Difference between torque and horsepower

That would have worked, when I “raced” my DKW 750 Junior, at Steamboat’90.

The Moggie three-wheeler beat me.

Uphill…:yum:

Matt, I forgot to respond to this particular point. I know you mentioned “slip” in the context of drag racers spinning their tyres a little bit whilst accelerating, which reduces ETs. I don’t know why this works, but obviously it does.

In cornering, though, I think that slip, as in slip angle, refers to the fact that the car goes in a direction that is not quite what steering input requests. As I understand it, that “slip” is because the tyre deforms so that the wheel is pointing in one direction but the tyre tread doesn’t quite match it. It’s an elastic deformation, because the wheel connects to the tread via the rubber’s elasticity. Wider tyres or shorter aspect rations reduce slip angle. I don’t think (but am not sure) that this kind of slip refers to slip of the tyre on the road, as in the drag racing example. If it does, I certainly see your point although (as in the drag racing example) I don’t understand why it works.

Precisely what slip angle is.

Best place to learn up on it…

https://www.amazon.com/How-Make-Your-Car-Handle/dp/0912656468

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I will look, Paul. I bought mine (below) circa 1981 and what little I know about handling is from that book. I read it several times back in the day. I subsequently bought several more HP books (welding, bodywork etc.) and they were nowhere’s near as impressive. It’s a great book with a large following…glad to see it’s still in print.

My only car at the time was my Corvair, and it’s section on swing axles wasn’t exactly inspirational. :slight_smile:

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Another one, maybe more useful to a person like you, who has a firm grip on physics.

Should I take it that the second book will likely be over my head as someone without a physics background? I will be ordering the other book, I’ve yet to be let down by any of the books I have seen suggested on JL

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Not at all: VanValkenburg’s book is just that more in-depth.

Personally, I’m “math-challenged,” but can muddle my way through it!

Hi Robert.I was using “slip” to describe relative motion between the tyre and the road surface rather than pertaining to suspension geometry and tyre angles…and I think the increase in friction is to do with the fact that the tyre surface adheres to the road surface and the tyre substance shears off the layer that is left on the road. It increases and is surprisingly back to level pegging at 100% slip…so the road speed is 50kph but the “naughtiness gauge” is reading 100kph!!! This has to work when a tyre is sliding sideways and rotating …it will be a combination of various vectors that has a resultant. The whole situation is also remarkably dependant of surface roughness. I had a problem a few years ago with steel parts sliding on aluminium when they shouldn’t. I had the aluminium sheet lightly garnet blasted and the difference was amazing. I had the opportunity to measure the increased mu but time pressure intervened…would have been an interesting bit of data…

NOTHING about swing axles is inspirational!

Are you sure about that? When those axles swig up in the middle of a corner I’m sure it would inspire some words of prayer to the drivers choice of god(s) :slight_smile:

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My foster father raced a Lotus 23B, and he had a home movie taken by a guy sitting in the passenger seat at speed at PBIR. At one point, they followed a Triumph Spitfire through a turn, and you can see those swing axles at work! It’s quite terrifying!

Another buddy of ours raced a 365 Porsche “bathtub” which also has swing axles. He came up with a scheme to connect a steel cable to one side of the rear suspension, over a couple of pulleys, and back down to the other side of the rear suspension. Hence, one wheel could not try to “tuck under” because it would have to lift the other wheel completely off the ground. Of course, this is a fundamental change to the function of the rear suspension, so as soon as it became popular it was banned in the Production Car Specifications. So he came up with a scheme to connect the cable to each side and run it through the roll bar so nobody could see it! If you ain’t cheatin’, you ain’t racin’!

Well I now have two books on order. I look forward to trying to muddle my own way through. Lol

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Ask away: If I cannot explain the physics, @Robert_Wilkinson can!!

I have the real world experience, he has the numbers!

Two words (the only ones that make swing axles livable): Camber Compensator.

:crazy_face:

On Formulas Vee, they use Z-bars, for zero roll resistance. Oddest damn setup…but it works!

Actually, a Z-bar does pretty much the same thing the cable does, it just has some spring to it. Another option is the cable with a coil spring in it somewhere.

I dunno what “zero roll resistance” means. They’re called Z-bars because they’re Z shaped, functioning exactly the opposite of a conventional anti-roll bar.

It means zero roll stiffness. The z-bar doesn’t quit get you there, but it’s in the right direction. A car body suspended with zero roll resistance will flop over from side to side, with no desire to stay upright. Tractors and similar often have zero roll stiffness on the front axle. One way to achieve this is to mount the body on a pivot located at the centre of a transverse spring. The spring resists up and down movement, but allows the body to flop side to side on the pivot. After Nader’s book, that’s what GM used for the rear suspension of the Corvair (lightweight coil springs were retained, though). In practice, the roll resistance of cars with z-bars or transverse springs depends on a stiff front rollbar. Cornering loads are first transferred rear-to-front, and then from outer front wheel to inner front wheel as usual. This reduces the weight jacking effect of swing axles.

Swing axles came about in rear engine cars because the diffy was part of the unified engine/transaxle and couldn’t move with the wheels, as was common. The real solution was true IRS, which Corvair introduced in late 1964, after only a single year with the transverse spring.

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That is what all modern FVs do.

GREAT, you guys have finally got everything figured out!!

I’ll still take torque over HP , let HP fall where ever it comes out at.

F1 are around 850HP ,but useless 200 torque.

for a street driven car!! NO

ron