speedo all wrong (help)

[muchacho260z]

hey all i just finished putting a new L26 into my 260z and i  need some help with the speedo. The problem is that i am going alot faster then the speedo shows. when im going 100km/h on the speedo but im really going 125km/h on the road.

does it have to do with changing the car from auto to a 5speed.

also when i travel at 100km/h the car revs at 3000 is that ok it feels to high.

 

 

 

 

[620Z]

What sort of box did you put in. I wouldn't think a Zed should be doing 3000 revs at 100klms. That is too high. I wonder what ratio your diff is? I would have though it would be 3.9 - 3.36 if the car was running an auto. If this is the case then your gear box might be the reason for such high revs. Can someone with a normal set up for their Zed confirm their rev's at 100klms. I would have thought it would be at or below 2,500rpm. Maybe you are reading it incorrectly because your speedo is now out. I would presume that you have thought of this and at least confirmed the 100klm speed by an extranal source.

[C.A.R.]

If the Zed is a 2+2 it will have the auto ratio of 3.54 - this will show about 2500RPM in 5th at 100kph.

If it's a 2 seater 260Z it will have an auto ratio of 3.7(?) so will show slightly higher in 5th at 100kph.

[JP240z]

i show about 2000-2100?

[muchacho260z]

i have a 260 2+2 with a 5 speed i think its a F4W71B.

i really didnt think the z should rev that high at that speed.

do you think i have to change the diff.

[Zeddophile]

Pretty sure auto 2 seater diffs were 3.54.

 

However, irrelevant.  When you swapped in the manual gearbox, you forgot to change the speedo sender gear over between the two.  They have different numbers of teeth depending on the diff ratio, and they are matched to the DIFF, not to the transmission (as you'd expect, since its on the output shaft).

 

Remove the speedo sender unit from your old auto, put it into your manual gearbox, and your speedo will read as it did before.

[muchacho260z]

thanks alot for that i will try it today and ill let u know how it goes.

[muchacho260z]

i removed the speedometer driven gear but now the speedo doesn't work. i removed the speedo cable from behind the speedo to see if it would spin but it doesn't. do u think it would be the speedo meter fitted wrong.

 

 

[Zedman240®]

First make sure your speedo cable hasnt broken, take it out and check its length. Then get underneath and check the diff ratio yourself. Count how many times you turn the input shaft so one of the wheels (if you dont have a lsd) turns once. And check what color your original speedo drive gear is to the other one in the manual trans. I have been looking everywhere for a list of which color speedo drive equals what diff ratio you are using to get speedo accuracy! I went to Nissan and bought a black one coz my speedo is way out....and because its a 69er ,its in Mph. If someone has that list please let me know! it will help alot of people!! Hope that helps a little.

[muchacho260z]

i put the sender from the auto into the manu box but it doesnt turn.

i have pulled the speedo cable out and it looks good.

 

when i put the man sender back that was is the man box it works again.

do you think that the sender is stuffed or is it that im doing it wrong.

 

[Zeddophile]

I have been looking everywhere for a list of which color speedo drive equals what diff ratio you are using to get speedo accuracy! I went to Nissan and bought a black one coz my speedo is way out....and because its a 69er ,its in Mph. If someone has that list please let me know! it will help alot of people!! Hope that helps a little.

 

Grabbed from HybridZ:

 

Speedometer Cogs

 

Yellow 16 Tooth 3.364.1

Black 17 Tooth 3.545.1

Blue 18 Tooth 3.70:1

White 19 Tooth 3.90:1

Red 20 Tooth 4.11:1

Purple 21 Tooth 4.38:1

 

Used to be on another site as well, which is now dead, so now it can be here as well.  And if anyone is looking for a blue one, I'm pretty sure that's the one I have floating around in the garage (came out of a 280zx box)

 

i put the sender from the auto into the manu box but it doesnt turn.

i have pulled the speedo cable out and it looks good.

 

when i put the man sender back that was is the man box it works again.

do you think that the sender is stuffed or is it that im doing it wrong.

 

Do the units look the same apart from the gear colour, or are the housings different?

If you turn the gear in the auto sender, does the little square drive on the output side turn?

Is the square drive a different size between the two units? (I have seen that on a different model car, a change in speedo cable ends.)

 

If your speedo worked before, then the sender shouldn't be a problem, but I think perhaps the auto sender unit housing may be slightly different and put the gear in a different spot?  Can't quite remember, it was a while ago...

You may need to CAREFULLY knock the little pin out of the gear, so that you can remove the gear from the unit, and put the auto gear onto the manual sender.

[Zedman240®]

Thanks Zeddophile for that info...appreciated! With your zed muchacho260z I think you still have your 3.54 diff in place and that's why you are going 125k's at that rpm. I bought the "black" gear for manual trans with 3.5 diffs from Nissan by accident thinking its for a 4.375 diff. It sounds like it might fix your prob if you still want to run that differential. I dont think auto senders work in man gearbox's. Let me know if you want that "black" gear....