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General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

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Old 09-11-2011, 01:14 PM   #41
XXRUSIANXX
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No but seriously...
I see what you are saying about there not being any real life testing. But with so many aftermarket parts available out there how many are actually fully tested past the intended design and application of the part.

We, as customers, rely on feedback from trial and error of others to know if a part is good or a worthless piece of paper weight that may kill you...

Hence me starting this thread...

You are an engeneer... tell us what you think about the design from what you see. Is it practical?
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Old 09-11-2011, 01:14 PM   #42
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Is that preventative or after the fact?
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Old 09-11-2011, 01:17 PM   #43
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Is that preventative or after the fact?
Don't see why it can't be both...
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Old 09-11-2011, 01:36 PM   #44
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seems like preventative measures rather than a fix for the problem. Once you've had the subframe issue it's already too late. You're going to have to fix it anyways, so what's the point of adding that after the fact?
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Old 09-11-2011, 03:04 PM   #45
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No but seriously...
I see what you are saying about there not being any real life testing. But with so many aftermarket parts available out there how many are actually fully tested past the intended design and application of the part.

We, as customers, rely on feedback from trial and error of others to know if a part is good or a worthless piece of paper weight that may kill you...

Hence me starting this thread...

You are an engeneer... tell us what you think about the design from what you see. Is it practical?
Many aftermarket parts are designed by companies who do not have the R&D budget, the proper technical professional staff or the labs. That rear floor support in my opinion, is a design concept that needs to be validated. How do we know if solves the original problem? Were is the over stress testing to see what failures first? As I said before.....would the device kill someone if it were to breakaway in an accident. Engineering best practices calls for a device of that nature to be welded in and not be made from aluminum. The welded zone would then been stress relieved. For you, the best fix is to cut out the trunk floor and then replace it with BMW's updated part and also apply the structural foam in the trunk pan cavity.

This is why BMW and many other car companies do not recommend changing the engineering intent of the product. Many people think that BMW wants to profit and have exclusive rights on modifying the car. No, it is to prevent law suits and injuring its customers. How many threads have we seen from aftermarket air intakes alone: hydro-locking engines, taking out MAF's and actually reducing power output.

Last edited by Optio; 09-12-2011 at 10:00 PM.
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Old 09-11-2011, 03:12 PM   #46
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No question about it that the BMW fix is the best... but at 3 times the cost or 10 times the labor.
This may be a viable solution to the problem.
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Old 09-11-2011, 03:52 PM   #47
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Many aftermarket parts are designed by companies who do not have the R&D budget, the proper technical professional staff or the labs. That rear floor support in my opinion, is a design concept that needs to be validated. How do we know if solves the original problem? Were is the over stress testing to see what failures first? As I said before.....would the device kill someone if it were to breakaway in an accident. Engineering best practices calls for a device of that nature to be welded in and not be made from aluminum. The welded zone would then been stress relieved. For you, the best fix is to cut out the trunk floor and then replace it with BMW's updated part and also apply the structural foam in the trunk pan cavity.

This is why BMW and many other car companies do recommend changing the engineering intent of the product. Many people think that BMW wants to profit and have exclusive rights on modifying the car. No, it is to prevent law suits and injuring its customers. How many threads have we seen from aftermarket air intakes alone: hydro-locking engines, taking out MAF's and actually reducing power output.
Very good and valid points. However, OP is looking for additional support, not to fix the sub- frame, but as a preventative step (read piece of mind). I would not use this product to fix existing sub-frame issue if it was free nor should anyone.

IMO, as a preventative step the product is nothing more than an additional support. Even if they did not have proper R & D, they are not changing the structural soundness of the original chassis and therefore not changing the original engineering intent.
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Old 09-11-2011, 04:32 PM   #48
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Very good and valid points. However, OP is looking for additional support, not to fix the sub- frame, but as a preventative step (read piece of mind). I would not use this product to fix existing sub-frame issue if it was free nor should anyone.

IMO, as a preventative step the product is nothing more than an additional support. Even if they did not have proper R & D, they are not changing the structural soundness of the original chassis and therefore not changing the original engineering intent.
I tend to agree with you.
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Old 09-11-2011, 07:34 PM   #49
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Very good and valid points. However, OP is looking for additional support, not to fix the sub- frame, but as a preventative step (read piece of mind). I would not use this product to fix existing sub-frame issue if it was free nor should anyone.

IMO, as a preventative step the product is nothing more than an additional support. Even if they did not have proper R & D, they are not changing the structural soundness of the original chassis and therefore not changing the original engineering intent.
The engineering intent has been changed by using the Mason system. For example, side impact deformation dynamics response of the cars body will be different. The risk could be fatal to the occupants. Also, Mason changed the loading vectors from the rear floor to the shock towers.

A lowest cost, possible; preventative measure, is to apply the BMW structural foam in the rear floor cavity.

Last edited by Optio; 09-11-2011 at 07:47 PM.
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Old 09-11-2011, 08:21 PM   #50
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The engineering intent has been changed by using the Mason system. For example, side impact deformation dynamics response of the cars body will be different. The risk could be fatal to the occupants. Also, Mason changed the loading vectors from the rear floor to the shock towers.

A lowest cost, possible; preventative measure, is to apply the BMW structural foam in the rear floor cavity.
Just read the TSB on the epoxy repair.
The TSB only applies to the LR section of the subframe. I guess doing the right side would be the same, but what about the front 2 points?
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Old 09-11-2011, 08:22 PM   #51
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Optio, like I said it's my opinion. There are to many If's to argue. It's a BMW not a Lamborghini. Side impact from a shopping cart, a semi, another BMW?. It's "perceive" peace of mind. You are right in so many levels, but impact analysis is not 100% predictable.
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Old 09-11-2011, 08:29 PM   #52
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I just checked prices on the epoxy. Each corner would cost around $250.
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Old 09-11-2011, 08:35 PM   #53
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Also, Mason changed the loading vectors from the rear floor to the shock towers.
Wouldn't the loading vectors be distributed between the subframe and shock towers, rather then changed to the shock towers?
Correct me if I'm wrong.
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Old 09-11-2011, 09:40 PM   #54
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Wouldn't the loading vectors be distributed between the subframe and shock towers, rather then changed to the shock towers?
Correct me if I'm wrong.
Yes!

But now Mason is applying an additional load to the shock towers for which BMW did not intend. The rear shock towers are designed to support dampening loads from the shocks, rather than loading from the weight of the car. Only BMW has the CAD model for the E46 body and re-engineering the body to understand the FEA would be a best guess. A street car needs a great deal of modifications for racing and the manufacturer is in the best position to perform the mods. I would recommend for you, to search on the net, to find interior photos of E46 M3's that BMW prepared for racing.

I can take any car off the street and destroy it by hard driving.

The epoxy can be applied just to the LR...this is where the Pareto failure occurs. A lower cost structural epoxy is available...search away for it!

Last edited by Optio; 09-11-2011 at 10:07 PM.
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Old 09-11-2011, 10:07 PM   #55
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The epoxy can be applied just to the LR...this is where the Pareto failure occurs.
Not always, I have seen it on the front as well. On an m3 to boot.
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Old 09-11-2011, 11:30 PM   #56
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Not always, I have seen it on the front as well. On an m3 to boot.
You saw the rates that Mason charges $125 to 175 per hour! My company books me out for $295 per hour. I have provided to you, pro bono engineering advice. My ethic stance, above all else, is for the safety of the public. I am not motivated by profit or personal gain. This is why you never hear about engineers on the 6 O'Clock news in any type of corruption or criminal cases. We hear about Bankers, Financiers, CEO's, Doctors, Pastors, School Teachers, Politicians, Police Officers, Accountants, etc, etc. Engineers are driven to the profession for technological pursuit and advancing human knowledge.

Do what you want...but if it was my car, I do not apply aftermarket devices. i have 30 engineering buddies with BMW's and Mini's and not one has experienced a structural failure. Also, none of them abuse the car or track it. When you abuse a street car, expect something to fail that would not typically fail from normal street use. Food for thought, BMW claims that less than 2% of the E46 rear floors have or will fail considering the entire population.
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Old 09-12-2011, 06:33 AM   #57
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You saw the rates that Mason charges $125 to 175 per hour! My company books me out for $295 per hour. I have provided to you, pro bono engineering advice. My ethic stance, above all else, is for the safety of the public. I am not motivated by profit or personal gain. This is why you never hear about engineers on the 6 O'Clock news in any type of corruption or criminal cases. We hear about Bankers, Financiers, CEO's, Doctors, Pastors, School Teachers, Politicians, Police Officers, Accountants, etc, etc. Engineers are driven to the profession for technological pursuit and advancing human knowledge.

Do what you want...but if it was my car, I do not apply aftermarket devices. i have 30 engineering buddies with BMW's and Mini's and not one has experienced a structural failure. Also, none of them abuse the car or track it. When you abuse a street car, expect something to fail that would not typically fail from normal street use. Food for thought, BMW claims that less than 2% of the E46 rear floors have or will fail considering the entire population.
Don't get me wrong, I do appreciate your advice. When I said that I have seen it in the front I did not say it to prove you wrong I am just looking for the best possible solution to the problem.

I think BMW's numbers may be a little(way) scued. I have seen 4 damaged subframes and I haven't inspected anywhere close to 200 cars for damage...not even 50.

But again, thank you for taking your time to drop in give your .02

P.S. Every second I spend time on this forum is pro bono work for me, although my rate is only $105, the idea is the same, that's how this forum goes round.
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Old 09-12-2011, 07:46 AM   #58
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so just a question for you op

youd rather drill 2 holes im guessing 2.5-3 inch in diameter in your car than to properly weld it in to secure it?
then what about the bottom of the bar assembly how does it attach?
does it weld in place?
do you drill out a hole through and attach to the subframe mount?
do you drill holes for mounting points and then bolts through the body?
because if i recall correctly (after replacing my own subframe mounts) that the bolt for those threads into a portion welded to the body.
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Old 09-12-2011, 08:16 AM   #59
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Optio - Rear sub-frame issues are real. If BMW stood by it's engineers there would not have a "safety recall" that cost them a lot of money and therefore there would be no need for aftermarket type of solutions from third party engineering companies.

Like I said before, engineering is not unlike any other profession, everyone does their best at what they are required, including BMW engineers (I take it your are not one). You have gone the extra mile and analyzed this way more than I would have, since you are not going to change anybody's mind on a forum thirsty for modifications and alternate solutions.
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Old 09-12-2011, 08:28 AM   #60
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Don't get me wrong, I do appreciate your advice. When I said that I have seen it in the front I did not say it to prove you wrong I am just looking for the best possible solution to the problem.

I think BMW's numbers may be a little(way) scued. I have seen 4 damaged subframes and I haven't inspected anywhere close to 200 cars for damage...not even 50.

But again, thank you for taking your time to drop in give your .02

P.S. Every second I spend time on this forum is pro bono work for me, although my rate is only $105, the idea is the same, that's how this forum goes round.
Have you considered http://www.turnermotorsport.com/p-91...ment-kit.aspx?
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