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Speedometer cable difference?


haubstr

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I've only had one 510 that was an automatic converted to a 5 speed. The cable looked the same on the ends but it had a sencor inline with 2 wires coming out of it. Worked fine though :D the sencor was kinda behind the head on the fire wall.

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I am hopefully putting in my dog leg this weekend which has the speedometer hook up on the same side as the auto I took out... I thought I heard that there was something different about the speedometer gear in an auto from the manual...

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When you have them out of the car, remove the speedo drive pinions and compare them. Just remember that the the pinion is really matched to the rear end gear ratio and if the tranny or the rear end is changed the pinion should stay with the rear end regardless of which tranny you switch to. It is possible that they are identical (same number of teeth) so leave it. If the auto and the dog leg came from cars with different rear end ratios, they will be different. Datsun used different color codes to represent the different ratios...

 

Yellow....16 teeth....3.36 rear end ratio

Black......17............3.54

Blue.......18 ...........3.7

White.....19............3.9

Red........20............4.11

Purple.....21............4.375 to be sure count the teeth

 

Remember... the speedometer drive pinion stays with the rear end.

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Don't quote me on this but, I think you are in the clear. The way I remember it the only 510 auto's with different rear end gears where 68/69 so if you got a 70's model it should work. The dogleg mount is farther back so you will need to mod the tranny mount or get a experimental engineering one. I think the cable will reach to, the way I remember it is a stretch. who's speedo works anyways :)

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Just remember.. the speedo cog in the transmission is matched to the rear end ratio. For example you have a truck with 4.375 rear gears. Your transmission will have a Purple or 21 tooth pinion drive cog in it. You blow up the tranny, but have a transmission from a 280Z car which had a 3.54 rear gear and has a Black 17 tooth pinion drive cog. You need to put your Purple, 21 tooth cog in the new 280Z car transmission to keep it with your 4.375 rear end. Think of them as a matched set. Don't worry about overdrive 5th gear if changing from a 4 spd,, the cog is driven off the output shaft in the tailstock

 

You never know for sure what drive pinion is in the tranny. The original owner may have ordered an optional rear gear like a 4:11. Pull the pinion and make sure it matches yours or put your old one in.

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So I can take the speedometer drive pinion (Gear)? from the Auto and it will fit in the Dog Leg?

Thanks for the help

I can't say for sure, haven't seen one. I have one from a really old 4 spd and it is physically longer than the later 4, 5, and auto ones. Take them out and see if they are the same size, it's even possible they have the same cog too, you have to look to be sure.

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BTW I'm running a 4:11 rear end with 12.5 X 33 tires. The tires are much taller than stock and effectively lower the rear ratio way below 4:11. I have a Blue or 3.7 cog in the 5 spd and it's better but not perfect. I believe that the speedo is reading low, and I am in fact going faster than it says, so I need to have fewer teeth on the cog to make the speedo cable turn faster. Maybe a black 3.54 cog?

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Here is my delima. Here is a pic of the 2 speedometer gears next to each other... The red is from the auto and the other is from my dog leg 5-speed... I tried to put the red one in the dog leg so it will still match my rear and it won't fit...

Do I have to keep the original one in the dog leg?

Thanks

 

?action=view&current=100_0470.jpg

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Here are some cogs I have collected The tall one on the left is from a real old 4 spd. The red one on the right looks like yours. The middle one is from, I think, A 280 Z car or more likely a 720 truck. Your dog leg one looks like my middle one. Try the j/y for a 720 truck (red cog/4.11). They are soft aluminum and will squash, maybe try vice grips on the outer cover of the speedo cable to protect the threads, and wiggle it to loosen.

 

http://http://www.geocities.com/zgarage2001/z.html

Have a look here under performance tips, and down to the fourth section: transmissions... They discuss these cogs.

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