e46 M3 suspension setup, or how to not downgrade your car with suspension mods

[Obioban]

Looking at converting my ohlins R&T to flat ride while I have them out to rebuild/service. What is the solution for the upper spring perch on the front? For instance if I'm getting a 2.5" spring that wont fit the standard radial bearing on the front (https://www.fcpeuro.com/products/bmw...g-31331090612a) correct? I have ground control street camber plates.

EDIT: just found these: https://www.ecstuning.com/b-turner-m...su4680777~tms/ Presumably they fit my camber plates as well?

Ohlins spring perches are 65mm-- they work with 65mm or 2.5" springs. GC can sell you upper perches to match. Then you can buy springs from anyone, in 65mm or 2.5".

[puma1824]

Thanks so much for the write-up. I have things to learn and need to find a shop that can help set up. I did find out more technical details on my Coilover kit. I wonder if I need to change the spring rates because it's going on an m3 touring conversion. Hmm, where to begin???


PRO-STREET Coilover Kit (Height Adjustable) BMW M3 E46 - Part # 2072.711

Metal to metal travel (total shock travel):

• Front: 130.3mm (5.12in)
• Rear: 169.7mm (6.68in

Spring Size:

• Front: 6” long 400lbs (2.5” I.D)
• Rear 6” long 450lbs (2.5” I.D)

Wheel Specs:

• Offset Front: ET+44
• Offset Rear: ET+27
• Bolt Pattern: 5 x 120
• Factory Setup, Front: 19 x 8.5
• Factory Setup, Rear: 19 x 9.5
• Factory Tire Size, Front: 235/35/19
• Factory Tire Size, Rear: 265/30/19
• Weight, Front: 23.15 lbs (10.5 kg)
• Weight, Rear: 25.02 lbs (11.35 kg)

[Obioban]

Thanks so much for the write-up. I have things to learn and need to find a shop that can help set up. I did find out more technical details on my Coilover kit. I wonder if I need to change the spring rates because it's going on an m3 touring conversion. Hmm, where to begin???


PRO-STREET Coilover Kit (Height Adjustable) BMW M3 E46 - Part # 2072.711

Metal to metal travel (total shock travel):

• Front: 130.3mm (5.12in)
• Rear: 169.7mm (6.68in

Spring Size:

• Front: 6” long 400lbs (2.5” I.D)
• Rear 6” long 450lbs (2.5” I.D)

Wheel Specs:

• Offset Front: ET+44
• Offset Rear: ET+27
• Bolt Pattern: 5 x 120
• Factory Setup, Front: 19 x 8.5
• Factory Setup, Rear: 19 x 9.5
• Factory Tire Size, Front: 235/35/19
• Factory Tire Size, Rear: 265/30/19
• Weight, Front: 23.15 lbs (10.5 kg)
• Weight, Rear: 25.02 lbs (11.35 kg)

I would begin with getting the corner weights of your car, the functional range of travel of your front springs, and the travel of your shocks.

[puma1824]

I would begin with getting the corner weights of your car, the functional range of travel of your front springs, and the travel of your shocks.

I got the travel of the shocks from Eibach. I need to get functional range & corner weights after all installed. The car is still being assembled.

Metal to metal travel (total shock travel):

• Front: 130.3mm (5.12in)
• Rear: 169.7mm (6.68in

[Thoglan]

Ohlins spring perches are 65mm-- they work with 65mm or 2.5" springs. GC can sell you upper perches to match. Then you can buy springs from anyone, in 65mm or 2.5".

Just flicked them an email thanks. Presumably the turner perches will fit as well though seeing as both camber plates work with the stock perches?

[lvm3sm46]

FWIW, Ohlins comes with a 8" 400 front spring and that provides almost an inch drop with stock front mounts.

If you try running a 350 7" spring at 13.5 ride height, you will be almost at the very top of adjustment threads on the collar after preloading the spring appropriately (ride height and spring preload same adjuster).

I tried a 336 7" spring and could not get it to more than barely above 13.25 after maxing out the adjustment collar/preload. The tire rubbed.

Rears at 628 I believe are 6" long (they might be 5", ill need to check).

Sent from my SM-G950U using Tapatalk

I'm returning to update this, mrgizmo is correct. I tried a 7" 300# spring on Ohlins and it maxed out at 12.75" from fender to hub center. I took that measurement after a 30 mile drive after install so I am going to assume its going to get lower. I think I am going to try 8" next to hopefully get me to 13.5- 14"

[Obioban]

I'm returning to update this, mrgizmo is correct. I tried a 7" 300# spring on Ohlins and it maxed out at 12.75" from fender to hub center. I took that measurement after a 30 mile drive after install so I am going to assume its going to get lower. I think I am going to try 8" next to hopefully get me to 13.5- 14"

Ohlins can’t run that high— you’ll be all bump no droop.

They have exceptionally little total travel (92mm up front IIRC, some of which is bump stop). You pretty much need to set your ride height to optimize bump/droop travel to have them be able to function. If you want to go off that, you need to alter the top or bottom shock mount to match.

[lvm3sm46]

So how did you get 13.5 front ride height when you were running them?

[Obioban]

So how did you get 13.5 front ride height when you were running them?

I machined some spacers to lower the the strut in the camber plate 😜

These days, however, Barry at 3DM makes a lower strut spacer that has the same result.

[lvm3sm46]

Weird cause you would think when I ordered them from him he would've mentioned I needed this. Oh well I guess I'll call him Tuesday to sort this out. Sometimes this shit is such a pia.

[wahsm]

Ohlins can’t run that high— you’ll be all bump no droop.
.

I feel like "All bump no droop" needs to be a bumper sticker.

[straight six m3]

Obioban, I might be looking at it wrong but how does that spreadsheet adjust for progressive springs like those in the KW V3s? Is it recommended to switch to something linear like Swift springs?

[cobra]

Obioban, I might be looking at it wrong but how does that spreadsheet adjust for progressive springs like those in the KW V3s? Is it recommended to switch to something linear like Swift springs?

The KW's are closer to dual rate rather than progressive springs. At static ride height, it's through the soft rate and resting on the stiffer rate, so you can use the stiffer rates for most of your calculations.

In general linears are easier to deal with but there is some merit to dual rate springs if they are implemented properly.

For reference the KW rears are 280lb/in initial rate and 550lb/in final rate, transitioning at 1.9". KW fronts are 160lb/in initial rate, 290lb/in final rate, transitioning at 2.0"

[Obioban]

If you have an actually progressive sprint, the best option would probably be to get it on a spring tester and measure it at that corner's corner weight.

[BigRussia]

Not sure if this is the right place to propose my question/issue but figure better than making a separate thread since alot of it relates to Obioban's OP info:

My car is on the Bilstein PSS10 (B16) coilovers. I'm trying to get to a proper 13.5" front 13" ride height with the .5" rake, but the rear doesn't go any lower than 13 1/4" even with the rear adjuster collars to max low. With fronts also being at 13 1/4" i basically have 0" rake ands the rear way higher than the front having my car looks like a drag muscle car lol. Only way i can get rears lower is if I remove the rubber spring pads (top is already thinnest BMW makes at 5mm) or just run with no collars (but then defeats the point of having height adjustablitlity for corner balancing). While the car rides great at the higher height I would just really like to get the rear 1/4" lower mainly for aesthetics as the car looks silly with over the top rake it has now and the wheel/fender gap is pretty ugly, almost looks like a stock height car.

I was wondering, has anyone tried getting ahold of the Bilstein Clubsport coilover rear springs and swapping them over into their B16s? Looking at the pics online and eyeballing them side by side the Clubsport rear springs seem to be shorter than the B16's. I figure some stiffer spring rates wouldn't hurt for track days either. I tried finding the springs online but doesn't seem Bilstein sells them separately

Has anyone had this issue with their Bilstein PSS10 B16 and rear just not lowering much or enough? And what is another solution I can try that doesnt involve removing the upper and lower rubber spring pads or the adjuster collar? As you can tell its been driving me a bit crazy, every time I walk into the garage and see how jacked up the rear is and that ugly gap 😅 I know im being OCD but I feel like we are an OCD bunch here eh?