280z with 5 speed ZX conversion 1st impressions

[Dave WM]

I was able to take my 75 280z out for a test run  with the 81 ZX 5speed today. Wow is all I can say, what a difference. I have the 3.54 diff and find it a very nice match up with the tall 5th (.75). I was concerned that the taller 1st may be a problem but it was a non issue, can barely tell the difference when starting off. From there its only better. The gears seem better suited in all traffic conditions, and when I was on the open road I put into 5th and was going 75mph at about 2600 rpm, 80 was about 3000. Prior to this 80 was 4000 (60 was 3000, 70 @3500). The car seemed much quieter and perfectly happy with the load (credit the torque of the L-28). Needless to say I am thrilled with this modification, I generally like to keep things completely stock, but this is just so much better I feel its worth it.

[Zed Head]

Which set of parts did you end up with?  You had a clicking noise and reinstalled some old parts to see if it would go away.  Just curious, to fill out the story.

Once you get off of that sand bar you might wish you had the 3.9 diff installed.  It wouldn't be a huge difference, just a little less finesse required when starting from a stop on a hill, and a bit less wear on the clutch.  I noticed it, here in the hills of the Portland metro area.

[Dave WM]

the final setup was the orig reverse gears (chewed up a bit) and the replacement 3rd gear you sent (gear/baulk ring/needle bearing). It still had a little bit of the noise to which I think was perhaps a slight defect in the output shaft. I the reasoning is since the 3rd gear resides on the very end of the shaft (4th floats on a needle bearing that rides on the main) any run out will be the greatest on that gear (3rd) this gets transmitted via the shift fork into the shift rod, and then into the front of the bell housing. I am not sure why the replacement you sent seemed less noisy if that is the case, but I just wanted to try it and see. If the trans was still noisy installed in the car the next operation would have been a complete tear down and check for run out of the main shaft. There really is nothing else to go wrong, the box is so simple. I know the next time I work on one of these the very 1st thing I am doing is checking for runout.

Edited November 25, 2017 by Dave WM

[Zed Head]

Are you going to see if you can split the two parts of bad 3rd gear apart?  I'd like to see how they're put together.

Could be that whatever caused your 3rd gear to start coming part also bent it a bit.  Maybe bent the shaft a bit also.  I hit a curb in a four wheel drive Pathfinder hard enough to bend the bearing cage around the outer front wheel bearings.  Took me forever to figure out why the front wheel would whine after driving some curvy roads.  I replaced only the inner race and bearings, in the old outer race and got another 100,000 out of it with no noise.

My point is that big chunky metal pieces will bend if you put enough force on them  It's surprising.

[Dave WM]

will take a look. I am thinking a bearing puller may work, the kind with the knife edge bevel.

[JSM]

So you have the rebuilt one in the car now? Or are you running the JY one you picked up?

Both the ZX and the 300z are gone from the yard.  I was bummed the 300z was gone as I needed the power steering hose. They have a 50% sale this whole weekend.  Would have cost me $3 for a $79 hose, grrrr.

[Dave WM]

its the rebuilt one that is in there now.

[87mj]

I am curious about your startup.  I found a guy willing to sell an '81 5 speed to me for $250.  I thought about buying it.  Do you need to shift earlier or later into 2nd than you did with the 4 speed? 

I assume the shift lever fit in your tunnel just fine while an early '71 or '70 would require cutting?

Edited November 26, 2017 by 87mj

[Dave WM]

1st is taller so you can stay in it longer, and shift in 2nd later. Its not really much of a big deal. the real benefit is just having that very tall 5th for low rpm high speed stuff.

One other thing I notice is the 4speed shifter seems tighter. It is different enough to notice but not so much that I would say a problem. It may have to do the kind of shift lever (not using the ZX but rather a notched for clearance non spring loaded shifter). I do have a ZX style shifter that I plan to bend and lengthen, but I don't know if that will feel any different.

As far as tunnel cutting on an early 240, I have no idea, it fits my 75 without cutting. Tip you do NOT need to remove the center console to install the shifter, just have someone help you by pushing down the shifter into place while you help guide the shifter into the transmission after its bolted up to the engine. there is not a lot of room but it can be done. Then install the pin and C clip and pull the rubber boot over the transmission shifter ears. The key is to have the shifter already in the car (push it up from the bottom to clear the large rubber gasket and leather boot) pushed up and out of the way while engaging the trans to the engine. This will save you the hassle of having to remove the center console (don't crack it) and all the associated wires for the lights and radio.