DIY - Budget BBK with G Series front and X5M Rear

[djrafacz]

Just feel like someone will be able to benefit off of this as a write up for everything that was involved in my G series front big brake upgrade / rear X5M upgrade.

FRONT

We can effectively either use the 348 or 395 G series front calipers on our cars. I opted for 395 since I will eventually put 22 inch wheels on and wanted it to fill out the wheel more and really why not?

I have an sDrive35i (332 rotors) and noticed that if I did multiple 80 MPH to 0 MPH stops within a couple of minutes, my brakes always felt like they couldn't handle it. So I read about the G series upgrade but there are no posts I can find with anyone's full experience and cost of doing this. So I will break it down for how I did it and what parts were ordered and what things I would change if I had to do it again.

CALIPERS

I started scouring eBay for any suitable calipers I could find. Since it is on a budget, I took my time to find cheap calipers. 395 calipers come on a bunch of G series cars. My search consisted of searching by vehicle type over part number. This part gets a bit confusing. There are multiple part numbers for what are seemingly the same caliper. There are also Alpina / Rolls Royce calipers which look the same.

Front Right (NON X): 34106891336 or 34106883410
Front Left (NON X): 34106891335 or 34106883409

Front Right (X Variant): 34106891328
Front Left (X Variant): 34106891327

They come from either 7 Series G11 or G12 OR 8 Series G14, G15, or G16.
The X Variant for each are from a X3M, X4M, X5, X6, or X7.

The only difference I was able to find through my search between them is the X series calipers say MX in the casting on the back, while the others do not. Does it make a difference? I am not entirely sure. Funnily enough I bought 2 separate calipers on eBay and one was from a M850i and the other was a X series car and that is what I installed, they are slightly different in color. If I were to do it again, I would probably hold out and buy a pair so they are matched to each other.



An easy identifying factor for these calipers is two things, both can be spotted if the seller takes good pictures.

First are the markings on the back of the caliper. Since I am going for the 395 caliper, this is what I was looking for.

4x40-44/395/36 and look like this.



Second is the spacing of the pins. These calipers are cast for 3 different spacings. 395 have the widest pin spacing if you look at the caliper. There are 2 indentations and the 3rd is a hole. This helped me identify by quickly judging pictures on posts when verifying if they will fit. KEEP IN MIND, WIDEST PIN DOESN'T NECESSARILY MEAN 395. IT COULD BE A 374 CALIPER AS WELL.



I received my calipers in different damaged conditions. One had paint missing like a wrong wheel was mounted and it ground away a bunch of paint on the inside half of the caliper. The other had some sizable dents and dings on it. Functionally they looked okay with no pinched hard lines, pistons looked okay, no punctured seals, etc. I took the gamble, did no refinishing work (why would I rebuild a 5 year old caliper? Other than peace of mind), and simply bolted them on in whatever state they were in. They are slightly different colors (probably because they came from different year cars OR because of the MX vs NON X caliper designation / different part numbers), but they are on opposite sides of the car so you never see both at the same time. If I want to revisit and powder coat / refinish in the future I can. I am fine with the way that they are.

BRAKE CALIPER HARDWARE

The used calipers I received were naked. No pins / no pads / no springs.
I ended up buying some eBay kit with pins and a spring. The pins you need are part number 34116872572. You need 2 per caliper, so 4 in total. The spring I received with my kit did not work (too short for the caliper spacing) but my new pads came with a new spring. If you need the spring it is part number 34116872573.

ROTORS

The only suitable options are either E70 X5M / E71 X6M or F85 X5M / F86 X6M.

E70 X5M
Front Right: 34116789070
Front Left: 34116789069

F85 X5M
Front Right: 34112284902
Front Left: 34112284901

The main difference between them is mostly top hat design. F85/F86 has aluminum top hats IF YOU BUY OEM, some aftermarket just have the design but the top hat is not aluminum. They are all directional 395x36 rotors. I found many options on the web for this, for either model car with a large variance in price. Since this is a budget big brake kit, E70 are the cheaper choice overall but are heavier.

Brand wise I really only had 2 options. Either buy a reputable brand I know of or try something new. I went with something new due to the price.

I would have gone with Zimmerman E Coat from FCP euro, but ended up buying Dynamic Friction Company (DFC) blank (not drilled or slotted) coated rotors from RockAuto.

Front Right: 60431147D
Front Left: 60431146D

BRAKE PADS

Really any 1868 / D1868 pad will work. Due to good reviews, I just went with Power Stop Z23 pads. Z23-1868 on Amazon. I opted to go for the Z23 due to various sources saying the Z16 ones were basically worthless. THESE PADS CLICK WHEN CHANGING DIRECTION (MOVING FORWARD TO REVERSE AND VICE VERSA). I read the reviews and there is something about the spacing of these pads or something, but they will pop once every morning when I just start driving. I have read that stock pads are “glued” to the pistons to prevent this. I might revisit it in the future.

BRAKE PAD WEAR SENSOR

Stock F15 brake pad wear sensors work fine. I needed mine fast so I just picked up cheap Chinese Amazon front and rear wear sensors. FYI the “sensors” are just two wires that have continuity. Once the rotor grinds the plastic away and breaks the connection, the warning light comes up on the dash. No reason to spend any extra money for a reputable brand on this IMO.

BRAKE SHIELDS

Keep the stock shields on your car. You will need to trim them or trim and bend them to make them fit. I did the latter.

BRAKE LINES

Stock lines will reach since the port is at the top of the caliper.

BRAKE FLUID

I had some Pentosin DOT 4 LV laying around. Almost any DOT 4 fluid will work.

WASHERS AND BOLTS

You WILL need to space the caliper out. There is absolutely no way these will bolt up otherwise as the caliper will be wedged against the rotor. From my calculations you need between 4.5 to 7.5mm of space. I grabbed some M12 washers from my local hardware store and measured it out. 2 washers ended up being 4.8MM and 3 were 7.2MM. I ended up using 2 per bolt as a test.
By my calculations, the best thing would be spacers / washers with the following dimensions. 30MM OD X 13MM ID X 6MM THICKNESS. Belmetric has some of these I ordered after testing in two different flavors. WC12x30CLZ or WC12X30SS. 1 Per Bolt x 4 Bolts.

I replaced mine with the above 6MM thick washers. I think it would be best to buy some slightly longer bolts. The stock bolt is M12x1.5x43MM, so with the 6mm of washer, you need M12x1.5x49MM.
I tried a M12x1.5 55MM bolt from an E60 Hub, but it made contact with the rotor.

I did poke around with a pick and it has maybe 1-2 mm of thread missing. I am going to keep the stock bolt for now.


FRONT COST BREAKDOWN
Slightly damaged Front Right Caliper: $163.50
Slightly damaged Front Left Caliper: $283.40
Brake Caliper Hardware Kit: $16.35
DFC Front Right Rotor: $119.81
DFC Front Left Rotor: $127.81
Brake Pads: $77.26
Brake Pad Wear Sensors (Front and Rear): $10.45
Brake Lines: $0
Brake Shields: $0
Brake Fluid: $0
Washers: $16.05
Bolts: $0

All prices are after tax and shipping to me.

FRONT TOTAL: $814.63

REAR

Rear Brake Upgrade has been covered before and it's pretty self explanatory. This will let you run 385 mm rear brake discs and bigger pads. It’s almost a complete bolt on solution.

CALIPERS

Rear brake calipers are from an E70 or F85 X5M. Part numbers are as follows.
Rear Right: Caliper 34217847228 / Carrier 34217847226
Rear Left: Caliper 34217847227 / Carrier 34217847226

These are available on eBay. Although most go for around $200 each shipped. I held out until I found a good deal on car-part. Sadly, they came black, which already doesn’t match the unmatched fronts.

ROTORS

I tried the Dynamic Friction disks in the front, why not get them for the back?

The only suitable options are either E70 X5M / E71 X6M or F85 X5M / F86 X6M.

E70 X5M
Rear Rotor (non-directional): 34216795318 (x2)

F85 X5M
Rear Right: 34212284904
Rear Left: 34212284903

Same deal here. F85 ones have aluminum top hats and are directional. Since this is a budget big brake kit, the E70 is cheaper.

Dynamic Friction coated rotors from RockAuto.
Rear: 60431148 (x2)

BRAKE PADS

I also matched these to the front. Power Stop Z23-919B. These won’t click like the fronts because it's a single piston caliper.

BRAKE PAD WEAR SENSOR

The kit I ordered on Amazon had both. Non-oem cheap sensors.

BRAKE SHIELDS

Keep the stock shields on your car. You will need to trim them.

BRAKE LINES

Stock lines kept.

BOLTS

Stock bolts.

REAR COST BREAKDOWN
Rear Right Caliper: $87.65
Rear Left Caliper: $87.65
DFC Rear Rotor (x2): $178.29
Brake Pads: $58.62
Brake Pad Wear Sensor (came with front): $0.00
Brake Lines: $0
Brake Shields: $0
Bolts: $0

All prices are after tax and shipping to me.

REAR TOTAL: $412.21

GRAND TOTAL: $1226.84

[djrafacz]

Now comes the fun part. Mounting them up.

FRONT

Take the wheel off. Take the caliper off. Take the brake rotor off. Clean your hub if you please.

Now remove your shield. 4 10mm bolts hold it on.



I just chose to trim off the small connecting part and then bent the top and bottom of it out of the way. You can trim the top and bottom if you please as well.



Bolt up the shield and bolt up the rotor.



I would spread your caliper pistons to their fullest extent at this point. You can swap your lines over at this point as well. Now you need to prepare the bolts. It will go Bolt | Knuckle | Washer | Caliper. It's a little tricky. Finally bolted up!



Install the pads, try to line up the “hooks” with the caliper holes.



Place the spring between the pads, hold it with one hand and install pin 1. It should slide most of the way in and leave just a nub at the end. Flex the spring with one hand and install pin 2, it should slide most of the way in and just leave the nub. Hammer it the rest of the way in.
Pins go in from the back. It goes Caliper | Pad | Spring | Pad | Caliper.



DONE!


REAR

Retract your parking brake with any tool of your liking. I had BimmerLink handy so that is what I used.
Unbolt your wheel. Take off your caliper. Take off the rotor. Time to trim the shield.
I flattened some sections and cut off the rest. Basically the lip has to come off. It bolted between the hub and knuckle, so cut it on the car.



Bolt up your rotor.



Install the caliper, reuse your old bolts.

Bleed your brakes. Rear passenger, rear drivers, front passenger, front driver. We bleed the front outer half first and then the inner half. I had a friend with a power bleeder help with this.

REAR IS DONE TOO!

[djrafacz]

Key Takeaways.

I instantly noticed a difference when backing out of the garage. The brakes just felt better, not bite wise but like it wasn’t such a struggle to stop. I can’t explain it any other way. I bedded the brakes and everything seems fine. The brake pads clicking / clunking once every time I move still bothers me.

The steering feels heavier. Obviously there is a lot more rotating mass, and I was surprised I felt it right away. It's not unwelcoming, just different. It weirdly feels more planted now? I do miss being able to flick the wheel one way and it basically turn itself.

Fuel economy has changed, whether that is me being more confident in stopping and having a heavier food, or the rotating mass. I went from approx. 17 mpg to 16.2 mpg after about a month.

Stopping power is completely noticeable, I can’t believe 332 rotors and single piston calipers were put on my car in the first place. Absolutely night and day difference for me.

I couldn’t see myself spending the money for a 4 pot rear. My 2015 X5 sDrive35i had 158k miles. Full of dents and dings. Plenty of other issues for me to spend my money on (leaky oil pan, trans service, engine mounts, etc).

I haven’t coded the MBPK to the VO, might have to after I finish up any other stuff I have planned.

[_ObiJon]

You had better prices than what I paid for my 50i calipers from eBay. Great DIY. Any pictures with the wheels on?

[crystalworks]

djrafacz Thank you for your efforts and documentation.

[tlow98]

Given the differing piston sizes, what did their change the brake bias to front/rear?

Nice, innovative. I like it.

[djrafacz]

_ObiJon Here is a pic! It took me months to find these calipers so I guess there's a different price to pay.



tlow98 Honestly, I do not know enough about brake bias feeling to answer how it feels front to back. It overall brakes a lot better than it did, which is good for me!

Next step: I heard through the grapevine that my stock 18" spare will fit with a big enough spacer. I guess I will find out eventually!

[Straddle55]

Great info and write-up!

F11 rotors are a no go? I don't want to hijack your thread, but I was wondering if the non-painted (even cheaper) F11 374mm rotor calipers would be able to swap. Any rotors that properly fit an F15 with those calipers?

https://f10.5post.com/forums/showthread.php?t=2075568

[djrafacz]

Straddle55 I think finding a suitable rotor would be the issue. Closest F15 /E70 rotor is 365 which is not big enough IMO. There are 374x36mm rotors that are 5x120 but I am not sure if the hub bore would work, most applicable cars have 72.6mm hubs and not 74.1mm like the X5/X6 platform.

If a suitable rotor is found, the 374 calipers are noticeably cheaper. I'm not sure what you would run for the rear, maybe a 345?

[Straddle55]

Thanks, yeah I figured but I thought I'd ask. Hub bore, rotor hat offset etc.