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Old 03-01-2012, 05:25 AM   #1
dan_1337
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How many of you have subframe reinforcement kits installed?

Just want a gauge of the number of people who track their car, have installed a subframe reinforcement kit in their E46 (or not installed) and how many times a year you would attend a track/motorkhana event.

I can completely understand why you would put one in as a preventative measure but if you don't have it, why haven't you had it installed?

I track a handful of times a year and don't have it installed just because it's a very expensive exercise and I'm just running the risk of having my subframe tear.
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Old 03-01-2012, 06:43 PM   #2
Rob43
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I haven't ordered my E46 Sub Frame reinforcement kit yet, but I figure I'll have one installed (welded in) within the next 3 to 4 weeks.

But,...........my reasons are quite different from yours. Unlike tracking several times a year, I see my chassis going through A LOT of high HP standing starts, for this reason I'm going forward with the install.

If my concern was tracking several times a year like yourself, I would inspect the sub frame to make sure everything looked good. If everything looked good, I would only install AKG Sub Frame bushings & Diff bushings. Very simply stated, a more ridged bushing will rock back & forth MUCH LESS than stock. Much less rocking back & forth translates into a sub frame that will probably Never tare. So if you're tracking & not abusing the chassis with standing starts, I'd say save your dollars & just do the AKG bushings.


AKG Bushings, these are the ones to buy. (IMO)
http://www.akgmotorsport.com/catalog...hp?maincat=e46


Good luck,
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Old 03-01-2012, 08:29 PM   #3
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I disagree. I would absolutely install a subframe reinforcement kit on any non-M E46, as I've seen/heard of far too many ripped subframe floors (even after being repaired by BMW), some such as mine which had ZERO track time at the time of the rip.

Plus, to Rob43...if you're going to install AKG subframe bushings, you already have the subframe out, might as well clean up the area and weld in a reinforcement kit while you're already there.
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Old 03-02-2012, 12:12 AM   #4
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I disagree. I would absolutely install a subframe reinforcement kit on any non-M E46, as I've seen/heard of far too many ripped subframe floors (even after being repaired by BMW), some such as mine which had ZERO track time at the time of the rip.

Plus, to Rob43...if you're going to install AKG subframe bushings, you already have the subframe out, might as well clean up the area and weld in a reinforcement kit while you're already there.

I hear you, and in a perfect world (money not being an issue) I'd agree.

But,....there's a huge price difference between a forum member doing his own sub frame bushing install (to save money), & having a shop do it plus weld in the reinforcement kit. You simply can't assume all E46 sub frames are already ripped, if the OP's sub frame is still in good shape, I'd install the bushings myself & call it a day.

This is my opinion, you of course you have yours; neither one is necessarily right in all situations.


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Old 03-02-2012, 09:46 AM   #5
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Quote:
Originally Posted by Rob43 View Post
I hear you, and in a perfect world (money not being an issue) I'd agree.

But,....there's a huge price difference between a forum member doing his own sub frame bushing install (to save money), & having a shop do it plus weld in the reinforcement kit. You simply can't assume all E46 sub frames are already ripped, if the OP's sub frame is still in good shape, I'd install the bushings myself & call it a day.

This is my opinion, you of course you have yours; neither one is necessarily right in all situations.


Rob
I figure if you are willing to hire a mobile welder and do the prep yourself, it is "only" another few hundred dollars to weld in the kit...which is insurance against having to drop the subframe again to do it when/if it rips. If a shop is doing a subframe bushing install, they might as well go ahead and do the subframe reinforcement while they're at it
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Old 03-04-2012, 11:36 PM   #6
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Thanks for the feedback guys.

I was more looking for numbers on how many guys who track have the reinforcement done due to the well documented fact that our subframes (M or non-M) are weak, and that tracking a car generally puts it under more stress than driving it around on the street - no matter how hard you drive on the street!
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Old 03-05-2012, 08:58 AM   #7
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I've yet to really understand why its of such importance for track vehicles to have the subframe re-inforcement done as opposed to street cars. If you're doing hardcore standing starts, then thats another thing.

From what I understand, the subframe has the most force on it during intense torque changes. Once you are at speed, smooth throttle application is the name of the game, so I'm not really following how track usage puts any more stress on the subframe mounts. Cornering forces are not the reason for the failures.
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Old 03-29-2012, 07:33 PM   #8
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I have the reinforcement kit welded in along with Powerflex yellow subframe bushes, I should've went with black bushes but its too late now. I've tracked my car a few times since I got it and did 4 autoX events, I do however drive my car like it aint mine everyday and I try to enjoy every bit of what its got and thats why I got those installed, plus I knew that E46 subfloor is ripping as it is on normal street driven cars so it was a good preventative measure for me.

Rob pointed out AKG bushes which are very good and I would also recommend then to anyone without a doubt, I have AKG tranny bushes on my car and love them. AKG makes top notch products!!!

jared_wiesner, hard cornering does put alot of stress on the sibframe, now not as much as if the car was drag raced all the time but definitely more stress then a street driven car. You're right that the subframe experiences alot of stress during intense torque changes but a street car doesnt experience those much, how many people drag race their E46 from stop light to stop light??? On the track the force of hard cornering travels through your rear end shocks, sway, control arm bushes all transmit that force into your sunframe bushes and if those are wear and old they'll transmit it to the subfloor which is weak as it is.

Best thing to do would be to get new (stiffer or even solid) subframe bushes along with reinforcement plates as if you put the plates and leave the old weak bushes untouched then you probably didnt change much. BUT , money being the most issue with car owners, second best thing would be to install new sunbframe bushes (as stiff as possible) and make sure all your other bushes are up to date (rsm, rtab,diff bush and most important YOUR SHOCKS )
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Old 07-06-2012, 08:52 PM   #9
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Subframe reinforcement done here. I try to go the track at least once every 2 months.....
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Old 07-06-2012, 11:16 PM   #10
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I've done the reinforcements. I wouldn't rush to ONLY have the reinforcements done. At the same time, if your subframe bushings are old or have a lot of mileage on them...I would do the reinforcement while replacing the bushings. I think solid bushings in this location are the way to go.

The whole problem is you can't really check the bushings unless you remove the subframe.
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Old 07-06-2012, 11:39 PM   #11
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Prior to getting my reinforcements done I had no cracks/tears etc but just wanted to put the matter to rest as I always had that subtle, annoying thought of tears around those "problem" spots. I attended about two track days (2x4hr sessions) here at EC before having my chassis strengthened. Loved the track time and well wanted to continue doing it whenever I could. I understand that occasional track-use is a costly past time but I believe having the reinforcements done is worthwhile.

Just as important though is replacing the old, fatigued bushings. So best to have this done at the same time.
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Old 07-07-2012, 06:20 PM   #12
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I have it. Why risk it? I track about 10x/year.
I'm never selling my car and it's pretty much a track car only. Piece of mind!
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Old 07-08-2012, 01:44 PM   #13
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I waited to have mine done and when taken in to have my TCKline dual set up and corner balanced, they checked and found 3 cracks !

So now I am going to have it done soon, along with bushings, etc.
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