Powerflex Rear Subframe bush or bush insert?

[JSz4]

I bought my Z4 about 6 months ago, it is now on 87k and as I'm using it for spirited road driving and the occasional trackday I'd like to give the suspension a bit of a refresh, especially since through fast corners the rear can feel a little unsettled

I was thinking of either buying Powerflex rear subframe bush inserts (£105) and fitting them myself or completely replacing the rear subframe bushes with Powerflex bushes (£174) but I'd need to pay a garage to fit them.

Just wondering if anyone else has experience of either the bushes or the bush inserts and whether replacing the bushes entirely will be worth the cost difference?

Secondly how much do garages charge generally to replace the bushes entirely, I assume it's a simple job but just very time consuming?

Cheers Jeremy

 

[JSz4]

Bump!

 

[GuidoK]

I've replaced those bushings (with strongflex variants btw.)

I personally wouldnt use the inserts. You still need to do most of the work and still you can have stock rubber giving out in the future.

And if you're planning to replace more bushings, dropping the rear axle is the way to go imho (basically remove exhaust&reinforcement bars, heatshield, disconnect handbrake cables, shocks, propshaft and lower the rear axle with a transmission jack).
That way everything is easily accesible.
If you (your mechanic) put your back into it, complete replacement can be done in a long day.
I got all used rear axle bushings (all 19 pieces) out in about 3 hours (once I had the rear axle off the car), and I'm not a professional mechanic. Having the right tools/enough tools is half the work

Fitting poly bushings is easy/quick as they dont have to be pressed in and thus a fraction of the work.

But you have to ask a garage how much time they estimate. They have to do it.

Polybushing your car will completely transform the handling. Everything is more preciece and you get a little bit more off power oversteer (understeer/oversteer is easier to control with the throttle).
This guy puts its in better words:
https://www.youtube.com/watch?v=0KLBGVClpX0


I have a spreadsheet with basically the possibilities for replacing the z4 bushings for polyurethane:
https://audio.home.xs4all.nl/zooi/z4/bussen/xls/

If you're thinking about doing this yourself I strongly suggest that you hire a ramp for a day or 2 incl transmission jack and have the appropriate tools.
With the axle off the car, any cosmetic jobs are also easy to do (but they usually take far more time)

 

[JSz4]

Thanks for the detailed reply.

Considering the cars mileage it sounds sensible to replace the bushes as you say and avoid the inserts. I'll look in to doing it myself but due to the age of the car I assume quite a bit will be seized and I don't have the equipment to press or burn the old bushes out. Thanks for the advice about dropping the rear axle though.

I found that vid really interesting as the coilovers, anti roll bars and polybushes are the suspension mods I want to do to my 3.0i and the polybushes definitely seem a good place to start to refresh the suspension.

The spreadsheet is very useful too, what made you go for the strongflex bushes over the powerflex ones and did you go for the red or yellow versions?

 

[Limonge]

I've replaced those bushings (with strongflex variants btw.)

I personally wouldnt use the inserts. You still need to do most of the work and still you can have stock rubber giving out in the future.

And if you're planning to replace more bushings, dropping the rear axle is the way to go imho (basically remove exhaust&reinforcement bars, heatshield, disconnect handbrake cables, shocks, propshaft and lower the rear axle with a transmission jack).
That way everything is easily accesible.
If you (your mechanic) put your back into it, complete replacement can be done in a long day.
I got all used rear axle bushings (all 19 pieces) out in about 3 hours (once I had the rear axle off the car), and I'm not a professional mechanic. Having the right tools/enough tools is half the work

Fitting poly bushings is easy/quick as they dont have to be pressed in and thus a fraction of the work.

But you have to ask a garage how much time they estimate. They have to do it.

Polybushing your car will completely transform the handling. Everything is more preciece and you get a little bit more off power oversteer (understeer/oversteer is easier to control with the throttle).
This guy puts its in better words:
https://www.youtube.com/watch?v=0KLBGVClpX0


I have a spreadsheet with basically the possibilities for replacing the z4 bushings for polyurethane:
https://audio.home.xs4all.nl/zooi/z4/bussen/xls/

If you're thinking about doing this yourself I strongly suggest that you hire a ramp for a day or 2 incl transmission jack and have the appropriate tools.
With the axle off the car, any cosmetic jobs are also easy to do (but they usually take far more time)

Hello, sorry for resurrecting a 7 year old thread. I will be taking the engine, gearbox and differential out, and I thought it would be a good oportunity to replace some of the bushings. I downloaded your excel spreadsheet (thanks for it!), and I was wondering which are the most recommended to replace, if not all. My driving skills are a "spirited granny", and the idea was to keep NVH acceptable, currently I have the B12 installed, and I have pending the H&R ARB's. Would you recommend Strongflex over Powerflex? They're much more affordable. I also found an even cheaper version in Poland, here's the link if you want to take a look: https://poliuretany.olkusz.pl/pl/bmw-serii-3-e46-1998-2005-komplet-tulei-zawieszenia.html

Thanks!

 

[kis]

I’ve purchased strongflex myself. I’ve yet to fit but they offer lifetime warranty on the red bushes. They’re 80 ShA. Which basically just means they’re equivalent to OEM but in a poly bush.

You’ve also got the reassurance of a base in the UK so you’ve got a “local” point of contact… assuming you’re based here as well.

In terms of what to get, I’m sure they have a whole car set of bushes, circa £400/500 from memory. That’s the route I went down.