How Slow can You Go?

Theoretically, that is. A discussion on another topic got me thinking about this.

Here's how you play:

First, your car MUST have a manual transmission. Automatics have all sort of black magic going on with fluids and converters and slippage and turbines and wizards and such.

Next, calculate your slowest theoretical speed, based on total gearing through your gearbox, transfer case (if any), and final drive, tire size, and idle speed of the engine.

Example:

My '93 Chevrolet K3500 dually has a 4.11 rear, and a 6.34 1rst gear (early NV4500) and a 2.7 low range in the transfer case.

Multiply all that together and I get a 70.355:1 (rounded) deep low gear.

Tires are 235/85R16. Circumference (C) = 99.68"

Assuming a 500 RPM idle on the 454, that's 7.11 RPM at the rear axle, 7.11 * 99.68 = 708.4 inches per minute, 59.03 feet per minute, or 3542 feet per hour, or approximately 2/3 of an MPH (0.67 MPH).

How slow can YOU go?

You win

Zero, you never said I had to engage the clutch.... Mic drop.

Well.. my truck hasn't moved under it's own power since 76 so.....

But, has a stock Eaton 5:14 rear axle and 7.06:1 1st gear.

They do this at antique car shows, the driver puts his left foot outside the car/truck to show he's not slipping the clutch. It's usually the Model Ts that win, I guess they can also retard the spark.

Dan

My '14 Grand Cherokee is an automatic but it has a neat hill ascent feature.

R = 0.6 mph (1 km/h)

N = 1.2 mph (2 km/h)

1st = 0.6 mph (1 km/h)

2nd = 1.2 mph (2 km/h)

3rd = 1.8 mph (3 km/h)

4th = 2.5 mph (4 km/h)

5th = 3.1 mph (5 km/h)

6th = 3.7 mph (6 km/h)

7th = 4.3 mph (7 km/h)

8th = 5.0 mph (8 km/h)

914Driver wrote: They do this at antique car shows, the driver puts his left foot outside the car/truck to show he's not slipping the clutch. It's usually the Model Ts that win, I guess they can also retard the spark. Dan

I've seen this done at Corvair shows. They call it the "slow drags".

I don't see a whole lot of players here. You guys bad at math or something?

Damn, I get 2.43 mph at idle in 1st gear, 4LO with the Jeep (29" tires, 3.73 diffs, 2.45 first gear, 2.72 low range). Of course, it's a slushbox, so it'll be a little slower in reality due to converter slippage, but still nowhere near slow enough to win this.

When you guys learn to do this on a bicycle or unicycle we will have something worth watching.

Huckleberry wrote: When you guys learn to do this on a bicycle or unicycle we will have something worth watching.

Harley Davidson?

Robbie wrote:

Huckleberry wrote: When you guys learn to do this on a bicycle or unicycle we will have something worth watching.

Harley Davidson?

Yeah, they do that

In reply to RealMiniParker:

I picked the guy on the blue bike from the beginning.

This is America - stop this foolishness.

Delta 88

How bout fastest? 1,200 rpm idle, 25" tire, 2.93 rear, 2.95 1st gear = 10.33 mph

In reply to ross2004:

A CJ5 in low range could run easily at engine idle speed.

volvoclearinghouse wrote:

914Driver wrote: They do this at antique car shows, the driver puts his left foot outside the car/truck to show he's not slipping the clutch. It's usually the Model Ts that win, I guess they can also retard the spark. Dan

I've seen this done at Corvair shows. They call it the "slow drags". I don't see a whole lot of players here. You guys bad at math or something?

Well, yeah... also,you started the bar really high, so people aren't going to go through the trouble of calc'ing their car, knowing it won't be better than yours.

I don't know what my gear ratios are for the Land Rover or the Dodge, so I'm not playing However, my V8 Miata is geared for a theoretical top speed of 264 mph.

Keith Tanner wrote: I don't know what my gear ratios are for the Land Rover or the Dodge, so I'm not playing However, my V8 Miata is geared for a theoretical top speed of 264 mph.

Which v8 miata? That's a horrifying thought in an NA. While no stranger to triple digit speeds, 108 in my BRG scared the crap out of me. I suspect it would have been slightly better with the plastic under tray in place (and maybe a front splitter), but going down hill it felt like the front end wanted to lift off.

I'll have to research na gear ratios to answer the original question, but I'll math it out sometime today.

volvoclearinghouse wrote:

914Driver wrote: They do this at antique car shows, the driver puts his left foot outside the car/truck to show he's not slipping the clutch. It's usually the Model Ts that win, I guess they can also retard the spark. Dan

I've seen this done at Corvair shows. They call it the "slow drags". I don't see a whole lot of players here. You guys bad at math or something?

nope, but this is counter-intuituve. i prefer to spend my time seeing how fast i can go.

In reply to Trackmouse:

It's not about being better..I'm more curious what minimum speed cars are set up for. The datapoints are interesting to me.

The locomotives I work on are geared for a minimum continuous speed of 11 mph. Obviously they can go slower, but it requires pulsing the throttle. Sort of like slipping a clutch.

Well I only have Auto's (with 4lo) but im interested....

4runner 1st is 2.804, 4lo, 2.566, 3.909 diff, 102.5" circ, 600 idle = 2.07 MPH

F450 1st 3.11 lo 2.72, diff 4.30, 100.2 circ, 600 idle = 1.565

MR2 (stick) Final drive ratio 4.312, circ 72.4, 600 idle = 9.5399

I suppose I win since my ram is moving maybe a centimeter a year or so.

It just happens to be down.

ross2004 wrote: How bout fastest? 1,200 rpm idle, 25" tire, 2.93 rear, 2.95 1st gear = 10.33 mph

I'm not sure of all the gearing, but my '92 F-250 with 3.55 rear, 31" tires and five speed manual in 2-hi will idle from first gear to fifth with careful clutching, and maintain 20mph at 900 rpm...