Poly Bush and Suspenson Options

[Whiskey98]

Hi all,

Apologies if this is in the wrong board, I would't say there's any technical issues, just looking for recomendations.

I'm currently swapping my 1990 320i with a M54B30, 6 speed box and 3.15 lsd. I currently have no plans to take this car on the track or drifting, but I'm looking to make a street performance car that is also practical for everyday use.
I'm also upgrading the brakes with the mondeo caliper mod at the front, and 325i rear wishbones and discs at the rear. The steering rack is being swapped with an E46 clubsport.

I have little experience with suspension upgrades, and I'm looking for that balance between performance and everyday comfort.
The car already has 16" wheels, and the Bilstein B12 pro kit fitted by the previous owner shortly before I bought it. I have also opted for 70A poly engine and gearbox mounts. The large mounting bush at the rear of the differential is also poly, not sure what durometer that is however. I will be reinforcing the front subframe using the kits commonly available online, and the 325i wishbones will be reinforced in the typical places too. I'm also considering fitting a front strut brace.
Currently, the rest of the suspension is stock

So my question is, what kind of places would also be beneficial to poly bush to improve handling somewhat without making NVH too unbearable for everyday use? Which places should I keep rubber?
Would it be beneficial to go for a thicker front or rear anti-roll bar? Currently mine are completely stock.

Thanks very much!
Peter

[rix313]

The car doesn’t sound much like a comfy cruiser already. If you have poly engine and gearbox mounts then I’d say you’re already very far down the road of increasing unwanted NVH. Polybushes will make the suspension feel harsher. The B12 kit is good but I know I noticed the difference with the eibach springs.

[reggid]

Anti roll bar bushes is a good place for poly.

[Whiskey98]

The car doesn’t sound much like a comfy cruiser already. If you have poly engine and gearbox mounts then I’d say you’re already very far down the road of increasing unwanted NVH. Polybushes will make the suspension feel harsher. The B12 kit is good but I know I noticed the difference with the eibach springs.

I've been mulling it over the past week or so and I'm 99% sure I'm going to go for poly all round. I'm going to go for the softer style poly bushes (steer well clear of the black stuff) and upgrade my front anti roll bar from 18.5mm to 21mm, and fit a rear anti roll bar 16mm. One exception for this is the front lolipops which I will keep rubber, but use the M3 style eccentric bushes.

The poly bush is already in my diff cover and I don't want to risk disturbing the thin casting by swapping anything over. I've heard of that area of the casting cracking if the rear subframe bushes are kept as rubber, especially old worn ones like mine likely are, which then allows excess pivoting forces on the stiffer diff poly bush leading to cracking. So poly bushes on the rear subframe to stiffen the whole thing up is a good idea, and then I may as well go poly bush on the trailing arms too.

I thought my E30 with the Bilsteins and Eibach springs was no problem for road noise already. Back when I was younger I fully poly bushed a Volvo 240 and didn't notice a huge difference in NVH, not enough to bother me anyway, and I regularly drive cars from the 50s to the 70s that aren't exactly known for their ride quality!