Better Gearing

[tabrinn]

I am looking to upgrade my 240Z to a 5 speed. I got a t-5 out of an 83 turbo 280ZX. Is this over kill for a hopped up 2.4L? What would be the best rear gear ratio? I was looking at the R180's out of a subaru. An R200 is stronger though in case I ever stepped up to a bigger engine. I just want something thats fun off the line that I won't have to rap out to get up to freeway speed. Any suggestions?

[sblake01]

IMO a T-5 is really only good with a turbo motor. The gearing is different from the Nissan trannys but I guess that's up to personal preference. A 3.90 81-83 ZX R200 and the 5 speed from the same is a good combo for both off the line and freeway.

[jmortensen]

Agreed. The NA 280ZX 80-83 transmissions had much closer ratios, and are a better choice. Of course to really make use of that close gearing, a new differential is in order. 3.90 gears are what the ZX's came with, 4.11's work well too.

The Subaru diff has a different spline count at the side shafts, so Z halfshafts don't work. At least one guy has modded the Subaru CV shafts to work, but it's not as straightforward as getting a Nissan R180 from a 200SX for example.

Info here:

http://forums.hybridz.org/showthread.php?p=721400

[zguitar71]

The 3.9 r200 are easy to find but do require some part changes to fit it in. The 4:11 r180 from the 200sx and pick-up truck are easy to find too and do not require any mods, just bolt it in. I personally would go for the zx close ratio 5 speed and the r180 4:11. The r180 will be plenty strong anough for a 2.4l with mods

[Pop's Z]

Having recently installed an KR180 from a 200SX with a 4:11 gear ratio, I can tell you it's not quite a bolt-in, but fairly easy none the less. The beauty of it is you don't need a 280 mustache bar, it's just a bolt-in, and you can use your own halfshafts. Our own jmortenson has a how-to for this over on hybridz, but here's the gist:To replace the R180 in the 70-73 you must first get the thread-in "buttons out of the old one in your car. To do this you should remove the diffy from the car leaving the halfshafts hooked up to the outer mounts, remove the ring gear-carrier gear set from the diffy. Then put it in a vise and remove the ring gear. Then drive out the small pin securing the big pin holding the spider gears in place. Then knock out the threaded "buttons" from each side gear. Then on the "new" R180-4:11 you must do the same removal of the ring gear-carrier gear set and ring gear to remove the lock-rings and an extra piece that's not needed (you'll know it when you see it...the "old" diffy doesn't have one). Then put the threaded "buttons into the side spider gears. You have to press them in place...I used the vise with wood blocks to protect the gears. Then put the "new" R180-4:11 back together, bolt in the carriers for the halfshafts, bolt the "new" R180-4:11 into the car, bolt up the halfshafts, use RedLine gearlube, get a red speedo cog for your tranny (Z Specialties in Washington has these) and enjoy the acceleration. It has transformed my car. I just got done putting an '83 ZX motor and 5-spd. in and it is a hoot to drive. Warning...watch out or you will spend a lot of time and money on this addiction. I know I have, but what fun!

Cheers, Mike

[Carl Beck]

I guess it depends - - - - I put the 4.11 in my Z when I was running a slightly mod'ed L24, on racing slicks (A-SR in the old days of auto-x). Years later, as the Porsches increased displacement... I had to go to a slightly mod'ed L28... to have fun with them on the freeways;-)

With either the 77/78 or 81/83 5spd. the 4.11 is way too much gear for street tires with my L28... it makes 1st. and 2nd. gear tire smokers... The L28 has so much more torque than the L24 did... if I had realized it before hand, I would have switched to a 3.9 at most.

Otherwise you better plan to spend the money on far wider wheels/tires for the street, and be willing to give up decent mileage on the highway above 65mph.

FWIW,

Carl B.

[jmortensen]

Tabrinn, this is a running disagreement between Carl and me. Running 225/50/15 tires with a 81-83 trans and it's matching 3.90 diff, the rpms should be 3070 at 75 mph. Running a 4.11 the rpms jump to a whopping 3235. To me that is more than acceptable. If you want to play around with tire sizes and diff ratios and see what you find, here's a calculator:

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

[jtl260z]

I love my 4.11 with my 82 zx 5-speed.

The minor changes involved (and the added weight) were well worth it.

[Sailor Bob]

Is there an R180 3.9? A guy in my neck of the woods has a rolling body from a 71 that was a track car - says it has a 3.9 r/e.

Edited November 1, 2008 by Sailor Bob

[snag point]

Ditto on loving the 83 5spd and 180 4.11. For my 73 /w a 280 engine it's pure gear grabing fun. Jon

[ConchZ]

Jon, that is one neat calculator. Good programming work, if you did it yourself!

[Walter Moore]

What years of Pickup trucks had the R180? Did it extend into the "Nissan" era, or were they strictly Datsun trucks?

When you swap the differential from a truck do you just pull the internal gears? I assume the truck would have a live axle, so the case is different isn't it?

(I see a lot of Nissan trucks running around these parts, so I am wondering if the few junk yards we have left might have one or two...)

I have a 5 speed from an 83, with my original 3.36 differential. I have finally gotten used to downshifting into 1st in tight corners, but the prospect of being able to stay in 2nd at speeds below 30 mph is appealing.