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Forced Induction Forum
Discuss supercharging, turbocharging and even nitrous and water injection here.

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Old 05-06-2015, 02:47 PM   #161
mgp333
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Quote:
Originally Posted by Rob43 View Post
The less damage you have, the simpler it becomes. So "IF" you have no damage on the underside (cracking or tearing), no reinforcement plates would be needed with a Bolt Through design.


Rob43
Thanks for the reply!

Gotcha. I read that the front mounts are pushing up instead of pulling down. Is this stress not an issue? Or is this taken care of by full reinforcement of the rear
mounts?
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Old 05-06-2015, 03:08 PM   #162
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Originally Posted by mgp333 View Post
Thanks for the reply!

Gotcha. I read that the front mounts are pushing up instead of pulling down. Is this stress not an issue? Or is this taken care of by full reinforcement of the rear
mounts?
Since the fronts almost never see a failure, it's virtually never an issue. Inspect ALL, but concentrate on the rear.


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Nitrous is a little trickier than boost, but it's not the spray that kills motors, it's STUPIDITY!!
I Know How To Fix The Rear "Bouncing" Problem On Your Cheap Coilovers Like: Jom RL FK SE & RK.
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Old 05-14-2015, 11:30 AM   #163
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So it sounds like a lot of people have claimed to have done this bolt through design but no one has posted any pictures!

Anyway, I'm trying to plan all of this out. The nice thing about this design is that you won't actually have to drop the subframe to have it reinforced right? However, it appears that in order to drill up from underneath one will have to remove the exhaust to get access to that driver side rear subframe mount. And when drilling up through the threads, it seems like one will have to be careful not to drill on the sidewalls of the bushing itself.

I'm still a little worried about the front mounts. I have seen a couple posts and pictures about cracks/failure on the front subframe mounts. I'm just wondering if there is anything additional I should do while I have it in the shop and they are going to town welding everything. Thoughts? 02PRUV mentioned that he seam welded a 5mm plate across the width of the floor for the fronts, but this is unclear to me.
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Old 05-15-2015, 10:53 AM   #164
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If you see failure in the front, it will mos likely be on the passenger side. the front of the subframe is forced upward, while the rear is forced downward, and torsional load will make the effect different left to right also. I went with a bolt through on the front, because my car is a drift car, and pulling the ebrake at 70+ mph puts huge downward stress on the front mounts.

Last edited by ShakotanRon; 05-15-2015 at 10:55 AM.
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Old 05-15-2015, 10:57 AM   #165
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Did you have to delete the rear seat in order to do the bolt through? I'm thinking of doing a bolt through on the front mounts connected to a couple small reinforcement plates so that I can still keep the rear seat. I'd like to brace it along the width of the car but don't see how I can while keeping the seats.

Got a pic?

Last edited by mgp333; 05-15-2015 at 10:59 AM.
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Old 05-16-2015, 06:26 AM   #166
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for anyone looking to do a bolt through, on the front mounts of a 4 door, with the trunk barrier, here are some pictures, of were the bolt is, from the top, its actually quite easy to find. There is a bracket on the vertical portion of the seat pan. basically start the cut an inch to each Side of this bracket, and 2 inches above the bracket. Then peal back and you will see the front mount. Once peeled back, if you choose to cut this rectangle out, as I did, cut about a half inch under the bracket. The bolt in the picture is my hardware, not oem. The oem harware size is m12x1.5 x140mm you will need a longer bolt for bolt through. And if you plan to use an m12 bolt, you will need to drill the threads out. I am using 7/16 right now which is roughly 11mm, because it is what is available to me, I will be upgrading to a 1/2" bolt, aswell as reinforcing the top side, when I take the car down for the engine swap. The rear has already been swapped to 1/2" hardware. I do not think that 1/2 is particularly superior for this purpose, I believe that m12, is sufficient. But again, this is what is available to me on a budget, and once my hp figures grow exponentially, the 1/2" bolts may be beneficial, since these bolts I BELIEVE are beeing placed in shear, with these bolt through modifications, especially, when reinforced, top side with a much stronger material than factory. But truthfully, I would rather place the bolt in shear, and hopefully make that the fail point, rather than my chassis.

The last picture, is my current rear reinforcement, executed by the p.o. it will work for now, but will be redone better when the new engine goes in.

This post has 3 pictures of the top side of the front.
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Old 05-16-2015, 08:31 AM   #167
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This post has 3 pictures of the top side of the front.
It looks like I could only see a brace for the rear. Did you just have a bolt and a washer for the fronts?
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Old 04-26-2016, 05:50 PM   #168
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hey, does anybody in the Atlanta area do this? I would like to get my stuff reinforced before I end up in a stick'd thread lol
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Old 04-26-2016, 05:56 PM   #169
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http://www.m3forum.net/m3forum/showthread.php?t=546116
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Old 09-22-2016, 02:34 PM   #170
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hey guys, I checked my sub frame, and had it checked, I have 56,900 miles on the car. so far no cracks or anything whats so ever

how much would it cost to do preventative maintenance? only curious bc I don't want to have it cracked down the road and pay a lot
im in the nyc area

any advice would be appreciated
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Old 09-22-2016, 03:17 PM   #171
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Originally Posted by BuzzE46 View Post
hey guys, I checked my sub frame, and had it checked, I have 56,900 miles on the car. so far no cracks or anything whats so ever

how much would it cost to do preventative maintenance? only curious bc I don't want to have it cracked down the road and pay a lot
im in the nyc area

any advice would be appreciated

Start reading at post #8, this is one of the best & most cost effective ways to do what you want since you have no current damage.

http://www.bimmerfest.com/forums/sho...d.php?t=920154



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SUMMIT POINT WV 1:24:229 SCCA
(DynoDynamics https:vimeo.com/8486878 Dyno Video)
"Chance Favors The Prepared Mind"

I BUILD SUSPENSIONS (Consult) FROM MILD TO WILD FOR RWD & Xi E46's
Quote:
Originally Posted by RacerX View Post
Nitrous is a little trickier than boost, but it's not the spray that kills motors, it's STUPIDITY!!
I Know How To Fix The Rear "Bouncing" Problem On Your Cheap Coilovers Like: Jom RL FK SE & RK.
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Old 12-06-2016, 09:16 PM   #172
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very interesting thread
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Old 03-25-2017, 07:07 PM   #173
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So some of you may have seen my post in the Mid-Atlantic regional section. I'm looking to get reinforcement plates welded and and looking for a reputable shop to do it in the area. since this seems like the goto subframe thread, I thought I'd post here. Any recommendations?
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