[4wheeljive]

Ok so my speedo reads faster than I'm going by about 15km, and I currently run a standard Sierra gearbox and transfer and diesel hilux diffs, 33s as well as the vit speedo to go with my g16b. I'm looking at putting 6.5s in so will this make it worse or better or comply undrivable on the road(my understanding that it will be worse) I know I can get my speedo adjusted but that's a last resort or how big do I have to go with my tyers

Glen.

[TryHard]

6.5s is one of best mods u could do in my mind .. as for speedo with 6.5s and 33s i think i would better i think .. i cant rember how it works .. and cbf adjusting speedo dont know why u would bother just figger out how much it is out and adjusting ur speed acordingly

[hutch]

I'm running 6.5 transfer reduction and 31" tyres and the GPS at 100kmh and speedo is 85kmh.

[Teracis]

Better than what mine currently reads which is 10% low...

It's okay as long as you remember and because the zook is seriously lacking power at the moment so you have to think about speeding up, but it wouldn't be hard to go speeding through something because you forgot the speedo was out!

[royce]

you need a drive adaptor box that goes on your speedo cable and re gears it to suit what you have, altering the spring tension on the needle is a poor way of doing it as it will only be right in one band and the odometer will still be out

incidentally, does the odo read that youve gone further than you have as well?

[jdk81]

I assume it is showing 100 km/hr, whilst doing 115km/h (what hutch said).
Playing with http://www.lepayne.com/gears.html and the lux ratios

Diff gears can mostly fix this
I assume your diff gears are 4.3 ratio (the output of the trasnfer is 9% undergeared).
Thus a ratio of 4.75 will correct this, however your options are 4.56 (4% undergeared) or 4.875 (3% overgeared).

Changing your transfer gearing won't affect your speedo reading. It will improve your gearing though.
6.5s in 4.3 lux diffs on 33s is a 9% reduction in high range, which means
your using more revs on the high way.

Changing the diff ratio will, the two benefits of this is that is will improve your speedo reading, and reduce torque loading on your transfer case.
The negative is it will mean you are carrying much more revs.
You could play with altering the gearing you put in the transfer case and diff gears to find what suits.

Or as royce said, correct the speedo. Or as I do, use a gps as your speedo.
In hindsight, I would have prefered diff gears (4.6) and transfer gears (4.16) instead of using standard 3.7 and going the 6.5s.

Bundera:(high pinion front)
84-85 TD =4.875
84-85 22R=4.3
85-92 22R =4.56

Hilux/4runner:
Petrol.
79-83 =4.875
84-88 =4.875
88-96 =4.875
V6 4runner =4.3

Diesel`s:(dosn`t include surf`s)
79-83 =4.875
84-88 =4.56
88-96 =4.3

[4wheeljive]

Ok cool I now know I have 4.3 diffs and the OD dose read further than I have gone but what I was asking was if I put in the 6.5 in ( I know they are a good thing) is how much further out will it through the speedo cause at the moment sitting on 100 km indicated at 3500 rpm I'm only doing about 85 according to the gps

[royce]

speedo wont be any different, the drive gears are after the transfer

[4wheeljive]

Cool thanks I didn't know that

[jdk81]

4wheeljive wrote:

Ok cool I now know I have 4.3 diffs and the OD dose read further than I have gone but what I was asking was if I put in the 6.5 in ( I know they are a good thing) is how much further out will it through the speedo cause at the moment sitting on 100 km indicated at 3500 rpm I'm only doing about 85 according to the gps

Now that you have provided more information, what I assumed earlier is incorrect.
Assuming currently you are using standard 1.3 transfer gears, and standard 1.3 gearbox.
What gear are you using whilst taking this reading, 4th or 5th?

If you are using 5th, after installing 6.5s your engine will be singing 5000rpm @ 100 km/h

[4wheeljive]

Yeah the reading was taken in 5th gear. 5000 rpm is not a happy cursing speed so either I need to re think my my setup or maybe go bigger tyers. Any ideas