On a suspension mission with my 525ix

[cdnalpina]

Hey everyone,

I am on a suspension mission with my Alpina B10 3.0 Allrad, based off the 525ix. The front shocks are totally shot and the only option I have found is OEM Boge struts at over $800 CAD each. I happen to have a set of E39 M5 springs and shocks but I’m missing the strut mounts. Dimensionally these look as though they will fit perfectly but I don’t know if the strut mount bolt orientation is the same as an E34. Would anyone here happen to know if they are or if you happen to own both an E34 and an E39 whether the front strut mount dimensions are identical?

Many thanks in advance!

Rob

[eddycooper]

From the online ZF catalog, it looks like you may have a few options:
TRW JGC114T - to 9/92. It's listed as being for the 525ix with M-tech front suspension.
TRW JGC114S - to 9/92. For regular suspension.
TRW JGC110T - from 10/92.

If you go OEM, you could try Schmiedmann to see if they result in cheaper than local prices.

[ross1]

Hi Rob,
How is that 7-er?
I happen to have a loose e39(528) front mount(31 33 6 769 582) sitting right in front of me. Measuring the distance between mounting studs I get 3 3/4" c to c. Not sure what the circle size would be.
If it quits raining I'll go outside and compare to my E34.

[cdnalpina]

From the online ZF catalog, it looks like you may have a few options:
TRW JGC114T - to 9/92. It's listed as being for the 525ix with M-tech front suspension.
TRW JGC114S - to 9/92. For regular suspension.
TRW JGC110T - from 10/92.

If you go OEM, you could try Schmiedmann to see if they result in cheaper than local prices.

Thanks for that Eddy!

I just looked up those part numbers and sadly they won’t work - it’s been the bane of my search. The strut assembly on my car (02/95 build) is a sealed unit, it’s not like an E34 535i with a cartridge insert and a large crown nut. So I need the entire strut assembly complete with the spring perch. I’m doing this on my phone, so I hope this works, but below is a link to what it looks like. #1 in the diagram looks like it could be a collar but but it is literally a plastic cap that covers the top of the strut.

http://ills.bmwfans.info/2qw.png

[cdnalpina]

Hi Rob,
How is that 7-er?
I happen to have a loose e39(528) front mount(31 33 6 769 582) sitting right in front of me. Measuring the distance between mounting studs I get 3 3/4" c to c. Not sure what the circle size would be.
If it quits raining I'll go outside and compare to my E34.

Hey Ross! How are you?!

I’ll have to catch up with you sometime about it - I just found out a crazy story about it a couple of months ago. I recently picked up a 1985 745i that was near me - looking forward to playing with that.

Thanks for the measurements! On Realoem the part number for the E39 M5 strut mount doesn’t cross over to the E34 525ix but I’m hoping that just has to do with the coil spring differences and not the stud orientation.

Cheers!

[henfjel]

Hi Rob, this is a very interesting topic. I'm in the midst of restoring my 525ix and I'm also looking for options for the front struts. Do you know if the E39 M5 struts fits the ix axle carrier? I've been doing some light googling to find the diameter of the E39 struts to no avail.

[demetk]

Would anyone here happen to know if they are or if you happen to own both an E34 and an E39 whether the front strut mount dimensions are identical?

Close but no cigar. Left mount is the e39, right is the e34. But it's only a mount. Holes can be drilled.

[ross1]

Yep, I also checked this yesterday. E34 mount is asymmetrical. E39 uses a small stub to position it correctly.

[cdnalpina]

Time for an update! I finally got my suspension bits all together and I have good news and bad news...

The good news is that the E39 M5 strut mounts actually line up exactly in the 525ix strut tower! Now the bad news... when comparing the two strut/spring assemblies side by side they are not a match. See below

F252383E-0FE0-4937-B58B-46D8EBAFBBED.jpeg

The problem is that, if you look at the bases of each strut, you can see that it tapers slightly on both. This is the part that recessed into the collar on the hub. The problem is the length of the recessed portion on the E39 strut is twice as long as the E34 unit. Problem with this is that the overage will hit the front CV axle. Otherwise the top of taper to top of strut are essentially identical in height. Tempted to see what it would be like if I mounted the E39 strut to the correct height in the collar but I think it will make the front end of the car far too high. Booo

[transeurope]

Are you sure that the underside of the e39 strut isn t massive? Maybe it just can be grinded off?

- - - Updated - - -

And are you sure the diameter is the same? Thought it was different?

[Tristan36]

why not use the longer and then just install lowering springs to get it back to stock height

[cdnalpina]

Are you sure that the underside of the e39 strut isn t massive? Maybe it just can be grinded off?

- - - Updated - - -

And are you sure the diameter is the same? Thought it was different?

The struts are otherwise identical in diameter and height aside from that one variance I noted on the tapered part. I don't know what would happen if I cut the bottom couple of inches off but I would assume that those bottom two inches have parts of the internal guts in there - not just filler.

- - - Updated - - -

why not use the longer and then just install lowering springs to get it back to stock height

I did contemplate that but wouldn't I need a strut insert that is shorter as it will make the whole front end of the car sit up far too high? If I'm adding height at the bottom I'd somehow need to reduce the height at the top. Spring is for sure one component of that but I would have thought the strut would be too.

[Tristan36]

springs should do the trick alone but it will give you a harsher ride quality. plenty of people just install lowering springs without any strut replacement the resistance the spring gives you is what set the height of a non adjustable strut. and if that works you could always upgrade to e39 coilovers and that would give you the ability to adjust the height with out sacrificing ride quality.

[polov8]

Don't Bilstein make front shocks for these? I'm pretty sure I've seen B8's somewhere.

[cdnalpina]

springs should do the trick alone but it will give you a harsher ride quality. plenty of people just install lowering springs without any strut replacement the resistance the spring gives you is what set the height of a non adjustable strut. and if that works you could always upgrade to e39 coilovers and that would give you the ability to adjust the height with out sacrificing ride quality.

Solid points. The coil over would be a smart way to go. I need to lose about 2.5” of higher on the E39 struts. I guess I could try cool cutting or lowering springs first and go from there.

- - - Updated - - -

Don't Bilstein make front shocks for these? I'm pretty sure I've seen B8's somewhere.

I never have been able to find anything other than oem for this specific model. If you do, I will PayPal you money for thank you beers!

[Topex]

Solid points. The coil over would be a smart way to go. I need to lose about 2.5” of higher on the E39 struts. I guess I could try cool cutting or lowering springs first and go from there.

- - - Updated - - -



I never have been able to find anything other than oem for this specific model. If you do, I will PayPal you money for thank you beers!

D2 suspension has a weld on coilover kit available for 525ix/allrad: D-BM-43-01

I also had shot front struts in my 525ix and just a pair of new struts would have set me back 800€+.

I modified E90 rwd Sachs front struts (311 403/404 with e90 top mount, spring, etc.) to fit my ix and the ride height seems close to the old stock suspension. I've only driven a few kilometers with them fitted so far. I don't know how good they will actually function on the car. My struts
NOTE E90 front axle has a lower maximum allowable front axle loading than the ix.

Also someone might be interested what I did to fit them in:
- Removed the stabilizer mounts and the overhanging bottoming bits from the e90 struts.
- Fabricated and welded in brackets to match the stock struts: bracket for the lower strut bolt, one for the wires/hoses and a thread for the brake pad wear connector.
- Removed the locating dimple from the top mount and the top mount fits straight in.
- Put a ~2mm shim between the bottom of the strut and the knuckle to increase the diameter to match the stock struts.

E90_525ix_s.jpg

[moroza]

One potentially useful datapoint: RWD E30 springs are physically interchangeable with E34 RWD springs, just softer. Do E30 325iX struts physically fit the 525iX? Do 325iX springs use the same basic spring dimensions as RWD E30? If so, you should be able to use 325iX struts and select a spring, OE or aftermarket, for any of the following: E34, E32, E28, late E24, possibly late E23, possibly other chassis.

And another: E90 upper spring perches are aluminum, and can be installed without further modification on V3 E30/E34 strut mounts, lowering the car ~6-7mm compared to the stock steel perch.

[Topex]

One potentially useful datapoint: RWD E30 springs are physically interchangeable with E34 RWD springs, just softer. Do E30 325iX struts physically fit the 525iX? Do 325iX springs use the same basic spring dimensions as RWD E30? If so, you should be able to use 325iX struts and select a spring, OE or aftermarket, for any of the following: E34, E32, E28, late E24, possibly late E23, possibly other chassis.

And another: E90 upper spring perches are aluminum, and can be installed without further modification on V3 E30/E34 strut mounts, lowering the car ~6-7mm compared to the stock steel perch.

E30 325ix struts seem to be a cartridge type, similar to E30 and E34 RWD models