33s 4.2TD GU with 3.9 diffs

[mnpalmer]

Hi all, just wondering who's running this combo, just fitted my 33s today and noticed how bad the speedo is out, 80 on speedo is 88 on GPS.... Hoping to get away with just calibrating the speedo, and not changing ratios... unless anyone has some cheap (but good!!) 4.3 gears.

thanks,
Mark

[bogged]

Hi all, just wondering who's running this combo, just fitted my 33s today and noticed how bad the speedo is out, 80 on speedo is 88 on GPS.... Hoping to get away with just calibrating the speedo, and not changing ratios... unless anyone has some cheap (but good!!) 4.3 gears.

thanks,
Mark

The only reason you want to change diff gears to correct the speedo? That would be $2500ish done with new gears and seals and labour...

try a speedo correction unit off ebay for $200ish...

[mnpalmer]

Thanks, but want to see how it has affected low range as well, ie is it going to be too fast now...??? Think I will just get the speedo fixed, will see.

[morkz]

3.9 and 33's

cant believe your speedo is far out...

when i first put 35's on my GU yeah it was about 10% but with 33's that seems a bit extremem i went out a few times with 35s and my 3.9 in my wagon it wasnt that bad in the bush.

but i ended up putting 4.6 and now its overgeared and would go back to 4.3's if i had chance.

for yours i wouldnt event bother changing it.

[*BESTY*]

I've got a 4.8 Petrol with 305/70R16 and Auto, I need the 4.3 diff ratio to improve low range and engine braking, but don't have a spare 2.5K to swap it just yet......and I don't think a speedo correction unit will alter my off-road capability

On road, the speedo doesn't bother me that much, you just get used to driving a bit lower than what the speedo says. All speedos are incorrect anyway, just use GPS for correct speed if that's your concern

[GUEEY]

i have just fitted 4.3 to my TD42T on 35s, it is exellent!
i am glad i didnot go 4.6 as most people recommended, it would have been reving its arse of at 100KLM per hour.
speedo is still out a little but at least it is reading over , not under.

Grant.

[patrol man]

i will swap you your 3.9's for my 4.1's this will fix your speedo, and my highway gearing. cheers Phill.

[mnpalmer]

Thanks guys for the replys. As for Phil, I think will try my 3.9s for a while now just with the speedo fixed. I've heard the same as others about 35s and changing to 4.6s so maybe if I get over my 'emotional girly moment' I might one day buy 35s and 4.3s!
Off to Toowoomba tomorrow and then onto somewhere with the brother in law for a camping trip so get to try out the new tyres for a long drive (from Canberra) and some good off road work. Tell you what; with the lift and the bigger tyres it now looks pretty cool, it was looking 'under-tyred' before with the 31s and 'a bit of a lift'...