5 speed wanted!

[willz]

I need a 5 speed transmission for my 78 620 pickup

ive found a few around for $100-$150 and would prefer to pay in that range

i hear the 280zx has a taller 5th gear than the 720 transmission and i would prefer that for highway speed

im in portland oregon

[datzenmike]

The 720 overdrive 5th is about the same as all other 5 speeds. In the 0.881 to 0.885 range

 

The '79 zx is the same. The '80 zx has a 0.77 and the '81-'83 has 0.745 and these are the ones you want.

[willz]

so I really need help finding an 81-83 280zx 5 speed

[I'm BLUE]

Springfield,OR

 

280zx transmissions for sale

 

http://eugene.craigs...3265385409.html

[datzenmike]

 

All three are L series 5 speeds. The top two will have the high 5th gear but only if from a Z car. No way to tell by looking. The bottom one could be from a ZX but is a '79 at best and won't have the tall gears.

.

[willz]

problem is i cant drive too well on the freeways, truck cuts out pretty bad at about 55-60mph, thats all i can really get out of her. I don't even drive on the freeway anymore. Been trying to sort that issue out.

[datzenmike]

I'd fix that problem first. A five speed won't allow you to go faster.

 

You may need a new fuel filter, valves adjust, new points, wires, rotor???

[willz]

things replaced within the last month:

cap, rotor, switched to electronic pickup dizzy, wires, spark plugs, fuel pump, alternator, battery, ignition switch, starter

 

i really need to fix the hole in my muffler... and that stock carb is a pos.

i guess fuel filter is my next option... at least its cheap.

[sfmichael]

The 720 overdrive 5th is about the same as all other 5 speeds. In the 0.881 to 0.885 range

 

The '79 zx is the same. The '80 zx has a 0.77 and the '81-'83 has 0.745 and these are the ones you want.

 

Good to know....thanks. What about speedometer calibration?

[datzenmike]

The speedometer is run off the output shaft using a plastic toothed pinion gear. Just keep in mind that the pinion gear is matched to the differential ratio. If for example you have an '84 2wd 720 and you get another 720 transmission that fits, it may be out of an earlier '80. The '80 could have a 19 tooth pinion gear sized to work with a 4.11 differential while yours is an 18 tooth pinion geared for a 3.889. Simply take your pinion out and swap into the new transmission. Your speedometer is now driven by your same matching rear end ratio and stays accurate.

 

If you should add taller tires to your 720 this will throw the speedometer out by reading slightly lower than actual speed driven. To make the speedo run faster reduce the number of teeth on the pinion. If you have an 18 tooth find a 17 tooth. Every tooth changes the speedometer by 4 to 6 percent or about 2 to 3 MPH at 50 MPH.

[sfmichael]

Cool...so pretty much the same as older American cars. Super simple. :thumbup:

 

I have the mentioned '84 720 that needs a little more power and a little more gear. Is the Z trans a direct bolt-in, and if not, what mods are needed to make the swap? Do you know the fifth gear ration of the '84 5 spd from the truck? Wanna make sure it's worth the effort. Thanks for the great info!

 

Also got a 38DGES and a header for the truck that I haven't installed yet, but been reading another post that mentioned replacing the head and or engine to add more power. Are there some relatively straight forward swaps that can make a big increase in power? I love the truck but she's kinda gutless, especially since I live in Colorado @ 6000'