Weighed: F80 basic stripper configuration - 3,450 pounds

[JoeFromPA]

Originally Posted by CanAutM3

Thanks for doing this BTW .

The good thing is that for $4, you can go back anytime with a full load of fuel .

Yeah, you literally just drive up during business hours, pay $4 (CASH ONLY PEOPLE!) and bam, you get your weight. Took maybe 3 minutes.

I'll go back with a full load of fuel and after I drill out some body panels

[Boss330]

Originally Posted by CSBM5

One thing to realize is that BMW quoted weights of course include stuff like mats, mobility pack, etc.

EU regulations doesn't require that stuff included in the curb weight. Optional equipment are not included in the weight.

OP:

You car has electric seats I assume?

I seem to remember a member from Sweden saying that they could order the F8x with manual seats. If correct, that takes out a big chunk of weight.

[JoeFromPA]

Originally Posted by Boss330

EU regulations doesn't require that stuff included in the curb weight. Optional equipment are not included in the weight.

OP:

You car has electric seats I assume?

I seem to remember a member from Sweden saying that they could order the F8x with manual seats. If correct, that takes out a big chunk of weight.

Yes, the U.S. does not allow for manual seats unless perhaps ordered through individual. So I have power seats.

[andy92782]

Does anyone know definitively how much weight is added with the steel roof/moonroof option?

Great thread, thanks for providing this info.

[Boss330]

Originally Posted by JoeFromPA

Yes, the U.S. does not allow for manual seats unless perhaps ordered through individual. So I have power seats.

Power seats is better than "electric seats" I guess... We just call them electric seats over here (in my native language). Sometimes direct translation comes out a bit strange...

[JoeFromPA]

It's not the translation, it's the translator.

[jtodd_fl]

3,450 pound stripper? Reminds me of this one time... oh... never mind.

[AMPowerJ]

The fact the car weighs less than its predecessor at all is good news. BMW is heading in the right direction. My hunch is the next generation will weigh even less than the F80. All this is good for handling, gas mileage, etc. Not so good when you have a collision with the soccer mom in the Suburban though.

[shortseller]

Originally Posted by andy92782

Does anyone know definitively how much weight is added with the steel roof/moonroof option?

Great thread, thanks for providing this info.

I thought I read 8 lbs but don't quote me.

OP - great thread.

[CSBM5]

Originally Posted by shortseller

I thought I read 8 lbs but don't quote me.

OP - great thread.

Definitely don't quote that figure, lol. It's in the region of 50lbs.

[shortseller]

Originally Posted by CSBM5

Definitely don't quote that figure, lol. It's in the region of 50lbs.

www.topspeed.com › BMW › 4 Series
Review by Justin Cupler - ‎Mar 18, 2014
Mar 18, 2014 - First up is a carbon-fiber roof that helps drop the car's curb weight by .... this setup is 11 pounds lighter than the same setup in steel. .... upgrades that BMW gave it when compared to the M3 Coupe make it well worth the wait.

[czarmar]

Originally Posted by JoeFromPA

The 18s with tires, as a set, are ~7-8 pounds less than the 19s with tires.

However, the 19" tires are lighter than the 18" tires.

Therefore, the belief is that from a static weight perspective the 18s will weigh less but from a dynamic perspective, taking into account unsprung rotating mass, it's either a wash or the 19s are slightly advantageous.

When accelerating or braking, the 18s with tires' rotational inertia is lower, because the mass of the wheel/tire is concentrated closer to the axis of rotation rather than the rolling radius. My thought is that the brake rotors, whether CCB or not, will have less affect on the rotational inertia because their mass is more towards the center, and the 18's will be fractionally better for acceleration above 40-50 MPH. In most cases that we've seen, this car is traction limited, not motor limited, at least up to 40-50 MPH, so additional reductions in the moment of inertia won't help.

When it comes to damping and moving the wheels up and down, the total mass of the wheel/tire/brakes will become relevant as unsprung weight. As far as weight, 19's with CCBs ~= 18's, so it would be a wash there.

[CSBM5]

Originally Posted by czarmar

My thought is that the brake rotors, whether CCB or not, will have less affect on the rotational inertia because their mass is more towards the center, and the 18's will be fractionally better for acceleration above 40-50 MPH. In most cases that we've seen, this car is traction limited, not motor limited, at least up to 40-50 MPH, so additional reductions in the moment of inertia won't help.

Rotational inertia effects are of course a function of acceleration which peaks at a very low velocity and then steadily drops as speeds increase. Hence the benefit of lower rotational inertia are highest at the slowest speed and visa-versa.

Braking is a different situation as you can generate a significant deceleration rate and hold it all the way to zero mph.

Radius of gyration is the value you're looking for to compare the 18 to 19 combo once you know their mass.

[Black Gold]

Originally Posted by shortseller

www.topspeed.com › BMW › 4 Series
Review by Justin Cupler - ‎Mar 18, 2014
Mar 18, 2014 - First up is a carbon-fiber roof that helps drop the car's curb weight by .... this setup is 11 pounds lighter than the same setup in steel. .... upgrades that BMW gave it when compared to the M3 Coupe make it well worth the wait.

That is 11 lbs over a steel non sunroof car.

Sunroof and parts add like 38 lbs so the cf removed 45-50 over a car with a sunroof

[andy92782]

Originally Posted by shortseller

www.topspeed.com › BMW › 4 Series
Review by Justin Cupler - ‎Mar 18, 2014
Mar 18, 2014 - First up is a carbon-fiber roof that helps drop the car's curb weight by .... this setup is 11 pounds lighter than the same setup in steel. .... upgrades that BMW gave it when compared to the M3 Coupe make it well worth the wait.

Perhaps the CF saves 11 lbs vs steel but by the time you add the additional weight of the glass roof, electric motor, etc you get a weight delta closer to 40-50lbs.

Personally I'm wrestling with the weight savings vs. the ability to add a roof rack/cargo convenience. If you want to add a roof rack you need to skip the CF roof.

[shortseller]

I knew I read that somewhere, didn't remember the moonroof was additive. CFMR would be killer.

[shortseller]

Originally Posted by andy92782

Perhaps the CF saves 11 lbs vs steel but by the time you add the additional weight of the glass roof, electric motor, etc you get a weight delta closer to 40-50lbs.

Personally I'm wrestling with the weight savings vs. the ability to add a roof rack/cargo convenience. If you want to add a roof rack you need to skip the CF roof.

I had a hard time with it also, I've had MR on all previous BMWs and knew I would miss it. Ended up going CF, for the aesthetic merits. Not sure I'd feel the weight diff in a DD in any event though.

[MaynardZed]

Originally Posted by CanAutM3

According to BMW Euro specs, the M3 is ~50lb heavier than the M4.

Ok, so maybe possible for stripper M4 to be under 3400 mark. I hope to have time next week to weigh my M4, but it's lightly optioned w/ HK and 19s so maybe around the same weight as Joes.

[CanAutM3]

Originally Posted by czarmar

When accelerating or braking, the 18s with tires' rotational inertia is lower, because the mass of the wheel/tire is concentrated closer to the axis of rotation rather than the rolling radius.

This is not necessarily true. It depends on the individual weight of the wheels and tires. An 18" tire is usually heavier than a 19" tire. Since the weight of the tire is farther away from the rotating center, its additional weight will have more impact on inertia than the reduced weight of the wheel.

For example, on the E92 M3, the optional 19" 220M wheel/tire combo was lighter than the 18" base wheel/tire combo.

My point is that without having the specific weight of the individual wheels and tires in 18" and 19" sizes, it is not possible to draw a conclusion on which option is lighter or has less rotational inertia.

Originally Posted by czarmar

My thought is that the brake rotors, whether CCB or not, will have less affect on the rotational inertia because their mass is more towards the center, and the 18's will be fractionally better for acceleration above 40-50 MPH. In most cases that we've seen, this car is traction limited, not motor limited, at least up to 40-50 MPH, so additional reductions in the moment of inertia won't help.

When it comes to damping and moving the wheels up and down, the total mass of the wheel/tire/brakes will become relevant as unsprung weight. As far as weight, 19's with CCBs ~= 18's, so it would be a wash there.

I did the calculation and established the mass factor of the disc rotors to be around 1.2, which is, as you stated, much less than the wheels and tires.

The CCB reduce the effective mass (actual mass + inertial effects) of the car by about 20lbs.

[czarmar]

Originally Posted by CanAutM3

This is not necessarily true. It depends on the individual weight of the wheels and tires. An 18" tire is usually heavier than a 19" tire. Since the weight of the tire is farther away from the rotating center, its additional weight will have more impact on inertia than the reduced weight of the wheel...

The extra weight of the 18" tire is in the sidewall which necessarily extends further towards the axis of rotation to meet the smaller wheel. Given the mass of the wheel barrel (which is likely the significant part of the wheel's mass) is also closer to the axis of rotation, all other things being equal (rolling radius, etc), the rotational inertia of the 18" wheel/tire combination would be less.

Now that we've gotten the weight of a stripper M3 pinned down, we must now start a debate over which wheels are faster! I propose that two identically equipped M3s save the wheel options do a drag race. I hypothesize that the 18" wheeled M3 will be .01% faster from 40-90 MPH!

I think the reason I'd consider the 18's are more for using the $1200 elsewhere in optioning the car, cheaper tires down the road, I think the 18's look good (although the 19's look GREAT), less risk of wheel damage and perhaps a slight comfort advantage. I don't think the performance/weight advantage plays into it. My car will have the sunroof anyways, so I'm already adding 50 lbs.

[///M///]

Originally Posted by JoeFromPA

Yeah, you literally just drive up during business hours, pay $4 (CASH ONLY PEOPLE!) and bam, you get your weight. Took maybe 3 minutes.

I'll go back with a full load of fuel and after I drill out some body panels

Awesome Joe can you name the scrapyard? I am curious what my E90 weighs with the Volks and the Akra For $4 it's a steal

[haynstyleM2]

Thanks for the info Joe; appreciate it.