Rubber support for rear axle options

[tomphot]

I’m going to overhaul my rear suspension now that I’ve completed the front (with mostly rubber).  It looks like there are 2 options for the rubber support for the axle.

33331103926 - https://www.wallothnesch.com/en/rubber-support-for-rear-axle-fits-for-left-and-right-and-for-all-models-and-years-of-manufacturing-33-18-09.html

33333400444 - https://www.wallothnesch.com/en/rubber-support-motorsport-version-solid-rubber-unit-fits-for-left-and-right-and-for-all-models-33-18-09.html

 

What are the differences between these?

Street use, not the track.

[modernbeat]

Looks like the street version has voids in the rubber bushing to provide the most isolation.

The version made by motorsport do not have the voids, and the bushing is solid for a little more stability and less isolation.

[Conserv]

You’re close to my age, Tom. I wouldn’t give the solid mounts a second thought. The OEM mounts are plenty firm for me. Forty years ago? I probably would’ve jumped on the solid mounts!
 

Your decision!

 

Best regards,

 

Steve

 

Edited May 9, 2020 by Conserv

[Buckeye]

45 minutes ago, Conserv said:

You’re close to my age. 

I am over 60 and know you get to have a loose END after 60,  but I know OEM mounts help a lot while driving

[tomphot]

Thanks guys, Full disclosure..... the unused solid mount was in the large parts stash that I got with the purchase of the car (Steve saw the boxes).  So I’m wondering how much do those 2 mounts effect the ride?  I’ve kept everything else rubber.  Is it worth buying the stock mounts for an old man ride?

[Conserv]

25 minutes ago, tomphot said:

... Is it worth buying the stock mounts for an old man ride?

 

There was a reason the factory used the slotted style from 1966-1977: it was a reasonable compromise.... ?

The factory never offered a “hard as rock” option. Just reciting history here... ?

 

Best regards,

 

Steve

 

Edited May 9, 2020 by Conserv

[iinca]

OE ftw! The hard mounts are for forum heros, bench racers and people with tight colons....

Edited May 10, 2020 by iinca

[AceAndrew]

I feel like a broken record saying this again... but, the rubber mount stiffness in the OEM mounts (like what w&n supply) CHANGED along with a part number change around 2015-ish.  Somebody at BMW screwed up on the newer ones and made them roughly 20% SOFTER than the “original” rubber mounts.  I had both on hand at the time and did a number of tests.  Wet noodles come to mind. As last checked a couple months ago, these are still the ones being sold.  

 

I get a good chuckle on the “stock rubber is the way to go” comes out in regard to subframe mounts.  If you even want close to what the original bmw 2002 engineers intended, then you need to be adding urethane stiffeners (or simply full rubber, like w&n).  Otherwise your 2002 is a little closer to being Boaty McBoatface, rather than the ultimate driving machine.

Edited May 10, 2020 by AceAndrew

[Conserv]

5 hours ago, AceAndrew said:

I feel like a broken record saying this again... but, the rubber mount stiffness in the OEM mounts (like what w&n supply) CHANGED along with a part number change around 2015-ish.  Somebody at BMW screwed up on the newer ones and made them roughly 20% SOFTER than the “original” rubber mounts.  I had both on hand at the time and did a number of tests.  Wet noodles come to mind. As last checked a couple months ago, these are still the ones being sold.  

 

I get a good chuckle on the “stock rubber is the way to go” comes out in regard to subframe mounts.  If you even want close to what the original bmw 2002 engineers intended, then you need to be adding urethane stiffeners (or simply full rubber, like w&n).  Otherwise your 2002 is a little closer to being Boaty McBoatface, rather than the ultimate driving machine.

I’m sorry, Andrew, but this is the first time I’ve heard you say this!

 

And are the units sold by W&N from the same manufacturer that BMW uses?

 

I will admit that my ‘76’s “new” mounts — pre-installation photos below — are NOS pieces I purchased from the dealer in 1983 (and they are the NLA “square taillight versions” that are handed, in that each rubber insert is “clocked” 45 degrees from “fore-aft”). The left unit appears to have a 1982 (“82”) date.

 

Part numbers:

33331113342 Left (casting number = 33331112591)

33331113343 Right (casting number = 33331112592)

 

Regards,

 

Steve

 

Edited May 10, 2020 by Conserv

[tomphot]

8 hours ago, AceAndrew said:

I feel like a broken record saying this again... but, the rubber mount stiffness in the OEM mounts (like what w&n supply) CHANGED along with a part number change around 2015-ish.  Somebody at BMW screwed up on the newer ones and made them roughly 20% SOFTER than the “original” rubber mounts.  I had both on hand at the time and did a number of tests.  Wet noodles come to mind. As last checked a couple months ago, these are still the ones being sold.  

 

I get a good chuckle on the “stock rubber is the way to go” comes out in regard to subframe mounts.  If you even want close to what the original bmw 2002 engineers intended, then you need to be adding urethane stiffeners (or simply full rubber, like w&n).  Otherwise your 2002 is a little closer to being Boaty McBoatface, rather than the ultimate driving machine.

 

Thanks, is this what your referring to?  So it's filling the gaps of the mounts and making the mount solid?

 

[iinca]

so everyone should be running solid poly subframe mounts? you mean the kind that transmit so much NVH  from your drivetrain that your colon has a good chance of exploding after 100 miles of high speed driving?....

 

is there anything in between exploding colon and boaty Mc Boatface?

 

Mine are current OE stock  and my rear end feels well planted. It's subjective....racer types want 

stiff and the other 99.9% of the world wants comfy/firm enough...

 

 

 

 

Edited May 10, 2020 by iinca

[TobyB]

Quote

 Somebody at BMW screwed up on the newer ones and made them roughly 20% SOFTER than the “original” rubber mounts.

 

I doubt BMW made them- they have a history of 'third partying' parts for the 'archive' cars...

 

As to the rear subframe mount affecting your colon, however, it doesn't do that.

The springs and shocks do, and the bushings are along for the NVH ride.

The problem with Andrew's floppy noodle bushing is that they'll allow the rear of the

car to steer itself, and from a driver's perspective, that sucks.  Tiny amounts of rear

toe change are perceptible to the average driver-

"It feels like it's going to spin out"

and if the rear subframe moves longitudinally on one side and not the other 

"The rear end steers itself when I hit bumps"

The one place I use low- deflection bushings in a street car is the trailing arm,

but then I fill the voids in the stock rubber subframe bushing, too.  It makes a big

difference for a very small NVH cost.

 

You can see it in the pictures Steve provided- as BMW realized they were

selling cars based on their 'sporty' appeal, they stiffened the bushings,

and then redesigned them to locate the subframe a lot more precisely.

 

t

 

 

[AceAndrew]

Toby, I suspect you are right in regards to an outside supplier.  

 

iinca, the back-to-what-bmw-intended recipe at this current time is to run the urethane inserts (or all rubber w&n mounts, which functionally do the same thing).  It is NOT like running straight polyurethane, which as you note, isn't great if you like your colon. 

 

Tomphot, yes those.  Also sold by Ireland Engineering.

https://www.iemotorsport.com/product/rear-subframe-mount-inserts-bushing-stiffeners/

 

To recap for posterity and simplicity...

 

BMW 2002 REAR SUBFRAME MOUNTS (stiffness levels 1-6)

 

1) BMW (and w&N) current stock mounts: Softer than original, Boaty McBoatface.

2) BMW (and w&n) current stock mounts w/ urethane stiffeners ( IE, Blunt, etc.). Also, poured-rubber.:  Closest match to BMW's original stiffness.

3) BMW NOS pre-2015 stock mounts w/ urethane stiffeners:  Slight stiffer than original, gives a great sporty feel without splitting your colon.

4) IE/other Urethane Subframe Mounts (roughly 80a durometer):  Definitely stiff, still streetable, but caters more towards dual-use cars and those so inclined.

5) AKG/Condor UMHW/Delrin/(95a/75d urethane):  While the 95a-specifically is labeled as "street friendly" you are getting up there.  These are all basically "solid" mounts with a tiny bit more give.  Generally not for street use, unless you are driving to the track.  Exception is maybe the high school kid who wants a race car for the street (we were all there once!).

6) IE SOLID mounts...I think Massive made some at one point as well:  These are a gutted stock mount with welded plates on either end. Basically, a straight metal/metal mount.  Race use only.

 

 

[iinca]

I was thinking the poured rubber option before you mentioned them. who sells that or is that DIY?

 

I was also considering making 'gel filled' control arms with my spare pair...box them in and fill with

magic hardening goo..

[kbmb02]

5 minutes ago, iinca said:

I was also considering making 'gel filled' control arms with my spare pair...box them in and fill with

magic hardening goo..

 

To make them heavier?