F30POST
F30POST
2012-2015 BMW 3-Series and 4-Series Forum
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > Suspension | Chassis | Brakes > Rear axle PU bush replacement - worth it?
Studio RSR
Post Reply
 
Thread Tools Search this Thread
      01-15-2020, 06:20 AM   #1
CrushJelly
Private First Class
102
Rep
128
Posts

Drives: M140i
Join Date: Dec 2016
Location: Australia

iTrader: (0)

Rear axle PU bush replacement - worth it?

Hey all

I have a bit of a dilemma that I'd appreciate some opinions on from more experienced folk here. I have done a few searches but couldn't find the exact info I was hoping for. Mine is an M140i, but the suspension and componentry is basically identical to the F30 cars.

My current chassis mods are as followings:

- Front strut bar (Ultra Racing - nothing special)
- Rear underbody brace (OEM)
- Front F8x lower and upper control arms
- SuperPro differential bushes
- SuperPro subframe bushes
- Bilstein B14

I have a set of H&R swaybars that are waiting to go in. It will be a hefty/expensive job. I was wondering whether the rear control arm bushes would be worthwhile to do whilst the subframe is disconnected.

I'd be looking at the SuperPro range.
https://superpro.com.au/find/superpr.../cid-999501544

Can anyone care to offer their opinions or experiences as to whether replacing the rubber bushes at the rear with PU would be worthwhile? There are quite a number of them, owing to the various arms on that multi-link rear end.

I had previously considered Hardrace sealed monoball rear arms, but have been told that aftermarket arms aren't ever as beefy as OEM parts so not to bother with them.
https://www.hardracesuspension.com.a...55&car_type=17
Appreciate 0
      01-15-2020, 08:19 AM   #2
anielsen71
Major
Denmark
557
Rep
1,499
Posts

Drives: F36 435xd
Join Date: Mar 2012
Location: Behind the wheel

iTrader: (0)

Garage List
I got all bushings in my former E91 changed to powerflex PU bushes.
That made a huge difference. More precise steering and more suttle rear end.
I would change if you are on it anyway
__________________
Brgds
Allan
‘15 F36 435xd Gran Coupé

Ex: E46 330d, E91 330dA
Appreciate 0
      01-15-2020, 03:06 PM   #3
CrushJelly
Private First Class
102
Rep
128
Posts

Drives: M140i
Join Date: Dec 2016
Location: Australia

iTrader: (0)

Awesome. Thanks
Appreciate 0
      10-16-2020, 04:23 PM   #4
CrushJelly
Private First Class
102
Rep
128
Posts

Drives: M140i
Join Date: Dec 2016
Location: Australia

iTrader: (0)

Posted the below on the babybmw forums but copying on here as most of the F3x chassis shares the same parts as on the F2x (minus xDrive, of course).

-----

Well, here it is, the last of the handling mods and the result of 4 years' worth of research, trials and tinkering to get the car exactly how I wanted it.



We finally managed to coax the stock rubber bushes out of the rear arms and replaced them with the polyurethane (PU) kind from SuperPro. First impressions were largely moot. The rear had always been stiff, owing to the subframe bushes (also SuperPro PU), but I wasn't quite sure whether there was really any material difference from the change to the rear arms.



However, after a few more KMs, it is quite apparent that imperfections in the road are now more apparent. The rear is, for the lack of a better word, tighter. It feels like the B14s are made to work more, but in no way does it make the ride harsher/crashier. I've always been impressed with the way the B14s managed to round off sharp feedback even though it was just as stiff as the stock adaptive dampers with Eibach Pro and Eibach SP Pro spring kits.

I can't help but note that this type of aggressive feel might not be to everyone's taste. But I love it and each to their own.

It has, however, raised my suspicions as to whether the B14s are under-damped/over-sprung, as I feel the rear being a smidget more bouncy over undulations. But then again, I'm not an expert and it could just be due to a greater transfer of road feedback. Having said that, the general feeling is still very much one of "control" and "tight".

We got these rear arm bushes as I was experiencing some axle tramp when losing traction under power. This was more prevalent in the wet. Initial launch trials in the dry point to a tied-down rear end with a smooth and controllable breakaway point, which is basically very similar to my initial thoughts when we had the rear underbody brace and subframe bushes installed (both done separately). This just adds a little extra.

For context, other handling-related mods on the car:

- Quaife LSD
- Rear underbody brace
- Front tower strut bar (Ultra Racing)
- Front F8x control arms
- H&R swaybars + adjustable endlinks (SuperPro)
- Rear subframe PU bushes (SuperPro)
- Rear diff PU bushes (SuperPro)
- Bilstein B14

Did I say this would be the last handling mod? 🤣🤣🤣

The next stage would be to re-spring and re-valve the B14s, although that won't happen for some time as I explore the current setup.







Appreciate 0
      10-19-2020, 03:59 AM   #5
Watsey
Major General
United Kingdom
6379
Rep
8,467
Posts

Drives: F31 330D sDrive M Sport
Join Date: Jun 2015
Location: On sabbatical.

iTrader: (1)

That's a nice setup, although personally I found the H&R bars to be too stiff with Ohlins R&T and am replacing them with Eibach units - the rear is already in and the front is being done in a couple of weeks' time along with SuperPro rear subframe poly bushes.

Interested in whether you noticed any significant changes/benefits by replacing the diff bushes with poly units.
__________________
Current : F31 330sD, remapped, Ohlins Road & Track, Millway camber plates, Quaife LSD, Stoptech brakes + Pagid RSL1 pads all round, Weichers front strut brace, Eibach front & rear anti-roll bars, Michelin MP4S.
Appreciate 0
      10-20-2020, 02:56 AM   #6
Freakystein
Enlisted Member
17
Rep
35
Posts

Drives: F30 335i
Join Date: Jun 2020
Location: Malaysia

iTrader: (0)

Quote:
Originally Posted by Watsey View Post
That's a nice setup, although personally I found the H&R bars to be too stiff with Ohlins R&T and am replacing them with Eibach units - the rear is already in and the front is being done in a couple of weeks' time along with SuperPro rear subframe poly bushes.

Interested in whether you noticed any significant changes/benefits by replacing the diff bushes with poly units.
I'm also feeling H&R is a bit too stiff for the rear with Ohlins, feel that the rear is a bit twitchy. What are you looking to replace with? Stock?
Appreciate 0
      10-20-2020, 11:35 AM   #7
zole2112
Modder of everything I own
zole2112's Avatar
147
Rep
491
Posts

Drives: 2013 335i Xdrive
Join Date: Mar 2017
Location: Appleton, WI

iTrader: (0)

If your suspension is like mine (2013 335 xi F30) and if you have access to a lift the rear sway bar, which should be the same as my xdrive, is really easy. I added some Powerflex bushing inserts when I dropped the rear subframe. I don't know about your front swaybar but the front on my xdrive is pretty easy as well. I supported the engine from below and lowered the front subframe (didn't have to drop it completely) and it was fairly easy to change out. I followed the instructions for the Dinan sway bars.
__________________
2013 BMW 335xi F30 N55 PWG/VRSF DP/ER CP/Injen CAI/AA FMIC/JB4 map 7/Fuel= E50 w/ E85:93oct/Stock LPFP & HPFP/CATuned coilovers/Megan Racing Rear Swaybar/Powerflex Rear Subframe Bushing Inserts/Dual aFe Power Mach Force Mufflers/Resonator Delete/MHD & BMS Race BEF
Appreciate 0
      10-20-2020, 12:16 PM   #8
Watsey
Major General
United Kingdom
6379
Rep
8,467
Posts

Drives: F31 330D sDrive M Sport
Join Date: Jun 2015
Location: On sabbatical.

iTrader: (1)

Quote:
Originally Posted by Freakystein View Post
I'm also feeling H&R is a bit too stiff for the rear with Ohlins, feel that the rear is a bit twitchy. What are you looking to replace with? Stock?
Eibach front (28mm hollow) and rear (16mm solid).

As per my previous post, what are your thoughts about poly bushes for the diff ?
__________________
Current : F31 330sD, remapped, Ohlins Road & Track, Millway camber plates, Quaife LSD, Stoptech brakes + Pagid RSL1 pads all round, Weichers front strut brace, Eibach front & rear anti-roll bars, Michelin MP4S.
Appreciate 0
      10-21-2020, 07:50 AM   #9
Freakystein
Enlisted Member
17
Rep
35
Posts

Drives: F30 335i
Join Date: Jun 2020
Location: Malaysia

iTrader: (0)

Quote:
Originally Posted by Watsey View Post
Eibach front (28mm hollow) and rear (16mm solid).

As per my previous post, what are your thoughts about poly bushes for the diff ?
All my bushes are still stock at this moment. Not sure i'm gonna change to Poly at the moment as i feel it's still feel fine for me. Will see how it goes if need changing down the road.

I'm trying to stick with the H&R at this point, changing the sways is a lot off effort on the F30.I'll be slowly adjusting the stiffness and see how it rides, currently am on 10 Front 12 Rear, feels pretty good. On the firm side and not crashy, unless the roads are very very bad..
Appreciate 0
      10-21-2020, 07:53 AM   #10
Freakystein
Enlisted Member
17
Rep
35
Posts

Drives: F30 335i
Join Date: Jun 2020
Location: Malaysia

iTrader: (0)

Quote:
Originally Posted by zole2112 View Post
If your suspension is like mine (2013 335 xi F30) and if you have access to a lift the rear sway bar, which should be the same as my xdrive, is really easy. I added some Powerflex bushing inserts when I dropped the rear subframe. I don't know about your front swaybar but the front on my xdrive is pretty easy as well. I supported the engine from below and lowered the front subframe (didn't have to drop it completely) and it was fairly easy to change out. I followed the instructions for the Dinan sway bars.
How do you feel about the powerflex bushing? I'm still sticking to stock at the moment and see how it goes..
Appreciate 0
      10-21-2020, 08:31 AM   #11
Watsey
Major General
United Kingdom
6379
Rep
8,467
Posts

Drives: F31 330D sDrive M Sport
Join Date: Jun 2015
Location: On sabbatical.

iTrader: (1)

Quote:
Originally Posted by Freakystein View Post
All my bushes are still stock at this moment. Not sure i'm gonna change to Poly at the moment as i feel it's still feel fine for me. Will see how it goes if need changing down the road.

I'm trying to stick with the H&R at this point, changing the sways is a lot off effort on the F30.I'll be slowly adjusting the stiffness and see how it rides, currently am on 10 Front 12 Rear, feels pretty good. On the firm side and not crashy, unless the roads are very very bad..
Sorry, the question regarding the diff bushes was intended to be directed to Jahjaman
__________________
Current : F31 330sD, remapped, Ohlins Road & Track, Millway camber plates, Quaife LSD, Stoptech brakes + Pagid RSL1 pads all round, Weichers front strut brace, Eibach front & rear anti-roll bars, Michelin MP4S.
Appreciate 0
      10-22-2020, 07:44 AM   #12
CrushJelly
Private First Class
102
Rep
128
Posts

Drives: M140i
Join Date: Dec 2016
Location: Australia

iTrader: (0)

Quote:
Originally Posted by Watsey View Post
Sorry, the question regarding the diff bushes was intended to be directed to Jahjaman
I did the subframe and diff bushes together.

Subframe bushes made a material difference to NVH, but also really tightened up the rear end under power. Noticeably better traction.

The diff bushes I'm pretty sure just added NVH without much else that I could notice.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 05:33 AM.




f30post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST