Big Wheelies - good or bad ?

Big Wheelies - good or bad ?

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Discussion

Benni

Original Poster:

3,510 posts

210 months

Monday 14th October 2013
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Hi DragHeads,

I like a good wheels-up launch from a car, have only seen it from the outside

and can only imagine what it looks / feels like from the driver´s seat.

When wheels lift, I think "yes, good weight shift and hooking up correctly", no time wasted there.

From the technical point, it is truly fascinating, because what is happening is that the little crown wheel

inside the rear axle is actually trying to climb up the pinion gear, and lifting the whole weight of the

car in doing so, regardless of vehicle weight and that big iron/alu lump up front.

All this stress on some square inch(es?) of gear contact patch, just WOW.

One of my FIA co-speakers at Hockenheim is Hendrik Modigh, also running Tierp track Radio

and specialising in rear axle gear adjustment for over 30 years, he left one evening and told me

that he has to help a Pro Stock Team because their axle gears "were not friendly to each other".....

But when do big and long wheelies become ineffective, because the power used up in lifting the car

is not used for pushing it forward, or is any (safely and straight landed) big wheelie a good wheelie ?

Yes, I am especially thinking of the Super Stockers, but some other cars in different classes have that habit, too,

do Drivers actually want that or are they eventually trying to tame the uprisal ?

Another thing I noted was that in a wheelie Situation, I can see diffent ways of body behaviour,

some cars stay horizontally straight (as in the relationship between "grille" and asphalt)

while others get all twisted up, is that due to too much torque or bad rear axle alignment ?





dorrisdormouse

127 posts

150 months

Tuesday 15th October 2013
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I think part of the thing where cars stay level or twist while wheeling is about chassis setup. I seem to recall Chris Isaacs building the rear suspension setup on his Vanguard specifically to avoid it. All to do with the torque of the motor. Wheelies look cool, and as you say you know you have the weight transfer so your maximizing your traction - but I guess that you are wasting energy climbing the ring rather than pushing you forward. Also it can be quite unsettling if you hit the wheelie bars hard, and your control is limited.

dorrisdormouse

127 posts

150 months

Tuesday 15th October 2013
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I guess also that a certain amount of spin is good for your driveline. It softens the stress running through all components.

Rat_Fink_67

2,309 posts

205 months

Tuesday 15th October 2013
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Twist is all down to chassis yeah. The torque of the motor tries to drive the left hand tyre down through the track, as it can't the chassis then rotates the opposite way around the driveshaft, which is why the left-hand front tyre comes up even though the motor is spinning in the opposite direction (a good example is to take a ruler or stiff rectangular piece of card, hold it in the centre then twist the rear left corner down - see what effect it has on the opposite end). We suffered quite badly with it in our old Camaro; the box section chassis was pretty easily overwhelmed by the motor and used to really pick the front left up. It made for great photos but fitting an anti-roll bar to counteract it actually shaved us off a decent chunk of 60ft time, from a 1.15 down to a 1.10 on average.

Once you get to certain power levels, you actually tune in and engineer controlled tyre-spin. Dead hook a car from Pro Stock upwards and all it will do is send the driver blind from tyreshake. All the pro (and high horsepower sportsman) cars tread the tightrope between spinning the tyres to build up wheelspeed, being too aggressive and actually breaking traction altogether and the opposite end of the scale being a dead-hook wherefore the tyre wads up, drives over itself and tries to shake the car to pieces. This is why getting the chassis, clutch, ignition timing, fuel delivery etc etc just right is so critical to getting a "big car" down the track. Not as easy it appears. With doorslammers it's even worse because you throw suspension in to the mix; as soon as you try to leave all the axle wants to do is disappear up it's own arse and in to the back of the car. Next time a pro mod goes in to shake, clicks it off and the person next to you tuts because they were expecting a 5 second pass on a 10 degree track, poke them in the eye.

Lower horsepower cars don't suffer as much as there isn't enough horsepower to cause a tyreshake situation, for those cars then optimum traction is usually the best way from A to B,so that no grunt is wasted. It's true though that whilst you're going up in the air you're not moving forwards. A high horsepower dragster is usually an example of how to leave the line in the most efficient way possible, skimming the front tyres slightly and motoring forwards.

ribaric

262 posts

174 months

Tuesday 15th October 2013
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I know that Rick McCann and Carla Pittau both like their cars to wheelie, super-stock style, indeed they built and set up their cars to do just that. It is also an advantage to them to get a solid hook, the absence of tyre spin reduces the variation in ET as it's unlikely they will spin exactly the same amount each time, this helps with the dial-in accuracy. That's much tougher for Super-Pro door-slammers, some of whom who can ill-afford the loss in ET so they are at a disadvantage to the dragsters ... all else being equal.

Camaro

1,415 posts

174 months

Wednesday 16th October 2013
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Speaking of Heaven and Hell, this was an impressive effort in Sweden this year...

http://youtu.be/p2-dc9TLd0k

Benni

Original Poster:

3,510 posts

210 months

Wednesday 16th October 2013
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Thanks for the answers so far, some good insights and first-hand experience there.

themadwelshman

122 posts

139 months

Tuesday 22nd October 2013
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http://www.flickr.com/photos/the_madwelshman/57113...

Large out of control wheelie from an altered!

Flying Phil

1,578 posts

144 months

Wednesday 23rd October 2013
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Interesting question - As an oldtimer here is another personal perspective. When we built our Altered in 1976 around a straight six Alfa Romeo 2600 engine we set the engine back as far as the rules allowed (25% of wheelbase to the front spark plug). We shortened the gearbox tailshaft and used a UJ to connect to the diff - no propshaft. It was only a 90" wheelbase (Sprite plus 10")to keep the car as small as possible and use the existing fibreglass front and back end!
All that was to get as much weight onto the rear wheels. Initially it was fine as the second hand ex racing car treaded tyres just spun when we produced power!
Then I had the axle narrowed, and polished Woolfrace wheels with SH M&H slicks fitted (Thanks to Vince Shaw Ex Alkymist dragster).
Suddenly I had traction off the line......and the front went up - and up!! I thought "Must let it down gently so don't back off quickly....anyway it came down, I waggled the steering - it seemed ok so I got back on the throttle.
When I got out back in the pits I discovered the front wheels had about 15 degrees of camber - the front axle was like a banana!
So a new stronger front axle was made and telescopic wheelie bars fitted with 6 valve springs and friction damping.
This arrangement worked well as it allowed 2 foot wheelies - As the car was never the quickest in Junior Comp I thought it would at least be watched off the startline with its wheels in the air!

Later when I fitted the Rover V8 and TR7 bodyshell it still wheelied


nitrousnige

3 posts

155 months

Monday 23rd December 2013
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Wheelies good - sorry, had to be done.....

Photo courtesy of Ivan Sansom and Rose Hughes

Edited by nitrousnige on Monday 23 December 20:10

themadwelshman

122 posts

139 months

Sunday 30th November 2014
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themadwelshman

122 posts

139 months

Monday 1st December 2014
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and another one that nearly ended in disaster!

https://www.flickr.com/photos/the_madwelshman/1514...

Upatdawn

2,182 posts

147 months

Wednesday 31st December 2014
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its not the going up that hurts, its the landing

having said that, two biggest ive seen....Lex Joon TF and Mickey Naylor FED TF....


Turn7

23,504 posts

220 months

Wednesday 31st December 2014
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Peter Wacker for the win surely ?

Upatdawn

2,182 posts

147 months

Thursday 15th January 2015
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Turn7 said:
Peter Wacker for the win surely ?
Nah...... Medicine Man/Mickey Naylor