guys ,
a few times i have read about fellow 8 members dragging this car, doing hard launch's etc. One of the things mentioned is wheel hop. This car has a inherant (sic)danger associated with that. I will try to explain what I mean.
With severe wheel hop the suspension/wheel is not just moving up and down as it may seem. It is also either trying to or is actually twisting. When this is happening the angle between the differential and the driveshaft changes. This puts a strain on the U joint. If it is severe enough(and I have seen it happen many times) the u joint breaks. Now in this car we have a carbon fiber driveshaft(yea mazda!) and if it pops the ground it probaly will break. So you have spinning, bouncing SHARP carbon fiber shards slapping against one or both gas tanks. GET THE PICTURE! Its the only car I know off that has rear wheel drive and the gas tanks surrounding the driveshaft!
An aftermarket suspension (springs and bars) helps a lot with this but for safety sake if you drag this car or hard launch this car get a drive shaft loop on it..
There is probaly more people out there that know more about this than me. If I am mistaken then I'll eat crow, bow my head and say I'm wrong.
take care folks
olddragger

 

Has anyone had this happen to them? EVER? On any car I mean.

 

Mugatu,
I have! Several times. Not with the 8,b ut when I was running the muscle cars. I have seen one time in which a car at the strip broke a FRONT u joint and the driveshaft dug into the ground and it actually almost flipped the car! Most of the time its a rear joint that lets go because of wheel hop etc. In the other case the guy broke a motor and transmission mount. This car like I said has gas tanks around the drive shaft. Wheel hop plus that makes me nervous. I broke a joint in a 55 chev running a big block once and the driveshaft almost came through the floorboard. Why do you think NHRA mandates a driveshaft loop in certain classes? I dont want to alarm anyone but it is something we need to be aware of.
olddragger

 

My dad dropped his driveshaft in a ford Granada on a highway going 55.. He wasnt dragging :p You never know!

 

driveshaft safety loop is partly to prevent the car from pole vaulting if the front joint breaks, and prevent the spinning driveshaft from chopping your leg or hip off if the rear one breaks.

i would think the carbon fiber is safer than a steel driveshaft, but i dont know for sure.

james

 

ophitoxaemia,
ive seen pole vaulting(like the way you said that!) but remember the gas tanks in this car are right beside the drive shaft. yes the carbon fiber shaft will be less likey yo pole vault(still like that) and or puncture the floor board but it sure may rupture the gas tanks.! you don't want that!
olddragger

 

I've had my 8 up in the air a few time and the drive shaft appears almost completely enclosed in the structural tunnel. I surely can't see it rupturing a fuel take or vaulting the car from where it is. It looks well engineered to me.

 

yes the power plant frame SHOULD protect the gas tanks. i think. maybe....

 

I think the carbon driveshaft would cause far less damage than say, an metallic type. Imagine if there was enough force for the U-joint to snap, and a metallic driveshaft were to tear through the body. That's more of a danger. Like Ophitoxaemia said, the driveshaft hoop will render a margin of safety. That's pretty bad if you're running stock drivetrain parts, and they snap after a hard launch. But hey, I don't think the original intent of any car is to launch hard all the time. It's not an anomaly, and I worry whether the drivetrain can handle my 380 rwhp.

 

if i'm correct...i think the driveshaft is not 100% carbon fiber either..I think it still has a steel shank...surrounded by Carbon fiber..still the majority being cf but still some steel..

 

You're probably right XeRo. A driveshaft would need some weight directed towards the center.

 

This SR upgraded frame seems to beef up the OEM tunnel. Could this help in case of a problem?

 

guys
all good points. Anytime there is a possibility of something significant happening I just like to point it out. U joints can break(especially with wheel hop). Everyone remember that. If you are launching hard or planning on dragging this car get the driveshaft loop. its not that expensive and if you ever put nitrious on or fi this car they will not let you on the strip without one(and a scattershield also)
Just a point . and hopefully consider. remember it only takes one time.
olddragger

 

mazda maniac,
thanks for this info. I guess it is a little differant for independant rear suspension cars. I'M so dang used to solid rear axles I wasn't even thinking about that. Ok I will go to the back of the room now and stand in the corner! Still wheel hop is bad. If you are going to hard launch I would highly recommend getting the heavier springs and bars.
thanks guys we live and learn
olddragger