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speedo correction

Posted: Sun Aug 02, 2015 6:37 pm
by ski
Howdy I have a 1991 ,cruiser 1hz running 35 inch silver stones and my speedo is 20km out,truck is coming up for cert on suspension work and I was thinking about speedo what do you guys do to correct this ? running lockers so don,t want to change diff ratios etc ,any ideas???. Cheers.

Re: speedo correction

Posted: Sun Aug 02, 2015 6:40 pm
by Mattman
If its a cable driven speedo you can often change the gearing to correct it. If its electronic jaycar do a correction unit.

Re: speedo correction

Posted: Sun Aug 02, 2015 6:47 pm
by derk
easiest way if you've got a bit of spare time in front of the computer is to make up a new label for the speedo on paint and print it out on some adhesive paper :D

Re: speedo correction

Posted: Sun Aug 02, 2015 7:00 pm
by ski
Jesus I have enough trouble working out how to use my sky/// . Cheers.

Re: speedo correction

Posted: Sun Aug 02, 2015 7:39 pm
by imsohi
Parrot and sons in Chch do a conversion unit if it is cable, i would ring them as they could prob sort out a elec one aswel. all we had to do was send them the difference in speeds ie GPS--->Atcual 20=25 50=58 70=83 100=116

They made up a unit and we installed was around the $300 mark

Re: speedo correction

Posted: Sun Aug 02, 2015 7:50 pm
by ski
Thanks man ,I presume its cable being such and old truck. Cheers.

Re: speedo correction

Posted: Sun Aug 02, 2015 8:18 pm
by skid
Use a gps ;-)

Have heard a couple of mechanics say that a gps is a legit speedo.
Not sure if tru, but cheap fix

Re: speedo correction

Posted: Sun Aug 02, 2015 9:19 pm
by Ashohman
i made ups some dyno labels and stuck them to the speedo just went for a drive with the gps and recorded what speeds were what cert man was happy with this ive got 50 60 70 80 90 100

Re: speedo correction

Posted: Sun Aug 02, 2015 10:04 pm
by churchill
These guys sell geared units that fit between your speedo cable and gearbox that can either speed up or slow down the cable to get the correct speed.
They reckon they have 50 ratios available(both up and down) and cost between $170-$250 depending on ratio.

http://www.robinsoninstruments.co.nz/ri_services.html

Re: speedo correction

Posted: Sun Aug 02, 2015 10:45 pm
by Mudde1
skid wrote:Use a gps ;-)

Have heard a couple of mechanics say that a gps is a legit speedo.
Not sure if tru, but cheap fix

Not True. GPS is not a legal speedo as it wont work in tunnels, deep cuttings etc.

Re: speedo correction

Posted: Mon Aug 03, 2015 3:58 pm
by mudlva
Got a reducer here
It was geared to suit 35s from ex31s
Screws onto the trans box outlet and then the speedo cable screws into the adaptor
Pretty easy
It was over a $100 if i remember
$50+courier if you are keen
Got to find it now .....