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Reinforced Subframe EPIC Failure

184K views 175 replies 65 participants last post by  79conman 
#1 ·
This subframe is reinforced with the standard HPF reinforcements...**** :banghead:

Car is at VAC Motorsports atm.










 
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#43 ·
Marcus,

Here is a link to the TMS reinforcement kit. On this page look at the PDF for installation of the kit which shows the top (inside the trunk) work that is needed. I didn't do this. I talked to TC at TC design and he said that if you have very minor cracking, you might not need to do this. But that is on my car that will never see more than 528 HP and no hard launches, since it is for the road track and not the drag strip.

http://www.turnermotorsport.com/BMW-E46-M3/c-87-bmw-reinforcement-kits.aspx

I hope that all works out to your satisfaction concerning the other issue. And I hope to see you at MFest with a car that will finally last.

Take care,
Terry
 
#48 ·
I agree, I wouldn't trust the Mason Engineering bar just because I'm skeptic of it. There's a strong possibility that some of these failures that have the TMS or HPF kit installed were due to bad welds upon installation.

Never the less it is shocking to see how violently it rips and lol at the people who epoxy in their reinforcement kits
 
#54 ·
My kit is welded in, but why "lol at the people who epoxy in their reinforcement kits"?

Benefits to epoxy, that I see:
1) Due to there being more area covered, it's a stronger bond than welding just around the outside of the plate.
2) weather sealed by the epoxy on the inside, so no chance of rusting from the inside out.
3) no chance of weakening the floor by bad welds during install
4) The load of the subframe is spread out over the entire area of the plate instead of just the edges... which should make it less stressful on everything.

The epoxy solution didn't exist when I did my subframe plates, which is why I didn't do it... but it does seem like a better solution to me. What do you see as the downside?
 
#53 ·
1) Strut bar- No, the "Boxed" design as pictured would totally eliminate the need for any type of strut bar.

2) TMS reinforcements- Only if you had preexisting rips/tears & you were attempting to patch them using that kit. If you had no rips/tears, the TMS kit would not be needed.


Good luck,
Rob.
 
#58 ·
yeah, I see what you're saying and you're probably right. I was just hating for no reason I guess, my bad!

Anyways, here's a question for you. The HPF kit is a bit thicker than the TMS right, do you think it's harder to get good fusion to the thin chassis metal this welds up to because of that additional thickness?

Also with those bars welded across from the frame rails, how about doing the same to the front subframe mount points so all four points are as robust as possible.
 
#60 · (Edited)
The front points don't see the same forces. The front points push up as the rear points are pulling done. I also have 5mm plate seam welded in on the underneath floor of the car from one side to the other on the front and rear mounts. This is strong enough for the front mounts and hold the stress of the front mounts pushing up by just distributing the load on a thicker peice of metal across the width of the floor.

Remember the plating I did on the floor was the first bracing I did. That was my version of the HPF/Turner kits. Then I had the whole floor pull done so the brace is version 2. I told people years ago this would happen with the Turner kits after my first experience, but I was laughed at by the masses on here and told I didn't know what I was talking about. I was also told I was basically lieing saying there was M3's in europe that make over 1000hp and now look at what is being posted on this forum. Notice a pattern. Maybe all the the people on here that just disregard what I have said just because I'm not an American might start to listen to some of the bullsh!t I say now without putting it down to all sh!t talk ;)
 
#65 ·
As a result of this thread we took a look at the HPF track car more closely and decided to tie the top side of the subframe mounts to the roll cage in both the HPF track M3 and the HPF drag M3. I'll post up pics on Monday.

Chris.
 
#69 ·
Good to see the forum do work for you with their original intention. Learn from others misfortune ;)
 
#68 ·
I have full boot/trunk space with my brace. It's only a 50mm hump in the floor. Actually it's good cause you can put smaller boxes behind it and it holds them between the back seat and the brace. But if you need to fold the seats down then you can still stick things all the way through with a full opening less 50mm where the brace is.
 
#70 ·
those that dont think epoxy works just dont know what real epoxy is... specialist epoxy for bonding metal has been used for high stress joints all over the aeronautics industry for decades and is now filtering down to motorsport in a big way... show me a car that competed in the latest Dakar rally that uses welds rather than bonding with epoxy and i will be very surprised...

epoxy also absorbs shock better than an weld and does not fatigue... there are places where welding makes more sense than epoxy because of surface area, but for reinforcement plates like the turner ones it really is the best way to do it no two ways about it...
 
#76 ·
Here are some pics before painting to give you a better idea











 
#87 ·
Looks like he's running the battery cable through there.
^^^ This is correct. That's where the factory battery cable runs:thumbup:
 
#91 ·
Hi im new here, and sorry if my writing isn't perfect! :) my m3 has started developing cracks, and I'm going for 02pruv's solution! (thank you 02pruv for nice pictures and info). The work is going to be done this weekend and i have bought steel, the hpf reinforcement kit and all new bushings for subframe, diff and rtabs (akg 75d).

From what i can understand, the subframe is bolted to a threaded block that sits between two layers of sheetmetal(?). To reedistribute the (downward) load from the subframe to the beam welded im the trunk, it looks like be has used long bolts. To accomplish this, do you drill from the underside through the bushing centre to the top, so it is aligned properly, thread from underside, put cylinders over the bolts and weld it to the beam before welding the beam itself?

Thank you so much for any help or thoughts. I have tried searching. :)
 
#92 · (Edited)
Glad it helps you.

What you have written is correct it's a long high tensile bolt and we did drill from the underside of the car through the subframe mounts straight up to line up. The only thing that you might of missed is that it's not just two layers of sheet metal. You have the sheet metal on the underside of the car, the sheet metal on the boot/trunk floor and between that there is a roughly 150mm gap that has a honeycomb style sheet metal section as well. That's why we also cut the boot floor out just underneath where the brace is and the underside of the brace we installed is welded to the top of the honeycomb section and then the boot floor was also welded onto the honeycomb section as well.

Just look closer on this picture and you can see the boot floor is cut out under the brace and underneath is the honeycomb section. You can also make out where we welded the boot floor to the honeycomb section in this picture as well.



Then this picture shows the welding of the brace to the honeycomb section as well.

 
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