Better Gearing

[Arne]

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

The Datsun 720 4X4 trucks used a 4.11 R180 in the front.

[jmortensen]

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

No, I'm not nearly that talented on a computer. It is cool though.

[tabrinn]

I already have the T5 tranny. I figured if it ever needs rebuilt, there are more people in my neck of the woods who are familiar with the BW than the nissan 5 speed.

I am assuming the L28 in stock form will probably have more torque than my hopped up L24. Hence my desire for better gears (torque multiplication). I just want to be able to light up the tires at will but still be able to cruise comfortably down the interstate at obscene speeds. I'll have to check my tire size to play with the calculator and unfortunatly the car is back at the body shop.

In you all's opinion, what would be the best cruise RPM (at 70mph) for the L24?

[tabrinn]

What if I keep the 4 speed and swap out the rear to the 3.54 R180? These seem more common than the 3.9. Has anyone gone this route? Impressions?

[WW2Winger]

Sorry Tabrinn, I don't have the answer to your question, but I have a question of my own. What sources are out there where I might find a R-200 in 4:11 ratio? Help.

[jmortensen]

200SX Turbo has a 4.11 R200. I'm not aware of any others in the US...

[WW2Winger]

Thanks John, I'll start the hunt. I don't think my budget will allow a limited slip. But, you know this as well as I do, eventually you end up buying the real stuff anyway so why not go ahead and look for it now? OK, now I'm hunting for a R-200 , 4:11 Lim. Slip. $$$$$

[zguitar71]

What if I keep the 4 speed and swap out the rear to the 3.54 R180? These seem more common than the 3.9. Has anyone gone this route? Impressions?

I ran an early 4 speed and a 3.54 for a while. it is about the same as a zx 5 speed and a 4.11 until you hit 5th gear. The draw back is the high revs in 4th and the big drop off between 2 and 3. The zx is a close ratio (not like the racing trans) so the motor stays in the power band better. If you can go with the zx 5 speed I would do it, that with a 3.9 or a 4.11 is better than the 4 speed.

[jmortensen]

Thanks John, I'll start the hunt. I don't think my budget will allow a limited slip. But, you know this as well as I do, eventually you end up buying the real stuff anyway so why not go ahead and look for it now? OK, now I'm hunting for a R-200 , 4:11 Lim. Slip. $$$$$

Is it assholish for me to say that I have one sitting in my shop?!! Sorry, couldn't help myself... :stupid:

Seriously though, I would expect you to pay about $200 for the diff, and the LSD is a big unknown. If you find yourself spending more than say $5-600 on the LSD, I suggest you take a look at a new KAAZ unit. They're really better than the Nissan unit and I think they run something like $800. Factor in some new seals, and you're probably looking at something like $750 or $800 for a good deal on an R200 in 4.11 with Nissan LSD, again assuming you can find all the components at a good price.

Then if you're like me you can get sucked into CV shafts... it never ends.

Edited December 6, 2008 by jmortensen

[soundmasterg]

Is it assholish for me to say that I have one sitting in my shop?!! Sorry, couldn't help myself... :stupid:

Seriously though, I would expect you to pay about $200 for the diff, and the LSD is a big unknown. If you find yourself spending more than say $5-600 on the LSD, I suggest you take a look at a new KAAZ unit. They're really better than the Nissan unit and I think they run something like $800. Factor in some new seals, and you're probably looking at something like $750 or $800 for a good deal on an R200 in 4.11 with Nissan LSD, again assuming you can find all the components at a good price.

Then if you're like me you can get sucked into CV shafts... it never ends.

What makes that new KAAZ unit better than the Nissan LSD Jon?

Greg

[jmortensen]

More clutches, stock Nissan out of the 300ZXT has a weak clutch pack. The Nismo unit has more clutches, the KAAZ has about 50% more than the Nismo. Also you can get the KAAZ unit in a 1.5 way or a 2 way, Nissan's are all 2 way. Which one is better is up for debate, but most would probably say that 1.5 way is easier to drive for road racing or autoxing.

[Garagegoon]

http://datsunzgarage.com/engine/

Small quote from there....

There were three different Zcar R-200 ratios from 1975-83, none were limited slip until 1987. 280ZX automatic transmission cars came with an R180, so if you want to find a 3.90 look for a 1981-83 5-speed in the junkyard. Don't try to analyze the confusing table in the Haynes manual, this is the easy way to do it:

Datsun R-200 list (not R180)

'75-79 280Z(X)s had a 3.54

'81-83 turbo ZX's had a 3.54

'81-83 non-turbo ZX's had a 3.90

the '85-86 200SX turbo had a 4.11

the '87-89 LSD was a 3.70

If you want performance get the R200 out of a junkyard '81-83 5-speed, NON-turbo ZX (3.90). if you're speed freak like me use the 4.11 out of the 200SX turbo. The '85-86 200SX turbos came with a R200 while the non-turbo models I've seen have a solid rear axle. While not LSD differentials the 4.11 adds more snap over the 3.90 and can make your Z a real rocket off the line. It came with CV halfshafts which aren't needed, just use regular Zcar R200 halfshafts on a 4:11 in a first generation Z.

1975 NOTE: 1975 R200s and driveshafts came with unique rear driveshaft/differential flanges. So if you plan on doing a later year R200 swap into your 1975 280Z, you should try to find a 1976-78 R200 driveshaft to use.

BTW: to get R200 halfshafts out, DON"T pry them out and damage the flange or spend an hour unbolting the differential-side. Simply unbolt the wheel end, and "yank" the halfshaft hard a few times. A little circlip in the diff holds it but it will pop right out, the yanks don't hurt it. To get them back in you can lock it in place by thumping the end with a mallet till it locks.

LIMITED SLIP DIFFERENTIALS

Despite the performance of the Z, Nissan only made a limited slip diff very late in the Z's life. They made 2 types: a standard LSD, and a LSD with a viscous internal drive. The 1987-89 Turbo 300ZX's had the "good" 3.70 LSD, and can be identified by it's finned rear cover. This cover needs to be replaced with the smooth R200 cover to fit properly to the 280Z mustache bar, and the front driveshaft flange on the diff. needs to be replaced with the one your driveshaft uses. The '88 white SE 300ZX came with the "viscous-drive" R200, and can be identified by a sticker on the driver-side of the diff that says "VISCOUS LSD". While the viscous model fits into an earlier Z, R200 halfshafts don't lock into them without some fabrication of new halfshaft fittings.

TO DETERMINE THE RATIO (internally)

If you're not sure which ratio R200 you have lying around the garage, check it this way: Remove the rear plate (drain the oil of course). Then rotate the large ring gear until you see these numbers stamped into the edge facing you.

If it's a 3.54 it will read "39:11"

If it's a 3.70 it will read "37:10"

If it's a 3.90 it will read "39:10"

If it's a 4.11 it will read "37:9"

The first number marks the number of teeth on the large ring gear, the smaller is the number of teeth on the pinion gear connected to the driveshaft. Someone suggested swapping ring and pinions around to create the ratio of your choice. I checked with my buddy the Z Doc, and he said it's very difficult to get the preload and tooth geometry setup properly (he tried it). Oh well.

HOWEVER: Since the 3.70 and 3.90 apparently use the same 10 tooth pinion, I wonder if a 3.90 ring could be swapped onto a factory limited-slip assembly? This would make a "factory" 3.90 limited slip!