Using 96 M3 suspension in 94 325i

[tekviper]

I have searched over the past couple weeks about using 96 M3 springs and shocks on a 94 325i and I am pretty sure I have it figured out, I am just posting for some feedback and wether or not there is any actual benefit for what I am planning. This is also posted in the e36 section of the forum but I suspect more attention here.

I have a 94 325i I will be replacing springs and shocks on. My plan is to use 95+ M3 bilstein sport struts and shocks;

F4-VE3-A585-H0 Left front strut
F4-VE3-A586-H0 Right front strut
F4-BE5-2453-H0 Rear shocks

Reason for going with the m3 is the swaybar tab on the m3 struts. I will eventually be upgrading the swaybar and endlinks to make use of the strut sway tab and discontinue use of the current lower control arm link. Checking with bilstein, i have found the part numbers for 95 M3 and 96+ M3 struts and shocks are the same. Easy enough so far.

For springs, I am looking to install HR Sports. Now, 94 325i, 95 M3, and 96 M3 all use different springs. The main difference I see is the top coil diameter of the springs. I am unable to find out if the HR Sport springs have any length or springrate differences between them, particularely between the 95 M3 and 96 M3. The 95 m3 uses a larger top coil diameter then the 96 M3 which leads me to bieleve they might be a slightly stiffer spring, I do not know this for sure. Also, the advertised lowering height is similare but shows less drop with 96 M3 springs, probably because the 96 M3 already sits a little lower from the factory then the 95 M3. Now I see no reason that I would be unable to use either 3 spring options (94 325i, 95 M3, 96 M3) provided I also get the appropriately sized top spring seat/perch and upper spring pad (unless I have completely missed something important). So the question is, which HR Sport springs should I use out of those 3 choices. I am partial to the 96 M3 springs because of my next planned change...

Currently my upper strut mounts are the original used on 94 325i's. I would like to use 96+ upper strut mounts in conjuction with the 96 M3 HR Sport springs, and 96 M3 upper spring perches/pads. Since I am not quite ready for camber/caster plates, I think using the 96 m3 front strut mounts would give the car a nice change in camber and caster.

As far as rear springs, I do not see any differences between my 94 325i and 96 M3 which would prevent me from using the 96 M3 HR sport springs in my 325i.

Does anyone have any feedback on my plans. Will everything work together as I am planning? Is there really any reason to use the 96 M3 HR Sport springs over regulare 94 325i HR Sport springs? Price differences are neglible, it's just a matter of choosing the best spring out of these 3 seemingly possible choices.

[bmw3er]

If you are getting the 96+ struts, you should pair them with the 96+ H&R springs. If you get the 96+ top mounts, you can swap the sides for the added camber. What ever you choose, you wont really be able to tell that the sway links are attached to the strut instead of the control arm, especially if you have the stock sways.

On my car, I have 95 M3 control arms, 99 M3 front subframe, rack, spindles and brakes, with 325i spec Bilstein/H&R sport combo. UUC sways attached to the control arms and camber plates. It wouldnt be worth it to me to change it all out just to get the different sway link mounting. Ill wait until I get coilovers, then get the M3 ones with the tab

[tekviper]

The Bilstein sport struts and rear shocks are the same for 95 M3 through 99 M3 should they should be equally accept the 95 M3 springs or 96+ M3 springs. I really don't know how much of an improvement using the strut as a sway mounting point is, but I will be upgrading the stock swaybar eventually and being able to mount it in the same fashion as the M3 just seems like a no brainer.

Checking Realoem, the front subframes are different between 94 325i, 95 m3, and 96 m3, do you know what's different? The steering racks are the same part numbers. The spindles are different, is the change only to accomodate the M3 brakes or is there an alignment change here as well?

Also how are you liking the bilstein sport/hr sport setup? Any rubbing issues with 17in wheels? The drop isn't very much and I think there will be plenty of room, I'd just like to be sure I don't need wheel spacers. I will be using 235/40/17 tires.

[bmw3er]

The Bilstein sport struts and rear shocks are the same for 95 M3 through 99 M3 should they should be equally accept the 95 M3 springs or 96+ M3 springs.
You already said that the upper coil diameter is different, so at the least you would need the correct upper mounts.

I really don't know how much of an improvement using the strut as a sway mounting point is, but I will be upgrading the stock swaybar eventually and being able to mount it in the same fashion as the M3 just seems like a no brainer.
The 92 325i uses the strut tabs as well, so you could use those too. The strut tab location is said to be 30% more efficient than the control arm location

Checking Realoem, the front subframes are different between 94 325i, 95 m3, and 96 m3, do you know what's different?
No, i dont know the difference, perhaps the M3 ones were stronger?

The steering racks are the same part numbers. The spindles are different, is the change only to accomodate the M3 brakes or is there an alignment change here as well?
The M3 rack I used had 90k less miles on it, so thats why it was used. The spindles were used to run the M3 front brakes.

Also how are you liking the bilstein sport/hr sport setup? Any rubbing issues with 17in wheels? The drop isn't very much and I think there will be plenty of room, I'd just like to be sure I don't need wheel spacers. I will be using 235/40/17 tires.
Its a decent daily driver/casual track or autox setup. There are deffinitely stiffer and more performance oriented shocks and springs, but it is a good first aftermarket suspension. Ive been running it on the track for 5 years, and I am finally ready to move to real adjustable coilovers. Most people get coilovers for looks or just to say they have them, when in reality most of them can't get anywhere near the limit of the car. There is no rubbing at all, and I run 235-40-17 as well on 8" rims. The only time I rubbed was when I had 18x8.5 M5 wheels with 255 wide tires. I rolled the rears anyway so I still have some room back there.

[tekviper]

You already said that the upper coil diameter is different, so at the least you would need the correct upper mounts.

My understanding is the upper strut mounts can be interchanged regardless of the spring diameter, it's the upper spring seat and pad that needs to be changed, #8 and #9. I would be using the 96 strut mounts with 96 springs regardless, just asking to make sure I am understanding the differences between the different suspensions.

Also I know it has been a while since you got your bilstein sports, but do you remember if the bumpstops are included? My bumpstops are completely shot so I would need to order new ones if not included with the bilstein shocks. Also, it should be a given that the new shocks will come with a new self locking nut for the strut rod?

[bmw3er]

yes on the nut, I don't think so on the bump stop. You might also need the rear plastic dust boots, they tend to break when you remove them

[jayhudson]

Please do not cross post in multiple forums.

Thanks - Jay