Hello, I am going to be refurbishing my 57 Chevy, and am putting in a 10 bolt rear end, right now non-positraction with 3.07 gears. It will be about 85% street, and 15% strip. I am deciding if I need a positraction carrier or not. I went to the antique drag races a few months ago, and a 32ish Ford slammed into the wall, crossing over the lane of the other car. Before he went sideways, he lost traction in the right wheel, then it seemed to correct a little, then he went total 90 degrees to the track and into the wall. His name might be "Hebrew National", because people who know him said he was a hot dog racer. Others said he has always had too narrow of tires on the car, but I am also wondering if a non-positraction rear end could also cause something like that, if the drive wheel loses split-second traction, and the other wheel suddenly is grabbing the pavement . Does anyone have an opinion? This is the type of education I prefer, that is, seeing the effects of design error on somebody else's car. I am poor in spirit and pocket.
Why would a car get "right-wheel squirrely" midway on the drag strip?
MikeMiloserdoff
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Hello, I am going to be refurbishing my 57 Chevy, and am putting in a 10 bolt rear end, right now non-positraction with 3.07 gears. It will be about 85% street, and 15% strip. I am deciding if I need a positraction carrier or not. I went to the antique drag races a few months ago, and a 32ish Ford slammed into the wall, crossing over the lane of the other car. Before he went sideways, he lost traction in the right wheel, then it seemed to correct a little, then he went total 90 degrees to the track and into the wall. His name might be "Hebrew National", because people who know him said he was a hot dog racer. Others said he has always had too narrow of tires on the car, but I am also wondering if a non-positraction rear end could also cause something like that, if the drive wheel loses split-second traction, and the other wheel suddenly is grabbing the pavement . Does anyone have an opinion? This is the type of education I prefer, that is, seeing the effects of design error on somebody else's car. I am poor in spirit and pocket.
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Can't speak for drag racing as I have never done it on the track. However I just put in a new 3.70 Eaton Posi in my 55 chevy. Did I need it, probably not, they way I drive the car but I figured since I am buy new gears anyways might as well go with a posi unit, can't hurt right.
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Positraction versus non Positraction
A non posi equipped car will track very straight, as one rear wheel will always be non powered, giving the car some directional stability. Under limited traction conditions, the right rear tire typically blazes away, while the left rear tire stays in contact with the pavement, with no spin. Having a non-posi equipped axle would not be the cause of the car darting into the wall.
A posi equipped car, under power, will be more likely to veer into the wall if the car is high powered or the traction is poor. This is because a good condition, properly functioning positraction will "lock" both axles together under hard acceleration, causing both tires to spin equally. There is no non-spinning tire to stabilize direction. However, under extreme conditions, like a car with slicks running into oil or water under one tire only, the holding power of the clutches in the differential will be overcome, allowing the tire on the very slippery surface to break loose some.
As a practical matter, if you have a street engine in your car, with a positraction axle, you should get adequate traction at the strip, and if you do break traction an engine making 250-350 HP will not usually throw the car sideways so fast that you cannot do something about it before it gets away from you.
What engine and transmission are you running? If you have an automatic, the car will tend to be easier to handle, traction wise, than a 4 speed car.
Driver.
A non posi equipped car will track very straight, as one rear wheel will always be non powered, giving the car some directional stability. Under limited traction conditions, the right rear tire typically blazes away, while the left rear tire stays in contact with the pavement, with no spin. Having a non-posi equipped axle would not be the cause of the car darting into the wall.
A posi equipped car, under power, will be more likely to veer into the wall if the car is high powered or the traction is poor. This is because a good condition, properly functioning positraction will "lock" both axles together under hard acceleration, causing both tires to spin equally. There is no non-spinning tire to stabilize direction. However, under extreme conditions, like a car with slicks running into oil or water under one tire only, the holding power of the clutches in the differential will be overcome, allowing the tire on the very slippery surface to break loose some.
As a practical matter, if you have a street engine in your car, with a positraction axle, you should get adequate traction at the strip, and if you do break traction an engine making 250-350 HP will not usually throw the car sideways so fast that you cannot do something about it before it gets away from you.
What engine and transmission are you running? If you have an automatic, the car will tend to be easier to handle, traction wise, than a 4 speed car.
Driver.
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There could be a hundred causes. Without knowing what set-up the car has it's pure speculation.
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Without knowing how that '32 was built there is no sense speculating how the accident happened. It could have been a number of things. Flat tire, broken axle, broken suspension member, anything really... Open rearends have been run for decades at the strip. Depending on how much power you are putting out I don't think you will have any issues (other then traction)... 
Mark
Mark
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Right on. That is why I essentially ignored the first question and focused on what type of handling properties he could expect between a posi and non posi diff. Many times, the guy that nails the wall hard with a lower powered car is just a cowboy and does not have the good sense to lift when it starts to go bad. No fault of the vehicle design in that case.
Driver.
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Generally light short wheelbase cars tend to be more squirrely than heavy long cars. a home built chassis with a straight axle might have spring rate and suspension geometry problems. Don Garlits had lots of problems trying to make a rear engine rail dragster handle. as stated before there are lots of factors. driver,s skill is importiant. could be something as simple as the wrong air pressure in one or both tires. Ive drove many semi trucks and some handled terribly. The long wheelbase low profile air suspension 15 year old peterbuilt was a better handling and easier driving than a brand new short spring suspension Mack. With a posi or locked rearend if you break a axle its all over. wheelstands are exciting however all else being equal they don't win drag races.
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As was pointed out above one-legger rears are safer to drive than posi's. But, as most all have done putting a posi in is well worth the costs. Open rears are lame, and you'll regret not doing it in a hotrod.
Building a stocker and just taking it out on highway cruises warrants an open rear, building a true rod means a posi is mandatory. It all depends on what kind of build you have in mind.
Building a stocker and just taking it out on highway cruises warrants an open rear, building a true rod means a posi is mandatory. It all depends on what kind of build you have in mind.
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My old truck driving buddy always running his lip (yeah hard to believe that) always saying that wheel stands prove all the power is to the ground and it cant get better.
I disagreed, Ive seen some cars just shoot straight outta the hole and fly straight as a bullet. I think, without a degree in suspension tuning that the latter is the better and more proficient, straight and gone, versus wasting power on the excessive wheel-stand,
(wheel stands are exciting however all else being equal they don't win drag races.) [/QUOTE]
I do love wheel-stands, and its obvious others do also, you seem to have experience in this arena, what say you hard, straight, fast, or wheels up ?:bowtier:
Watch a Pro Stock or similar fast drag car run. It may lift the front wheels but just barely. Lifting them more than that means you're wasting force and power lifting the front end. It also means you can't steer while the wheels are in the air. And if the car does lift the wheels, you want them to come down gently, otherwise there's more wasted motion.
I have 2 drag cars. one has a stock chassis with caltracs the other is a balk half ladder bar car. the ladder bar just shoots out on launch but the stocker lifts the front about 12 on launch. unfortunately the stocker need do do this somewhat to get weight transfer and stay stuck on the launch. taking a peg leg to the drag strip is like taking a one legged girl to a dance.
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Some of the faster Pro Stick cars demonstrate how it's done.
A huge quick horizontal leap.
Very little to no daylight under the front tires.
Hardly any wasted vertical energy.
Perfect ant-squat physics.
Some are very fast and fun to watch.
It's a beautiful thing.
Don
A huge quick horizontal leap.
Very little to no daylight under the front tires.
Hardly any wasted vertical energy.
Perfect ant-squat physics.
Some are very fast and fun to watch.
It's a beautiful thing.
Don
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248 Posts
Thanks for your well-read reply, it was very understandable. I will be using a 350 engine with about 10.5:1 compression and .515 lift on GM cast iron heads with 1.60 / 2.02 valves. NOS Crane "prior to Bankruptcy" medium street cam, Transmission will be a TH350, rear end currently non-positraction with 3.07 gears. Torque converter about 2600 RPM stall perhaps.
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