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      11-26-2018, 05:27 AM   #79
Bozman52
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Drives: 2015 M5
Join Date: Nov 2017
Location: Cambridge

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. . . so I'm still looking into brake mods for my 530d.

One thing that I hadn’t researched much up to this point was tangible evidence of the actual improvement these brake mods make, so I started looking into braking distances. The 550i has the larger front and rear rotors that would be an easy upgrade for my 530d, so I pulled up 550i braking distances. As I can’t get figures on an F10 with X5M calipers, I figured the M5 would be a decent comparator to judge what slapping on some Brembo multi-piston calipers would do. Here’s what I’ve found for 60-0mph braking distances:

530d- 118ft (http://www.zeperfs.com/en/fiche4317-bmw-530-d.htm)
550i- 116ft (MotorTrend)
M5- 110ft (MotorTrend)
M5- 113ft (http://www.zeperfs.com/en/fiche3969-bmw-m5.htm)

The short story is that there isn’t nearly as much difference as I’d expected. I appreciate that these braking numbers will have been done at different outside temperatures, on different track surfaces, with different tires, etc. Nonetheless, I really expected the M5 to stop a LOT quicker than the numbers I’m finding. Given that the mod I’m looking at would put 550i calipers/rotors on the rear and 4-piston X5M calipers/rotors on the front, I’d expect to see an improvement somewhere between the 550i and M5 numbers.

After seeing these numbers, I’m having a hard time justifying spending $1,200-1,500 on this brake upgrade just to shorten my stopping distance by a couple feet. Moreover, the X5M upgrade will add 7kg per front wheel to my car (and 2-3kg per rear wheel), so I’ll have to sacrifice some acceleration. Other than the obvious cosmetic improvement, I just can’t see why this would be a valuable upgrade to my 530d. I could put a full set of KW coilovers on the car for this kind of money, which would be a much more noticeable improvement!

I’m happy for dissenting opinions, as deep down, I totally want to do the X5M brake conversion . . .
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