New Zealand Datsun Club

Hey team,

Sorry to make possibly an unnecessary post but a few weeks back i remember seeing a post somewhere that one of you clever whizzbangers put up regarding the speedo cogs and what way you need to go to increase/decrease speedo reading vs number of cogs on the drive.

For the life of of me i cant find the post. Can someone either post the details in here again please or direct me to where it was posted and then delete this?

Little bro's 620 ute is almost ready to go in for cert but speedo is reading 110k when hes only doing 100k. cant remember what cog he has but will get him to whip it out and then will work out what we need to get.

Also likely i am going to need the same information for my own car shortly

Cheers, Garth

I believe it was Kitch who posted about this as he needed to adjust his to get coupe a cert. I had a quick look for the post but couldn't find it. I'm also pretty interested in this as my 1200 coupe seems to be overstating the speed. Apparently last night I was going 100mph but I don't quite believe that

YELLOW = 16 tooth = 3.36
BLACK = 17 tooth = 3.54
BLUE = 18 tooth = 3.70
WHITE = 19 tooth = 3.90
RED = 20 tooth = 4.11
PURPLE = 21 tooth = 4.38

Datsun speedometers tell lies all day anyway. Even ones that are close at 100kph, quickly go right out the window as the speed increases.

Right so same trouble with my car. At 50kph I'm ready 40mph on the dash so 10mph out. Whipped my cog out and it's a 21 tooth? So I'm guessing I need to go down to
About 19? Can anyone confirm correct and does anyone have one for sale

My head hurts, aren't you heading the wrong way? Lower ratio diffs have bigger cogs by the look of that, 21 tooth for 4.__ If you give it information you are running a higher ratio diff it will think it is going even faster I would have thought, so instead of reading 40, when you want it to read 30, it will now read 50.
I have no experience of this, and have probably just made a public dick of myself proving this, as I could be reading it wrong, but that is how I read the info above. If you want the speedo to read slower you need a lower ratio drive, ie larger number, thus more teeth.
Anyone with experience able to clarify??

Yeah my head hurts now also. I think your right Vaughan. In which case it looks like I'll be hard pressed to get one with more then 21 teeth?

I am thinking you are wanting to move that way with your little wheels etc. compared with what it came out of, but once again, I have no experience so don't take my word on it.
Mr Nissan isn't known for reinventing the wheel, what drives do utes have? Vans etc.
Could be worth a look.

I was talking to E.Parrot the other day about calibrating speedo etc. They basically said to use a gps or phone app that can measure speed, and take down the readings you get from 30kph, 60kph and 90kph (I'm pretty sure that's what they said) then bring your speedo to them and they can calibrate it based on that!

Datto_610 wrote:I was talking to E.Parrot the other day about calibrating speedo etc. They basically said to use a gps or phone app that can measure speed, and take down the readings you get from 30kph, 60kph and 90kph (I'm pretty sure that's what they said) then bring your speedo to them and they can calibrate it based on that!

Oh mean! Someone had mentioned them but wasn't sure if they still existed! I'll sort that and get in touch with them! Cert man didn't mention any issue with how far my one is out but it would be nice to have it accurate!