Quote:
Originally Posted by bbnks2
I've seen plenty of people (including my own steering wheel) say 2.9 turns. I also see a lot of 2.7 numbers. The 15.3:1 and 2.5 turns is probably from European cars with EPS (variable electronic rack) . 1M is put at 2.2 turns. I think it's more like 2.3-2.4 for a 135i with a 1M/M3 rack swap so sorry for saying 2.5... Gotta remember that suspension kinematics differ slightly between these cars as well.
Regardless, steering ratio is just the relationship between steering wheel input and resulting steering angle at the wheel. Modified suspensions and wheels change this relationship and not all makes and models of cars have the same range of steering angle to cover. Wheelbase, track width, and suspension kinematics need consideration also if you want to compare car-to-car. The rack ratio itself doesn't mean much if you still need to do k-turns to turn your car. 30* of steering in a Porsche can produce significantly tighter actual turning radius than 30* of steering on a BMW. Believe it or not, Porsche cars generally have significantly shorter wheel bases than BMW's. 97." wheelbase vs 105" wheelbase...
On a track the M3 rack makes a difference too. You go from crossing arms in tight turns to only needing half as much movement. Is it a NEEDED mod to get a round a track? No. But, it's a welcomed difference.
On a side note, I killed my stock rack at 70k miles and now the replacement M3 rack is also leaking fluid at 115k miles. Anyone else destroying power steering racks? I am not lowered excessively. Around 4" of ground clearance so like .75-1" of lowering maybe.
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I absolutely hear what you're saying. My point was simply that I wouldn't characterize the 135i standard rack as particularly slow. The E46 M3 rack was about the same, and the E36M rack was slower (both longer wheelbases.)
It should also be mentioned that faster ratios aren't necessarily better, depending on usage, due to loosing precision, as well as the so-called "sneeze" factor at high speeds. A rally car, like an STI, makes more sense with a super fast ratio vs. a 911 GT3 RS, which is going to be doing very high speeds on a track. I guess, our BMWs are somewhere in between.
Either way, the M3 rack surely adds "twitchiness" to the 1M, which many love.
If my standard rack goes, I'm not sure which I'd pick.
I'm surprised you've blown two racks already. That does seem a little odd.
