Sedan weight reduction
02-19-2018, 12:29 PM
#92
If you are still concerned about protecting the integrity of the rear crumple zone, I'll offer up a cheap idea that will let you save some weight for a track day. Lay out some plastic sheeting in the bottom of the donut shaped hole used to store the spare and use a high density expanding foam to fill the void between the sheet metal and the foam tool kit holder. If you are careful, you will end up with a removable foam insert to replace the much heavier spare wheel and tire. The plastic sheeting is just to make it easy and clean to swap in and out.
In summary, the spare just serves as a way of transferring force from a collision into the main structure of the uni-body, by filling the void with foam, you can achieve the same effect as the spare.
By the way, I've loved following along with your build and I appreciate your focus for performance over aesthetics.
Maybe you can help me with your engineering experience. Right now, I am just trying to fix the airbag light that does not seem to go off with the resistor that worked perfectly fine before. It might come down to something as simple as the fact that I got a 2 ohm resistor instead of 2.2 ohm.
The light did not go on until I kept the wiring the same on the airbag sensor when I plugged in the factory seat. I had the airbag light reset, but then when I re-wired in the resistor the airbag light came back on. I am thinking that maybe the car noticed the main wiring harness on the stock seat at 2.2 ohms and my resistor at 2.0 and now it always notices that? I think if I re-wire it up like stock with the stock seat, reset the airbag light, disconnect the battery (so the car never senses the difference in wiring), and re-wire my resistor, it should work. Thoughts?
I like your idea with the foam, but I am not sure you would get the same support with soft foam as you would with an aluminum wheel. Either way, I keep it in for track days as I figure taking weight off the rear end is the wrong end to do it for weight balance.
05-24-2018, 07:54 AM
#94
Administrator
iTrader: (8)
Wait, aren't those the rears you're measuring? I thought the rear weight loss is 5lbs per rotor, whereas the front weight loss was 10lbs, in which case they under-reported the difference.
Anyway, isn't the point (or maybe the most important point) of the lightweight rotors is to improve launch response and braking control? Although reduced unsprung inertial mass (?) is significant, the overall weight loss to the car is minimal. And obviously they look fantastic, that's a given.
Last edited by Rochester; 05-24-2018 at 11:12 AM.
05-24-2018, 12:13 PM
#97
Administrator
iTrader: (8)
05-24-2018, 03:59 PM
#100
Administrator
iTrader: (8)
05-24-2018, 04:09 PM
#102
That's a M.A.S.H. reference! My boss says that all the time.
I didn't realize it was that tough to tell the inside of the rotor from the outside as they look pretty different, but I guess maybe if you didn't see them in person. I'm still trying to figure out how you thought they were rear rotors or why I would take the time to pull the rear rotors off the car.
That's what I thought too, but my calipers slid right on without having to open the brake pads after coming off the used stock rotors. From that I concluded that there is no way I shaved almost 2 full pounds off of each rotor from use.
I didn't realize it was that tough to tell the inside of the rotor from the outside as they look pretty different, but I guess maybe if you didn't see them in person. I'm still trying to figure out how you thought they were rear rotors or why I would take the time to pull the rear rotors off the car.
That's what I thought too, but my calipers slid right on without having to open the brake pads after coming off the used stock rotors. From that I concluded that there is no way I shaved almost 2 full pounds off of each rotor from use.
05-24-2018, 04:29 PM
#103
Administrator
iTrader: (8)
Good catch.
05-24-2018, 05:07 PM
#105
I do not doubt your scale or the info. Just seems everyone else is convinced the OEM rotors are 30 pounds. I'm guessing they went off of someones posted information then just feed off of each other but no one actually checked the facts. Do a quick google search. EVERYONE claims 30 pounds, even Centric. Typically how bad information gets spread. At least know we have the truth!