4.7 5spd tranny ratios?

[4.7Jer]

Hi all! New guy here, just ordered a 2001 RC Sport 4.7 5spd. Anyone know what the transmission ratios are?

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2001RC Sport 4.7, 5spd, 3.92 limited slip

[Duner]

I don't know the actual specs, but... very low 1st, big jump from 1-2, too big of jump from 2-3, just right 3-4, big jump 4-5. It's a truck transmission. 1st gear is for pulling stumps and getting heavy loads moving. It shifts light for a truck but pretty clunky compared to a car trans. It's also very noisy... it rattles with the clutch out in nuetral at idle and whines quite a bit thru the gears. These are just my observations. I shouldn't be so harsh about it though... like I said: it's a TRUCK transmission.

Duner
'00, CC, 4.7L Sport, 5-speed, 3.92 gears, 14.87@91

[HankL]

TRANSMISSION: NV3500 - MANUAL, FIVE-SPEED OVERDRIVE

Description Synchronized in all gears
Gear Ratios
1st 4.02
2nd 2.32
3rd 1.40
4th 1.00
5th 0.73
Overall Top Gear
2.34 w/3.21 axle,
2.59 w/3.55 axle
or 2.86 w/3.92 axle


Lots and lots more Dakota technical spec's at this website that DC keeps for journalists:

http://us.media.daimlerchrysler.com/...e_dakota_e.htm

and

http://us.media.daimlerchrysler.com/...ota_spec_e.htm

[4.7Jer]

Thanks guys! I was expecting (but not really wanting) some real wide ratios. I've teased some Mustang owners about the "granny" low gear in their Tremec's. Guess it's my turn to be teased now

[Duner]

Great, thanks Hank!

Now thanks to Hank's info, I have broken down what the shifts look like in the next gear. If you consistently shifted at 5500 rpm (as an example) here's where the rpms fall to in the next higher gear:

1-2 @ 5500 = 3174 in 2nd @ 27.38 mph (2326 drop)
2-3 @ 5500 = 3318 in 3rd @ 47.41 mph (2182 drop)
3-4 @ 5500 = 3928 in 4th @ 78.57 mph (1572 drop)
4-5 @ 5500 = 4015 in 5th @ 110.0 mph (1485 drop)
without speed limiter 5500 rpm in 5th = 150.68 (dream-on)

These numbers are with my truck which has 3.92 gears (4.7L). When racing I shift it at higher rpms...as close to the rev-limiter as I can judge without hitting it. Yes that's reving it past the "sweet spot" but it sure helps when you hit the next higher gear. And no, I haven't ever gone fast enough to shift to 5th in a 1/4 mile! LOL But I have hit the speed limiter in 4th - 115 mph @ 5750 rpm!

On paper it looks like they did a pretty good job. If it wasn't a truck trans, they would be able to make 1st gear higher and get the ratios closer together. Look at that 1st gear 4.02! Just for comparison... 1st gear on the 46re automatic that's in the R/Ts is 2.45! No wonder the truck rockets across intersections!

[HankL]

Duner,

You might enjoy playing around with the Java calculator for gearshifts at this site:

http://prestage.com/carmath/dynochart.asp

You have to estimate some torques at different rpms - check out the graph for the 4.7 at the 4adodge website.

[Duner]

Originally posted by HankL:
Duner,

You might enjoy playing around with the Java calculator for gearshifts at this site:

http://prestage.com/carmath/dynochart.asp

You have to estimate some torques at different rpms - check out the graph for the 4.7 at the 4adodge website.

Thanks Hank,
I entered as many of the variables as I was able and let the calculator do the math for me. It showed me pretty much what I knew already! hehehe you have to wind it up! The only thing I really do differently is: with street tires I have to shift earlier than the calc says. If I shift as late as it says, the truck spins the tires too wildly in 2nd. Now after looking at the calc's output, that would probably be due to the GAIN of the 34 Lb/Ft of torque on that shift. With slicks on it sure makes a nice 60' showing! I might have to try shifting a little sooner (5600 instead of 5800 on 3-4 shift) based upon these results. I'll give it a try the next time out. It's my guess that with the addition of a Mopar PCM, the hp and tq curves would change a little bit and maybe allow shift points higher than 6000 rpm. Here are the results the calculator spit out:

Your best shift points are:
Best shift point for the 1-2 shift is 6000 with a GAIN of 34 Lb/Ft of torque.
Best shift point for the 2-3 shift is 5800 with a LOSS of 35 Lb/Ft of torque.
Best shift point for the 3-4 shift is 5600 with a LOSS of 15 Lb/Ft of torque.
Best shift point for the 4-5 shift is 5600 with a LOSS of 15 Lb/Ft of torque.

It's nice to see that even on paper (computer screen?) that the shift points are where I already shift at....duhh, like as high as it will wind without hitting the rev-limiter!