Top speed?

[euroZ06]

So, i popped my phone speed app and decided to do a little top speed test.

Car is a 68 charger, auto tranny, has a 440 (originally 383 car). Previous owner said it has 3.23 gears.

I dont have a tach, but it seemed that i had no more gear to go faster than 175km/h (about 110mph per phones gps speed app). Still seemed to have plenty of power left.  The wheels are 15 inch and pretty big tires (60 or 65's).

Does this mean im at 3.91 gears?

When i had my 73 charger (4spd manual) with 3.23's i was able to do almost 210km/h (130mph).

Im reading all these magazines and hear all these stories about ppl doing 140+mph, and im like "what gears are those?!)....

[MoparMotel]

I'm curious as well, my uncle was a highway patrolman and he said the 69 Polara's with the 440 would make the speedo disappear at 140+

[Homerr]

Jack up the back end and trans in neutral.  Turn the driveshaft and count the turns vs. tire to figure out ratio.

[euroZ06]

But is there any resource with top speeds for each tranny and rear diff?

I found one that puts it for 440, manual and auto and rt's as well, but doesnt list the gear ratios for those cars. And it all showed over 200km/h (like 130-140mph), so i must have really low gears...


My speedo is set up weird, its in mph, however speed is closer to km/h, but a bit less. So i burry the needle (over 150mph)... So assuming my speedo is waaaay off, perhaps those numbers are saw online were based off the speedo which wasnt accurate to begin with. But shoot, didnt dayton do like 200mph with a 440??! What kind of gears does it come with? Cause its also quick through 1/4 mile.

[ws23rt]

You are asking several things here.  Here is an example that might help.

Let's say that the max engine rpm is 6000.   Also that the transmission output is 1 to 1. (most are)  And your rear gear is 3.23 to one.   And further your rear tires are 26" in Diameter.

A 26" tire dia. equals 81.681" Circumference.--Or  6.807'----Every turn of the tire moves the car 6.807 feet.

At 6000 engine rpm/trans. output running through a reduction of 3.23 to one rear gear the tires will be turning at 1857.59 rpm.

So one tire turn is 6.807 feet and every min. (1857.59 wheel rpm x 6.807 feet =12644.58 feet per min. Times 60 min. equals 758674.92 feet per hour

So 758674.92 feet per hour divided by 5280 (feet per mile) equals  ---143.68 miles per hour.----

[euroZ06]

You are asking several things here.  Here is an example that might help.

Let's say that the max engine rpm is 6000.   Also that the transmission output is 1 to 1.  And your rear gear is 3.23 to one.   And further your rear tires are 26" in Diameter.

A 26" tire dia. equals 81.681" Circumference.--Or  6.807'----Every turn of the tire moves the car 6.807 feet.

At 6000 engine rpm running through a reduction of 3.23 to one rear gear the tires will be turning at 1857.59 rpm.

So one tire turn is 6.807 feet and every min. (1857.59 wheel rpm x 6.807 feet =12644.58 feet per min. Times 60 min. equals 758674.92 feet per hour

So 758674.92 feet per hour divided by 5280 (feet per mile) equals  ---143.68 miles per hour.----

So def not 3.23 gears then... Can u do same equation for 3.91 and 4.10 gears?

[ws23rt]

You are asking several things here.  Here is an example that might help.

Let's say that the max engine rpm is 6000.   Also that the transmission output is 1 to 1.  And your rear gear is 3.23 to one.   And further your rear tires are 26" in Diameter.

A 26" tire dia. equals 81.681" Circumference.--Or  6.807'----Every turn of the tire moves the car 6.807 feet.

At 6000 engine rpm running through a reduction of 3.23 to one rear gear the tires will be turning at 1857.59 rpm.

So one tire turn is 6.807 feet and every min. (1857.59 wheel rpm x 6.807 feet =12644.58 feet per min. Times 60 min. equals 758674.92 feet per hour

So 758674.92 feet per hour divided by 5280 (feet per mile) equals  ---143.68 miles per hour.----

So def not 3.23 gears then... Can u do same equation for 3.91 and 4.10 gears?





Yes I could but so could you. ---6000rpm divided by 3.91=1534.53------6000 divided by 4.10=1463.41.

You fill in your tire size and engine rpm as needed

[Brass]

http://vexer.com/automotive-tools/speed-rpm-calculator

[euroZ06]

So it looks like i have 4.10's ((( def not fun for the autobahn... Shit. I was hoping for a high cruising speed... Right now im rolling around at 60mph (by ear on rpm speed). Ugh, i hate changing diffs

[Troy]

That's all theoretical. The calculators don't account for drag from trying to push the car through the air. Yes, a Daytona did 200 mph on a track - but that car was a race hemi, lowered for race duty, lightened by tossing out all the consumer amenities, and geared properly. It wouldn't have done well in the 1/4 mile. Ones that are fast in the 1/4 mile aren't fast at the top end. This is mainly due to the rear axle gearing. A decent ratio for the street is a 3.23 as it will still get moving pretty well but won't rev terribly high at a decent speed. My Challenger had 3.91s when I got it and I could barely do 61 mph without it revving over 3,000 RPM. I switched to 3.23 and can cruise at 74 at the same RPM. My old Charger and Barracuda had 2.76 rear gears and cruised at around 2,400(?) at 75 mph. Taking off from a light wasn't very exciting though.

Troy

[RallyeMike]

No tach + unknown gears + unknown tires = unknown answer.

If you want to go 140 with reasonable comfort, throw in some 2.76's (assuming you have an 8-3/4 axle).

[Dino]

The fastest I've done in the 69 was a few ticks over 120 with 2.96 gears and 26"-ish tall tires. It had plenty power left but I was running out of road. I should be able to get some nice speeds with the current 3.23 gears and 28" tall tires but I couldn't say how fast exactly it can go. I think the nose will start lifting when you push it close to 140 though...

[ws23rt]

The fastest I've done in the 69 was a few ticks over 120 with 2.96 gears and 26"-ish tall tires. It had plenty power left but I was running out of road. I should be able to get some nice speeds with the current 3.23 gears and 28" tall tires but I couldn't say how fast exactly it can go. I think the nose will start lifting when you push it close to 140 though...

Agree---these cars get rather light at those speeds.  Also a point to mention is paying attention to speed ratings and condition of tires.

I had my old Hemi RR to 150mph once on a private road.  It took two lanes to keep it straight.---Never again---

[moparnation74]

The fastest I've done in the 69 was a few ticks over 120 with 2.96 gears and 26"-ish tall tires. It had plenty power left but I was running out of road. I should be able to get some nice speeds with the current 3.23 gears and 28" tall tires but I couldn't say how fast exactly it can go. I think the nose will start lifting when you push it close to 140 though...

Agree---these cars get rather light at those speeds.  Also a point to mention is paying attention to speed ratings and condition of tires.

I had my old Hemi RR to 150mph once on a private road.  It took two lanes to keep it straight.---Never again---

Nice!  Too bad we don't have that on video.....

[John_Kunkel]

'69 CHP cars had 3.23 gears and Mohawk Pursuit Radials that were about 29"+ in diameter. Plug that into your calculator and you'll find that 140 mph isn't all that difficult.

[cavemanno1]

If anything over 3.23 is bad for cruising why the factory put 3.54 and 4.10's in all the Dana 60's?Surely people wanted to do long distances and not just race around town with them.Or all Dana60 cars intended use were for mainyl for the strip?

[Mike DC]

        
The Dana 60 housing literally doesn't fit a taller (lower number) gearset than 3.54.  It's basically a truck axle.  Trucks call for lower axle gears than cars because they usually have taller tires as well as the need for greater grunt.    

People were just accustomed to vehicles that spun higher RPMs on the highway 50 years ago.  Lots of cars were sold with optional 3.55 ratios even in the 8.75 axles.   People didn't do as much everyday commuting & errands on 70+ MPH highways in those days.  They only expected engines to last 50,000 miles running well.