I'm going to be replacing some bushing on the rear of my Z3 (same suspension as E30) and considering the poly option.

How's the group's luck, and opinion of poly replacements? Ride harshness? Squeaky?

Powerflex is the brand I'm looking at if that matters.

This car is one of three in the stable  and only ever gets used for nice weather top-down driving.

They can be ok if done properly, they need to be regressed occasionally.

I’d stick with the OE rubber if you’re just taking it for nice day drives.

I use graphite-impregnated poly on my '66 Mustang. Very stiff and no squeaking.

Rubber is best for a road car. If you go poly, get some Prothane or Energy Suspension grease. It's expensive and messy, but they stay quiet for years instead of weeks with other greases I have tried.

Listen to the post above about the squeak.

Poly lasts...but not as flexible as OEM rubber.

If you do go poly....get a tube of Superlube synthetic grease for assembling.

I use poly on the leaf springs, motor mounts, transmission mount  and shock bushings on my rock crawler Jeep.

They hold up to the abuse, but very little flexing.



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I use them in my '66 Mustang for their stiffness. I built it for road-racing. It rides like a gravel truck but corners like a fiend. It's so tight I can change lanes on the freeway with engine torque.

Thanks for the feedback. I've decided to run OE bushings at the control arms and Poly at the subframe and diff mounts.

This all started from a leaky shock (23 yrs old!), so I'll be able to rebuild the control arms pretty quickly, then drop the entire
assembly and do the mounts and brake hoses when it gets to hot for the top-down life ( or winter)

When I was looking for bushings about 5 years ago, I remember someone advertising something like a hybrid bushing.
It was harder than rubber, but not as hard as the polyurethane.
This was for a '66 Mustang, so I'm not sure if this was Mustang-specific or not.
I wound up going with the stock bushings to keep the ride from being too rough.

Superpro in Australia has those. I recommend them. They are a pain to install but they work very well.
I don't like poly unless its the only option. Before choosing which route to go, you need to find out if your suspension moves around or not (2-D which poly does great, or 3-D which poly doesn't). Poly will not flex much and that is great for road feel. This is fine until you hit a big pothole and crack an arm because they don't absorb much force, and just transfer it up the chain, and in a 2-D manner which is different than stock rubber bushings which can deform/move around in 3-D manner. Poly does change the amount of forces going in and out of the system and you need to make sure your parts are stout enough to handle it. There are suspension setups that require "flexible" bushings that can move. My car, a 85 corvette, requires the rear suspension bushings to move ever so slightly in 3-D. The front doesn't.  I went with superpro all the way around. I don't like aftermarket rubber bushings because they try to hit the lowest pricepoint and throw garbage material in the product, by guessing or outright ignoring the correct formula and durometer required. OEM or a company with a good reputation is the way to go. I would go Superpro OP.

Not a fan of poly in general, feels like a half measure. Delrin isn’t all that much harsher than poly, but has significantly freer rotational movement and doesn’t squeak.

This is definitely true and something to be aware of. Lots of Euro and Japanese stuff (and most modern stuff in general) need to have bushings that move in 3d compared to a lot of old school American stuff that might just be 2d.

While not applicable to OP, I've seen guys that go from poly to heims/sphericals on a car and have to add spring rate because the the way the suspension cycles was so much better compared to how the poly bushings binding up, effectively created additional spring rate.

Subframe bushings?  A lot recommend poly or even solid alum on E46 to prevent the panel the subframe mounts to tearing. It's an issue on the Z3 also, but mechanism may or may not he different. Probably be good to look into this if you're dropping subframe.

Motor, trans, and diff bushings can be poly, but they will introduce NVH.

RTABs go with OE or monoball($$$).  Poly can bind.

For what its worth, E46 I rallycross just has poly trans and solid rubber engine. Poly trans/diff when I get around to installing. I do not care about ride quality on this vehicle.

Edit: saw your follow up post, good choice.

This is the way.  I have 4 cars with poly on 4 links. Use the nasty stick grease and they will not squeak.  I use poly for cab/body mounts, sway bars, etc.  I have never had one fail.

I have a whole grease tube of it I bought 20 years ago. Still have 3/4 of it. That stuff is no joke.

These are supposedly pretty damn good poly bushings and such.

https://whitelineperformance.com/

This is what I've experienced in my applications.  Body mounts, & sway bars.
You NEED the right lube.  I use the energy suspension poly lube.