Sunroof Impact on Handling

Toxicgoober · 03-29-2016, 01:01 AM

I got curious, and then got carried away, as I tend to do quite often, and ended up doing a little research/rough math that I figured y'all would find interesting. Back when I rode motorcycles daily I did a similar thing regarding why you lean on a bike when cornering, which also led to researching why sport bikes/performance cars have fatter tires, and whether they actually need them or not, as well as how total weight affects cornering and transitions.

As you can see I ask too many questions. Well this time happens to be about the relevance of sunroof weight on the roof of a car and how it might impact handling. I have to admit I was skeptical of the impact, or at least the magnitude of the impact. I personally like the look of the new Camaro's Mohawk haircut much better than the flat horizontal plane of the sunroof, but had pretty much resolved to get it anyway since it would be nice to have occasionally and probably wouldn't make much difference in handling as some have stated, or so I thought. Having completed some very rough calculations/estimations/approximations I might be changing my mind. If nothing else I at least have to admit defeat regarding my previous assumption that the weight was inconsequential.

So, here it is:

First let's assume some rough approximations, sufficiently accurate to serve the purpose of this discussion.
Sunroof weight - 40 lbs
Height of sunroof above ground - center of gravity height (CGH) + 3 feet
Weight of vehicle - 3500 lbs
CGH - 20 in. or 1.67 ft.

Each of these are rough approximations of the dimensions we will need to find out how much of an impact the sunroof located on the top of the car will have on the total system of the vehicle. I'm not accounting for an exact weight of car or sunroof, nor have I physically measured the exact CGH or height above that where the sunroof would rest. I am also not accounting for suspension height changes. This is a very simplified model for an abstract concept in a perfect situation. Note that CGH is typically about 20 or so inches from the ground for most street legal consumer cars, and more like 30 inches for SUVs/trucks. The CGH is found through difficult to achieve (for most consumers) empirical testing, including usage of scales at each corner of the car, and inclining the vehicle to a sufficient angle to measure the weight change on, traditionally, the front end of the vehicle. CG along the horizontal axis is of no concern in this example either.

Calculating the amount of force the weight of the car can potentially exhibit around the axis of the horizontal plane in a very simplistic manner yields approximately 5,800 lb-ft (CGH x Wt).

Taking the sunroof by itself, using a similarly simplistic method of calculation, yields approximately 186.8 lb-ft [(CGH + 3)(Wt)].

So, considering that the sunroof weighs only about 1% the total weight of the car, it has the potential to exhibit about 3% of the force around the horizontal axis, because of the extra leverage it possesses sitting so high up.

I didn't expect this result at all. So apparently it does make a pretty significant impact after all, and those "gimmicky" carbon fiber roofs are relevant on cars like the BMW M3. I know this was lengthy; hopefully it was interesting as well. Thanks for reading!

Sent from my iPhone using Tapatalk

Glen e · 03-29-2016, 01:30 AM

Wow....

bigdonut · 03-29-2016, 01:50 AM

Cool! Thanks for sharing! Pretty simple physics problem but nothing I would have thought about.

Toxicgoober · 03-29-2016, 02:15 AM

Quote:

Originally Posted by Glen e

Wow....

Hey I warned you haha!

BowtieV8 · 03-29-2016, 02:19 AM

So...it ruins the look a little, and negatively impacts cornering performance. And it costs extra. And it reduces interior headroom a little.

Don't get the sunroof. Got it!

vet757 · 03-29-2016, 02:27 AM

It may raise the CG, but is not something youll notice driving around the streets IMO. Perhaps something a track driver should consider, but at that point skills come into play. Personally I like the roof style without the sunroof and the extra headroom.

CamaroATL · 03-29-2016, 02:46 AM

Quote:

Originally Posted by BowtieV8

So...it ruins the look a little, and negatively impacts cornering performance. And it costs extra. And it reduces interior headroom a little.

Don't get the sunroof. Got it!

ruins the look? my car looks bad ass when my sun roof is open vs. closed, and I prefer it over the model that doesn't have the sunroof, and a hundred times more than a convertible.. speak for yourself.

fastball · 03-29-2016, 05:13 AM

Moonroof/no moonroof will not affect handling either way.

You're thinking way too deep about it.

And I'll never own a car without one after having it on my last two.

andrec10 · 03-29-2016, 06:00 AM

Take a look at this CT article...

https://www.carthrottle.com/post/sun...ce-and-safety/

Toxicgoober · 03-29-2016, 06:03 AM

Quote:

Originally Posted by fastball

Moonroof/no moonroof will not affect handling either way.

You're thinking way too deep about it.

And I'll never own a car without one after having it on my last two.

Oh I know; welcome to my brain lol. No real point to it. Just thought it was interesting to see once and for all how much it actually does contribute. It would be further interesting to see what percentage it raises the CGH in comparison to the non-sunroof model. I'll still probably get one though in all honesty. Too nice on a good day to not have that open top. Another interesting topic would be how much lower the CGH would be of the vert, even though the overall weight might be higher.

Toxicgoober · 03-29-2016, 06:06 AM

Quote:

Originally Posted by andrec10

Take a look at this CT article...

https://www.carthrottle.com/post/sun...ce-and-safety/

Nice find! Hopefully I don't get the sunroof and land upside down on a precariously placed pointy rock.

Number 3 · 03-29-2016, 06:19 AM

If you can tell the difference.....................you should have sponsors paying you to drive.

Yes, it makes a difference by adding a bit of weight up top. And yes, you are putting a hole in the roof.

But you would need to need to be really, really good to tell the difference.

The weight of the car can vary 1% car to car, if not a bit more. Comparing a full tank vs. an empty tank is over a 100 lb. difference in your own car.

So yes, it makes a difference, and no I'm pretty sure you can't tell the difference.

LesBaer · 03-29-2016, 06:48 AM

Quote:

Originally Posted by Number 3

If you can tell the difference.....................you should have sponsors paying you to drive.

Yes, it makes a difference by adding a bit of weight up top. And yes, you are putting a hole in the roof.

But you would need to need to be really, really good to tell the difference.

The weight of the car can vary 1% car to car, if not a bit more. Comparing a full tank vs. an empty tank is over a 100 lb. difference in your own car.

So yes, it makes a difference, and no I'm pretty sure you can't tell the difference.

Yes, I can tell the difference and no I don't need sponsors. If I go to the track with this car and a sunroof, I won't be able to fit my head in there with a helmet.

Yes, I can also tell the difference by looking at it as well. The beautiful roof lines are gone.

And yes, I can tell the difference in cost because scratching the sunroof not only paid for my NPP, but also saved me money down the road when it breaks, like every sunroof in every car does eventually.

If no one can tell the difference, I wonder why they don't offer it as an option on the 1LE? Because maths makes better lap times. You can't physically tell the difference between 4.0 seconds and 3.7 to hit 60mph, but for some reason it will cost you more $. This is no different.

Adding a sunroof negates 20% of the weight savings that were engineered into the Gen6 chassis. This is a car that was made to be equally at home on the track or the drive to work. If you want, get it. This is an SS after all. I just don't think your argument makes sense for the people who want to configure a top performing SS. It's called min/maxing...

motorhead · 03-29-2016, 06:51 AM

Sounds like a buddy of mine that is into guns. He spends all kinds of money for match grade compnets, expensive gun builds and countless hours playing with differnt loads on his deer rifle, not a competition gun, just to shoot quarter sized groups at 100yds. Meanwhile I use a completely stock 700bdl 270win with 49gr of 4064 and 130gr Seirra boat tail. (Did do a trigger upgrade). I shoot maybe half dollar size groups at 100yds. Guess what? The deer is still dead. When he gives me crap about my inferior weapon, I just point out all the deer it has managed to drop over the years ,and that I never lost one.

The point is that sunroof or no sunroof, it will show no real world difference on any track. I commend your attempt though. It does seem funny to me though that you are trying to find finite differences with estimated data.

03-29-2016, 01:01 AM	#1
Toxicgoober Drives: 2014 Maxima Join Date: Dec 2015 Location: Louisiana Posts: 280	Sunroof Impact on Handling I got curious, and then got carried away, as I tend to do quite often, and ended up doing a little research/rough math that I figured y'all would find interesting. Back when I rode motorcycles daily I did a similar thing regarding why you lean on a bike when cornering, which also led to researching why sport bikes/performance cars have fatter tires, and whether they actually need them or not, as well as how total weight affects cornering and transitions. As you can see I ask too many questions. Well this time happens to be about the relevance of sunroof weight on the roof of a car and how it might impact handling. I have to admit I was skeptical of the impact, or at least the magnitude of the impact. I personally like the look of the new Camaro's Mohawk haircut much better than the flat horizontal plane of the sunroof, but had pretty much resolved to get it anyway since it would be nice to have occasionally and probably wouldn't make much difference in handling as some have stated, or so I thought. Having completed some very rough calculations/estimations/approximations I might be changing my mind. If nothing else I at least have to admit defeat regarding my previous assumption that the weight was inconsequential. So, here it is: First let's assume some rough approximations, sufficiently accurate to serve the purpose of this discussion. Sunroof weight - 40 lbs Height of sunroof above ground - center of gravity height (CGH) + 3 feet Weight of vehicle - 3500 lbs CGH - 20 in. or 1.67 ft. Each of these are rough approximations of the dimensions we will need to find out how much of an impact the sunroof located on the top of the car will have on the total system of the vehicle. I'm not accounting for an exact weight of car or sunroof, nor have I physically measured the exact CGH or height above that where the sunroof would rest. I am also not accounting for suspension height changes. This is a very simplified model for an abstract concept in a perfect situation. Note that CGH is typically about 20 or so inches from the ground for most street legal consumer cars, and more like 30 inches for SUVs/trucks. The CGH is found through difficult to achieve (for most consumers) empirical testing, including usage of scales at each corner of the car, and inclining the vehicle to a sufficient angle to measure the weight change on, traditionally, the front end of the vehicle. CG along the horizontal axis is of no concern in this example either. Calculating the amount of force the weight of the car can potentially exhibit around the axis of the horizontal plane in a very simplistic manner yields approximately 5,800 lb-ft (CGH x Wt). Taking the sunroof by itself, using a similarly simplistic method of calculation, yields approximately 186.8 lb-ft [(CGH + 3)(Wt)]. So, considering that the sunroof weighs only about 1% the total weight of the car, it has the potential to exhibit about 3% of the force around the horizontal axis, because of the extra leverage it possesses sitting so high up. I didn't expect this result at all. So apparently it does make a pretty significant impact after all, and those "gimmicky" carbon fiber roofs are relevant on cars like the BMW M3. I know this was lengthy; hopefully it was interesting as well. Thanks for reading! Sent from my iPhone using Tapatalk Last edited by Toxicgoober; 03-29-2016 at 02:19 AM.

03-29-2016, 01:30 AM	#2
Glen e Retired from Car mfrs.... Drives: 2LT RS/HR-V Join Date: May 2013 Location: /Fort Lauderdale Posts: 10,048	Wow.... __________________ Glen CLICK HERE for detailing a new car: detailing for non detailers CLICK HERE for how to rinseless CLICK HERE for EASY wheel sealant

03-29-2016, 06:00 AM	#9
andrec10 Drives: 2016 Camaro 2SS 6SP/Suby Legacy 6 Join Date: Oct 2015 Location: Hyde Park, NY Posts: 844	Take a look at this CT article... https://www.carthrottle.com/post/sun...ce-and-safety/ __________________ TFPK40 Its Here! Finally came home on 3-31-16! Red Hot 2SS,6 Speed, NPP, MRC, Adrenaline Red interior, Silver Rally Stripes, NAV, Sunroof, 56W Split Spoke Wheels, Body color Hood vents, Body color Splash Guards and winter protection package. Ordered 1-28-16: 1100 2-11-2016 :2000 2-15-2016: 3000 TPW of 3/7...That went quick! 2-26-2016: 3400 Status TPW 3/7 3-5-2016 : 3800 3-8-2016 : 4300 3-11-2016 : 4B00 3-15-2016 : 4200 3-22-2016 : 4800 3-29-2016 : 6000!

03-29-2016, 06:19 AM	#12
Number 3 Hail to the King baby! Drives: '19 XT4 2.0T & '22 VW Atlas 2.0T Join Date: Dec 2008 Location: Illinois Posts: 12,172 View My Garage	If you can tell the difference.....................you should have sponsors paying you to drive. Yes, it makes a difference by adding a bit of weight up top. And yes, you are putting a hole in the roof. But you would need to need to be really, really good to tell the difference. The weight of the car can vary 1% car to car, if not a bit more. Comparing a full tank vs. an empty tank is over a 100 lb. difference in your own car. So yes, it makes a difference, and no I'm pretty sure you can't tell the difference. __________________ "Speed, it seems to me, provides the one genuinely modern pleasure." - Aldous Huxley

03-29-2016, 01:50 AM	#3
bigdonut Drives: Nothing Join Date: Sep 2015 Location: Los Angeles Posts: 148	Cool! Thanks for sharing! Pretty simple physics problem but nothing I would have thought about.

03-29-2016, 02:19 AM	#5
BowtieV8 Longtime Chevy Girl Drives: Not a VVette…yet Join Date: Apr 2015 Location: CA Posts: 152	So...it ruins the look a little, and negatively impacts cornering performance. And it costs extra. And it reduces interior headroom a little. Don't get the sunroof. Got it!

03-29-2016, 02:27 AM	#6
vet757 Drives: ^^^This Join Date: Nov 2015 Location: Virginia Beach, VA Posts: 747	It may raise the CG, but is not something youll notice driving around the streets IMO. Perhaps something a track driver should consider, but at that point skills come into play. Personally I like the roof style without the sunroof and the extra headroom.

03-29-2016, 05:13 AM	#8
fastball Banned Drives: 2017 Camaro 2SS 6MT Join Date: Aug 2006 Location: Cleveland, Ohio Posts: 4,372	Moonroof/no moonroof will not affect handling either way. You're thinking way too deep about it. And I'll never own a car without one after having it on my last two.

03-29-2016, 06:51 AM	#14
motorhead Drives: Love the one you're with Join Date: Sep 2009 Location: Downtown Charlie Brown Posts: 11,850	Sounds like a buddy of mine that is into guns. He spends all kinds of money for match grade compnets, expensive gun builds and countless hours playing with differnt loads on his deer rifle, not a competition gun, just to shoot quarter sized groups at 100yds. Meanwhile I use a completely stock 700bdl 270win with 49gr of 4064 and 130gr Seirra boat tail. (Did do a trigger upgrade). I shoot maybe half dollar size groups at 100yds. Guess what? The deer is still dead. When he gives me crap about my inferior weapon, I just point out all the deer it has managed to drop over the years ,and that I never lost one. The point is that sunroof or no sunroof, it will show no real world difference on any track. I commend your attempt though. It does seem funny to me though that you are trying to find finite differences with estimated data.

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