240z Steering wheel on a 280z… while keeping the horn pad

A while back I picked up a 240z steering – I just love that wood-grained look (though it is composite). I did a nice refurbish on the 240z steering wheel shortly there after, but never got around to installing it… till this past weekend!

There isn’t much around the forums in the way of doing a 240z steering wheel on a 280z. Actually, it’s probably because  in terms of the steering wheel itself, there’s no conversion needed – the 240z steering wheel fits the 280z steering gear exactly. The issue I had was really mating a 280z horn button to the 240z steering wheel!

Check out the visual difference between the 240z (left) and 280z (right) horn pads…

Datsun-240Z-OEM-Horn-Pad 74-76 Horn Pad

I wish it were that easy of a swap, but upon removing the 280z steering wheel and comparing it to the 240z’s, the difference was apparent. The contact plate has 3 screws in the 280z, and only 2 screws in the 240z’s.  This different proved to be all the work, thus having to make an adapter to mate the two.

YES, I could have bought a 240z horn pad (avg $40 – $75), but I have a horn pad…and some metal…and a brain. And i like the challenge! :] Let’s go make a 240z-to-280z horn mating plate!

The 240z steering wheel has two screw holes for the horn assembly, while the 280z has three.

DailyDatsun-240z-steering-wheel Daily-Datsun-240z-280z-steering-wheel (9)

Upon disassembling the 280z horn (three screws), you’ll notice the contact plate has rubber washers and plastic guides (so that the contact plate doesn’t connect the horn pad and steering wheel). On the steering wheel, you’ll see that the 280z has a connection spring (12 o’clock). In the 240z steering wheel picture above, it uses a wire instead.

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The horn contact is located here in this pic at 4 o’clock.

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Datsun 240z to 280z steering wheel horn mating plate – design plan:
2 3/4″ diameter
3/4″ dia center hole
1 1/32″ distance between centers for 240z mounting holes
1 25/32″ lengthed iso triangle for 280z mounting holes (you can just trace these from the contact plate)

I didn’t have a compass, but I found a Mother’s polish can did the job.

Daily-Datsun-240z-280z-steering-wheel (5)

I had some time, so here’s PDF of the mating plate design in case anyone else wants to use it. It should be to scale – let me know how it goes!

DailyDatsun-240z-to-280z-hornMatingPlate copy

The NIBBLER! Since i don’t have a band saw (nor the room for one), the Nibbler gets all the attention.

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Daily-Datsun-240z-280z-steering-wheel (4)

Drilled the holes and test mounted the mating plate. Not too shabby. Use drill bits smaller than the screws used in their respective places so they can bite into the metal, make contact, and maintain electrical continuity.

Daily-Datsun-240z-280z-steering-wheel (3)

Here it is assembled on the car. Important to note that the 240z wire SHOULD NOT be hanging outside of the 280z contact plate… yeah, your horn will be ringing all day if you do. It SHOULD be connected to the 280z contact plate on the back side. Don’t add anything to the face of the contact plate because you want to have an even surface to make contact anywhere you press the horn button.

Daily-Datsun-240z-280z-steering-wheel (2)

Since soldering didn’t work on the contact plate, I simply just protected the mating plate (from further contact), bent the contact wire head, and press fit it under the contact plate.

Tada! installed. love it. and it still goes beep-beep.

Daily-Datsun-240z-280z-steering-wheel (1)

2 Replies to “240z Steering wheel on a 280z… while keeping the horn pad”

  1. Hi Justin, first of all, great wright-up, thanks especially for the pdf. A question: The 240 steering wheel I bought did not have a wire attached as yours does…I’m not sure where/how it was attached to the wheel in its original configuration. Apart from it my horn does not work and blows the turn signal fuse when the horn pad is pressed. Words of wisdom?

    1. Hey Mark! Thanks for the kind words – glad the pdf helped out. The wire that comes out of the steering wheel attaches to the backside of the steering wheel (but from the inside). It basically extends the contact from the backside of the steering wheel to the horn pad. I think what’s happening when you’re blowing your signal fuse is that more than just the horn contact is touching the steering wheel contact… so when the horn is pressed, it’s passing more voltage through the signal circuit than it should handle. Take a look at the 6th picture on this page (just below the line, ‘The horn contact is located here in this pic…’). You’ll see the horn contact at 4 o’clock (that metal tang), but you’ll also see much of the turn signal switch at the 7 o’clock to 11 o’clock range. To test, just take some masking tape and block off those metal bits there, put the horn back on, and re-test. One thing i forgot to ask.. w/o out the wire, does your horn still work properly? Without it, that’ll probably give some insight on how it’s making it’s connection to work, and helping find the issue.

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