[Nomana]

hi guys
Is it possible to replace rotors for bigger ones with stock caliper?
If so what do i need to make it works?

[madmonkey]

I'm sorry, but what you're asking to do doesn't make sense to me. The point of having larger rotors is to have larger calipers to hold larger brake pads for more braking power. Just installing larger rotors won't do anything for performance and you may have clearance issues with the smaller caliper brackets, not to mention out of spec rotor wear that might cause braking issues.

If you want to change rotor size, you should be installing calipers to match. The braking system is engineered to work a specific way and messing with this is just asking for trouble.

[Polo08816]

Originally Posted by madmonkey

I'm sorry, but what you're asking to do doesn't make sense to me. The point of having larger rotors is to have larger calipers to hold larger brake pads for more braking power. Just installing larger rotors won't do anything for performance and you may have clearance issues with the smaller caliper brackets, not to mention out of spec rotor wear that might cause braking issues.

If you want to change rotor size, you should be installing calipers to match. The braking system is engineered to work a specific way and messing with this is just asking for trouble.

But bigger rotors look good...

[Orion4]

if your calipers don't match the rotors in the correct circumference, etc. , you have compromised the braking surface contact area. Additionally, the caliper mounting brackets and mounting holes may well no longer align due to interference with the larger diameter rotor. Just asking for problems, IMHO

[Polo08816]

Originally Posted by Nomana

hi guys
Is it possible to replace rotors for bigger ones with stock caliper?
If so what do i need to make it works?

Originally Posted by Orion4

if your calipers don't match the rotors in the correct circumference, etc. , you have compromised the braking surface contact area. Additionally, the caliper mounting brackets and mounting holes may will no longer align due to interference with the larger diameter rotor. Just asking for problems, IMHO

I asked my mechanic about this and he said if you heat up your rotors enough, they will expand and thus look bigger. The key is to keep them glowing red because of the thermal expansion properties of metallurgy.

[Mr. Tasty]

Originally Posted by Polo08816

I asked my mechanic about this and he said if you heat up your rotors enough, they will expand and thus look bigger. The key is to keep them glowing red because of the thermal expansion properties of metallurgy.

holy shit, thought you were OP for a second lol.

We need another plague.

[Nomana]

Iv got used rotors and think they look good.
Just for the look though.

[Orion4]

Originally Posted by Polo08816

I asked my mechanic about this and he said if you heat up your rotors enough, they will expand and thus look bigger. The key is to keep them glowing red because of the thermal expansion properties of metallurgy.

Yup! the "Bigger Hammer" approach!

[Jadar]

Originally Posted by Polo08816

I asked my mechanic about this and he said if you heat up your rotors enough, they will expand and thus look bigger. The key is to keep them glowing red because of the thermal expansion properties of metallurgy.

Not sure if serious

[Mr. Tasty]

Originally Posted by Jadar

Not sure if serious

it's super obvious sarcasm.

OP is literally asking for larger rotors without changing the calipers. Not only does it not make sense in theory, the caliper won't bolt up to the assembly as the larger circumference pushes the caliper outward.

[NISFAN]

Of course bigger rotors improve braking performance.....even with the same calipers and brake pressure (the other two variables in brake performance). It has more torque (force x distance to moment) due to the longer moment. It also has more 'metal' passing through the caliper for a given rotation.....and finally on the thermodynamics side, there is more mass in the rotor to act as a heat soak, and more surface area to dissipate said heat. All positive things for a brake system.

So technically, a larger diameter rotor is a good thing. The weak link being the tyre to road contact friction, which can often be overcome even on smaller rotors, so ultimate braking performance may not be improved.

Coming back to the question, on radially mounted calipers, it is easy enough to add a spacer between hub and caliper to accommodate a larger rotor. Sadly BMW do not use radial mounts, so a more complicated spacer would be required. Not worth the 'effort'.

A simple upgrade would be to use parts from an higher model. OP has posted pics of the ATE single piston calipers. A good upgrade would be to fit the 370mm M Performance 4 pot / 2 pot brembo supplied calipers.

[madmonkey]

Originally Posted by NISFAN

Of course bigger rotors improve braking performance.....even with the same calipers and brake pressure (the other two variables in brake performance). It has more torque (force x distance to moment) due to the longer moment. It also has more 'metal' passing through the caliper for a given rotation.....and finally on the thermodynamics side, there is more mass in the rotor to act as a heat soak, and more surface area to dissipate said heat. All positive things for a brake system.

So technically, a larger diameter rotor is a good thing. The weak link being the tyre to road contact friction, which can often be overcome even on smaller rotors, so ultimate braking performance may not be improved.

Coming back to the question, on radially mounted calipers, it is easy enough to add a spacer between hub and caliper to accommodate a larger rotor. Sadly BMW do not use radial mounts, so a more complicated spacer would be required. Not worth the 'effort'.

A simple upgrade would be to use parts from an higher model. OP has posted pics of the ATE single piston calipers. A good upgrade would be to fit the 370mm M Performance 4 pot / 2 pot brembo supplied calipers.

Because, Science!!...

but seriously, OP needs to get M performance brake pads and calipers to go with his used M Performance rotors he just got. Let's hope he has the wheel clearance for the upsized calipers...

[enjoythemusic]

But going larger adds unwanted unsprung weight. Go small and light and you'll improve acceleration. Much better 0 to 60 and 1/4 mile times.

And yes, the above is sarc. Going fast may be fun, yet at some point the music needs to stop.

[Jadar]

Originally Posted by Mr. Tasty

it's super obvious sarcasm.

OP is literally asking for larger rotors without changing the calipers. Not only does it not make sense in theory, the caliper won't bolt up to the assembly as the larger circumference pushes the caliper outward.

lol just making sure. I run MP BBK totally aware how brake systems work.
Sometimes what you read on here you scratch your head..

[Polo08816]

Originally Posted by Mr. Tasty

it's super obvious sarcasm.

OP is literally asking for larger rotors without changing the calipers. Not only does it not make sense in theory, the caliper won't bolt up to the assembly as the larger circumference pushes the caliper outward.

+1. The calipers will not bolt up to the hub assembly brackets without modification.

My suggestion for the OP is to fabricate his own bracket extensions using sheet metal and make sure to use some self tapping metal screws. It'll definitely secure that caliper just fine.

[Orion4]

Originally Posted by Polo08816

+1. The calipers will not bolt up to the hub assembly brackets without modification.

My suggestion for the OP is to fabricate his own bracket extensions using sheet metal and make sure to use some self tapping metal screws. It'll definitely secure that caliper just fine.

Oh, oh!! Now you've "let the cat out of the bag"!!

[F32Fleet]

Originally Posted by NISFAN

Of course bigger rotors improve braking performance.....even with the same calipers and brake pressure (the other two variables in brake performance). It has more torque (force x distance to moment) due to the longer moment. It also has more 'metal' passing through the caliper for a given rotation.....and finally on the thermodynamics side, there is more mass in the rotor to act as a heat soak, and more surface area to dissipate said heat. All positive things for a brake system.

So technically, a larger diameter rotor is a good thing..

This is false. It's the distance between the hub and the calipers that matter. It's called leverage.

Ex. While using a torque wrench do you grip it at the end of the wrench or close to the nut you're tightening? You of course grip the wrench at the end. Your grip acts like a caliper and where you place it determines the amount of force needed to move the nut.

[6times7]

Originally Posted by F32Fleet

This is false. It's the distance between the hub and the calipers that matter. It's called leverage.

Ex. While using a torque wrench do you grip it at the end of the wrench or close to the nut you're tightening? You of course grip the wrench at the end. Your grip acts like a caliper and where you place it determines the amount of force needed to move the nut.

I say F32Fleet, old chap, could you explain the difference between a moment (wrt the engineering term, not the informal measure of time) and leverage (which ever use of the term you are referencing).

Thanks awfully.

[NISFAN]

Originally Posted by F32Fleet

This is false. It's the distance between the hub and the calipers that matter. It's called leverage.

Ex. While using a torque wrench do you grip it at the end of the wrench or close to the nut you're tightening? You of course grip the wrench at the end. Your grip acts like a caliper and where you place it determines the amount of force needed to move the nut.

Can you explain to the audience how you move the caliper further away from the hub without using a bigger rotor?

...and what ^^^ he said.

[F32Fleet]

Originally Posted by NISFAN

Can you explain to the audience how you move the caliper further away from the hub without using a bigger rotor?

...and what ^^^ he said.

You need BOTH a larger rotor and the appropriately sized bracket. Just adding larger rotors doesn't change anything because the pads still apply pressure over the same distance along the rotor per/revolution.

For example. The front caliper of the M-Sport Line and the M-Performance Brake Kit are exactly the same (4 piston, same pad size/sweep area) however the M-Perf kit bracket places the caliper farther from the hub and the rotor has a larger radius so when the calipers are engaged they do so over a longer distance per revolution vs a smaller rotor of the M-Sport Line.

This is all else being equal.

[RM7]

Originally Posted by Mr. Tasty

it's super obvious sarcasm.

OP is literally asking for larger rotors without changing the calipers. Not only does it not make sense in theory, the caliper won't bolt up to the assembly as the larger circumference pushes the caliper outward.

It makes perfect sense in theory. With mountain bikes, we run from 140 to 220mm rotors all with the same brake caliper, using adapters and different rotors to space them out accordingly. This is possible because the brakes are standard, they all use the same mounts and there are no "special" brakes produced for "special" bikes. With cars, it's almost the complete reverse, the calipers and rotors are often custom to that specific model and trim, whether it be the caliper-half, or the mounting bracket. In theory, you could use a different caliper half, machining it yourself if need-be, or possibly machine an adapter (theoretically easier), but it's not practical to do either of these things, most people don't have access to machine shops where they can churn out this stuff and it's a better use of your time, money and effort installing better calipers that are better matched to the bigger rotors.

[Stlthnmrdrd]

No