finding diff ratio

[GOT MUD]

ive done abit of a search but cant find anything on the topic so what i want to know is there a place to look for the ratio on the diff centre i know i can find it on the id plate for my truck but this is out of a differant truck so iwant to find out if its okay to slip in its a limo mine hasnt got one (yet)plus is there anything else i need to figure out before the swap like if the front would be okay to run with the new rear any help would be great cheers

[Daisy]

to check if LSD or not

Jack up rear diff.

turn a wheel in one direction... If the other wheel moves in same direction - you've got an LSD or simliar.

If wheel goes the opposite way.. you've got an open centre.

To work out ratio..

While vehicle is jacked up.. mark a dot on the tailshaft and count how many times the tailshaft turns as you turn the tyre 10 times.

so.. if tailshaft turns 41 times at 10 rotations of the tyre.. you've got 4.1 ratios... so on.

TOM

[GOT MUD]

thats top shelf info GQ never new about the finding ratio trick
but i can do that with the centre in the truck but what about the lsd that sitting on my shed floor right now i was hoping it would be stamped on it but i couldnt notice it

[Daisy]

thats top shelf info GQ never new about the finding ratio trick
but i can do that with the centre in the truck but what about the lsd that sitting on my shed floor right now i was hoping it would be stamped on it but i couldnt notice it

LSD DIFF - has its own centre which is easily identified by a 'LSD housing' below


OPEN DIFF - identified by being able to see the spider gears which is the diff centre below.


Hope that helps

[GOT MUD]

sorry GQ i think i didnt word last post right i know the one the floor of the shed is a lsd but what ratio would it be ie 4.1 how can you tell

[bru21]

does it have the crown wheel and pinion. if so count the teeth on the ring gear and on the pinion gear. mark the start with whiteout and count.
you will get a number like 40 and 10 for example. 40 / 10 is 40 hence 4.0:1.

cheers bru

[big red]

you can count the crownwheel teeth and divide that by the pinion teeth.
ie: 51 divided by 11 equals 4.636 navara diff.
37 divided by 8 equals 4.625 GQ diff.

[GOT MUD]

thanks for info guys i going to do it now

[GOT MUD]

yep worked out ratio 4.625 so it should be right to put in and ill have a limo thanks for the help guys

[XterraGuy]

Late to the party, but to clarify a few things:


To identify an LSD when installed, do as described and jack both rear tires off the ground and spin one, but THE TRANSMISSION MUST BE IN NEUTRAL when doing so, otherwise the other tire will rotate the opposite direction even if there's an LSD in there, but it will take more effort to do so if there's an LSD.
The pic of the 'LSD Housing' vs the open one isn't quite accurate. The open diff shown is a 2-pinon unit, easy to spot, but the 4-pinion open and some 4-pinion LSDs look very similar. See the 4-pinion LSD in question here:
http://mywebpages.comcast.net/xterra/tech/LSD/
Admittedly, this is the pure-clutch unit that we get in the USA. The Australian market got some of these too I believe, but most of you got the clutch w/ pressuring ring type which does have the non-tapered case shown in GQ's photo.

Ratio is on the plate in the engine bay on the firewall or over the wheel arch, or on a sticker on the door jamb. Look for the axle code (HG46, HG indicates the H233 axle, 46 indicates 4.6x ratio). Barring that, you can count the driveshaft rotations as described. If the gears are still in place in the diff, you can count the teeth on the gears and divide, but better yet, look on the edge of the ring gear, the tooth counts are stamped into it as seen in photo #4 in the above link, just divide the two. 48:11=4.363 ratio.

Brent