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what diff ratio

Posted: Sun Mar 08, 2009 9:07 pm
by outback_pootrol
picked up my little hilux the other day, its a 79 2litre petrol 4 speed, and want to run 35's on it, just wondering what would be a good ratio to make it go pretty well, will 4.88 be enough or will it be great, i see 4.8's for $400set

not much of a highway use rig,

Posted: Mon Mar 09, 2009 2:01 pm
by booflux
Depends on what the current gearing is? if its currently 4.56 then 4.88s wont make much of a difference if its currently 4.11 then it will make a big difference.

Posted: Mon Mar 09, 2009 4:19 pm
by sloshy
I would say it has 4.8 in it from factory being an old petty.

Posted: Mon Mar 09, 2009 6:11 pm
by outback_pootrol
i jacked one wheel up and spun it, the tail shaft rotated 2.5 times to a single wheel rotation.

wtf did i do wrong cause it dont seem to be right

Posted: Mon Mar 09, 2009 6:53 pm
by xxxhilux
if you can turn one wheel at a time you have an open diff and you need to turn the wheel around twice and see how many times the drive shaft turns around if you turned the wheel once and got 2.5 when you turn the wheel twice you will probly get 4.8 mabay, mabay 5.1 if your diffs have already been changed

Posted: Mon Mar 09, 2009 7:30 pm
by outback_pootrol
xxxhilux wrote:if you can turn one wheel at a time you have an open diff and you need to turn the wheel around twice and see how many times the drive shaft turns around if you turned the wheel once and got 2.5 when you turn the wheel twice you will probly get 4.8 mabay, mabay 5.1 if your diffs have already been changed
i have air lockers and if i went twice wouldnt it be a 5.0:2.
correct me if im wrong but i believe its like this, say for eg, a 4.88:1 ratio,
thats the tailshaft spinning 4.88 times to each 1 rev of the tyres, is that right?

Posted: Thu Mar 12, 2009 2:46 pm
by xxxhilux
when your testing the ratios of ur diff if your only turning one wheel to test it you need to turn it twice or you just have the only 2.5 diff ratios ive ever heard of in a lux

Posted: Thu Mar 12, 2009 7:38 pm
by sava75
Here is a handy diff ratio calculator for those interested...

The diff ratio you need = The size of tyres you want multiplied by your current diff ratio divided by your stock tyre size.

Example if you want 35's, you have 4.11's and stockys are 31's.....

35 x 4.11 / 31 = 4.64

Then you can round down this number to find a ratio that is commonly manufactured

Diff gears you would choose are most likely 4.56

Posted: Fri Mar 13, 2009 7:37 am
by Zeyphly
what rpm does it sit on at 100 km now, with the little wheels?

Posted: Fri Mar 13, 2009 5:50 pm
by outback_pootrol
Zeyphly wrote:what rpm does it sit on at 100 km now, with the little wheels?
100km???? she is good for about 80, i cant find anywhere on the thing about what ratio it has,,, am i looking hard enough or is it on a complience plate or something??

thanks

Posted: Sat Mar 14, 2009 4:38 am
by xxxhilux
if you cant work out what ratio diffs you have you shouldnt work on your own vehicle get someone else to do it. Some people are just to dumb but its ok if your abit slow.

Posted: Sat Mar 14, 2009 7:02 am
by booflux
Theres a trans/axle code on the vin plate, first part is your gearbox type last part is your diff code.

Going on what you have said I would Sloshy was on the money and you have 4.88, basically I wouldnt run a 5.29 so would look at crawler gears to accomadate the larger tyres off road and just deal with the on road sluggishness.

Posted: Sat Mar 14, 2009 8:20 am
by ShAgGS
this might help, providing the diffs are still factory ratio..

Example: G292 = 8.0" 4.10 final ratio 2 pinion

Code:
1ST R&P SIZE 2nd/3rd R&P RATIO 4th DIGIT PINION SET-UP
F = 7.5" 07 = 3.900 2 = 2 pinion
G = 8.0" 08 = 4.110 3 = 2 pinion LSD
10 = 4.375 4 = 4 pinion
14 = 4.875 5 = 4 pinion LSD
25 = 4.556
28 = 4.300
29 = 4.100
31 = 3.91
38 = 3.42
43 = 3.56
54 = 3.90
66 = 3.07
.
.Code:
Ratio Ring/Pinion Color Crawl:Ratio
3.42 ...42/12... Purple ...31:1
3.90 ...39/10... Red... ...36:1
4.10 ...41/10... Pink.. ...37:1
4.11 ...37/09... Orange ...37:1
4.30 ...43/10... Blue.. ...39:1
4.37 ...35/08... Green. ...40:1
4.56 ...41/09... Yellow ...41:1
4.88 ...39/08... White. ...44:1
5.29 ...37/07... None.. ...48:1
5.71 ...40/07... None.. ...51:1
.