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Speedo issue


Dawgz83948

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So the speedo in my truck hasn't worked since I bought it. I replaced the speedo cable and put the correct blue gear (3.70) in the transmission. The old yellow cog was worn in the middle which is why I thought it wasn't working in the 1st place. After doing all that, the speedo still doesn't work. Has anyone had the gear in the tranny break? Or is it just a bad speedometer?

 

 

 

BTW it appears to be a 5sp 280z or zx transmission (it bolted to the l16 and l20b and to the stock driveshaft).

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D you replace just the gear or the complete pinion assy plug in?

 

 

I replaced the whole assembly. The pinion assembly itself came out of a 280zx so I assume I don't have to notch it for it to work correctly.

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The Nissan gears are not offset like some other brands. The drive gear in the transmission doesn't go bad, it's a hard gear whereas the driven gear is the soft part.

 

That leaves the cable and the speedometer itself.

 

It is somewhat common for the cable to go bad, and cause gears to the get chewed up.

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I replaced the whole assembly. The pinion assembly itself came out of a 280zx so I assume I don't have to notch it for it to work correctly.

 

280zx trannys had two types of pinions. '80 and newer won't work on earlier trannys. A '79 zx won't work on an '80 or newer. Here's how to tell what year 5 speed you have.

 

Pre '80 4 or 5 speer has the speedo pinion mounting bolt at the top...

280zzxFS5W71Btail003Large.jpg

 

'80 and newer have them at the bottom

post80sFS5W71BtailLarge-2.jpg

 

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The bolt is on top. The cable is new so I doubt the cable is bad, but I'll check it again. Won't be the first time something new is broken.

 

 

 

http://www.ebay.com/itm/370575730585?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

I bought the blue one.

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Pull the dash end off and drive down the driveway and see it the cable is turning. IF NOT....

 

You'll have to part drain the tranny to check the pinion, but I would say that the blue one is for the '80 and up 5 speed (hard to see in that picture) and the gears are not in mesh. The only way it will work is to cut a new key-way slot 180 around on the other side.

 

Compare your pinion to these two.

transcogs.jpg?t=1241995615

 

 

I swapped a diesel 5 speed tail onto my '79 zx 5 speed to get a shorter shift throw. This changed the mounting bolt position for the pinion. The fix was to just cut a new key-way. I used an angle grinder and cut off blade (and a steady hand) very easy to do and took 5 seconds. Works perfectly

 

This isn't mine but similar

pre80pinionint0post80ransmods001.jpg

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