Clubbers,

While I had my Z up on stands, I gave a push-pull to the half-shafts. The left (driver's) side seemed to have some play. I removed the half-shafts, expecting a worn U-joint but instead discovered that the source of the play was the differential itself. I don't have a micrometer and its unmeasurable with a ruler, but their definitely is some in-out movement, along with an accompanying clunk (faint) when I tug and push on the bracket that attaches to the half-shaft.

It's a 1972 with the 4-spd stock differential, a R-200.

Is this something to be concerned about? Or normal play in an unloaded condition? The right (passenger side) does not have any play.

Chris

I thought the 72 had an R180..

I could be wrong.

Normal. The side gears and pinion gears inside all have a bit of lash, you're just feeling it through the halfshaft. If the halfshaft moved up and down a lot or the car made some hellacious noise when you turned, then you should be worried, but what you're describing is normal. Also normal to be able to twist the driveshaft a little bit before the halfshafts start to move.

Thanks Jon,

Your description of a normal differential matches what mine does. It's always a relief to not have to spend time and money.)

Zedyone_ I believe automatics used the R180, manuals the R200 in 1972. For the next few years as well, maybe even until the ZX.

Chris

I don't think the R200s were used in the Zs until 1975, in the 280Z. You either have an R180 or someone swapped in an R200.

The R200 was put into US Z-cars starting with the 260Z 2+2, continuing on to the 280Z and so forth. The 240Z never got an R200 from the factory.

Lots of people install R-200's whether they need it or not. If you drop a V-8 or engine with tons of power in your Z, you probably need one. If not, you're wasting money.

Lots of people install R-200's whether they need it or not. If you drop a V-8 or engine with tons of power in your Z, you probably need one. If not, you're wasting money.

I don't know about you, but I don't think putting in a 3.9 R200 was a waste of money in my (non-V8) Z. Many others install the R200 in order to change overall gear ratio, along with the added strength. Aalthough you can find R180 diffs with similar ratios, they are tougher to come by. I don't see any problem with having an R200 in an L-powered Z, it just didn't come from the factory that way.

I went off what my Chilton's manual said by visually matching the type of connection to the half-shaft. Hayes refers to 240Z type and 260Z type transmissions at one point and R180 = 260Z and R200 = 240Z at another point and that manuals received R200s and automatics R180s.

The FSM is silent on the R180 vs. R200 question. The illustrations in the 1972 FSM match up with what is installed on my 1972 so I assumed that it is the factory differential. Because it has a flange-type connection which two independent repair manuals identify as R200s, I made the big guess that 1972s had R200s.

Could be wrong, of course.

More generally, what's the difference between the two other than how it connects to the half-shaft?

Chris

I was off by 1/2 year. Dang.

Here's a really good read on Z car differentials - http://forums.hybridz.org/index.php/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

I went off what my Chilton's manual said by visually matching the type of connection to the half-shaft. Hayes refers to 240Z type and 260Z type transmissions at one point and R180 = 260Z and R200 = 240Z at another point and that manuals received R200s and automatics R180s.

The FSM is silent on the R180 vs. R200 question. The illustrations in the 1972 FSM match up with what is installed on my 1972 so I assumed that it is the factory differential. Because it has a flange-type connection which two independent repair manuals identify as R200s, I made the big guess that 1972s had R200s.

Could be wrong, of course.

More generally, what's the difference between the two other than how it connects to the half-shaft?

Chris

Both the R180 and R200 diffs have flange connections to half-shafts (driveshafts in Nissan-speak). Thus, 240Z half-shafts can be used with the R200. They are not the difference.

The biggest difference between the R180 and R200 are the physical size (180mm ring gear vs. 200mm ring gear).

Edited November 2, 201113 yr by LeonV

Both the R180 and R200 diffs have flange connections to half-shafts (driveshafts in Nissan-speak). Thus, 240Z half-shafts can be used with the R200. They are not the difference.

The biggest difference between the R180 and R200 are the physical size (180mm ring gear vs. 200mm ring gear).

That makes sense.

I've been busy with big (mis)adventures on the underside of my Z. Finally got it though. I think.

Chris

The 73 240z I am working on makes "some hellacious noise" when I turn to the right. What should I be worried about? BTW the driver side boot is ripped. I am hoping new u-joints will solve the problem... is this wishful thinking?

Normal. The side gears and pinion gears inside all have a bit of lash, you're just feeling it through the halfshaft. If the halfshaft moved up and down a lot or the car made some hellacious noise when you turned, then you should be worried, but what you're describing is normal. Also normal to be able to twist the driveshaft a little bit before the halfshafts start to move.