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Thanks,

Dude

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Thanks,

Dude

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I've never maxed out any car's top speed other than with a speed limiter (or, more often, my own fear causing me to lift the throttle!), but I'd have to think that if you're redlining, then wind resistance isn't the problem. I could definitely be wrong, though.

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I am sure the speedo is accurate a 70 MPH. And at 70 Im turning about 4000 RPM. But I am NOT sure after that.

Mikebotz, I ran the top speed calculator with a 4.11 final drive and the numbers were right on the money. However my diff is stamped as a 3.55??? In fact, its the stock diff which had never been out of the car. What the heck?

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Well, for 50% more RPMs (6000 vs 4000) wouldn't you just get 50% more speed (105 mph vs 70 mph)?

I am sure the speedo is accurate a 70 MPH. And at 70 Im turning about 4000 RPM. But I am NOT sure after that.

Mikebotz, I ran the top speed calculator with a 4.11 final drive and the numbers were right on the money. However my diff is stamped as a 3.55??? In fact, its the stock diff which had never been out of the car. What the heck?

4000 RPMs at 70 mph sounds like a lot of revolutions for a 3.55 rear end IMO.

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That's 66.66%, not 50%. If you want to double 4000, it would be 8 grand.Well, for 50% more RPMs (6000 vs 4000) wouldn't you just get 50% more speed (105 mph vs 70 mph)?

4000 RPMs at 70 mph sounds like a lot of revolutions for a 3.55 rear end IMO.

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Nope, you're wrong. Trust me, I calculate % increases all day long for my job, with salaries.That's 66.66%, not 50%. If you want to double 4000, it would be 8 grand.

I said "50% more" - which means 50% on top of what's already there. 50% of 4,000 is 2,000, so on top of 4,000 is 6,000.

To check my math, take 4000 x 1.5 (or 4000 x 150%) and you get 6,000.:thumbsup:

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Since you're using a spreadsheet, just reverse the formula and see what it pops out for a rear end ratio.

Steven

PS - Rooster, you're wrong about the percentage increase. You were looking at it backwards - you were taking 4000/6000, which is where you got the 66%.

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Thats a good idea! If I had a 3.55, then the drive shaft should turn over 3 and a half times for ever tire turn right??? If its a little over 4, then I have a 4.11????

Good idea, thanks,

Dude

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So, if it is a 4.11, then its NOT stock, but the diff housing IS stock because I decoded the stamping on it.

So, would it be better, easier to swap the rear end or put one of those aftermarket overdrive units that bolt to rear of the trans????

Or should I just not give a s---???

Dude

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My car with 355's goes over 100 in 2nd gear.

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The gears are on the in side. 4.11 gears could very easily have the stock housing.

So, if it is a 4.11, then its NOT stock, but the diff housing IS stock because I decoded the stamping on it.

So, would it be better, easier to swap the rear end or put one of those aftermarket overdrive units that bolt to rear of the trans????

Or should I just not give a s---???

Dude

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how do you drive the car? Do you like the off-the-line acceleration? Do you take it to the strip? Do you mostly cruise and roadtrip?Or should I just not give a s---???

Dude

If you don't put that many miles on it I'd say screw it and enjoy the seat of the pants feel of the taller gears.

What trani has around a 1.2 final drive ratio?

If you are sure your speedo is correct and you checked the rear ratio then your trani has about a 1.2 final drive ratio.

Weird.

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The rear is a 3.55 confirmed!!!. At 3000 rpm I am at 55. 4000=75; 5000=95

and 6000=110 maybe a little over.

The only thing it could be is the transmission.

Yellow73, If I were at 100 mph in second gear, Id be at 7000 prm.

SO, according to the numbers, my THM 350 has a third gear of 1.2 to 1 instead of a 1 to 1.

Anybody ever hear of this???????????????????????????????????????

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No.The rear is a 3.55 confirmed!!!. At 3000 rpm I am at 55. 4000=75; 5000=95

and 6000=110 maybe a little over.

The only thing it could be is the transmission.

Yellow73, If I were at 100 mph in second gear, Id be at 7000 prm.

SO, according to the numbers, my THM 350 has a third gear of 1.2 to 1 instead of a 1 to 1.

Anybody ever hear of this???????????????????????????????????????

Try this ...

Get on a highway with mile markers. Get your car to an indicated 60 mph. At a constant rate of 60 mph, you should cover that distance in 60 seconds. Your odometer should also register a mile between the markers. This should show how far off your speedometer is.

Also, have you independently verified that your tachometer is indicating the correct RPM?

Good luck! You've got something screwy going on here!

Steven

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I WAS RESPONDING TO ELDUDERINO THINKING HIS TOP SPEED WAS 136! He was virtually doubling the top speed and I was saying fine, if you can rev to 8 grand.Well, for 50% more RPMs (6000 vs 4000) wouldn't you just get 50% more speed (105 mph vs 70 mph)?

4000 RPMs at 70 mph sounds like a lot of revolutions for a 3.55 rear end IMO.

You might calculate salaries that way, but nobody calculates gear multiplication that way. Part / total = %/100

The total is 6000, the original number is 4000. 4000/6000 = 66.66%. It 's a ratio and that is proper math formula for that type of calculation.

OldVettefan, I was trying to do it "forwards" not "backwards" like this guy did.

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