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1985 720 5 speed tranny


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5 speeds were an option on the 620 starting at the beginning of the '77 model year, so if you have one in a '76 it was put there and no easy way to tell what it has inside.

 

620 and 720 truck 5 speeds came with two sets of ratios that I call wide and mid. There is a close ratio set used in the 280zx that could be used but wasn't available on the trucks. The 4 speeds also came with these two different sets. So very simplified the 4 and 5 speeds were the same gearing but with an overdrive 5th gear added.

 

WIDE RATIO

1st.... 3.592

2nd... 2.246

3rd.... 1.415

4th.... 1.000..... 4 speeds stop here

5th.... 0.882

 

With a 3.592 first gear this helps multiply the torque for take offs on an incline with a heavy load. Specially needed with the lower torque L20B. This ratio is used in the '79 620 with the 4.11 and the '80 720 2wd with the 3.889 rear end. All year 720 4x4s and diesel pick-ups use the wide ratio.

 

 

MID RATIO

1st.... 3.321

2nd... 2.077

3rd.... 1.308

4th.... 1.000.... 4 speeds stop here The '76 would have this

5th.... 0.833

 

Used with all '77-'78 620 and '81 and up 2wd 720s. The '77-'78 had a 4.375 rear axle and the 720s after '81 had larger motors with much more torque so the mid ratio could be used on these.

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5 speeds were an option on the 620 starting at the beginning of the '77 model year, so if you have one in a '76 it was put there and no easy way to tell what it has inside.

 

620 and 720 truck 5 speeds came with two sets of ratios that I call wide and mid. There is a close ratio set used in the 280zx that could be used but wasn't available on the trucks. The 4 speeds also came with these two different sets. So very simplified the 4 and 5 speeds were the same gearing but with an overdrive 5th gear added.

 

WIDE RATIO

1st.... 3.592

2nd... 2.246

3rd.... 1.415

4th.... 1.000..... 4 speeds stop here

5th.... 0.882

 

With a 3.592 first gear this helps multiply the torque for take offs on an incline with a heavy load. Specially needed with the lower torque L20B. This ratio is used in the '79 620 with the 4.11 and the '80 720 2wd with the 3.889 rear end. All year 720 4x4s and diesel pick-ups use the wide ratio.

 

 

yea cuz i got my 5 speed off a 76 620 and its all fucked up.

 

MID RATIO

1st.... 3.321

2nd... 2.077

3rd.... 1.308

4th.... 1.000.... 4 speeds stop here The '76 would have this

5th.... 0.833

 

Used with all '77-'78 620 and '81 and up 2wd 720s. The '77-'78 had a 4.375 rear axle and the 720s after '81 had larger motors with much more torque so the mid ratio could be used on these.

 

yea cuz i got my 5 speed off a 76 620 and its all fucked up. even after being rebulit! so the mid would be better for gas mileage?

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Gas mileage is affected more by the rear end gearing than the by the overdrive gearing.

 

But .833 is better than .882 for fuel economy. The downside is a higher first gear. The differential gearing has even a bigger spread and affects all gears.

 

Also you need to consider the tires you have fitted. Very tall tires will upset the gearing of the truck.

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Gas mileage is affected more by the rear end gearing than the by the overdrive gearing.

 

But .833 is better than .882 for fuel economy. The downside is a higher first gear. The differential gearing has even a bigger spread and affects all gears.

 

Also you need to consider the tires you have fitted. Very tall tires will upset the gearing of the truck.

 

ok yea cuz ive still got the stock wheels

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  • 2 weeks later...

Just a FYI, there are several reasons why I and most people won't ship large/heavy items:

- to properly crate an engine or tranny, and then take it to a shipper takes several hours, and no one is willing to pay me for my time on top of the shipping expense since it usually doubles the 'pick-up' price for the part

- the buyer sometimes says "that's not what I wanted" when the part arrives, and then wants the seller to take the part back

- something happens in shipping and the buyer wants the seller to pay for repairs (or the seller ships a broken part and says it happened in shipping)

- some buyers want to wait for the part to arrive before they pay, and then don't pay

I've been through all of these more than once, that's why I no longer ship anything over $100, or that doesn't fit an an Express Mail box.

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Just a FYI, there are several reasons why I and most people won't ship large/heavy items:

- to properly crate an engine or tranny, and then take it to a shipper takes several hours, and no one is willing to pay me for my time on top of the shipping expense since it usually doubles the 'pick-up' price for the part

- the buyer sometimes says "that's not what I wanted" when the part arrives, and then wants the seller to take the part back

- something happens in shipping and the buyer wants the seller to pay for repairs (or the seller ships a broken part and says it happened in shipping)

- some buyers want to wait for the part to arrive before they pay, and then don't pay

I've been through all of these more than once, that's why I no longer ship anything over $100, or that doesn't fit an an Express Mail box.

 

ok yea that makes sense

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2wd

gas/z24

i believe its 26"

 

 

I have one from a 81 also but its from a l20B not sure if there the same, I deal with shipping companys all the time

 

An L transmission won't work on the Z series motor. It's also likely too long.

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Well your transmission is an unknown as the '81 didn't have an L20B in it. If the L20B was swapped in then so was the transmission. Unless you know exactly where it came from it's hard to say. Could be out of an '80 720 as they did have L motors, could be from a 620 or even a 280zx.

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Just looked the truck is and 80

 

 

 

 

I would like to look at your 1980 5 spd. transmission if you can't sell it complete, and are going to scrap it, I would like to buy the front case, as long as it is a 1980 tranny, which I can tell from one look at it.

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Just looked the truck is and 80

 

 

 

 

 

 

 

WIDE RATIO

1st.... 3.592

2nd... 2.246

3rd.... 1.415

4th.... 1.000..... 4 speeds stop here

5th.... 0.882

 

With a 3.592 first gear this helps multiply the torque for take offs on an incline with a heavy load. Specially needed with the lower torque L20B. This ratio is used in the '79 620 with the 4.11 and the '80 720 2wd with the 3.889 rear end. All year 720 4x4s and diesel pick-ups use the wide ratio.

 

 

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  • 2 weeks later...
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