assembly, so the X5M uses the secondary shock absorber (bump stop) to hold the dust cover.

If I was to do it over again I would remove the non-M dust cover and replace it with a washer like on the top of the assembly, then use the X5M bump stops with integrated dust cover. I have the X5M bump stop w/covers if anybody wants to buy. Brand new. The X5M bump stops are softer at the tip so they allow more undamped movement before the solid portion kicks in, which will be more abrupt and sporty. The non-M bump stops will be more progressive because they are more uniform. At least this is my take on it.

I would do the above with the poly donut isolators. Somebody should check to see if the poly donut isolators can be adapted to the non-M rear shocks. They need to slide on the aluminum sleeve or at least engage the sleeve properly (with care) when the piston nut is torqued.

The poly donuts with the non-M upper mounts would probably put NVH between the regular E70 and X5M.

When you install the upper mount to the front strut, mind the proper orientation of the rubber mount in the upper mount. You rotate it depending on the side of the car - seems to aid installation. I don't see how a different rotation of the spring around the central axis of the strut would affect anything once installed. Best to follow instructions though.

A lot of parts are interchangeable with some analysis. X5M springs are probably shorter, but would need to check.

The Bilstein B12 kit is pretty attractive if you want a X5M type stance; B12 kit (with correct rear upper mount), poly donuts, B8's have integrated bump stops, then X5M rear bump stops or use the bump stop in the kit. Initially was going to get the B12 but it was on pandemic back-order and I switched to a sport/comfort concept due to that and uncertainty how the air springs would perform at the pressure needed to lower the rear because I do like the air suspension. I bought the rear spring perches just in case I ever need them.

Pics below are the X5M (Forget the date), like 2012. The others are around a 2012 35d. Hope this helps.

[robnitro]

Originally Posted by josiahg52

Those were the ones! I recognize your name from the post.

I forgot to mention that I think they're a poor man's koni special active/fsd, with a similar variable damping, but with a couple of differences.

These Monroe OEspectrum shocks have been used in Audi and some other cars that marketed smooth yet quick handling...

I haven't tried the konis so I can't say they're equal to them, but I did shy away from koni because the reds I had on my vw tdi rusted quickly... when I heard they still have crap paint, I decided to try something else.