[boyerizm]

Probably a stupid question but is it possible to mount the 4 pot grey Brembos on the rear?

I got an awesome deal on these used but now I'm looking at the price for rear M-Performance 2 Pot calipers and it's ridiculous. Even with the deal I'm probably better off buying the BBK.

I'm wondering if I just picked up 2 more if I could run these on the rear. So basically I'd have the same calipers on all 4 wheels.

[Onizukachan]

I’m guessing you mean the 340s. So why not get 330s for the rear?

[boyerizm]

Originally Posted by Onizukachan

I'm guessing you mean the 340s. So why not get 330s for the rear?

As I gather the 330 rear m sport brakes are the single piston, I think I have the stock 328i single piston (even though it is M Sport Trim) but I can't really imagine there is much of a difference between the two. Maybe I'm wrong.

If you can run 345 in the rear i don't see why you couldn't run 340s. Unless the bolt spacing is different on the calipers…

[Onizukachan]

There is a big difference between the 312/300 ( you have singles up front) and 340/330 in performance. I upgraded to 340/330.


And your last sentence is why… they will not bolt up.

[brigade24]

interesting question...you can't put a 340mm rotor in the back because of the parking brake...but...big but, will a 345mm rotor fit under the 340 caliper if it will bolt (not saying it will) that way you keep you parking brake setup and all is stable in the world.

i went from a single pot to dual pot caliper in the back with the 345 discs...i only really notice a difference at the limit.

[Boostedphil698]

Why not just buy the M Performance BBK from getbmwparts.com? You'll have an OEM BBK.

[Ennoch]

Pretty sure the piston sizes on the front calipers will be way out for them to work on the back, various Impreza owners have mooted the idea over the years after fitting a front BBK and always come up with the same problem. Changing the M/C doesn't really work either as the F/R ratio will still be off.

[boyerizm]

Originally Posted by Onizukachan

There is a big difference between the 312/300 ( you have singles up front) and 340/330 in performance. I upgraded to 340/330.


And your last sentence is why… they will not bolt up.

Thanks to you and everyone else! Yeah looking at some pictures seems like the bolt receivers are far closer on the rear calipers than the fronts. I guess I'll just have to bide my time and keep looking. Or just upgrade the fronts only but this feels kinda half assed even if I won't notice a real world difference.

[boyerizm]

Originally Posted by Boostedphil698

Why not just buy the M Performance BBK from getbmwparts.com? You'll have an OEM BBK.

I got the calipers dirt cheap, $250 for the pair thinking it would be a good deal. But the rears are going to cost close to 1k for the pair. So Im inclined to agree with you by the time you buy rotors and all the other stuff you probably should have just bought the BBK.

[boyerizm]

Hrmm there's always the Alibaba option

https://m.alibaba.com/product/160007...00000%22%7D%7D

[Pussiwillow]

Haha i was thinking about this idea
Buying 6 pot front and moving the front calipers to the rear
But as you seen already, mounting area is different
I'm sure someone can make it work but. Ya

[Ennoch]

Just did a quick bit of checking; front brakes have 4x 40mm diameter pistons and the rears are 2x40mm, so the front brakes have twice the piston surface area of the rears. While disc size comes into it as well, given the grey calipers are a 345/330 setup we can say it's not a million miles off being discountable. So ultimately the brake bias is going to be 66% front and 33% rear, maybe closer to 70/30 if we include disc size. If you put the front calipers on the back you're going to end up with 50/50 (essentially you're doubling the rear brake's stopping power) which might seem sensible but with weight transferring so much to the front under braking you're going to end up with very, very overbraked rears. I'm not sure even an aftermarket bias adjuster valve could cope with that level of imbalance, and if it could, would you even want to go down that route? Your pedal would also be significantly longer unless you upped the M/C diameter which in turn would then increase the effort required to get the original braking force from the front brakes.

[Onizukachan]

That’s another reason why not.
Go to the junkyard and find a set of 330 rears and done. The extra 7 mm is not as big a difference as the first 15.

[Logicoeur]

Originally Posted by Ennoch

Just did a quick bit of checking; front brakes have 4x 40mm diameter pistons and the rears are 2x40mm, so the front brakes have twice the piston surface area of the rears. While disc size comes into it as well, given the grey calipers are a 345/330 setup we can say it's not a million miles off being discountable. So ultimately the brake bias is going to be 66% front and 33% rear, maybe closer to 70/30 if we include disc size. If you put the front calipers on the back you're going to end up with 50/50 (essentially you're doubling the rear brake's stopping power) which might seem sensible but with weight transferring so much to the front under braking you're going to end up with very, very overbraked rears. I'm not sure even an aftermarket bias adjuster valve could cope with that level of imbalance, and if it could, would you even want to go down that route? Your pedal would also be significantly longer unless you upped the M/C diameter which in turn would then increase the effort required to get the original braking force from the front brakes.

Greys are 340mm.

[Ennoch]

Originally Posted by Logicoeur

Greys are 340mm.

Well whatever they are, the points I made still stand...it ain't gonna work!

[johnung]

Originally Posted by boyerizm

Probably a stupid question but is it possible to mount the 4 pot grey Brembos on the rear?

I got an awesome deal on these used but now I'm looking at the price for rear M-Performance 2 Pot calipers and it's ridiculous. Even with the deal I'm probably better off buying the BBK.

I'm wondering if I just picked up 2 more if I could run these on the rear. So basically I'd have the same calipers on all 4 wheels.

It's not a stupid question. No it will not work. Forget about it. I've done several F30 brake upgrades and I know this stuff well.

If you are starting with front 312mm/rear 300mm, then 340/330 is a big upgrade. It's the standard brake setup on an F30 335i/435i.

But you have to check which rear emergency brakes your car has. If you have the larger 185mm then you are fine. The handbrake is cut into the inside of the rear rotor hat like a drum brake and incredibly expensive to change if your car came with the smaller 160mm. See attached photo for how to use your VIN to lookup your handbrake size.

Some cars also have smaller front and rear metal brake backing shields. Larger front shields are simple bolt on. But rear shields are not. But mechanics came up with a simple trick to cut a section out of the shield to get it on. Then it becomes a simple bolt on too. See photo.

I have never seen a 330mm x 20mm rear rotor with the smaller 160mm e-brake. If someone knows a source please let me know. But they do make the rear 345x24 rotor with both sizes of handbrakes.

The used price for a pair of 345 Brembo rear calipers is usually between $450-$550 in good condition. Just wait if there weren't any at a reasonable price when you checked.

If you need to change the color on new calipers use G2USA Caliper Paint but follow instructions carefully especially for the air temperature range during painting. Powder coating is an option too but much more expensive. You have to remove pistons and seals to bake them after powdercoat so it's basically a caliper rebuild.

When you upgrade to any of the Brembos you need to code the cars brake bias. This is not a BimmerCode type of coding. It doesn't take long at all but you'll need to find an independent BMW mechanic with esys to do it.

You're going to need a full brake bleed anyway with ISTA to get the air out anyway so have him do it. See video link. Probably charge you 1-2 hours labor.

It's very important for safety to fully replace your brake fluid every two years since it picks up moisture over that time. Moisture destroys expensive brake components from the inside.

While you are at it just get a set of StopTech's stainless steel brake lines for about $110. Much firmer brake pedal feel. See photo

Brake bleed procedure courtesy of FaRKle!

F340/R330 would be a huge brake upgrade for your car, compared to stock F312/R300.

F340/R345 squats very controllably under heavy braking while F340/R330 tends to nose dive a bit when you stand on the brakes.

F370/R345 have the same braking power as with 340's on the front. Brake pistons and pad swept areas are identical. But the 370's have more mass to dissipate heat better and prevent fade under repetitive braking on the track or in very aggressive street driving.

Do yourself a favor and get a set of Hawk 5.0 brake pads. Best street pads by far. See photo for part number for various sized brake upgrades that we have discussed.

Best street rotors are StopTech fully crossdrilled. Incredible bite and best in rain. There's a reason that BMW puts full crossdrilled on M3/M4. See photo.

Hope this helps!

[boyerizm]

Originally Posted by johnung

Hope this helps!

It does. You’re a rockstar.

The only thing I’m thinking about now is the ESYS coding. Reason being I really wanted to DIY the brakes. Honestly most of the mods I do aren’t truly for performance gains, I’m just an engineering geek. Do you think I could do it all, importantly the brake bleed, and drive it to a mechanic to do the final coding/check my work? Or would it not be drivable until the coding happened?

As an aside, I was also only half joking about getting those Alibaba calipers btw. $290 for a pair of 245s is a pretty sweet deal. I’m 99% sure it’s a bad idea but…if I only used the caliper housing and pistons. Pads, rotors, lines would all most likely be what you’ve recommended. Maybe it’s worth a shot.

[Onizukachan]

For 340/330 the bias remains the same so no coding required. I have it on mine, which is why I can say that with confidence.

Other than that quibble I agree with the above 100%

[johnung]

Originally Posted by Onizukachan

For 340/330 the bias remains the same so no coding required. I have it on mine, which is why I can say that with confidence.

Other than that quibble I agree with the above 100%

I am pretty darn sure that the brake bias coding is different for the Brembo front 340 and 370 calipers. (In esys I'm pretty sure that the code is S2NH). So anyone who upgrades from front F30 brakes that are 312mm x 24mm, or 330mm x 24mm to either of the Brembo 340 or 370 should have their brake bias recoded. Not saying you can't drive around without recoding but the brakes won't work optimally.

If a car already has front 340's from the factory and upgrades to front 370's then recoding isn't necessary because they use the same brake bias code.

[johnung]

Originally Posted by boyerizm

It does. You’re a rockstar.

The only thing I’m thinking about now is the ESYS coding. Reason being I really wanted to DIY the brakes. Honestly most of the mods I do aren’t truly for performance gains, I’m just an engineering geek. Do you think I could do it all, importantly the brake bleed, and drive it to a mechanic to do the final coding/check my work? Or would it not be drivable until the coding happened?

As an aside, I was also only half joking about getting those Alibaba calipers btw. $290 for a pair of 245s is a pretty sweet deal. I’m 99% sure it’s a bad idea but…if I only used the caliper housing and pistons. Pads, rotors, lines would all most likely be what you’ve recommended. Maybe it’s worth a shot.

The coding won't effect your ability to drive it. It's the bleeding that's the issue. Changing calipers out (and hopefully install stainless lines at the same time) will get air in the system which the best manual bleed won't remove. So it could brake very poorly until you get the ISTA procedure done.

Please don't attempt that rig job with your brakes. It's a safety component. Don't take the risk. Just not worth it

[Ennoch]

The coded bleeding is only needed if you get air into the ABS module. Replacing calipers shouldn't need it, and if you're careful when doing the lines then that shouldn't require it either (just fill both the lines and calipers up with fluid first). When we work on the rally cars you don't have the ABS module to worry about but replacing calipers and lines tends not to need much fluid which means the air isn't tracking back up. Lines are lines and calipers are calipers, whether fitted to an F30, a Morris Marina or a Gp.N Evo.

[Onizukachan]

johnung

My understanding is that it is when you go to dual piston 345 rears that you need to recode as those would require different bias, ergo 340/330 to 370/345 requires the recode, but a 312/300 to 340/330 still with single piston rears doesn’t. That why the direction from bmw are to add S2NH to VO on the 335i/340i as well.