Rear Suspension rebuild advice needed

[MAG22]

Unfortunately, my 2016 ZCP was hit pretty directly in rear passenger tire pushing it forward and now its lodged up against the front edge of the wheel well. It's being picked up tomorrow for a BMW appraisal and estimate. Assuming that the subframe mounting points into the body (I think there's only 4 bolts) are not affected, I'm hoping they might work with me to get some upgraded bits.

Surprisingly, it seems to me that only control arms and trailing arms at the very least will have to be replaced. So whatever arms I need, hopefully I can get SPL's in there. Bushings are pretty stressed, so I think I'll have the opportunity to get something different there too. If they have to drop the subframe, it's likely a good time to do the sway bar, right?

So three questions:
1.What can be done that will not negatively impact the ride quality, NVH, etc?
2. What can be done if I'm super tolerant of a stiff ride and NVH?
3. And lastly, which I'll probably choose, which is an in-between of the first 2 questions.

The car is driven on track 10ish days a year, hopefully more as time and money allow.

Thanks in advance

[Theruleslawyer]

If i had to drop the subframe id do the diff brace and rear bar.

For kinematics id be more worried about wear than nvh if you do a lot of street miles, especially in weather. But i haven’t messed with my rear much.

[jfritz27]

Originally Posted by Theruleslawyer

If i had to drop the subframe id do the diff brace and rear bar.

For kinematics id be more worried about wear than nvh if you do a lot of street miles, especially in weather. But i haven’t messed with my rear much.

Good point on the wear with exposed spherical bearings. Those will get rusty/squeaky eventually.

If money is no object you could go nuts and replace every arm in the rear. But honestly, unless you're consistently on the ragged edge / on the limit of your current setup, I'm not sure you're going to feel a big difference by doing all that swapping. Adjustable toe arms would be the one exception, and would definitely recommend that. If subframe is going down, like theruleslawyer said, might as well throw in adjustable swaybar so you'll have options for adjustability down the road. A diff plate and stiffer bushings all around can give a more direct feel and increase responsiveness of drivetrain to on- and off-throttle inputs, and gives a little nice extra diff whine if you like that. But again, the potential benefit from cost standpoint I think is questionable unless again you feel that that quality is lacking.

[Theruleslawyer]

FWIW check out the millway stage kits
https://www.millway.se/millway-motor...-m2-m3-m4.html

Its gives you a good idea of what order to do your kinematics in.

[MAG22]

Money is always an object, but we'll see how willing they are to work with me on upgrades. I'm wishfully hoping some upgrades will turn out to be a wash.

I'm not that good yet that I ride that ragged edge often.

So adjustable toe arms...I'm not well versed in this, but I have heard about the turner ones with lockout plates. Is it the adjustability that make s these so worthwhile or is it the solid mounting/heem joints.

Which adjustable sway bars are recommended? Seems like it between Hotchkis, Dinan and H&R. Do I need adjustability in the arms and the end links or do they accomplish the same thing?

Good thought about rusty rod ends.

[Theruleslawyer]

Originally Posted by MAG22

Money is always an object, but we'll see how willing they are to work with me on upgrades. I'm wishfully hoping some upgrades will turn out to be a wash.

I'm not that good yet that I ride that ragged edge often.

So adjustable toe arms...I'm not well versed in this, but I have heard about the turner ones with lockout plates. Is it the adjustability that make s these so worthwhile or is it the solid mounting/heem joints.

Which adjustable sway bars are recommended? Seems like it between Hotchkis, Dinan and H&R. Do I need adjustability in the arms and the end links or do they accomplish the same thing?

Good thought about rusty rod ends.

Lockout plates means you won't knock out your alignment when you ride curbs. I did the camber bolt shims for the same reason. The stock toe bolts only give you enough adjustment for -1.8- -2 camber at typical toe. By adding toe arms you not only make life easier when aligning, you add the ability to set the toe and camber you really want rather than a compromise. They also take out deflection of course.

https://www.bimmerworld.com/Suspensi...-M2-M3-M4.html

The adjustable end links correct geometry if you're lowered. Some bars will bind or impact other suspension components and you can get the RSB back to the correct position. End links have nothing to do with toe arms really.

[FaRKle!]

Originally Posted by Theruleslawyer

For kinematics id be more worried about wear than nvh if you do a lot of street miles, especially in weather. But i haven’t messed with my rear much.

+1 if this isn't purely a weekend/track car. I'd definitely look at booted spherical bearings or putting boots on arms that don't come with them.

Might be worth doing new or motorsport wheel bearings/hub (33408328351, 33008328143) too since you track a decent amount.

[MAG22]

Well, good news I guess. Only the 2 upper control arms were bent. I don't see a point in messing with things because the replacement parts are so few.

Thanks for info though. I learned a lot about the rear suspension through this ordeal.