What's the worse factory calibrated speedo you've come across?

[burnz]

Originally Posted by davenl5l

Every car I'm stuck behind on sa country roads

only on a single lane road, different story on a duel lane road..

[au350hp]

Originally Posted by jpblue1000

No speedometer can be 100% accurate all the time. A typical tyre has 2-3% diameter through tread wear over its life. Manufacturers opt for reading high, as too close to the actual and they may be liable for fines received etc.
JP

Its a shame the Police aren't a little more aware of this fact. It would save a lot of time & money wasted at court.

[Nikked]

Originally Posted by Roostercam

Its a shame the Police aren't a little more aware of this fact. It would save a lot of time & money wasted at court.

Not sure I understand...of the police radar gets you doing 10km/h over, thats got nothing to do with the speedo reading higher then actual speed...

[davenl5l]

Originally Posted by burnz

only on a single lane road, different story on a duel lane road..

No because most of them drive in the fast lane

[burnz]

Originally Posted by davenl5l

No because most of them drive in the fast lane

exactly, the speedo don't work in the right lane..
drive faster..

[jpd80]

From 2007, the rule has been 0 (dead on) to 10% fast +4kph
No speedo is permitted to read slower than actual speed.

[mick taylor]

Originally Posted by 4stanger

Yeah/Nah.
Could have a speedo issue, but it did read near enough correct speed under 100km/h, I did get done by the police radar in a built up area, doing 70 in a 60 and that was about what the speedo was reading at the time.

https://fordforums.com.au/showpost.p...6&postcount=31

Wheels magazine test back in 1977, was where I realized the toranas had a speedo issue in the higher speed regions, not just mine ; http://planetsoarer.com/ford/fast/page7.jpg

My SL/R5000 speedo was just as spot on as my HX Sandman both had 3.08 diff and 14in wheels and both valve bounced at 200KM/H with the stock engines.

If the Torana is running 13in wheels and 3.08 diff maybe it's to do with the selection of the speedo gear that in the gearbox, mine was a green one I believe.
Maybe they were putting in a 2.78 ratio speedo gear with 13in wheels with 3.08 diff, a white speedo gear I think 2.78 was.

Sure some speedos may of been wonky ones but I can not see why they would of been as the speedo would be just the same setup Torana or the big Holden, behind the face that you see.
All the LH-X Torana's my mates had speedos were fine at reading and they were driving flat out on the highway a lot of the time.

If you work out the % difference between 3.55, 3.36 3.08, 2.78, 2.60 and then look at the wheel and tyres differences 13in to 14in, well I am sure Holden just tossed in what ever will do, as such was no real big deal back in the days. you had a red and a pink and a green a blue a white speedo gears that i can remember that I have seen for the Aussie box.

[Vesper Martini]

No wonder I'm always being held up by Subaru's

MY SZII is bang on, but only after being fitted with slightly larger OD tyres

[roKWiz]

Back in the day my old HX Sandman was out by 10km/h, a HJ 10km/h out.
At present I have a 92 T3500 Mazda truck which over reads 10km/h as well but is matched by the fuel gauge that under reads by a quarter tank. At least I never run out of fuel.

[mick taylor]

Originally Posted by 4stanger

Yeah/Nah.
Could have a speedo issue, but it did read near enough correct speed under 100km/h, I did get done by the police radar in a built up area, doing 70 in a 60 and that was about what the speedo was reading at the time.

https://fordforums.com.au/showpost.p...6&postcount=31

Wheels magazine test back in 1977, was where I realized the toranas had a speedo issue in the higher speed regions, not just mine ; http://planetsoarer.com/ford/fast/page7.jpg

Holden's with stock 253 or 308 with 3.36 diff and 14in wheels could only do about 180KM/H flat out as the stock valve springs just went into valve bounce around 5000RPM and the 308 V8 with a 3.08 ratio diff could do 200KM/H with 14in wheels.

The Torana with 13in wheels and 2.78 diff is much the same gearing as it is with a 3.08 ratio and 14in wheels.

I have that old wheels test mag still, i bought that mag when it came out.

When i got my SL/R5000 it was around 1989 and it had 14in wheels put on it and a LSD 3.08 diff and she hit 5000rpm at 200KM/H because of valve bounce and the same was true with my Sandman with a 3.08 diff, so the speedos and tacho must of been not that bad.

You could rev them stock engines out to 5500rpm but in top gear i would say that with the time span at high revs the springs start to get a shimmy by then and they lose some more tension then, so they can not hold 5500rpm for long.

[mick taylor]

Originally Posted by roKWiz

Back in the day my old HX Sandman was out by 10km/h, a HJ 10km/h out.
At present I have a 92 T3500 Mazda truck which over reads 10km/h as well but is matched by the fuel gauge that under reads by a quarter tank. At least I never run out of fuel.

What diff ratio and wheels and tyres ?

Here look at this HQ Holden service book i have says in mph
Tyre 6.95X14 and 3.08 diff ratio = 23mph @1000RPM
D70 X14 ' '= 23.2 mph ' '
F78 X14 ' '= 24 mph ' '
7.35X14 ' '= 23.4mph ' '

So tyres make a difference as well and all.

[Junkyard-Dog]

Looking back, my BA's speedo was fairly accurate. It used to tell me I was going 100km/h when I was going 97-98km/h with newish tyres.

[roKWiz]

Originally Posted by mick taylor

What diff ratio and wheels and tyres ?

Here look at this HQ Holden service book i have says in mph
Tyre 6.95X14 and 3.08 diff ratio = 23mph @1000RPM
D70 X14 ' '= 23.2 mph ' '
F78 X14 ' '= 24 mph ' '
7.35X14 ' '= 23.4mph ' '

So tyres make a difference as well and all.

I had the Sandman standard GTS rally wheels and was later shod with ER 78 steels and 3.08 salisbury.
The HJ Kingswood 202 had same wheels and tyres and standard banjo diff.
They were always out by about 10km/h @ 100km.
Had a new WB van with the same misreading speedo.