on my 521 i did the tranny swap to a 240z and when i connected the cable the mph was out of wack, so i removed it 2 1/2 years ago and haven't fixed the problem and i really want to know how fast i'm going. rite know i'm driving by following other drivers and it sucks when the streets are empty.lol

i don't got cable but i'll buy a new just need to know if i have to change the speedogear from the tranny and put the old one in?

if anybubby can help, thanx in advance

thanx mark but when i mean out of wack is that i'm barely in 1st gear and it says i'm going 50mph. i did have my wife follow along side of me to know fast i was going at 5ooorpm she told me 105mph.

it was fine with the stock 4 speed. so it doesn't make that much of the difference. i'm gonna buy a new cable. it might of been the way it was routed then. thanx

A bad cable won't make it run fast. Or slow- makes it jumpy.

Now this is helpfull! My truck has 4:11's with 33's (was 4:375 but had to change)and the speedo is REALLY wrong. Every trans I see I pull the cog, almost all are blue (3:70) even a diesel 5 spd. My drive cog is in the transfer case and all that I have pulled are blue also. So I need a black or yellow. The only black one I found was from a 4 spd. and has longer housing.

Trouble with that is it might have an optional rear end gear installed at the factory. A list would only point in the right direction, only way to be sure is to pull them and count the teeth. The Z car garage warns not to trust colour, always count teeth.

I have several blue, a red, a white and a black(but it only fits a 4 spd.)

240 w/4 spd came with 3.90
240/260 w/5 spd came with 3.364
260 2+2 came with 3.70
260 w/4 spd came with 3.364
Auto trans modles came with 3.545
Probably different ones were available from factory or may have been changed.

Went through one of those speed radars where they display your kpm. I put the speedo exactly on 50 kpm, and the radar said 58, so doudling to 100 kph or roughly 61 mph, I'm goung 16 kph x 0.621 = 71.92 or 11 mph over at 60!!

Dealer is supposed to have them, the FS5W71B was used up to at least '75. The Z Car Garage says to knock out the roll pin and remove just the plastic gear on it's little axle. The replacement goes back on the same way. The plug with the O ring that holds it in the trany stays the same. How can this be? Each gear would have a different no. of teeth and a different diameter, woulden't it. So if you used a larger diameter it would squash against the drive gear in the tailstock, a smaller one woulden't reach the drive gear.    
I'm missing something here I guess.

Also the housing or bung that holds it has a groove in it that allows a small bolt and key to hold it in place. Chrysler used to have a similer set up but the housing could be turned like a dial. The ratios were stamped on it like a clock, all you did was install it at the ratio you were useing and lock it down. As I said I have a red, blue and black... all are different diameter. I think the plug with the plastic gear should be changed as a unit. The gear would be cheap, but with the housing and all the machining and threads cut into it... even if available, $$$
Well I went back and re read the article (Datsun Z Car Garage)and it said to only change the cog so I think they are wrong or misunderstood.