Need information about OEM Brakes 650Xi and more...

[Oizon]

Hello forum!

Introduction: I'm trying to find some information about the OEM brakes for BMW 650Xi F13. I've decided to possibly change to an aftermarket brake kit since I need to replace my front rotors and pads. I found a nice kit but I'm not sure if its really worth it. I'd really love to have at least slightly more braking power, less unsprung weight and cooler look with a new kit. I've searched the internet and could find most of the answers so I came here.
P.S. I'm a street driver and don't track my car but I'm planning on adding extra ponies with a tune, exhaust, intake and upgraded intercoolers. Also slightly wider wheels (+10mm front / +20mm rear width) on new forged wheels.

1. I couldn't find any information about rotors and calipers weight for the OEM brakes. So far I only managed to find rotor sizes. If anyone has any solid info please share it with me. Worn out rotors and pads will have less mass but will still give a good reference point if someone managed to weigh them.

2. OEM Caliper piston amount and material. I've talked with the shop support from where I'm planning to buy the brakes kit. They told me that my car uses single piston calipers and that they are made of cast iron. Can anyone confirm that?

3. I have an electronic hand brake. Do I need some special rear calipers when choosing a right brake kit. Same online support told me that I might need some dual rear caliper setup to be able to use my E-handbrake. Or as an alternative I can only upgrade the rotor and leave the factory calipers for rear wheels. Is that all true?

4. I noticed that rear rotors are much smaller than the front ones. And most of the aftermarket kits offer almost same diameter rotors as an upgrade kit. They are only different in thickness. Example: 348x36mm front + 345x24mm rear. Is it worth is going with an increased rotor size for the rear? Will it "unbalance" braking somehow?

5. Came across an internet topic where author pointed out that people ignore the fact that many aftermarket brake kits come with a 4-6 piston calipers (front). He says that to be able to use the full potential of such kit you need to consider or upgrade your master cylinder. It might not have enough fluid pressure to be able to brake properly so to say. My question is: does 650Xi or similar has big enough cylinder or does it need some kind of upgrade in that regard?

I found this awesome brake kit with cross drilled rotors, fixed forged aluminium calipers and aluminium rotor hats. That shop online support says that I will definitely loose unsprung weight but I'm not sure how much exactly or of it's really true. I want just enough braking power so that my wheels can take it without locking up too soon. Bigger rotors + bigger calipers = extra mass which I don't want. Carbon ceramics are out of question because of the price. I want the perfect middle ground. Any tips, answers, personal experiences and suggestions are very much appreciated.
Thanks for reading!

[Walt White Coupe]

Not to rain on your parade, but to me your plan sounds like a lot of dollars, a potential can of worms with many headaches for a very little reward.

[Oizon]

Originally Posted by Walt White Coupe

Not to rain on your parade, but to me your plan sounds like a lot of dollars, a potential can of worms with many headaches for a very little reward.

Hello. I totally understand what you're saying. I've spent some time doing a research about tune and such. Figured the "safe" amount of HP that can be added and went from there. I have a full list of parts that will be changed which I can post here if you want to have a look. I'm not 100% sure how much exactly labor will cost but I'm estimating about 10k$ worth of upgrades and labor if to take brakes into account. I'm planning to add about 150ish HP to get about 600 in total. That price doesn't sound too bad taking in account that you can spend about 8 grands on a competition package on a new (F13) M6 and get about 32hp for that. Also M6 is RWD only which is good for driving for about 3-4 months a year where I live. I hope I won't get too much trouble regarding reliability of the car.

[AndyTiskF06]

One way to go is to source the full M6 brake kit, there are plenty of options on eBay with low mileage car donors. It would be around $1500-$2k for a set of good condition calipers. After that, just buy M6 rotors and good pads, ceramics are great for dry driving, but take a little to heat up.

This is the simplest bolt on option with the most bang for your buck in my opinion. You can also upgrade to stainless steel lines while you're already doing this.

All in you should be under $4k and it will be a nice OEM package that will bolt right on

https://www.ebay.com/itm/33465095685...pid=1282524043

Here's a full set example, I would still get new pads though

[Opie55]

I don't recall too much discussion on here about brake upgrades. You could run some searches and you might find something. So I don't think many here will know details like rotor weights, etc. Keep in mind that factory rotors have aluminum hats. If yours have been replaced with aftermarket, they may not. You can tell by the row of large rivet heads because they are two pieces. You would definitely need rear calibers that can accommodate the e-brake. They are electric motors that spin the pads in and are integral to the caliper. You can see them in the eBay photo posted above. To me, if you don't track, then any actual improvement in braking will not be used 99.999% of the time and what you are really getting is a small cosmetic change for a lot of money. I'd just paint my calipers a cool color and call it a day.

[Opie55]

I also might suggest you try posting or searching in the F-Chassis 5-Series forum. Basically the same set up, and 5 series guys are way more likely to do upgrades like that.

[Oizon]

Originally Posted by AndyTiskF06

One way to go is to source the full M6 brake kit, there are plenty of options on eBay with low mileage car donors. It would be around $1500-$2k for a set of good condition calipers. After that, just buy M6 rotors and good pads, ceramics are great for dry driving, but take a little to heat up.

This is the simplest bolt on option with the most bang for your buck in my opinion. You can also upgrade to stainless steel lines while you're already doing this.

All in you should be under $4k and it will be a nice OEM package that will bolt right on

https://www.ebay.com/itm/33465095685...pid=1282524043

Here's a full set example, I would still get new pads though

Hello. Thanks for this advice. These brakes look pretty good but sadly when I enter my car information in there it then says that these parts don't fit. May be rotors are too big for let's say 18" wheels? I have OEM winter 18" wheels. I'm also surprised that these rotors don't come with aluminium hats. Also thanks for showing me that eBay page btw.

[Oizon]

Originally Posted by Opie55

I don't recall too much discussion on here about brake upgrades. You could run some searches and you might find something. So I don't think many here will know details like rotor weights, etc. Keep in mind that factory rotors have aluminum hats. If yours have been replaced with aftermarket, they may not. You can tell by the row of large rivet heads because they are two pieces. You would definitely need rear calibers that can accommodate the e-brake. They are electric motors that spin the pads in and are integral to the caliper. You can see them in the eBay photo posted above. To me, if you don't track, then any actual improvement in braking will not be used 99.999% of the time and what you are really getting is a small cosmetic change for a lot of money. I'd just paint my calipers a cool color and call it a day.

Yeah I'm still deciding on what to do. I really like the looks of cross drilled rotors. The also seem to offer slight advantage when breaking in wet conditions. But then again tires slide more during same conditions as well so there might not be any benefit in the end. Painting calipers might also be a cheap way to go. And yeah I had a look at that eBay page above. Payed attention to the rear calipers with that black attachment (e brake motor). This M caliper is awfully similar to the stock 650 rear caliper if I'm not mistaken. I wonder if they are actually different or if the M variant is actually any better than stock? Anyways thanks for your tips.

[Opie55]

There's no reason you can't get cross drilled rotors if they are offered by someone as OEM replacements. That's just a direct swap. I personally will stick with original BMW rotors because I like the look of the shiny aluminum rotor hats. In my climate anyway they stay shiny.

[AndyTiskF06]

Originally Posted by Oizon

Hello. Thanks for this advice. These brakes look pretty good but sadly when I enter my car information in there it then says that these parts don't fit. May be rotors are too big for let's say 18" wheels? I have OEM winter 18" wheels. I'm also surprised that these rotors don't come with aluminium hats. Also thanks for showing me that eBay page btw.

eBay will say it wont fit your car, as your car is not an M and their algorithm goes off of stock parts. With that said, the M6 brakes should clear 18 wheels without issue, worse case is you might need a spacer if you're not running BMW spec'd winters. The BMW winter set for the M is an 18" square setup

https://www.shopbmwusa.com/product/6...L-AND-TIRE-SET

So the wheel size shouldn't be an issue

As for the rear calipers, the majority of braking is handled by the front wheels, this is why you will see multi-piston front calipers and single piston rears. Also why the front calipers, pads and rotors tend to cost more over rears.

As someone mentioned if you are looking just for a little more stopping power and cross drilled look on the rotors, look for StopTech rotors to just replace the stocks and get some nice pads. This will improve stopping power a little while not being too harsh or a track set-up. There is a compromise the performance brakes, where if you go to track performance brakes, they don't perform well when they are still cold or in wet conditions, so you will actually see reduced braking performance in day to day driving.

Below is the rotors that I got as replacements for my stock ones. They grip really well and perform better than stock, and I live in New England with lots of rain and snow.

https://www.carid.com/2015-bmw-6-ser...roduct_ab_v3=1

For pads, look at EBC, HAWK or more OEM pads like Textar, Pagid, or Jurid. I ended up going with Jurid, as I couldn't source higher end pads in time.