[johnung]

Curious if anyone has the EXACT weights of the front Brembo 4-piston calipers in 340 and 370 sizes? They use the exact same pistons, pads, pins and clip so the only difference in weight should be from the 15mm extended casting.

I don't think the weight difference is significant but don't want to ignore it if the information happens to be available. Just playing around with some unsprung weight calculations. Thanks!

[Logicoeur]

How can they affect unsprung weight if it's fixed to the upright? Only the rotor would.

[johnung]

Originally Posted by Logicoeur

How can they affect unsprung weight if it's fixed to the upright? Only the rotor would.

I'm no guru on this subject. I'm pretty sure unsprung weight is wheels, suspension components, brakes- anything that's not supported by or riding on top of the suspension, like the body itself. Wheels are connected to rotors connected to hubs connected to brake calipers & pads, and other suspension components including the springs.

So it's everything riding on top of the springs that is considered "sprung" weight. So that would mean anything that is riding on that top spring mount where it bolts to the body.

[Gen13 F36]

That's not really the components you need to do something to get less unsprung weight.

[n8thegreat]

Originally Posted by johnung

I'm no guru on this subject. I'm pretty sure unsprung weight is wheels, suspension components, brakes- anything that's not supported by or riding on top of the suspension, like the body itself. Wheels are connected to rotors connected to hubs connected to brake calipers & pads, and other suspension components including the springs.

So it's everything riding on top of the springs that is considered "sprung" weight. So that would mean anything that is riding on that top spring mount where it bolts to the body.

My understanding of unsprung weight is that it is better classified as rotating mass. Weight above or below the spring acts normal to the ground. You are better off losing two pounds by exercise than shedding one pound per front caliper. A 2lb change in rotating mass will have a greater affect on performance.

[Gen13 F36]

All the the suspension components, wheels and brakes components are unsprung weight.

You will not find any brakes upgrade that will give you less weight.

[Techno 9000]

Carbon ceramic surely?

[johnung]

Originally Posted by Gen13 F36

All the the suspension components, wheels and brakes components are unsprung weight.

You will not find any brakes upgrade that will give you less weight.

This thread kinda went off on an unintended tangent as I was comparing weights of various brake rotors and just got curious about the weights of the 340 and 370/380 calipers.

[Gen13 F36]

Originally Posted by johnung

This thread kinda went off on an unintended tangent as I was comparing weights of various brake rotors and just got curious about the weights of the 340 and 370/380 calipers.

Thread has a mind of its own

Anyway, just a comparison I did a front brake upgrade on my S14 Silvia to a Brembo GT 4 piston good for 13.5" rotors... they weight 11 lbs.

Its probably close to that.

[johnung]

Originally Posted by Gen13 F36

Thread has a mind of its own

Anyway, just a comparison I did a front brake upgrade on my S14 Silvia to a Brembo GT 4 piston good for 13.5" rotors... they weight 11 lbs.

Its probably close to that.

Cool, thanks!
I looked into the BremboGT kits but wouldn't fit under my stock 18" wheels. Wanted to keep stealth look and not spend money on wheels. Then I found the StopTech full floating in 370x30 stock size. Worked out perfectly!

[Gen13 F36]

Originally Posted by johnung

Cool, thanks!
I looked into the BremboGT kits but wouldn't fit under my stock 18" wheels. Wanted to keep stealth look and not spend money on wheels. Then I found the StopTech full floating in 370x30 stock size. Worked out perfectly!

Did you weight the rotors?

[johnung]

Originally Posted by Gen13 F36

Did you weight the rotors?

Didn't because I didn't have an accurate scale. Should have taken them to the post office self serve scale. But I have the weight somewhere that I got from a StopTech spec sheet, I believe.

[johnung]

Originally Posted by johnung

Didn't because I didn't have an accurate scale. Should have taken them to the post office self serve scale. But I have the weight somewhere that I got from a StopTech spec sheet, I believe.

These are actually the coated rotors so they are completely coated inside vanes and holes. The coating starts out gold. It wears off the rotor faces instantly and the gold coating turns black everywhere else. Here's a photo of the rotors gold before they were driven.

[Logicoeur]

Really wish stoptech made those in 340mm as well. Only option we have is ECS

[Gen13 F36]

Isn't stoptech make regular 340mm and 330 mm drilled ...just not 2 piece floating rotor Johnung mention.

[johnung]

Originally Posted by Logicoeur

Really wish stoptech made those in 340mm as well. Only option we have is ECS

The StopTech 370mm x 30mm were about a 5-6 week wait special order. I really like them because they are very similar to the rotors that the BremboGT brake kits use. Those GT calipers & rotors are very different in size (less diameter but thicker) and very expensive- meant for racing. (Tracking would use the slotted rotors)

[johnung]

Originally Posted by Gen13 F36

Isn't stoptech make regular 340mm and 330 mm drilled ...just not 2 piece floating rotor Johnung mention.

Yes, StopTech makes the two-piece drilled fixed (rather than floating) rotors. They are excellent! I have them in the 345mm x 24mm size for the rear. See photo.

[johnung]

Originally Posted by johnung

Yes, StopTech makes the two-piece drilled fixed (rather than floating) rotors. They are excellent! I have them in the 345mm x 24mm size for the rear. See photo.

Here's how they look behind the stock 400M wheels. It's a sleeper stealth car so no outrageous wheels or massive drop.

[Watsey]

Originally Posted by Logicoeur

How can they affect unsprung weight if it's fixed to the upright? Only the rotor would.

Unsprung mass is everything which is not suspended off the road by the vehicle's suspension springs. This includes tyres, wheels, discs, calipers, the suspension itself, and a proportion of the various wishbones / control arms (because one end is attached to the wheel hubs and therefore unsprung, and the other end is attached to the chassis and therefore sprung.

Sprung mass is the rest of the vehicle (in simple terms).

[Watsey]

Originally Posted by johnung

These are actually the coated rotors so they are completely coated inside vanes and holes. The coating starts out gold. It wears off the rotor faces instantly and the gold coating turns black everywhere else. Here's a photo of the rotors gold before they were driven.

Nice upgrade