Stupid drag racing question, but I'm not proud .....

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'70_Duster_340

'70_Duster_340

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How come when I see cars hooked up at the strip, it's always the left front wheel that lifts into the air first at launch ???

I'm sure there's a simple answer, so go easy on me guys :-#

Kenny
 
The motor spins to the clockwise (if your sitting in the car) so every else spins that way also causing the car to roll over to the right and pull the left front wheel up first. But if the car has a stiff chassis they will lift more level.
 
AdamR said:
The motor spins to the clockwise (if your sitting in the car) so every else spins that way also causing the car to roll over to the right and pull the left front wheel up first. But if the car has a stiff chassis they will lift more level.
Click to expand...

Yup, torque of the engine trying to tear itself out of the driver side engine mount and sometimes succeeding.

Terry
 
An old tech school teacher allways said "there is no such thing as a stupid question" Don't feel bad about asking someone if you don't know.

Toolmanmike
 
toolmanmike said:
An old tech school teacher allways said "there is no such thing as a stupid question" Don't feel bad about asking someone if you don't know.

Toolmanmike
Click to expand...

The way I heard it was,There is no stupid question but the one you didn't ask !!! If you look at a lot of racers,you will see either solid motor mounts (vibrate your car like crazy) or Torque staps that tie the drivers side down when you get on it !!! It's also a great way to tell if you have a broken motor mount !!!Lifts too high when you put it in gear and step on the gas slightly,or for the passenger side, put it in reverse and step on the gas slightly !!Plus it will also tell you if your tranny mount is bad !!! Hope this gives you a little more info !!
 
toolmanmike said:
An old tech school teacher allways said "there is no such thing as a stupid question" Don't feel bad about asking someone if you don't know.

Toolmanmike
Click to expand...

Absolutely right! There are no stupid questions. That's one of the things that makes FABO what it is. I know there has to be at least one other person out there that was wondering the same thing. Any other questions ... ask away.
 
Just to clarify. The crank in the motor spins clockwise as you view it from the front. The reason the left wheel rises is because the torque of the motor trying to spin in the opposite direction of the crankshaft is restrained by the motor mounts & lifts the frame on the left.
 
AdamR said:
The motor spins to the clockwise (if your sitting in the car) so every else spins that way also causing the car to roll over to the right and pull the left front wheel up first. But if the car has a stiff chassis they will lift more level.
Click to expand...


what happens when the front right wants to come up first?


myride_baby.jpg
 
...and the water spins the other direction going down the tub drain 'down under' as well.
 
Get a really good balance job on your engine and you won't have that vibration with solid motor mounts. I ran solid mounts in my old '69 340 Swinger years ago and hardly had any engine vibration at all. Or maybe I just didn't notice it because of the nasty cam I was running at the time. Anyway, it was fun and I was 30 years younger. Think I'll build another and do it again!
 
'64 Cuda said:
Just to clarify. The crank in the motor spins clockwise as you view it from the front. The reason the left wheel rises is because the torque of the motor trying to spin in the opposite direction of the crankshaft is restrained by the motor mounts & lifts the frame on the left.
Click to expand...


One of these is used because of that.

Barracuda444-vi.jpg

One end bolts solidly to the engine, the other end is rubber insulated, but attachs to the drivers side of the K frame. This prevents the engine mount from seperating and pulling out of the frame from the torque. They sell blow-proof mounts that have either a bolt going throught from top to bottom, or are designed to interlock if the rubber fails. You could also install a torque strap, like I did. Especially with a 4 speed car, where a mount failure could cause the Z bar to bind, or pop out... and give you more headaches. Besides a nice dent in the hood from the air cleaner wedging against the bottom of the hood. :toothy10:

But this twisting motion wants to yank the left front tire first.
 
LOL!!!!!!!!!! That's a good low-buck approach that works well. Been used time and again and works as effectively as it looks like it will. Save yourself some cash too!
 
I personally like the motor plate s over the solid mounts as engine sits lower in the chassis with the solid mounts. I run 1/4 thick industrial rubber between plate to frame and always run a rubber trans mount. cut water pump housing down 1/4 inch for correct pulley alignment and you have a pretty smooth ride .the ss springs compensate for this driver side lift and keep both tires planted equally due to the bias of spring segment locations for each side. I street drive my dart on occasion and get no vibration with 600 plus hp at the rear wheels
 
6pakattack,
You stated above that it would also indicate your tranny mount was bad. What are the symptoms of a bad tranny mount?
Thanks,
C
 
The scientific explanation is down to Mr Newton -

"For every action there is an equal and opposite reaction"

.....and Goody - although our water does twist the other way down the plug hole, our Mopars still lift the front left - :bootysha:





and just so 70 Duster gets the full story -

As the motor spins the crank in a clockwise direction - the pinion wants to "climb" the crown wheel (this is the "opposite reaction" bit)

Of course the pinion cant move, so three things happen:

1. - The right side of the axle starts to twist UPWARDS into the wheel well (This is why the right wheel in a single spinner is the one that skids)

2. - The frame twists full length in the opposite direction to the engine rotation - as the housing resists the "twisting" energy -

3 - it also causes the axle housing to "rotate" across its length - so we use a snubber and caltracks or whatever to stop it twisting and trying to lift both back wheels off the tarmac. This is why Chebbies "squat"


So going back to 1 and 2 - Mr Newton comes to the party again, and as the right wheel raises, the rear right qtr of the car drops, the chassis twists even more and the left front comes up.

Now IF the rear end is tied down with a snubber and clamps, the "torsion" created by the pinion wanting to climb up the crown wheel is transferred back up the frame and the left front corner twists anyhow.

Of course this is why we stick the battery on the RIGHT side in the trunk - with the car wanting to pick up its right wheel, the more weight on that side keeps the wheel pinned down to the asphalt.

(A lot of folks see the left rear side go higher, and think thats the side that needs traction - In reality, the left side is reacting to the right rear wheel trying to "pick up" - like a "see saw" or fulcrum)

Now onto # 3 -

Newton also effects whats happening with the diff housing as well - Not only does the pinion rotation cause the right wheel to lift, but the twist of the housing is like a horse "pig rooting", its trying to lift both wheels off the road, so we limit the pinion rotation.


At least thats the way we "Aussies" understand it anyhow, :D
 
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