R180 gear swap?

[jmortensen]

Gordon's site is a GREAT resource, but all of the parts listed there are LSD specific pieces.

[Z Speed]

Ahh, my mistake Jon. Thanks for clarifying....

[snag point]

I have a 4.11 r180 with a 1981 280zx 5 spd in my 240z . I love the off the line power and close ratio between 2nd and 3rd. 5th gear is tall enough that my hwy revs are fine. Tomorrow I will write down some rpm's , gear and speed and report back. Jon

[BadDog]

Snag, what did you get that diff out of?

[snag point]

I got the r180/4.11 from a guy who said he bought it from the Bob Sharp racing shop years ago. I have no way to document his story, but it is a 4.11. I thought that I had a 1981 5spd tranny. but when i compare my real life rpms to speed. It looks like I may have a 1979 5spd. Today I drove to town and I got 18, 32, 45, 57,and 75 mph at 3500 rpms as I ran the gears. This matches the geocities transmission calculator for a 79 5spd with a 4.11. A 1981 to 83 is shown to run at 21, 35, 49, 65,and 87 mph at 3500 rpms. I do like the 4.11 as it really wakes up my Z. I have a 1983 5spd kicking around and I just might put it in when I put in f54 l28 that I have been working on for my Z. Jon

[bradyzq]

I have an early 280ZX 5 speed and an R180 4.11 combo in my 240. I love it.

The diff was from a 200SX (84-88) non-turbo, non-v6. Just garden variety 4 cylinder IIRC. The Z stub axles didn't snap in though, so it had to be opened up and some mixing and matching performed. But I don't think any new parts were required.

HTH.

[BadDog]

So what do you have, a '79 ZX 5-speed? According to the transmission calculator, you must be turning more RPMS in 5th that you would've with the 4 speed and 3.364 diff....

[bradyzq]

The transmission was free and had lived under a deck when I picked it up, so I can't be sure what year it is. But I seem to remember calculating a .77 5th gear.

I run a few RPM lower in 5th with the 4.11, than I did in 4th with the 4-speed. But basically, it's 5 gears in the space of 4. And 1st is fun now.

But even more fun is the 2-3 shift. NO more huge gap!

[BadDog]

That's interesting, because when I charted the various tranny/diff combos, I got 3443 RPAM @75mph with the 4-speed and 3.364 and 3635 RPM @75 mph with the 79 ZX 5-speed and 4.11 diff....

[bradyzq]

OK. Been out of the Z game for awhile, but it's coming back to me, slowly. IIRC, a 79 ZX 5 speed is the same as a 280Z 5 Speed, at least ratio-wise, specifically 5th gear (0.85).

I don't have that tranny. Is there a 1980-only ZX 5-speed with a slightly different 5th than the later 5-speed?

4-speed with 3.36 diff top gear overall ratio = 1.00 x 3.36 = 3.36:1, 3422RPM @ 75MPH

my 5-speed with 4.11 diff top gear overall ratio = .77 x 4.11 = 3.16:1, 3219RPM @ 75MPH

And I think the later ZX tranny would drop the revs a bit more to 3140RPM or so @ 75MPH.

[bradyzq]

So, to nit-pick, it seems I have the earliest ZX-only 5-speed.

If I was grasping at straws, I would say the 79 box is actually a 280Z tranny!

[BadDog]

Must be!