I have a '72 240z into which I swapped a 5-spd from a 280ZX of indeterminate year.

I took the stock shift knob from a '72 4 spd, went to screw it onto the 5 spd and it wouldn't fit. I kind of forced it while turning 10 or 15 times and it "felt" like it grabbed, but a quick 2-3 shift this morning popped the knob off and onto the passenger footwell.

Frustrated, I took a spare shift knob from my former RX8 (M10x1.25) and it fit perfectly.

What gives? I was under the impression that all of the non-T5 5 speed gearboxes had the same shift knob threading. This is most certainly not a T5 gearbox.

Anyone else run into this before? Assuming this lever left the factory with this gearbox, does having an M10 threaded shift lever shed any light as to the year of the 'box?

No stock Nissan S30 or S130 shifter that i know of has anything but 8x1.25 threads. Get a thread gauge and figure out what you have. A picture of this shifter rod would be nice too.

Maybe get a 8mm nut from, hmmm... what's handy and easy to get to.... a nut from the brake master cylinder where it bolts to the booster? See if it fits on the shifter. Then you have a known quantity for comparison.

Edited September 1, 201410 yr by zKars

No thread gauge but I do have one of those cheesy go/no go size chart things that you can pick up at a hardware store and it indicates M10.

An M8 nut from my box o' bolts did not fit on the rod, too small. An M10 nut did fit. To ensure my old knob was in fact an M8, I took an M8 bolt from a kit and it threaded fine, no cross threading or fetching up.

My RX8 shift knob is a known quantity, it is 10x1.25. It threads fine, tightens up nicely by hand with no cross threading or binding up.

As far as a picture - The only one I have of the gearbox outside of the car is back when I bought it, and it only shows where it attaches to the ears. It is below.

Edited September 1, 201410 yr by mckennar

As Jim said, it should be M8x1.25. I bought a shift knob on ebay from datsun_bluebird. It was an M10 thread in the knob. I drilled out the thread and used a threaded insert to get M8 threads.

Good, now you know for sure you have an M10 threads. How they got that way, well that's another mystery. The shift rod in your picture sure looks like a regular old Datsun shifter. I wonder if someone cut the old shifter shorter, and since it thickens as it gets closer to the base, they found it was easier to put M10 threads on it. Sounds like you have to convert the threads in the knobs you want to use to M10 threads.

I could send you another shifter rod with the usual threads on it....

Jim,

I bet that's exactly what happened (someone cut it shorter and threaded it) because it does taper slightly at the very top of the rod for about 2 threads.

I appreciate the offer re: the replacement rod - I think I'm just going to drill out the new knob and use a threaded insert.