Quote:
Originally Posted by dcaron9999
Sorry for dumbing down and hijacking this thread somewhat, but what is which makes the most difference between replacing stock rear guide rods versus rear upper links with M3 equivalents?
I have M3 rear subframe bushings, Quaife LSD with 3.46 final drive, and running Extreme Performance tires. There is a fair bit more torque getting transferred to the suspension arms now especially with stage 2 agressive tune. Perhaps not as much as would be the case with R-comp tires though. Just trying to prevent some bending back there, and toe out during hard accelerations ...
Thanks for any insight ...
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Here is the marketing mumbo-jumbo that tells you you need rear M guide rods and upper links:
"Wanting more control and improved handling from your non-M 1 or 3-Series? This is not only an extremely common handling upgrade, but one of the best upgrades you can do. These M3 control arms are one piece of solid aluminum instead of your factory control arms which are weak sheet-metal. If your BMW has power upgrades or sportier tires the factory arms flex and twist, causing lack of stability and unpredictable handling.
That's where the M3 control arms really shine. They feature a much sturdier design with a sealed monoball bushing that allows the arms to rotate instead of twisting. You can expect much more predicable and precise handling, without losing your ride quality. There are absolutely zero drawbacks to this upgrade."
Analysis:
"best upgrades" - very dubious claim
"weak sheet metal" - absolutely false as my testing has shown
"flex and twist" - misleading. Rubber bushings "flex and twist" but the steel arms themselves to do not flex or twist significantly.
"causing lack of stability and unpredictable handling" - no realistic evidence to this effect. The aluminum arms actually have more compliance than the steel ones (ignoring the bushings). Total compliance is not vastly different between the OE and M parts. I haven't tried them yet but when the placebo effect is removed, I expect the benefit to be subtle. As I have noted, only the guide rod is actually stiffer.
"sealed monoball" - only the guide rod gains a monoball and loses a rubber bushing. The OE upper arm already had one monoball and one rubber bushing.
"arms to rotate instead of twisting" - the implication that the OE steel arms twist is misleading. What actually "twists", which is the same thing as "rotates" is the rubber bushing. Functionally there is no difference.
"zero drawbacks" - aside from the expense, I agree.