speedo out by 8-10km/h

**tbdefender** · 2nd June 2013, 06:26 PM

For some reason i have a 8-10 km/h discrepancy in my speedo. 60km on the road is actually 70km on the dial and it follows up the speeds. I have an ARB air locker in the rear but would this be the reason ?(it was like this since i bought it, will fix it if i can but doesn't really bother me) does the speedo cable have a changeable gear on the input end? and where would i get something like this (I'm in SA but net shopping savvy) and also would i need more or less teeth on it?????

Any help would be awesome

Thanks

**Basil135** · 2nd June 2013, 06:32 PM

I am going to take a punt here, but I am guessing your tyres are not standard size.

Check what diameter tyres the car shipped with, and then compare them to yours. Thats probably what is throwing your speedo out...

**tbdefender** · 2nd June 2013, 06:35 PM

funny that, as soon as i posted this i thought it will be my wheel/tyre combo. Yep definitely not standard. But is there a fix?

**SiddersC** · 2nd June 2013, 07:45 PM

Change back to or close to standard

Depending on year, you may be able to fit a truspeed?

**Eevo** · 2nd June 2013, 07:52 PM

jaycar have a device

Speedo Corrector MkII Kit - Jaycar Electronics

Speedo Corrector MkII Kit

When you modify your gearbox, diff ratio or change to a large circumference tyre, it may result in an inaccurate speedometer. This kit alters the speedometer signal up or down from 0% to 99% of the original signal. With this improved model, the input setup selection can be automatically selected and it also features an LED indicator to show when the input signal is being received. Kit supplied with PCB with overlay and all electronic components.

**steveG** · 2nd June 2013, 08:46 PM

Yes, there are different speedo input gears that go in the output housing on the transfer case. They are different colours to indicate how many teeth they have. From memory the actual drive gear on the output shaft (the metal one) is the same on all LT230's so can adjust just by swapping the plastic one.

Here's the colours and tooth counts:
http://www.aulro.com/afvb/technical-...orm-gears.html

Steve.

**Cobber** · 2nd June 2013, 09:00 PM

I'm not sure how to go about rectifying it other than changing your tyres back, but I recently saw a vintage Buick with a little aftermarket digital speedo hooked up, not too dissimilar to what cyclists use.

I'm not sure where it was linked to (cordlessly by the looks) as the owner wasn't around, however maybe somebody here has seen something similar?

Tombie · 2nd June 2013, 09:29 PM

What size tyres are you running?

**stealth** · 2nd June 2013, 11:36 PM

I put 8.25 x 16 tyres on my defender and the speedo was dead accurate according to the Princes Highway speed check at Lara. Out by about 7% on 7.50 tyres.

**debruiser** · 3rd June 2013, 05:41 AM

Here's an interesting bit of information; well I thought it was interesting.

Setting the scene: I had a 07 ranger and father-in-law had a 03 bravo both showed 10% under speed at 100km/hr (meaning shows 100 - your only doing 90). I changed tyres up a size to try to fix and also to attempt better highway mileage but that's another story. I then noticed that Dad's 90 Patrol is the same! BUT my 03 focus was spot on all the way up to at least 140ish....

Did some research/light reading one day. Found out that car manufacturers have different standards (set by the Government) for speedo accuracy. Seems that cars must be spot on whereas 4x4s fall into a different category and can be out by as much as 10% under! There was heaps more jibber jabber about yada yada... but that was the message I picked up.

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