Does anyone know what size the screws are that hold the seat mechanism covers on or where to buy them? I've repaired the covers where the screw holes were broken off but I'm missing a couple. It looks like they are 3 mm x 0.6 thread pitch x 6 mm long but all the sources I've found show they only make 3.5 mm x 0.6 thread pitch x 6 mm long. I've looked at Motorsport and Z Car Depot and JDM but they only sell the covers at crazy prices.

If anyone is interested in my repair I can post pics. I took thin aluminum sheet, cut small pieces, bent them to the contour of the cover at the missing hole, drilled holes in the pieces to match the cover and used JB Weld to secure the pieces in place. Worked perfectly.

Post the pics please. Belmetric is a source for screws. How did you come about your measurements on the screws?

Here's the pics of the repairs. Stronger than the plastic and fit over the mechanism just fine. A dab of black paint will finish them off.

I used a drill bit gauge to estimate the screw diameter and used a pitch gauge that came with a tap and die set to get the pitch. The screws fit into the 1/8 hole (3.16mm) but not the 7/64 hole (2.78mm) so I assumed it was 3mm. the 0.6 pitch was an exact match.

I checked Belmetric and they only have 3.5mm 0.6 pitch. None of the vendors I checked make a 3mm 0.6 pitch so I'm guessing the 3.5mm is the right one even though the physical dimension is closer to 3mm.

Edited May 8May 8 by BOBZCARS

It is typical for the actual diameter measurement of external threads to be a small amount below their designated size.

In other words, it would be expected that an M3.5 screw to be slightly smaller than 3.5mm in diameter.

Well, I ordered a few 3.5mm screws from Belmetric and they are indeed larger than the Z car seat screws. So the Z car screws are actually 3 mm which it appears no one makes these days.

2 minutes ago, BOBZCARS said:

Well, I ordered a few 3.5mm screws from Belmetric and they are indeed larger than the Z car seat screws. So the Z car screws are actually 3 mm which it appears no one makes these days.

Did you look on Amazon? Sometimes I buy them there when Belmetric doesn't have them

Yup, Amazon doesn't carry them either. I can't find them anywhere. Weird.

What's also weird is that my tap and die set has a die and tap for 3mm with 0.6 pitch. Go figure. Also has a 3mm with 0.5 pitch.

I use McMaster-Carr for most of my specific hardware.

I will check back home for you as I just took my 280z seats apart but I bet they are just standard metric M3 (3mm) screws. Even in the US they can’t be that hard to find I would think.

I tried McMaster-Carr as well and they only have the 3.5mm in a 0.6 pitch. Even a Japanese supplier of screws and bolts only listed the 3.5mm in a 0.6 pitch.

I checked the screws on my seat mechanism cover and those too are ether M3,5 or something imperial. Bit strange as those screws are fairly rare even here in Europe.