I want to upgrade my stock differential in my 1971 Datsun 240z. I already upgrade to the 5spd tranny from a 280zx. Do I have to go with a all new assembly or can I get a mechanic to change out the gears? I want to get a better acceleration.

you can goto hybridz.com and check out their drivetrain ->differantial guide. It has everything u will ever need. I just don't have the link right now. I'm at work. I'm sure someone else will chime in and throw ya the link.

Here you go.

http://forums.hybridz.org/showthread.php?t=116207

Why not do it yourself?

This may help, too.

http://forums.hybridz.org/showthread.php?t=119990

No need to go to Hybridz, just do a search here . All the drive train have been changed so many times I cannot remember. 3.9 or 4.11s will do what you want . You will most likely need to change to a R-200 for the stronger diff. Nissan pickups FWD front diff can be found in 4.11s . I personally haven't done the 4.11 swap but many here have. I believe the truck front diff is a 180 like you have now. If so this would be the easiest change over. I did install the 200 though and it is a easy swap. Do a search and you will come up with all the details .

Dont you need a lot of different parts besides just the differential to do the swap of the r200? I really want to put a r200 in it. But I dont know where to get one or the other necessary parts to install it.

  beandip said:

Nissan pickups FWD front diff can be found in 4.11s .

Wouldn't the diff sping the wrong direction or at the very least wouldn't the gears make contact on the wrong side of the teeth? I would assume that you would at the very least have to switch out the ring and pinion gears, is that wrong?

  Quote

Wouldn't the diff sping the wrong direction or at the very least wouldn't the gears make contact on the wrong side of the teeth? I would assume that you would at the very least have to switch out the ring and pinion gears, is that wrong?

Nope. The output shaft from the transfer case is spining in the correct direction and the front diff is part time use only. The gears can make contact on either side of the teeth without any undue wear (you can drive your 240Z in reverse, correct)?

I thought the benefit of a R200 was for setups with greatly increased torque. Otherwise why put a heavier diff in your car? You can change gear ratio in either, right?

For a stock L28, a R180 is fine.

I agree, no need for an R200 unless you are a serious racer with a built engine. The R200 needs the mustache bar from a 280Z to install.

Some say the truck front diff, when installed in the back will whine, due to being "broken in" spinning the other direction.

To get the stock gear ratios, you'd want a 3.9:1 rear diff. Assuming your 5 spd was from a '82 or '83 ZX.

If you want a zippier car at low speeds but higher RPM on the freeway, the 4.11 or higher.

Some have installed the Subaru LSD R160 with 3.9 or 4.11. It usually is strong enough to handle the load most of us will subject it to. If you are frying your tires on a drag strip, not the best solution. Modifications to install are unknwn to me.

As to your question of having new gears set-up by a mechanic vs. finding a complete unit. The mechanic will be about $200 if the man I consulted with is typical. Plus gears of course. A different diff is less money and time.

  =Enigma= said:

Wouldn't the diff sping the wrong direction or at the very least wouldn't the gears make contact on the wrong side of the teeth? I would assume that you would at the very least have to switch out the ring and pinion gears, is that wrong?

This is the same diff all they did was install it upside down in the front of the trucks. I have one and will be putting it in my Z!

Nissan didn't install the R180 upside down in the trucks. They just turned it around so that the cover faced the front of the truck and made the diff drive on the "coast" side of the gears as John Coffey said earlier. It's weaker that way, but it is in the front end, so it doesn't take as much punishment. Flipping it upside down would leave the pinion several inches above the oil, which wouldn't last very long at all.

Reasons to stay with the R180:

1. Lighter

2. Fits with no mods

3. Can be found in lower ratios from the 200SX, but needs a slight mod described in the hybrid z FAQ post

Reasons to go with R200:

1. Stronger

2. Can handle V8 power

3. 87-89 300ZXT came with LSD

4. Very easy to find 3.90 gears from 280ZX

The "what parts do I need" question is answered in that FAQ that Mat linked to as well.