[spxxx]

Does anyone know if the Stoptech ST-60 E90 BMW kit (rotors + calipers) will be a direct plug and play bolt-on for the E82?

It seems like they should be but I want to confirm before pulling the trigger.

[feuer]

Yes, but (I think) not with stock e82 wheels since they have high offsets and won't clear the calipers. I know you track so you probably don't have stock wheels.

[spxxx]

Originally Posted by feuer

Yes, but (I think) not with stock e82 wheels since they have high offsets and won't clear the calipers. I know you track so you probably don't have stock wheels.

Thanks for the info! I run Apex Arc-8 so should be okay on that front.

[spxxx]

Originally Posted by feuer

Yes, but (I think) not with stock e82 wheels since they have high offsets and won't clear the calipers. I know you track so you probably don't have stock wheels.

Are you sure the rotors are plug and play too? It looks like E82 calipers and rotors bolt right up to E90s (people have posted about 'upgrading' their E90s to E82 Brembo brakes) so I'm assuming it should be fine to bolt up E90>E82...

Thanks for the help!!

[feuer]

Originally Posted by spxxx

Are you sure the rotors are plug and play too? It looks like E82 calipers and rotors bolt right up to E90s (people have posted about 'upgrading' their E90s to E82 Brembo brakes) so I'm assuming it should be fine to bolt up E90>E82...

Thanks for the help!!

Correct, front knuckles, bearings, brakes and etc are 100% identical.

[spxxx]

Originally Posted by feuer

Correct, front knuckles, bearings, brakes and etc are 100% identical.

You are the man. Stoked to not boil fluid

[jumbosrule]

Hope you haven't gone too far on this yet - I did a little research for you.

The calipers are different in the E90 vs the E82 - they have the same bolt hole pattern, but NOT the same size caliper pistons. You cannot swap them and expect it to behave.

StopTech BBK for E90:
STP83.154.004G.71 - ST40 caliper with 345x28 rotor

Calipers for this kit:
SCL372.420.3171 ST40 caliper, 28-34 mm pistons, 28mm wide Right
SCL372.420.3172 ST40 caliper, 28-34 mm pistons, 28mm wide Left

StopTech BBK for E82
STP83.165.004G.71 - ST40 caliper with 345x28 rotor

Calipers for this kit (DIFFERENT PART NUMBERS)
SCL372.420.1171 ST40 Caliper, 28-30 mm pistons, 28mm wide Right
SCL372.420.1172 ST40 Caliper, 28-30 mm pistons, 28mm wide Left

SO - if you use the E90 calipers on the E82, you will move brake system balance to the front because you are increasing piston size on the front rotor. This will make your stopping distances LONGER because your rear brakes are now doing less work than they should.

OE brake system balance is already biased towards the front of the car for safety. In performance applications, this is generally too much front bias and if you make this caliper change, you will be moving even more bias to the front of the car. This can work on your car but the performance will probably not be better than stock.

On the up side, it SHOULD take care of fluid boil!

[spxxx]

Originally Posted by jumbosrule

Hope you haven't gone too far on this yet - I did a little research for you.

The calipers are different in the E90 vs the E82 - they have the same bolt hole pattern, but NOT the same size caliper pistons. You cannot swap them and expect it to behave.

StopTech BBK for E90:
STP83.154.004G.71 - ST40 caliper with 345x28 rotor

Calipers for this kit:
SCL372.420.3171 ST40 caliper, 28-34 mm pistons, 28mm wide Right
SCL372.420.3172 ST40 caliper, 28-34 mm pistons, 28mm wide Left

StopTech BBK for E82
STP83.165.004G.71 - ST40 caliper with 345x28 rotor

Calipers for this kit (DIFFERENT PART NUMBERS)
SCL372.420.1171 ST40 Caliper, 28-30 mm pistons, 28mm wide Right
SCL372.420.1172 ST40 Caliper, 28-30 mm pistons, 28mm wide Left

SO - if you use the E90 calipers on the E82, you will move brake system balance to the front because you are increasing piston size on the front rotor. This will make your stopping distances LONGER because your rear brakes are now doing less work than they should.

OE brake system balance is already biased towards the front of the car for safety. In performance applications, this is generally too much front bias and if you make this caliper change, you will be moving even more bias to the front of the car. This can work on your car but the performance will probably not be better than stock.

On the up side, it SHOULD take care of fluid boil!

Interesting, I bought them (and will try them out) maybe using a somewhat higher friction rear pad to help balance them a bit. I'll do some before and after 100mph braking tests. Thank you for doing that research, I ran it by Harold at HPA and he didn't think there would be an issue. We shall see, my main concern is heat management, the stock Brembos stopped fine for me.

[spxxx]

Originally Posted by jumbosrule

Hope you haven't gone too far on this yet - I did a little research for you.

The calipers are different in the E90 vs the E82 - they have the same bolt hole pattern, but NOT the same size caliper pistons. You cannot swap them and expect it to behave.

StopTech BBK for E90:
STP83.154.004G.71 - ST40 caliper with 345x28 rotor

Calipers for this kit:
SCL372.420.3171 ST40 caliper, 28-34 mm pistons, 28mm wide Right
SCL372.420.3172 ST40 caliper, 28-34 mm pistons, 28mm wide Left

StopTech BBK for E82
STP83.165.004G.71 - ST40 caliper with 345x28 rotor

Calipers for this kit (DIFFERENT PART NUMBERS)
SCL372.420.1171 ST40 Caliper, 28-30 mm pistons, 28mm wide Right
SCL372.420.1172 ST40 Caliper, 28-30 mm pistons, 28mm wide Left

SO - if you use the E90 calipers on the E82, you will move brake system balance to the front because you are increasing piston size on the front rotor. This will make your stopping distances LONGER because your rear brakes are now doing less work than they should.

OE brake system balance is already biased towards the front of the car for safety. In performance applications, this is generally too much front bias and if you make this caliper change, you will be moving even more bias to the front of the car. This can work on your car but the performance will probably not be better than stock.

On the up side, it SHOULD take care of fluid boil!

Wait, these are the numbers for the ST40 kit, not the ST60 kit.

[feuer]

Originally Posted by jumbosrule

OE brake system balance is already biased towards the front of the car for safety. In performance applications, this is generally too much front bias and if you make this caliper change, you will be moving even more bias to the front of the car. This can work on your car but the performance will probably not be better than stock.

Originally Posted by spxxx

Interesting, I bought them (and will try them out) maybe using a somewhat higher friction rear pad to help balance them a bit. I'll do some before and after 100mph braking tests. Thank you for doing that research, I ran it by Harold at HPA and he didn't think there would be an issue. We shall see, my main concern is heat management, the stock Brembos stopped fine for me.

True and also not true. E82 135i and E9x 335i share the same brake master cylinder part 34336779720. The reason for the ST calipers being different is because at the time they ware designed nobody new the DCT/ABS is programmable and ST build the calipers to match the calipers on the car. So shortly: you can absolutely run 335i brakes on 135i with any adverse effect.

[jumbosrule]

Originally Posted by spxxx

Wait, these are the numbers for the ST40 kit, not the ST60 kit.

My Bad - here are the other part numbers:

The StopTech six piston caliper kit for an 08 E82 is

83.165.6700.71 6 Piston Caliper, 355x32mm Slotted Rotor

And the calipers in that kit are
SCL372.634.1173 ST60/28-30-34/32
SCL372.634.1174 ST60/28-30-34/32

Originally Posted by feuer

True and also not true. E82 135i and E9x 335i share the same brake master cylinder part 34336779720. The reason for the ST calipers being different is because at the time they ware designed nobody new the DCT/ABS is programmable and ST build the calipers to match the calipers on the car. So shortly: you can absolutely run 335i brakes on 135i with any adverse effect.

StopTech always designs calipers to match the factory force output so that brake balance is maintained just like factory balance. The E90 and the E82 have different vehicle weights, different center of gravity and different brake balance. The piston sizes inside the caliper were designed differently to maintain balance for each application. They are not meant to be interchanged, even if it is physically possible to bolt up a caliper from one application to the other.

[feuer]

Originally Posted by jumbosrule

StopTech always designs calipers to match the factory force output so that brake balance is maintained just like factory balance. The E90 and the E82 have different vehicle weights, different center of gravity and different brake balance. The piston sizes inside the caliper were designed differently to maintain balance for each application. They are not meant to be interchanged, even if it is physically possible to bolt up a caliper from one application to the other.

The brake cylinder from 135i is identical with that from 335i. 135i are actually smaller and worse performer brakes than 335i brakes. As you said, with other words, 335i brake won't work 100% on 135i but the reason being is the DTC/ABS coding. If DTC/ABS is re-coded brakes will work 100%.

[spxxx]

Originally Posted by feuer

The brake cylinder from 135i is identical with that from 335i. 135i are actually smaller and worse performer brakes than 335i brakes. As you said, with other words, 335i brake won't work 100% on 135i but the reason being is the DTC/ABS coding. If DTC/ABS is re-coded brakes will work 100%.

The bias will be still off? Larger Piston size will create more front bias.

[juld0zer]

Don't forget pedal feel in the equation.
You might either get a longer pedal travel to achieve similar friction, or a similar/slightly higher pedal because the rear circuit fills and reaches peak pressure before the front has enough fluid to work optimally - due to tandem master cylinder characteristics.

But Stoptech does boast about having excellent pedal feel even on an M3 with just a front BBK - so please do tell us how it goes. Upgrading brake hardware is not that simple on our cars because there is a huge amount of computer influence in how the car stops.

If all you want is more thermal capacity, why not try the 340mm version of the F30 Brembo kit which is standard on F30 335i? Rotors have great ventilation design, calipers and pads are cheap. They are a bit ugly compared to Stoptechs though

[feuer]

Originally Posted by spxxx

The bias will be still off? Larger Piston size will create more front bias.

It will be front bias either way given that you will run better and bigger front brakes with presumably more aggressive pads. 135i brakes were offered as Performance brake upgrade on 330i for example that is different weight, different weight distribution, different center of gravity, different brake master cylider bla bla and they work. It will be OK go ahead with the swap.

[spxxx]

Originally Posted by feuer

It will be front bias either way given that you will run better and bigger front brakes with presumably more aggressive pads. 135i brakes were offered as Performance brake upgrade on 330i for example that is different weight, different weight distribution, different center of gravity, different brake master cylider bla bla and they work. It will be OK go ahead with the swap.

Hey there, thanks for the info. I've been running the E90 stoptech kit on my E82 without issue but as I've gotten faster around the track I've noticed more ABS interference than seems normal. Do you know the % change in brake bias by using e90 front calipers and stock E82 rears?

[feuer]

Originally Posted by spxxx

Hey there, thanks for the info. I've been running the E90 stoptech kit on my E82 without issue but as I've gotten faster around the track I've noticed more ABS interference than seems normal. Do you know the % change in brake bias by using e90 front calipers and stock E82 rears?

Unfortunately I don't and will depend on the brake pad material too, not just pressure and size of piston and pads.

[spxxx]

Originally Posted by feuer

Unfortunately I don't and will depend on the brake pad material too, not just pressure and size of piston and pads.

That's true, I guess I can calculate the difference in piston sizes between E90&E82 to get a close estimate. I've started running a more aggressive rear pad and an endurance racing pad up front to balance things out a tad which did help somewhat.

I'm actually considering the F30 performance brake setup with the 4-pot caliper & 370mm rotor but I want to figure out how much this will effect bias.

I should probably just stop being cheap and buy a set of E82 Stoptech ST-40s up front. :