The higher the gear# the quicker off the line & lower the top end. So... you can easily find a 3.9 R200.... 81 - 83 280zx 5 speeds have the 3.9 diff. Or try to get a 4.11 set...

 

i have a complete set up off a 1981 280zx turbo auto matic tranny rear end ill sell u everything is there !

 

Why would that help him? He already has the 3.54 diff.

 

The turbo's had the worst diffs for acceleration. The R200 2 seater manual cars are best with the 3.9. But that turbo 200SX (cant remember years) would be even quicker with the 4.11 that Nismopick mentioned.

 

i got a question what about a 1984 300zx turbo manual tranny rear diff ? would that have the 4.11 and if so what type of mods would i have to do to make it hook up right on my 1982 280zxt ? just wondering...


p.s. my friendi m halping has a 4th month of 84 300zx turbo and the donor car is a 3rd month of 84 300zx turbo.. the only differance is that her car is a auto and the donor car is a manual...

 

Did ya read what J just said???

No Z31's came w/ 4.11's.... only the mid 80's 200sx's.

The Z31T had the 3.54's just like the 280zxt (makes perfect sense, as the Z31T used the BW T5 tranny):

http://www.az-zbum.com/information.differential.shtml

So if you still (for some reason) wanted the 300zx diff... pull it & install it in the 280zx. Wa-frickin-la.

 

I just pulled a diff out of my turbo parts car and installed it without checking the gears visually. I swear this thing is a 3.7 not a 3.54; someone already changed it out... so, you should open up the back and find the stamps for the number of teeth to be sure.
Later Z31's had 3.7 gears

 

Some of the 79's supposedly had the 3.7's too.

 

The 5-speed '79 2+2 and the '79 GL's came with a 3.7 R200.

The 3.7 didn't show up again until the '84-'86 NA 300ZX.

The '84-'86 Turbo 300ZX had the same 3.545 R200 that the 280ZX Turbo had.

The '87-'89 NA's all came with 3.9 R200's and the '87-'89 Turbo came with the 3.7 R200 LSD.

 

uuhhh, ya but this was an all stock 1983 280ZX turbo 5-speed that I pulled the diff from. That's why I was surprised to not get the tall gearing I was after.

 

so should i swap in the 79 rearend i have in the brown parts car ..would it better then the one i have in her now ?

 

Depends on what you have and what you want to go too.

Do you want better acceleration or better $3.05 a gallon gas mileage?

 

I like my 3.9. Good excelleration. 3.7 would be a good compromise. But 3.545 is a little low. My NA was keeping up with my turbo 2+2. I can only attribute it to the lower gearing and extra weight in the 2+2.

 

I actually went from a 3.9 to 3.545 in my turbo. But it's better to go with taller gearing in the turbo if it keeps you in the boost longer...

I've calculated with my setup, that I should be at the VERY top of 3rd gear at the end of the 1/4 mile with the 3.545 rear end. The 3.9 required a fourth gear shift that killed the acceleration and with the 3.5:1 first gear in the T5 made it all but useless.

A nice side affect is better gas mileage on the highway in 5th gear... and with gas prices at $7/gallon (for 100 octane) it'll make it an economical choice as well...

I also went from the 3.36 diff in my 240 to a 3.7 and swapped the stock 4 speed for an '83 5-speed. The taller gears in the 5-speed made the 3.36 diff a dog. The 3.7 brought it back but not entirely, but I got the LSD so I can live with it...

Worst case, I swap the clutch pack from the 3.7 into the 3.9 r&p when it comes time for a rebuild.

 

1/4 mile? Whats that? Run it til you run outta road or hit the first turn Auto-X usually sees more benenfit from a higher gear ratio due to the shorter acceleration distances though.

 

True, but surprisingly enough, with a turbo, road racing is more similar to the gearing needs of a 1/4 mile drag strip than auto-cross. Mostly because there tend to be more "sweeping" turns, long straights and a LOT higher speeds.

 

Yeah on a longer road course the lower gears would definitely be more beneficial. Unless of course you're driving a grossly underpowered vehicle.

 

Yeah, I hate it when that happens...

 

I have a 79 and I have a 3:9, Im not sure if its stock but comeing from the owner that It did I would be suprised If he had changed it. Either way Im thinking the auto is going to have to go. either for a 5spd or a better automatic. A bit too slugish on a N/A. Also I have what appears to be a power steering pump :S
I thought the zx's only came with power assist(rack & pinion)???

 

The 3.5 is alright. I could see it being better on a turbo, just because it could probably make up for acceleration by having that turbo. On an N/A it's ok. I really need to get myself a manual, but I have to admit with the 3.5 Auto my 2+2 is fantastic when it comes to gas. I'm thinking about possibly keeping it like that, or if I ever change it out go to a 3.7 differential. That way I could get more acceleration and still maintain a bit better gas mileage. Or like I said keep my 2+2 the way it is and find myself a good 2-seater to play around with as my Z meant to go faster.

I was playing around with it, from a dead stop to 50mph, I was pretty dissapointed. I floored it and got nowhere. This was in Drive mind you. I played around with shifting later with the manual kickdown. Went from 1-->2-->D and without even flooring the pedal I got much better acceleration out of it. It made me a little happier.

 

No '79 280ZX that I'm aware of came from the factory with the 3.9 R200. It didn't show up until 1980.

It's highly possible that it was swapped either by the previous owner or the one before him.

The stock '79 automatic came with a 3.545 R180. So, if the swap to a 3.9 R200 was done, it'll be easy to tell.

Look under the rear end of your car and measure the length of each axel. If one is shorter than the other, you have an R200. If they're the same length, you have an R180. If it is the R180, I'd bet money you don't have anything shorter than the 3.545 rear end unless someone put in a NISMO unit with shorter 'competition' gears.

I've got a friend with a NISMO 4.38 R180 LSD in the back of his 1970 240Z.

 

The only Automatic 280zx I've had the misfortune of driving was my grandma's and it was pretty sluggish compared to the five speed cars. The car was in a perfect state of tune so it wasn't the engine

 

I guess I should have posted this earlier in the thread, but if anyone is wondering what diff they have, or what other diffs & trannies come on the S30 & S130 Z's... Check this site:

http://www.geocities.com/z_design_studio/

 

I've noticed the only gear the car seems to get acceleration in, is about 2nd. When I push it to the floor I get the acceleration that actually pushes me into my seat, but other than that it's kind of lackluster, but on the plus side the car does do great on gas.