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01-28-2019, 06:39 AM | #1 |
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M3/1M Front Control Arms: Not That Good?
Hello,
I've just been told by an experienced mechanics, moreover race driver especially on BMW, that the usual 1M Front Control Arms mod on (in that case) a 135i is not a good one: according to him, it makes the car unsafe and unpleasant to drive. The reason he gives, is that the wheel carriers are different ( 31216793923 vs 31212283435), therefore the suspension overall behaves differently (thus the different arm lengths). He told me, that when steering, the inner wheel would turn waaaaay too much compared to the outer wheel. This could be OK for drifting, but not race driving. What do you guys think? Did you already hear that? Is this simply an alignment issue? |
01-28-2019, 11:29 AM | #2 |
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There are others here with more knowledge on the front end part numbers that can speak to the differences between the two you listed, but I don't think I've ever heard anybody here have a bad review after transitioning to the 1m/m3 arms.
It's a pretty standard upgrade that's been around for years.
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135i - E82.N54 2009 BSM - MHD / xHP / DCI, PR CP & 7.5" Race IC / N55 mid & Borla . . WL RSFI, Koni, Eibach & Dinan CP's, M3 CA's / EBC Red's & Firehawk 500's X1 - E84.N20 2013 MGM - JB4 - The Wife's, now with new turbo & ewg |
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01-28-2019, 01:29 PM | #3 |
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The two parts you are talking about are the M and Non M front spindle. Geometry is sensibly different, but not to the extent you are talking about.
Using M arms is perfectly fine, if you have a problem this is probably a aligment issue. I'm running M arms front with M3/1M steering rack, and the car is fine. |
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01-28-2019, 02:52 PM | #4 | |
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However, the pickup points on the front knuckles are damn near the same. The Knuckles are different but I think it has more to do with the orientation of the strut (Caster) than anything to do with the control arm pickup points. The longer M3 control arm does affect the wheels dynamic range of motion though without a doubt. It probably adds bump steer. I would just argue against it being "unfavorable" or "drift-car" since anyone doing M3 control arms also probably has lower offset wheels and/or spacers which would negate this. The 1M uses the same front knuckles as the 135i but also uses the M3 control arms... If you were still running stock high offset 7.5" wheels with 225 wide tires i'd say maybe it might feels weird (it does when I use my winter wheels), but, with low offset 9" 255/40 up front the car feels better. the other big issue is that you are widening the FRONT track width but not the rear. So, yes, again, could have negative consequences (more playful rear) but not if you understand track width and you also widen the rear to match... or play with spring rates to account for the difference... etc. Last edited by bbnks2; 01-29-2019 at 07:16 AM.. |
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01-29-2019, 01:10 AM | #5 |
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01-29-2019, 07:18 AM | #6 |
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01-29-2019, 10:14 AM | #7 |
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OP is not talking about the M3 FCA upgrade, he's talking about the m3 and non-m front spindles which I've never heard of being upgraded.
M3 FCA are different, there aren't drawbacks to that. |
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01-29-2019, 01:58 PM | #8 | |
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Making the lower control arm longer (M3 control arm) changes how the wheel moves throughout its range of motion (e.g. potentially increasing bumpsteer). A longer control arm will also change the scrub radius (wheels and offsets will determine how this change will "feel" to the driver). Motion ratio will also change (the spring rate will feel "softer"). Whether or not it will be an unfavorable change is difficult to answer as it will depend on other factors and driver preference. Bottom line is that swapping in the M3 knuckle won't change much of anything as the pickup points appear to be similar between both cars. The knuckle varies for other reasons than pickup points of the control arms. As far as his mechanics comments, M3 control arms are not ridiculously longer than stock. This is not a "drift car" mod to increase the control arm length 3 inches per side in order to gain 60* of steering angle lol it's like 1/4" change... I was planning on plotting bump steer along with other suspension kinematics this winter, but, the car is always broken so forget that project. Last edited by bbnks2; 02-13-2019 at 07:39 AM.. |
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01-29-2019, 08:22 PM | #9 |
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I have the full M3 control arm kit front and rear and the only negative is NVH. Tires noise and harshness over bumps is significantly louder. Beyond that the effects are all positive. Steering feel is much better and all looseness is gone from the rear of the car. Handling is way more precise.
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02-05-2019, 05:17 AM | #10 |
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I still think we need a subframe reinforcement plate like the 1M/M3 to reduce the harshness that the ball jointed lower control arms transfer.
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02-06-2019, 04:49 PM | #11 | |
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02-06-2019, 05:58 PM | #12 | |
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https://www.turnermotorsport.com/p-3...2-e9x/?pdk=AwE I purchased this one and now they have an upgraded one as well. I did not purchase the rear ones. |
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02-06-2019, 06:09 PM | #13 |
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Are there aftermarket parts for the 135i that improve handling while also being 'stock' fitting/no negative effects?
BMW performance suspension? |
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02-06-2019, 09:24 PM | #14 | ||
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02-06-2019, 10:45 PM | #15 | |
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I have the front arms and like others noticed an increase in NVH but it's well worth it.
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02-07-2019, 09:14 AM | #16 | |
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Do you think I should buy the rear ones as well? |
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02-07-2019, 11:39 AM | #17 | |
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I think about them occasionally, but, always find some other way to spend the money. PS. If you're still on runflats you'll end up with a pretty harsh ride after the BMWPS & front arms are in.
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02-07-2019, 12:03 PM | #18 |
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The rear guide rods are definitely worth your while to do.
Just look at the none M and M comparison: https://www.hpashop.com/BMW-Rear-Gui...?categoryId=-1 |
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02-07-2019, 04:45 PM | #19 | |
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02-07-2019, 05:55 PM | #20 | |
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02-07-2019, 07:54 PM | #21 | ||
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02-07-2019, 08:55 PM | #22 |
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