Any 18+ GT's dailying the 4.09 rear?

[boB]

The speed of the drive shaft is dictated by the internal gearing of the transmission. So if the engine is running at 4,000 rpm, in a gear that is 1:1, the driveshaft is spinning at that 4,000 rpm. The rear wheels are spinning at 877rpm. If you down shift to 3rd, and that ratio is 1.42:1 as it is on the MT82D4, that will bring your engine RPM up to 5680, causing the driveshaft to spin at that speed, but the car will be going the same speed, because the rear wheels will still be spinning at 877rpm. (5680÷(4.56×1.42)).

If the driveshaft is spinning at 4000 rpm in 4th and we downshift to 3rd the engine will rev to 5680 but the driveshaft will still be at 4000.

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[Silver Bullitt]

If your traveling at 80 mph and accidentally downshift to 2nd vs. 4th, then engine will over rev past redline. The driveshaft dictated the engine to over rev.

No, the transmission caused the engine to over rev. The driveshaft should still be at the same rpm it was before you downshifted (assuming you are at the same speed). Come on peeps, it's really not a difficult concept to understand.

 

[Silver Bullitt]

If the driveshaft is spinning at 4000 rpm in 4th and we downshift to 3rd the engine will rev to 5680 but the driveshaft will still be at 4000.

Correct (once again, assuming the vehicle speed is constant).

 

[slink]

No, the transmission caused the engine to over rev. The driveshaft should still be at the same rpm it was before you downshifted (assuming you are at the same speed). Come on peeps, it's really not a difficult concept to understand.

I agree, it's not that difficult to understand. Upon deceleration, the driveshaft caused the transmission to rev higher and therefore the engine to rev higher. Simple physics.

The transmission transmits power either from the engine or the driveshaft. Depending if you accelerating or decelerating.

 

[Silver Bullitt]

I agree, it's not that difficult to understand. Upon deceleration, the driveshaft caused the transmission to rev higher and therefore the engine to rev higher. Simple physics.

The transmission transmits power either from the engine or the driveshaft. Depending if you accelerating or decelerating.

The transmission was merely shifted to a different ratio gear. If you want to believe that your power is coming from the rear diff/wheels, go for it. Why do you even have an engine in your car?

 

[slink]

The transmission was merely shifted to a different ratio gear. If you want to believe that your power is coming from the rear diff/wheels, go for it. Why do you even have an engine in your car?

I have the engine for acceleration purposes and I also use it as an engine brake when decelerating, I also like the engine exhaust note .

 

[GreenS550]

Rather than changing the axle ratio, have you considered changing the transmission to a '15-17? That way you are not turning the rear axle so fast constantly. I put a 4.10 in my old Bullitt and it was fine. But, it seems in our '19 Bullitts the gear spacing is just all wrong. I think in 5th at 7400 the car will be going 160 MPH. What is 6th for then, eh?
I don't know what this would do to the rev matching feature and might just be too much of a hassle. You would definitely like the better ratio, I'm sure of that. Your gas mileage wouldn't really change to speak of.

 

[FruityJudy]

Post #7 started all this clusterfuk of a thread. How about just getting the driveshaft balanced and not listening to all this bullshit

 

[Silver Bullitt]

I also use it as an engine brake when decelerating,

So, you finally realized you were wrong.

 

[bootlegger]

How do you N/A modded guys with 4.09+ rears put the power to the ground on the street? I can't get it down with 3.73s, E85, and 285 rear sticky tires.

 

[Fetlock]

Just curious, has anyone done comparisons for a manual of stock gears to 3.73 to 4.09 for 0-60 and quarter mile times? Do they make much of a difference?

 

[slink]

So, you finally realized you were wrong.

I included the engine braking to illustrate how this works.

You do realize that on electric cars, upon deceleration, the power generated by the tires is used to generate electricity to recharge the batteries. The electric motors become generators on deceleration.

 

[Sivi70980]

I thought I knew kind of how a drivetrain worked, then I read this thread, then I didn't know how a drivetrain worked, then I did, then I didn't, then I forgot everything you all talked about and I think I get it again.....

 

[boB]

Just curious, has anyone done comparisons for a manual of stock gears to 3.73 to 4.09 for 0-60 and quarter mile times? Do they make much of a difference?

It can partly depend on shift points: if we can get to 60 in 2nd gear with 3.73 but 4.09 requires a shift to 3rd then 3.73 will probably be quicker.

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