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      03-13-2018, 11:11 AM   #23
Yapakanichi
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Just My 2 Cents...but I Have All Poly Suspension Bushings. It's Stiff Yea. Handling Is Superb. I Would Go That Route. I Mean Hell If You Are Doing That, Get The Diff Bushings Too Since You Gotta Drop The Diff To Access All The Bushings.
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      03-16-2018, 03:50 PM   #24
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Quote:
Originally Posted by GuidoK View Post

Thats not possible from a technical pov imho. But that doesnt automatically means that solid mounts will cause problems.

According to Turner Motorsport's website solid mounts actually reduce mechanical stress on the chassis.

"The stock rubber bushings have serious drawbacks when used hard on the racetrack - they wear out quickly, and the flexible material allows extreme changes in alignment. Switching to solid bushings will eliminate the deflection and flex, keeping the suspension motions in their intended alignment and providing more feedback to the driver. On the E46 M3, solid bushings can help prevent rear subframe failure as the sheetmetal chassis will no longer flex along with the rubber mount.

Excessive movement here transfers to unwanted suspension motions elsewhere and is also a major contributor to failures in the rear floor sheetmetal.

While our Delrin-Aluminum subframe mounts conform to various racing series these all-aluminum mounts are the ultimate in reducing flex and deflection. The rubber stock mounts, and the Delrin mounts to a small degree, flex and deflect as various forces are applied throughout the subframe - on and off throttle loading, cornering on flat surfaces, bumpy surfaces, weight transfer, sticky race tires, etc. Too much flex from worn rubber mounts will transfer to flex where the subframe meets the chassis/floor. This is the primary cause for the infamous rear subframe failure. These fully solid aluminum mounts have absolutely zero flex to them so they will not contribute to rear subframe issues."
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      03-16-2018, 04:09 PM   #25
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Quote:
Originally Posted by ANILE8 View Post
According to Turner Motorsport's website solid mounts actually reduce mechanical stress on the chassis.
But without any physical explanation. Their only real explanation is that they sell stuff that fits in that place,

Their statement that "the sheetmetal chassis will no longer flex along with the rubber mount" is nonsense. The rubber mount only allows the sheetmetal to flex with a force corresponding with the force exerted by the rubber bushing, being the rubber's spring constant or Young's modulus.

Young's modulus for aluminium is about 69GPa, for rubber its somewhere between 0,1 and 0,5 depending on the shore rating.

This is a good example why you shouldnt trust explanations by companies that have a substantial financial gain without going over it by yourself. They're trying to sell. Not to help.
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      03-29-2018, 05:57 AM   #26
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Quote:
Originally Posted by GuidoK View Post
This is a good example why you shouldnt trust explanations by companies that have a substantial financial gain without going over it by yourself. They're trying to sell. Not to help.
The way things are heading with uber highend performance vehicles today is solid mounting.

We are going to have to agree to disagree on this one I think. Is that why the new 2019 Porsche GT2 RS comes stock with solid rose joints and bushings

If you are man enough you will eventually go solid



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      03-29-2018, 06:57 AM   #27
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Quote:
Originally Posted by ANILE8 View Post
The way things are heading with uber highend performance vehicles today is solid mounting.

We are going to have to agree to disagree on this one I think. Is that why the new 2019 Porsche GT2 RS comes stock with solid rose joints and bushings

If you are man enough you will eventually go solid
I fail to see the resemblance from an engineering pov.
The reasoning: "a gt2rs has it too, so it make sense that I have it" makes no sense. Did you make a fatigue study to the parameters of your z4 subframe in relation to the chassis, used materials and acting forces?
I bet bmw have, and so have porsche. Maybe a reason why the porsche is build totally different?
Like I said, first of all the width of the mounting points of the subframe are a key factor in relation to the acting forces on the chassis. This is even without considering the structural build of the chassis itself.

Let me point that out to you for the examples displayed in this topic:

Z4/e46 subframe with mounting width, where the e46 is known for chassis damage resulting from forces coming from the undercarriage:


F80 subframe with mounting width (huge compared to z4):


Porsche 911, even bigger, beefier: part of a massive wide subframe assembly where also the engine and gearbox is fitted in (in the picture only parts of the subframe assembly have been fitted, more is yet to be bolted in):


But you do to your car what makes you happy. But please dont think you have all the engineering parameters covered, because you didnt address a single one. Except that you have to be 'man enough' of course.

In the end it all comes down to how long you want the car to last. If you're fine with a car that will potentially be a technical write off in 20k miles then go ahead, but if you expect any 100k reliability you're taking a risk, especially if you drive it as someone who is 'man enough'
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Last edited by GuidoK; 03-29-2018 at 07:03 AM..
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      03-29-2018, 07:06 AM   #28
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Hahaha, thanks for your concern.

I'll take my chances of ripping my chassis apart and driving over my diff when it falls out and not lose a minute of sleep over it.
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      03-29-2018, 12:04 PM   #29
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      03-29-2018, 05:51 PM   #30
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Just got these from AKG



Poly 75D race use.

Btw, I have to comment on the customer service at AKG, it's bloody FANTASTIC!!
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      03-30-2018, 12:23 PM   #31
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Quote:
Originally Posted by ANILE8 View Post
According to Turner Motorsport's website solid mounts actually reduce mechanical stress on the chassis.
And there in lies your misconception i guess.
Word indeed, hah.
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      03-30-2018, 03:20 PM   #32
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Quote:
Originally Posted by MOTK View Post
Quote:
Originally Posted by ANILE8 View Post
According to Turner Motorsport's website solid mounts actually reduce mechanical stress on the chassis.
And there in lies your misconception i guess.
Word indeed, hah.
Yes, of course you must be right....

Thanks for such a valuable contribution to this topic.

Whatever was I thinking
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      03-30-2018, 05:09 PM   #33
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Sorry, obviously not 'manly' enough.
crack on with it...
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      03-30-2018, 08:25 PM   #34
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Another great how to vid on the whole process.

I'm sure he did a fatigue study to the parameters of his E46 subframe in relation to the chassis before install too



You can do the install with the subframe in the vehicle but I removed it as I am also fitting solid subframe bushings, solid rear upper inner control arm monoball bushings and solid rear trailing arm monoball bushings and it is just easier to drop the entire subframe if you are doing all this. No you do not need a lift, it can easily be done on jack stands.

The E46 platform is notorious for chassis quality issues. Most people have never changed their diff bushings and they are still running the factory rubber OEM type bushings. Does this then mean that the soft OEM rubber bushings caused the structural problems in the E46 chassis that they are experiencing?

I would say, not entirely because the primary issue is with the weak E46 chassis that has a large amount of body flex compared to the Z4M chassis, especially compared to the structural rigidity of the coupe version. Simply blaming chassis damage and cracks on OEM or solid bushings is probably not entirely accurate or realistic. In either case, that is not the main reason people normally install them.
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      03-31-2018, 02:03 AM   #35
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Quote:
Originally Posted by ANILE8 View Post

The E46 platform is notorious for chassis quality issues. Most people have never changed their diff bushings and they are still running the factory rubber OEM type bushings. Does this then mean that the soft OEM rubber bushings caused the structural problems in the E46 chassis that they are experiencing?

I would say, not entirely because the primary issue is with the weak E46 chassis that has a large amount of body flex compared to the Z4M chassis, especially compared to the structural rigidity of the coupe version. Simply blaming chassis damage and cracks on OEM or solid bushings is probably not entirely accurate or realistic.
There's a little voice inside my head telling me that you dont have an engineering degree or any experience on a theoretical level in that field.
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      03-31-2018, 02:16 AM   #36
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Quote:
Originally Posted by GuidoK View Post
There's a little voice inside my head telling me that you dont have an engineering degree or any experience on a theoretical level in that field.
As this thread is for members who are interested in installing solid diff bushings. If you have nothing further to add then I suggest you re-frame from attempting to bully others who disagree with your views.
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      03-31-2018, 02:31 AM   #37
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I'm not bullying you, I'm just seriously questioning your claims.

Above all this one:

Quote:
Originally Posted by ANILE8 View Post
that the factory flexible rubber mounts are responsible for causing the damage in the first place, solid mounts actually reduce mechanical stress.
Because its utter nonsense.

But apparantly you're not interested in gaining any knowledge about material fatigue effects.
And it's not a matter of disagreeing with my views, its a matter of disagreeing with common engineering knowledge. To be precise, its disagreeing with a german guy called August who discovered all this over 150 years ago (so its not even cutting edge stuff, it held its ground in the engineering world for over 150 years.)
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      04-01-2018, 11:54 PM   #38
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Guys, seriously.
Just let him put in the solid diff mounts and report back on results.
I, for one, would be very interested to know.
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      04-04-2018, 12:17 PM   #39
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Internet tough guys over here. Yea let's see what happens...gosh..

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