How to calculate diff gear ratio's with cover off.

[gav240z]

To find the ratio of a differential you need to take the cover off look at the crown wheel(The large wheel with teeth). Then then take a look at the pinion which also has a set of teeth but is the small part.

 

Now you can count the teeth on each or you should be able to find a number in the format for example 37:9 if you find this number it's a simple task of dividing the numbers by each other 37/9 = 4.11111111 or 4.11.

 

I hope this helps since I didn't know this till I read it on an item for sale on ebay.

[C.A.R.]

39\11 = 3.54 which I removed from my Zed

39\9 = 3.9 which is now in my Zed = much better acceleration!

[Jimbo]

Hey Lurch,,, How come you had a 3.54 diff?? did you do a auto to manual swap? I have not long done this & am looking for a 3.9 diff, so am interested in your post...Thanks....Jimbo....

[gav240z]

Hey guys can anyone tell me what a series 1 280zx manual is likely to have for a diff ratio?

 

I'm pretty sure it was a series 1 280zx Manual because it still had the universal joints in the back.

 

I'd like to get a 3.9 or a 4.11 for my Z .

[Zeddophile]

That depends on whether its an R180 diff under there, and whether its a 4 or 5 speed. My guess would be a 3.7 ratio R200, but.... anyways, check this:

http://zhome.com/ZCMnL/tech/GearRatios.html

[C.A.R.]

Hey Lurch' date=',, How come you had a 3.54 diff?? did you do a auto to manual swap? I have not long done this & am looking for a 3.9 diff, so am interested in your post...Thanks....Jimbo....[/quote']

Hey Jimbo, I bought my Zed with that ratio R180 diff in it - no wonder it accelerated so slow...

My Zed IS a factory manual car, but it had been ?fiddled? with by a previous owner. So I have NFI why the 3.54 R180 was put in.

I removed the 3.9 R180 Diff from a C210 auto sedan ? it was a straight bolt in.