in accurate speedo reading

[monroc]

Hello everybody, I just had a replacement 4 speed auto gearbox fitted in my au falcon ute . now the speedo is around 1o k's fast also the acceleration does not seem as it was... The gearbox that was in my ute came from a series 3 au ghia (i bought a wreck which from memory was a tickford just wondering were there different ratios between models i am really unhappy about it but i am not sure what box was fitted thanks everone

[arm79]

Apart from running and model specific design changes those 4 speed autos are basically identical internally, ratios included, since they were first installed in the EA in 1989 till they went in the last gas FG, whenever that was. 2010/2011 maybe.

From an AU perspective I believe they are identical in every way from AU1 to AU3.

In regards to the speedo problem, it will likely be because you didn't change the speedo drive gear over when you swapped the box. Which hopefully you didn't because it will make everything I write next moot.

On the drivers side extension housing of the box you will find this sensor bolted into it:





The gear attached to it, green in this case, is specific to the diff ratio and tire size and simply clips on.

Hopefully you still have your old trans as you'll need to swap the gear from the old to the new. I'm not familiar with the colours used on an AU, but there are 8 different ones from memory. Willing to take a punt the one from the AU3 ghia will be black or grey. But couldn't guess what your old one is.

Whether you swap just the gear or the whole speedo sensor is upto you. Just matching the right gear with the diff/tire combo is whats important. That will fix the speedo.

It's also possible this is causing what you feel is poor acceleration. If the computer thinks the car is going faster than it actually is, it will be shifting up earlier. Might give the impression the car feels slower because its not hanging onto gears as long.

[SteveM]

Hi, It's Steve here at Maldon in central Vic. I have an AU 2 ute and the speedo consistently reads 10 KPH below the road speed; I have checked this with a Tom Tom GPS that "lives" in another vehicle. Don't know if this is any help - I'm not much of a mechanic, but I don't think that under any circumstances we can rely on speedos for accuracy much these days, and I have had a ticket 9another vehicle) to prove it! Doubt that this info is much help, but is offered just the same.
Cheers

[mad2]

Originally Posted by SteveM

Hi, It's Steve here at Maldon in central Vic. I have an AU 2 ute and the speedo consistently reads 10 KPH below the road speed; I have checked this with a Tom Tom GPS that "lives" in another vehicle. Don't know if this is any help - I'm not much of a mechanic, but I don't think that under any circumstances we can rely on speedos for accuracy much these days, and I have had a ticket 9another vehicle) to prove it! Doubt that this info is much help, but is offered just the same.
Cheers

have you changed your diff ratio? [ or speed pinion gear?] as i think my old AU was the other way re speedo[?]. i remember that at 103 on the dial i would be doing 97 actual. this was speed checking with the speed check on the Princess hwy. when i changed the diff ratio from the standard 3.23 ratio to the 3.45 ratio my speedo reading got closer to my actual. so when i was doing 101 on speedo my actual was 100. i didn't change the gearing for the speedo sender & was glad when i found out how much it had changed & which way.

my current BA is 'about' 1/2 k's the other way ie 100 actual is approx 101/102 k's.

[SteveM]

Nope, haven't changed anything. Bog standard AU 2 Tradesman with added sump guard off RTV, that's it.....................
Cheers
Steve