16.75:10 R-180

[Zvoiture]

Just removed the diffy from my free '79 parts car last night. Tried the Royce method and got 16.75 turns of the input for 10 turns of the axle. So this is a 3.365? I was told it was a R-180 by the person who gave me the car. Does this make sense to all you diffy pros out there in regards to year/ratio/model??? I guess I need to go back and try and find all the available specs...

steve77

[Royce]

According to http://www.geocities.com/z_design_studio/ the available ratios for '79 280ZX are...

4-speed R180 3.36

5-speed R180 3.36

2+2 4-speed R200 3.36

2+2 5-speed R200 3.7

All Automatic R180 3.54

It also looks like that was the only year a 3.36 was put into a 280ZX. Sorry, I don't know where they got their data, however, it does seem to confirm your findings. Also, it suggests that if your 280ZX is equiped with a 5-spd it would have the earlier "280Z 5-spd" ratios. Sorry if that brings bad news!

Now, I have a question for you about the 280ZX diff! I am just curious but do the half shafts attach to stub axles at the diff by 4 bolts (at the diff end) or is the axle attached to a yolk which is held to the diff by one bolt? Sorry, if that is confusing, it will make more sense if you are looking at it!

[Zvoiture]

"Also, it suggests that if your 280ZX is equiped with a 5-spd it would have the earlier "280Z 5-spd" ratios. Sorry if that brings bad news! "

No bad news here...I am not a drag racer. I much prefer to cruise at 90 on the freeway quietly and efficiently. I was actually kinda hoping it was a 'tall' one.

Now, I have a question for you about the 280ZX diff! I am just curious but do the half shafts attach to stub axles at the diff by 4 bolts (at the diff end) or is the axle attached to a yolk which is held to the diff by one bolt? Sorry, if that is confusing, it will make more sense if you are looking at it!

There is one 14mm head bolt (probably 3-4" long) in each shaft whose head is nesting in the center of the yoke closest to the diffy. I took a box wrench to it and as you loosen it, the splined stub begins to move out of the diffy. Removing it completely and the stub comes completely out of the diffy.

steve77

(steve79 gets lighter every day...)

[Royce]

Thanks for the info on the diff axles. I changed the diff in my 240 from a 3.7 R200 back to a 3.54 R180 that has the same axle setup you described. I pulled it out of my 260Z but I figure it probably originally came from a 280ZX. Hard to tell what is original after almost 30 years.

Speaking of your ZX getting lighter, my 260Z probably weighs 500lbs now. I hated to do it but the unibody was wasted!

Have fun!

[Zvoiture]

I jacked up the rear to get the diffy out and put the stands under the rear rails and when I took the jack off, the front tires came off the gorund! I threw the hood on and both rear tires and both seats and a battery on the hood to bring it back down! NOW this thing really looks gorgeous. My wife is about to murder me. OH, YES, and then one of my good Z friends (YES TIM, YOU!!!) came over and while I was out of the room told my wife "...it is probably full of black widows." THANKS A MILLION!

steve77

(it IS full of black widows)

[Royce]

Funny, I had a very similar experience with my 280Z. Once that motor and trans are gone the front gets very light, especial with jack stands under the rear frame rails. I meant to take a picture with the hood down and me "lifting" the front, but there was just to much Z crap in the garage to get a good picture!

Yes, lots of the black widow spiders around here too! They don't seem to be bothered much when sprayed with carb cleaner either!

[Zvoiture]

So how do you tell the difference between a 180 and a 200? Is there a bolt pattern or something?

steve77(200)

steve79(180)

steve 71(Alleged 200)

[Royce]

I used to have a couple of each laying around the garage but now I only have a R200 with both my R180s being in cars. It is easy to tell them appart when they are side by side but not so easy if you don't have the other for reference. The R200s rear pumpkin is almost round, or square with rounded corners, while the R180 is more narrow and therefor rectangular with rounded corner. Also the rear mount bolts that attach to the mustache bar are much thicker and the heavier R200.

I'll try to take a look and find something more distinguishable this week.