i was down at my dealer's part shop looking up some interior stuff and i noticed something that can be ordered without any problems...

as we all know, the xB with it's shape makes it on the verge of being top heavy.

well, an idea hit me. while looking up specific parts i noticed that you can order the entire roofing panel and inner support ribs.

i asked the parts guy about it, he said "ya, it's mainly for the body shop but all ya gotta' do is cut the spot welds on the old one and just weld the new one on, real easy.". this is where i got to thinking... carbon fiber roof panel...

think about it, keep the support ribs in, use your old roofing as a starting point to make bolt or adhesive points for a carbon fiber panel. ofcourse, you'd want to have a roll-cage inside at this point but it would be a major weight reduction to the weight of the top. hell, with the roll-cage, you could probably get rid of ALOT of the support ribs up there, just enough to hold the carbon fiber panel and keep it from bowing.

what do you all think? i've seen xB's here and there that look sick with a carbon fiber over-lay on the top, but imagen an actualy carbon fiber roof panel...

after taking my headliner down and seeing it all for my self, the roof barely is a support at all and a roll cage would completely take over the support rib's job plus more. i think it would be a good "looks" upgrade while at the same time being a very nice performance upgrade.

 

Not that I, nor anyone else, would want to rain on a parade here, but that scheme would pretty much render it a track-only car.

The thing about serious, functional roll cages, is that they often interfere with how a car absorbs energy in a crash, not to mention that the cage becomes more hard surfaces to break bones on. A car with a cage pretty much requires racing seats, harnesses, and helmets. You don't want that when you have to run to the store for some eggs.

However, on a track car, that arrangement would be the bee's knees, especially with how many carbon fiber replacement panels you can get (hood, fenders, hatch, bumpers, etc).

 

I wanted to do this inbetween the two rubber ribs on the roof, no cage.. FTW!! lol

 

This has been done... twice if I remember correctly... I'll try to find pics.

(One was that camo box that went up in the house-fire)

-Ken

 

i don't care what people think when they get into my car, but i will have 5 point harness for every sitting spot. even if it's to just go to the store for a short time, ****'s be wearing a harness cause i wont have my stock seat belts anymore after the roll-cage is in *harness bars are part of the cage*.

i'd love to see those pics though! i've only seen the lay-overs, looks cool but does no fuction other then adding weight to the top. but to see an actual fuctional carbon fiber roof would be AWESOME!

from what i can see, could just cut the stock roof off the spot welds and use the mounting/spot weld edges as the adhesive/bolt spots for the new roof. use the stock roof as a mold reference.

also, those visual ribs on the rear side of the roof, is that for rear end crash strength or are they areodynamic specific or do they do no purpose other then just to be there? think if it has no purpose, why not just a clean smooth top all the way back?

 

yep the ALL Star XB had it as well as a few others back in the day...all of them said it was damn noisy in the interior

 

Ive seen this done on a white xB and the Camo, may it rest in peace.

 

been done I've also see a few, seems like a waist of time and money.

 

i'd like to see a pic of one of these settups.

and it's not really a waste at all, takes quite a bit off of our top heavy xB. i've had my own look at how the roof is connected and how it's suported and from what i'm told by body shops who have worked on the roof of the xB, it really doesn't suport much at all, the ribs under the roof panel are what suports any stress and those are hardly even holding onto the roof panel... nothing but a sticky foam that holds it together with about a half inch gap between the two.

it would be a difference between aprox 62-65lbs with the original metal panel and around 14-16lbs with a carbon fiber one.

 

I have to wonder how much weight a roll cage would add vs the weight saved by a CF roof.

 

Are you sure it would be that much weight reduction and still maintain rigidity? BTW, the CF fenders don't save ANY weight, they are heavier than the stock fenders. CF parts on these cars are mostly for appearance. You save a little weight on the hood and hatch, but not from replacing the sheet metal, but from the supports and reinforcement. But those parts are just covers, they don't really make up the structural part of the vehicle, which you're looking to mess with.







IIRC, the complaint about "noisy" was for the CF headliner...

 

depending on where you want the roll cage, how far back and what thickness of metal vs. tube sizing it would be anywhere from 100-200lbs added. this is why you do weight reduction is to counter the weight added from the rollcage and to help the power to weight ratio.

 

*nod* But what I was saying is that you are suggesting removing the stock roof & possibly supports, adding a rollcage to counter the stiffness issues, then put a CF roof on. I don't see that as someplace you'd come out ahead on weight. Also a rollcage would add weight from the floorboards up to the roof which would do nothing for the top-heavy nature of the xB.

If you're doing it for looks that is cool. But you'd honestly save a lot more high-up weight by gutting the interior and replacing the side/rear glass with lexan.

Now I'm wondering how much weight could be shaved from an xB with a serious gutting, glass replacement, door guts removal, engine accessory removal, etc.

 

i'm not going for the fenders, i know they are heavier then the stock fenders already. the hood only saves about 8lbs and really is only for looks at that point and the rear hatch only save about 15lbs and is for looks aswell. the roof panel, however, doesn't suport hardly anything at all, 0.05 inch thickness sheet metal *steel* which by my estimates and knowledge of metals is about 1.9-2.1lbs per square foot which comes out to around aprox 56-62lbs without taking into account the ripples near the rear part of the panel and the added flat spots for spot welds and the bend up towards the windshield which could very well put it around 65lbs. CF of the same thickness *which you would use thinner with multiple layers of 3 or 4 layers* of 0.05 would weigh around 0.300lbs per square foot, plus resin and clear coat would bring that around 0.500-0.600lbs per square foot. so as an average, lets say it was 0.55lbs per square foot it would come out to around 16-18lbs.

being it's the VERY top panel, that much weight reduced helps ALOT on the top heavy problems of the xB. this isn't unnecessarily meant to reduce the weight of the xB all together, but to reduce the weight off the top to lower the center point of gravity for better cornering and less chances of tipping.

 

and adding a rollcage, the only parts adding more weight would be the crossing bars on the top while the rest of the weight is based below the windows. chromoly steel isn't AS heavy as it may seem. also if it's not a track specific cage then it wont weight that much at all. lets say i used 2" tubing of a thickness of 1/4" on the walls, it's about 2.4lbs per foot, with the settup i'm going for, there's going to be about... oh i'd say about 67 feet of tubing all together which would be around 160lbs. 30lbs of that would be near the top, in otherwords, the CF roof would be countering the added weight to the top area plus saving about another 10 lbs.

 

This is not a good idea. The roll cage may protect you in a crash but the roof and it's supports ties in the A, B and C pillars. Without this. the car's body will torque and feel trashy. It will probably hurt any type of aggressive driving because of the loss of rigidity. That is why convertibles have to have a lot more support to brace the car without a roof and usually weigh more. The roll cage cannot do this and if you have ever put one in, it's heavy. I agree with Improbcat, cut the weight off of the car and it will blow away any roof cutting. Plus I don't think it looks too good.

 

as i mentioned above, the roof panel on the xB does NOT help hardly at all with the rigidity of the whole chassis in question. i'm told this by both the parts personnel AND the body shops here who have done a few of these panels already. the ribs under the panel carry all the stress, the roof panel bends and warps like a mother ef'er. a good example of this would be to drive over a rumpy road with the rumps hiting one side at a time slowly and have someone outside watching. the roof panel warps and flexes like crazy! body shops say you can take the panel right off and feel almost no difference because the ribs are supporting the stress.

th ribs arn't just poles going from side to side, they are a butterfly kind of shape and don't even connect to the roof panel. the only thing the roof panel is connected to are the outer edges while the ribs have a sticky foam spray'ed up in there which even then isn't a structural thing cause you can push your finger right through the stuff.

i'm also told by toyota that the roof panel doesn't give any safety to drivers and passengers during a roll over that the ribs, once again, take the stress. the roof panel is just sheet metal and is only designed specifically for looks.

for a good reference, anyone recall the video of the two idiots who were driving drunk, 80mph on wet roads without seat belts and rolled the xB? notice the damage that took place and notice the bend points of the roof panel. they all start and end at the ribing spots while the sheet metal was demolished BECAUSE it's not meant for protection from anything else except some debris if you were to roll over.

when i was having a problem with a rather annoying sound coming from the rear right side quarter panel, we were trying to see exactly what kind of things caused it. during some little slow test runs i remember freaking out about how much warping and flexing was happening on the roof panel over the rest of the xB and if you lived around in my area i'd happily give you the numbers of those who were helping me and all you'd have to do is ask what my reaction was...

i wouldn't consider this as a possibility unless i had already done quite a bit of my own research towards it. i know all about the importants of having the roof panel in most cases. for example, i love nissan 350Z's, i think they are a sexy car would love to see one as a targa top and have seen it done, but it ruins the strength of the whole car unless you stiffen it up your self. that is why the convertible 350Z weighs nearly 600lbs more than the coupe. but when looking at the xB, it's roofing is hardly anything at all and using CF in place of it would replace any strength the original roof had, if it does at all, without any problems at all. remember, while CF is in good health *no cracks or damage* it is twice as strong as steel yet only weighs 20% as much and the more layers you add, the stronger it gets. did you when they build sky scraper buildings that they use carbon fiber for the flooring? they do this to less'en the weight of the building and increase it's strength and durability towards massive winds and earth quacks and those buildings have a much higher level of flex and warp problems then a car does...