Speedometer Calibration

[dquintal]

hey guys this is my first post so im not sure if im doing it right or not haha

Was just wondering, im thinking of buying some 18" rims for my VS and it just has the standards rims on it atm, I think they are 15"

I just wanted to know if I have to get my speedometer calibrated or will it still be correct?

ps. the new wheels are 235/40r18 if that makes any difference

 

[hako]

Try this link: Tyre Size Calculator - Changing Tyres - Etyres

Also welcome to the forum!!!!

 

[justbad4you]

YES YOUR SPEEDO WILL BE OUt, i had 16in on my old ute and the speedo was saying 60 when the gps was saying 54 ,my 16in weels made the speedo out by 6kmh ( in my favor) if you go all the way up to 18in your speedo willl be out more, also you may need a camber kit for the 18inch ( i didnt need the kit with 16inch)

hey guys this is my first post so im not sure if im doing it right or not haha

Was just wondering, im thinking of buying some 18" rims for my VS and it just has the standards rims on it atm, I think they are 15"

I just wanted to know if I have to get my speedometer calibrated or will it still be correct?

ps. the new wheels are 235/40r18 if that makes any difference

 

[Jxfwsf]

YES YOUR SPEEDO WILL BE OUt, i had 16in on my old ute and the speedo was saying 60 when the gps was saying 54 ,my 16in weels made the speedo out by 6kmh ( in my favor) if you go all the way up to 18in your speedo willl be out more, also you may need a camber kit for the 18inch ( i didnt need the kit with 16inch)

wasn't the 16" wheel that did that, i bet if you put the stock 205/65/15's back on it'd be close to the same, the speedo's are generally slightly out, as above use the tire size calculator, from a quick look the 18's you are thinking of using are a huge 2mm smaller overall outer diameter (from new tires to bald tires would make more of a difference)... 1/5 of sfa really

i had 205/65/15's then i put 225/55/16's on, checking against a gps it made no noticeable difference at all

 

[Andreas]

I have 235/40R18 95V on my VS ute and the speedo is spot on. Checked with GPS and speed check on the Hume Hwy south of Albury.
I've had patrol cars on my tail for a few Km's on the Hume Hwy no probs, they must like black VS utes!!

I have toyota utes and a ford ranger at work, all are 5 km slower than the GPS.

 

[Brett_jjj]

If you know someone who does memcal tunes etc, you can get them to adjust the speed sensor ratio in the tune. This will change where the auto trans shifts as well as changing the speedo reading. I change this setting when doing tunes for people who have fitted a lower ratio diff.

 

[someguy360]

If you know someone who does memcal tunes etc, you can get them to adjust the speed sensor ratio in the tune. This will change where the auto trans shifts as well as changing the speedo reading. I change this setting when doing tunes for people who have fitted a lower ratio diff.

I didn't know there was a way to alter the speed on via the tune on a VS?

I installed a different ratio diff in my VS and it threw my speedo out by 10km, I had my tuner adjust the tune to make the shift points more to my liking but they said I would need a speedo corrector box (jaycar) for the speedo issue

 

[Brett_jjj]

No need for a corrector kit on VS V6's, all I do is work out the speed sensor ratio that suits the new diff ratio, and overwrite the old ratio values with the new values, the auto trans will shift at the correct revs, and the speedometer will read correctly. Changing the gearshift points is totally different from adjusting the speed sensor ratio. Theres a lot of "so-called" tuners out there who dont know a real lot, but they certainly know how to take the cash.. A good mail order tune for a pretty much standard V6 should cost no more than $50 if the memcal is supplied, considering the little amount of time and effort it takes to do one..

 

[The1]

the problem is fiddling with the vss calibration in the tune isn't really the correct way of fixing things, as far as the gearbox is concerned nothing has changed, the output shaft speed is the same, speed from the diff to wheels has changed, also playing with the calibration can upset the gear shifting. So a jaycar box is easiest method to fix the speedo.

That said either way will work whatever you want to use it upto you.

 

[Brett_jjj]

Yeah, Ive never had any problems with it, except for when testing the tunes in my VS that has a standard diff ratio,when I fit a tune to my car that has a higher VSS ratio set to suit a lower diff ratio, it shifts higher up in the rev range and puts the speedo out. The guys who have fitted the tunes to their cars have said the shifts and speedo are spot on for the diff ratio theyd fitted, its just a matter of getting the VSS ratio to match whatever diff ratio is used..