240z diff ratio

B101 · Post by **B101** » Mon Nov 12, 2012 11:03 am

i need to get a hold of Dave Turners in Auckalnd, looks like i have busted a tooth of the crown gear and its spat it out the cover. First i need
to know what ratio my diff is?
should there be a number stamped on the crown gear?
if not. . . i have been told to turn the driveshaft and count how many turns the shaft does to one full rotation of the wheels?
is this correct?

djz · Post by **djz** » Mon Nov 12, 2012 12:37 pm

That doesn't look good, did it have oil in it? The ratio will be stamped on the crownwheel and will be two numbers separated by a colon, something like 37:9 etc divide the first number by the 2nd number to get the ratio.

B101 · Post by **B101** » Mon Nov 12, 2012 1:34 pm

took her out the second day and when i went to put her back inside i saw oil
on the ground and had a look, then HELLO!!!
So i put my finger inside and could feel that there was a tooth missingfrom the crown wheel.
might take it a bit easier when im changing into second gear. was very impressed though took it up to 7750rmp no swet in 1st 2nd and 3rd.
ive been told to take the case off the back of the diff just incase the numbers arnt there??

nzeder · Post by **nzeder** » Mon Nov 12, 2012 2:50 pm

DJZ is correct you have to remove the cover from the rear of the diff - turn the crown wheel until you see the number stamped on it - most likely will be a 3.9 for a 5sp manual 240z so 39:10 is what should be on the crown wheel.

us2 · Post by **us2** » Mon Nov 12, 2012 5:31 pm

Hey Brian. You have PM

Andy · Post by **Andy** » Mon Nov 12, 2012 6:31 pm

I am sure there are forum members who can help with your needs, bad luck the diffs are pretty strong

B101 · Post by **B101** » Tue Nov 13, 2012 7:41 am

so i got her apart last night and this is what i found

us2 · Post by **us2** » Tue Nov 13, 2012 8:08 am

Yep, thats a smashed spyder gear.

You may have to temper your enthusiam for the cars performance somewhat.

Anything can be smashed if you try hard enough.

B101 · Post by **B101** » Tue Nov 13, 2012 9:12 am

us2 wrote:Yep, thats a smashed spyder gear.
You may have to temper your enthusiam for the cars performance somewhat.
Anything can be smashed if you try hard enough.

i got a hold of the original owner who put her together 12 years ago. sounds like its had a hard life on and off the track and the 1/4 mile.
he even sent me the original dyno sheet and 1/4 times he had done straight after he built the new engine.
the car was set up for av gass.

he had built 5 other Z since in the waikato maybe some has heard of him ( Phill Howz )???

i guess it was just a matter of time for the old girl. time for some new parts i think

nzeder · Post by **nzeder** » Tue Nov 13, 2012 10:23 am

well just replace the open center with an LSD

assume the crown wheel and pinion are in good shape.

Andy · Post by **Andy** » Tue Nov 13, 2012 10:58 am

Is it a R200? Theres an open centre here free to a good home.

B101 · Post by **B101** » Tue Nov 13, 2012 12:54 pm

nzeder wrote:well just replace the open center with an LSD assume the crown wheel and pinion are in good shape.

yea the crown wheel and pinion are fine

how hard is it to change over to an LSD?? first time taking a diff apart so am rather new to this info

B101 · Post by **B101** » Tue Nov 13, 2012 12:55 pm

Andy wrote:Is it a R200? Theres an open centre here free to a good home.

its a R180

would also like to keep it around the same ratio if i can

Andy · Post by **Andy** » Tue Nov 13, 2012 1:17 pm

Its probably a 3.9 but you only need the centre, however there must be complete R180's around ready to go and most seem to be 3.9's?

B101 · Post by **B101** » Tue Nov 13, 2012 1:28 pm

it sure is a 3.9
might be worth posting up an add for a R180?