Bilstein B6 Strut installation in knuckle

[E46m3zcp]

They are correct, you do not use the OE washer. I’m understanding from this thread that Bilstein includes their own washer that is installed in place of the OE one.

They don't provide any washer with the B6. I'm starting to think Joseph from Bilstein answered quickly without checking. What is making more sense to me is to use the stock washer. TMS advise to use the stock washer in their installation manual for their street/track camber plates.

If used with the washer, the strut shaft is blocked in upward motion as the washer will squeeze against the rubber on the bottom of the bushing. Otherwise I guess it could potentially shred the bearing's metal core out of the rubber and poke upward 🤨 like in your photos.

[Bry5on]

Ah, I stand corrected, thank you.

[Bry5on]

I remember now! This was a common problem with the e31 8 series when installing bilsteins. If the washers were left out, the upper strut bearing would fail and the strut would dent the hood. The e31 uses the same style of strut mount as the e46 M where spring and damper loads are decoupled. See: https://www.bimmerforums.com/forum/s...top-inequality

edit: image from linked thread:

[Tbonem3]

Maybe I've not had an issue because I use new components, and not old rubber? Or because my spring rates are stiffer, thus less likely to bottom out?

I agree the *correct* way to install would be to have the washer (or perhaps a thinner one to play it safe, but also recapture precious travel?)

It's also correct to torque every fastener to factory spec, yet I don't, and my car hasn't fallen apart after 100k and 13 years of hard driving.

Everybody has different tolerances of risk I suppose. MCS specifically says NOT to run a bump stop with their dampers if you can believe it.

[Tbonem3]

What I can't figure out is the ridiculously thick spacer TMS includes with their street plates, esp since TMS advises to re-use the factory washer. Perhaps it's purely to provide the same stack height as stock? Even though that's not a "good" thing?

[Bry5on]

Maybe I've not had an issue because I use new components, and not old rubber? Or because my spring rates are stiffer, thus less likely to bottom out?

I agree the *correct* way to install would be to have the washer (or perhaps a thinner one to play it safe, but also recapture precious travel?)

It's also correct to torque every fastener to factory spec, yet I don't, and my car hasn't fallen apart after 100k and 13 years of hard driving.

Everybody has different tolerances of risk I suppose. MCS specifically says NOT to run a bump stop with their dampers if you can believe it.

It’s quite likely that both the high spring rates and new rubber are contributing factors for sure. That’s wild that MCS advises that.

Acceptable fastener preloads can be pretty wide in practice, to your point, as long as you’re not dealing with extreme temperature swings and thermal expansion or something similar. I’ve had to deal with cases that vary from cryogenic -300F to very hot 400F temps clamping dissimilar materials, and in those cases you need a very specific preload (torque) in the fastener!

Related, just recently I was trying out a new canyon route in my e46 (stock M3 springs + konis) and I came around a corner only to find a *very* large bump without enough time to stop first. I both hard bottomed out and also caught some air! Certainly this isn’t common for most folks, and I definitely miss Southern California roads. Good example of how mileage can vary, literally.

[Bry5on]

What I can't figure out is the ridiculously thick spacer TMS includes with their street plates, esp since TMS advises to re-use the factory washer. Perhaps it's purely to provide the same stack height as stock? Even though that's not a "good" thing?

My guess is that spacer is calculated to prevent the washer from contacting the street plate metal at 100% deflection of the urethane bushing. When using the Bilsteins with TMS street plates, it does look like you can run without that spacer/washer, as the strut diameter is big enough to not punch through the camber plates, and the shaft is stepped and tapered.

[Tbonem3]

Definitely.

I will say, after visiting m3 related forums for years now, I can't say I remember any threads where people have found the stock washer to have saved the day from disaster. I'm not doubting the possibility, I'm doubting the likelihood of occurrence.

I still don't understand how much force the stock mount is seeing in normal operation - isn't the spring taking the full weight of the corner and extra forces from inertia? I can see it taking more load from pulling, but not pushing where I envisage the spring doing all or almost all the work.

The bottoming out of the spring or perhaps the bump stop is the situation where I can see the washer acting as a safeguard from punching though, not normal operation/driving.

[K-Dawg]

What I can't figure out is the ridiculously thick spacer TMS includes with their street plates, esp since TMS advises to re-use the factory washer. Perhaps it's purely to provide the same stack height as stock? Even though that's not a "good" thing?

I believe the purpose of that 7mm spacer is to make room for articulation and give in the camber plate urethane bushing. Without the spacer, the big washer would be in contact with the camber plate body. IMO, the spacer isn't necessary if the factory washer isn't used (coilovers).

[K-Dawg]

Definitely.

I will say, after visiting m3 related forums for years now, I can't say I remember any threads where people have found the stock washer to have saved the day from disaster. I'm not doubting the possibility, I'm doubting the likelihood of occurrence.

I still don't understand how much force the stock mount is seeing in normal operation - isn't the spring taking the full weight of the corner and extra forces from inertia? I can see it taking more load from pulling, but not pushing where I envisage the spring doing all or almost all the work.

The bottoming out of the spring or perhaps the bump stop is the situation where I can see the washer acting as a safeguard from punching though, not normal operation/driving.

Imagine mounting a damper in a vice, then attaching the strut mount (with no spring). Now imagine moving that strut mount up and down rapidly for hours on end. That's the force exerted on the strut mount. Yes, the spring is carrying the weight of the car, but the strut mount is feeling the damper's resistance to motion.