[aa406079]

Here are some (POOR) first pics

A few things to keep in mind...these are 35 series sidewalls so they're a little bit fatter than the 30s this is because I don't want to mess with the odometer and tachometer until I've worn out this initial set of tires and I'm ready to do some engine powertrain tuning ... which will include calibrating to,smaller 30 series tires on 19 inch rims ... this will also raise the effective gearing... somewhat mitigating one of the small criticisms of the M6 cars for track use ( Pobst)

The car is fresh off the truck and they just removed the spring shipping/ towing spacers so it's sitting a bit higher thqn where it will finally settle.

The wheels came in the same offsets as the OEM 20 inch and came in at 21.5 and 22.5 pounds front and rear as advertised...

Weight savings of 8.5 lbs per corner...

They feature the same offset and concavity... but the OEM'S design accentuates that concavity more because its bends and angles are more abrupt and eye catching while the new wheels bend at more gradual angles for longer distances...

I'd love to snatch up a set of 19" good reproductions of the OEM design for my winter tires...

[glamcem]

Originally Posted by aa406079

Here are some (POOR) first pics

A few things to keep in mind...these are 35 series sidewalls so they're a little bit fatter than the 30s this is because I don't want to mess with the odometer and tachometer until I've worn out this initial set of tires and I'm ready to do some engine powertrain tuning ... which will include calibrating to,smaller 30 series tires on 19 inch rims ... this will also raise the effective gearing... somewhat mitigating one of the small criticisms of the M6 cars for track use ( Pobst)

The car is fresh off the truck and they just removed the spring shipping/ towing spacers so it's sitting a bit higher thqn where it will finally settle.

The wheels came in the same offsets as the OEM 20 inch and came in at 21.5 and 22.5 pounds front and rear as advertised...

Weight savings of 8.5 lbs per corner...

They feature the same offset and concavity... but the OEM'S design accentuates that concavity more because its bends and angles are more abrupt and eye catching while the new wheels bend at more gradual angles for longer distances...

I'd love to snatch up a set of 19" good reproductions of the OEM design for my winter tires...

One of the reasons why I want to lower the overall diameter is also shorter effective gear ratio also
It looks like going with 305/30/19 and lowering the overall diameter would make the effective ratio ~3.90 .

My Apex wheels are bit on the heavy side 24.6lbs and 24.7 lbs respectively but Trofeo R tires are on the light side (28 lbs for 305/30/19 size). At some point I want to try real R comps like Z214 or R7s ..they're even lighter !! 295/30/19 and 315/30/19 R7s are the tires I am considering and they only weigh 25lbs

Since they're the outer side of the rotating mass the effects of the tires are even higher than the wheels or the rotors. Speaking of rotors, Girodisc rear rotors on the C7 Z06 are about 6lbs (and 2-3 lbs lighter for front) than the OEM rotors. Since C7 Z06 and our cars share the same exact calipers, I will see if I can use the Gen 5 hat with the C7 Z06 rings. That would give me an additional 6-7 lbs rotational mass reduction and makes it about 13-14 lbs savings on each corner. That's HUGE

Any track feedback of those wheels of you have? Are they known for heavy track use? I know they're forged but never heard of them like CCW, Forgeline, HRE ..etc

[aa406079]

I'm the guinea pig really.... Vertini and Stance wheels collaborated on this new series of fully forged aluminum wheels...

PLEASE keep me updated with your findings... I would love to knock off some more rotatational unsprung mass!

[glamcem]

Originally Posted by aa406079

I'm the guinea pig really.... Vertini and Stance wheels collaborated on this new series of fully forged aluminum wheels...

PLEASE keep me updated with your findings... I would love to knock off some more rotatational unsprung mass!

will do , Girodisc is local so if I could convince them to create a hat for our cars, it would be a great option for those who are looking for lightweight, affordable, rotational 2 piece rotors

I will keep you posted

[Corner carver]

Originally Posted by glamcem

will do , Girodisc is local so if I could convince them to create a hat for our cars, it would be a great option for those who are looking for lightweight, affordable, rotational 2 piece rotors

I will keep you posted

I'd be very interested in this also!

[Hard Parker]

Originally Posted by aa406079

New wheels and tires.... 32 lb weight savings
(Effectively closer to 100 lbs less inertia)

New Kevlar race seats ... 82 lbs weight savings

Custom rear seat delete... 26 lbs weights savings

We are down from 3740 lbs... to 3600 lbs even!

(Effectively down to approximately 3530-3540 lbs if accounting for unsprung inertia of the wheels/tires...)

On a scale yet? Havent read through thread yet so sorry if been posted

Also if weight saving was priority why a 1LE? A base 1SS weighs way less

[DjsBadger]

Originally Posted by aa406079

32 lb weight savings ... and that's unsprung rotational mass...I imagine it all behave like triple the weight savings due to less inertia to spin up and slow down...

Taiwan isn't (PRC) China.

Taiwan is not a 3rd World Country.

As a degreed engineer, the 3:1 ratio sounds high, and even if it is a valid approximation for some parts, it won't be accurate for all parts. The moment of inertia affects the energy required to spin an object.
For instance, a wheel is best approximated by the combination of a a thin solid disc plus a thin cylindrical shell. A driveshaft is very easily modeled as a solid cylinder with a given height(length). Unless the shaft is hollow, which has a different equation for moment of inertia. See link for some basic equations.
https://en.m.wikipedia.org/wiki/List...nts_of_inertia

In general, rotating objects with larger diameters such as wheels will have more of an effect than saving the same weight from a smaller diameter like a drive shaft. Think of how a skater's spin will speed up as they pull their arms and knees in towards their body. They are reducing their inertia by moving mass towards the axis of rotation, without changing weight. Also, just because one wheel weighs less than another does not mean its inertia is less. If one wheel has more mass at the center, and the lighter wheel has more weight at the outer hub, it is possible the lighter wheel could require more energy to accelerate.
That is why ceramic and carbon brakes are so beneficial in racing, they are removing mass that is located away from the center of rotation.

[aa406079]

Originally Posted by Hard Parker

On a scale yet? Havent read through thread yet so sorry if been posted

Also if weight saving was priority why a 1LE? A base 1SS weighs way less

Psssst....

.....

RTFT

[aa406079]

Originally Posted by DjsBadger

As a degreed engineer, the 3:1 ratio sounds high, and even if it is a valid approximation for some parts, it won't be accurate for all parts. The moment of inertia affects the energy required to spin an object.
For instance, a wheel is best approximated by the combination of a a thin solid disc plus a thin cylindrical shell. A driveshaft is very easily modeled as a solid cylinder with a given height(length). Unless the shaft is hollow, which has a different equation for moment of inertia. See link for some basic equations.
https://en.m.wikipedia.org/wiki/List...nts_of_inertia

In general, rotating objects with larger diameters such as wheels will have more of an effect than saving the same weight from a smaller diameter like a drive shaft. Think of how a skater's spin will speed up as they pull their arms and knees in towards their body. They are reducing their inertia by moving mass towards the axis of rotation, without changing weight. Also, just because one wheel weighs less than another does not mean its inertia is less. If one wheel has more mass at the center, and the lighter wheel has more weight at the outer hub, it is possible the lighter wheel could require more energy to accelerate.
That is why ceramic and carbon brakes are so beneficial in racing, they are removing mass that is located away from the center of rotation.

Thank you for input! I've been trying to get a ballpark answer from several sources but so far not much more than generalities...

In regards to inertia... the wheels are 1" smaller diameter... I have also chosen a wheel design with less material on the edges than the flared edges of the stock 1LE wheel... my chosen career field requires a fairly good grasp of physics fundamentals... so yes I have a basic understanding of inertia and mass... I am attempting to optimize what I can on this car...

I tried to go with a relatively conservative number based on a range of predictions... care to weigh in with a ballpark reduction percentage/figure ?

[DjsBadger]

I did a quick check online to see if anyone has writen a calculator for converting rotating mass to non rotating mass. The following link seems pretty good.

http://hpwizard.com/rotational-inertia.html#weight

I did not spend any time checking the numbers, but the way he (or she) approximated the various parts looks legit.

From the link:
Just give me the answers

Shaving a pound from your tires is equivalent to shaving at most 2 pounds of non-rotating weight. That's PER TIRE, so a pound off each tire could worth close to 8 pounds of weight reduction. For wheels, the multiplier is closer to 1.6, so saving 5 pounds per wheel (20 total) would feel like a static weight reduction of 32 pounds. For brake discs, it can be as low as 1.2. Regardless of the equivalent weight ratio, you're best off reducing weight as much as possible, as you might expect. For flywheels...you'll have to read the detailed section. Sorry.

The 2 : 1 ratio was the number I recall hearing back in the day when F1 teams first started switching to carbon fiber brake systems.

[aa406079]

Originally Posted by DjsBadger

I did a quick check online to see if anyone has writen a calculator for converting rotating mass to non rotating mass. The following link seems pretty good.

http://hpwizard.com/rotational-inertia.html#weight

I did not spend any time checking the numbers, but the way he (or she) approximated the various parts looks legit.



The 2 : 1 ratio was the number I recall hearing back in the day when F1 teams first started switching to carbon fiber brake systems.

I've been looking for something like this for a while!

Thanks much for that link!

I will amend my equivalent mass estimates with the 2:1 ratio

[aa406079]

Break in complete!

Fresh from the detail shop....

[aa406079]

Well after 5 weeks... I've put a few miles/ km's on the beast

[aa406079]

Heres a visual update on my ongoing mods...

ALP 5 x head laser jammer installed... Seems to be working well.. ( needs cosmetic finishng)




Valentine 1 detector hardwired ( already saved me two tickets)

Curb alert and front camera installed ( aural alert works great)

Got it set up perfectly... didn't go off for this curb and I cleared it





Black exhaust tips installed and muffler painted black





NPP fuse ( best 5 min reversible mod u can do on the M6)

Phone mount ( clipmount)



Finally enjoying the car now that all that's left is the seats and some trim mods for the next 12-18 months...