Will car do wheelie

[dfink]

Weighed the car after some more weight shaving activities and wound up around 1850lbs. The front of the car only weighs 600lbs. I got to thinking about it and is there any possibility of lifting the front off the ground at a pro-solo. For those who don't know pro-solo is a drag race start with a solo finish. Car is 275 RWHP and will be running 23.5X12X16 hoosier radials in the rear. I was planning on setting up a launch controller utilizing the tec3r valet function switched to the clutch.

So what do you think wheelie or no wheelie.

[oregonmon]

If you do, you will be seriously awesome and I've gott see photos!

[efhughes3]

I'm pretty sure wheelies will have a detrimental effect on the tub. Not to mention CV's, shafts, etc.

[78SCSLANTNOSE]

Can a 911 wheelie?

[aadrew10]

Why would a wheelie hurt a CV joint or drive shaft? There is no more torque going through them than with a heavy car with the same amount of power that can't do a wheelie.

There is also less bending moment on the tub than with a comparable car (same power) that is heavier. The only risk to the tub is from slamming the front end down from high up.

Interesting to think about. Let me know if I'm wrong, but give reasons.

- Andrew

[efhughes3]

Originally Posted by aadrew10

Why would a wheelie hurt a CV joint or drive shaft? There is no more torque going through them than with a heavy car with the same amount of power that can't do a wheelie.

There is also less bending moment on the tub than with a comparable car (same power) that is heavier. The only risk to the tub is from slamming the front end down from high up.

Interesting to think about. Let me know if I'm wrong, but give reasons.

- Andrew

Um, let me see......yep, you got it. The slamming thing. Lifting a front end isn't what hurts, it's that sudden stop at the end. I'm pretty sure the tub wasn't designed to take that kind of shock.

On the axles and CV's.....don't you think that if you're ramming enough torque thru the drivetrain to lift the front end, that there will be some pretty harsh loads put on the components? These just weren't designed for those types of shock load. Do a search on Juan Ruiz and his work developing a turbo drag car. As I recall, the shafts were his weakest point and the problem he couldn't move past. Heavier cars don't run 911 1/2 shafts and CV's-they typically have heavier components.

[jwetering]

I think you have a shot...but there's only one way to find out.

[NineOhOne]

Originally Posted by efhughes3

Um, let me see......yep, you got it. The slamming thing. Lifting a front end isn't what hurts, it's that sudden stop at the end. I'm pretty sure the tub wasn't designed to take that kind of shock.

Aww...flibbidy floo:

[aadrew10]

Then we can agree that having a car with enormous horsepower is bad for CV joints, regardless of whether it can pull a wheelie or not. Since his car may wheelie from being very light weight, and not from an enormous amount of power, he's good to go! Since his car is so light, the bump from setting the front end back down shouldn't be too much more than the stock version going over a big bump on the highway.


Can't wait for these photos!!

[dfink]

All points are well taken and are all really the reason for the post. I don't think I particularly want to be doing wheelies 2 feet in the air. Reason for post is to determine if it is likely or not to do it. Must be some engineering types can calcualte that sort of thing. I don't really want to be surprised. I guess the only way to know will be to try and see. If it actually does it once then I may have to change things a bit. It does have a full cage but is also a cab with removable hard top so no support there.

It would however initimidate the heck out of anybody watching. As long as it came back down before that first turn.

[sancho]

I think you should film it, I wanna see this

[wayner]

Driving down the highway in a stock 72 911, we hit a bump in the road from construction, bottomed the front suspension, bumped our heads on the roof and then stared at each other for a moment before we each blurted out "did we just do a wheelie?"

Yes we did...

[smokintr6]

This is very crude... Neglected as much as possible, and used a wheelbase that I found online, for a newer 911. you could massage this to get closer.

Found your CG as follows

(+600 x LA)-(1250 x LB)=0
(LA+LB)=7.708 ft, wheelbase

(600(7.708-LB))-(1250 x LB) = 0
4624.8-600 x LB= 1250 x LB

4624.8 = 1850 LB >>>> LB = 2.5 ft

Then resolve the moment or pure twist required at the rear wheel if the weight at the front went to 0

You would still have the weight of the car acting roughly at the CG (1850 lbs).
This force is acting about the rear wheel bearing with a lever arm of ~2.5 ft.
Therefore you would need to apply ~4625 ft lbs. of torque in the opposite direction to maintian static equilibrium...if you can hook it up.

So if you made 250 ft lbs, and picked up a 3.5 torque multilier for first gear, and whatever the final ratio is... might be able to get there, if you could get it to the ground.

Keep in mind, I'm not an engineer, just play one on the internet. AAAND this is very crude, just something to think about. Engineers feel free to correct me.

[smokintr6]

Either way, I'm sure you'll get close enough to snap som optically illuding photos.. I've got a little more ass than you do, but my car is a fat lady as well!

[mack6820]

Can you smell what the clutch is cooking?

[aadrew10]

smokintr6,

That's a good start, but doing a wheelie also depends on the height of the car's center of gravity. (the higher the CG, the easier it is to wheelie) If we can get a good estimate of the height of the CG on the car, we would be able to find out the exact torque required to pop a wheelie. It will be less than 4625 ft-lbs.

- Andrew

[smokintr6]

Andrew, sure.... And I'd imagine you could further complicate the calculations by taking into effect the rear spring rate. As the rear would squat down you would begin to rotate about the rear axle, farther reducing the moment effect of the car's mass. The more you rotate the less torque is required to maintain. Wheelie bars for the autocross anyone?

I was really just posting as food for thought... perhaps it's so off that it's misleading? Now I really want to know how much torque it would take!

-Ryan

[Richard Burns]

Why would you want to do a wheelie?
While the front is going up the car aint goin forward.
Richard,
.

[signature65]

I love the smell of race gas and tire smoke in the morning. Some things are inheriently guy things.....burn outs, wheelies, speed, and T&A......is there much more to life?

[aadrew10]

dfink,

Can you guess how high the center of gravity is?