1970 Datsun 240Z — steering wheel vibration only at one highway speed

OP here — recorded a short video and noted speed, temp, and whether it was in gear. I'd rather look cautious in this thread than stuck later.

Start with the test that can prove you wrong. Swap the cheap/easy piece first on the 1970 Datsun 240Z and see if the fault moves. You'll know quickly if you're on the wrong tree. Stop there until you know. Worth doing even if the car feels fine right now. That's my plan before I call anyone.

If it were in my driveway, capture voltage while the 1970 Datsun 240Z is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. This is from a 1970 Datsun 240Z in Westchester. Had a similar mess a couple years ago and that's what finally sorted it. This is the version I'd tell a friend.

Ask what changed right before it started. Loaded-suspension checks on the 1970 Datsun 240Z catch play that a wheels-hanging inspection misses. Don't erase codes until someone who can help has seen them. That's the whole play. Next check is the cheap one I can do in a driveway.

OP update: scanned the 1970 Datsun 240Z again and still only have the one pending code, no new lights. I'll poke at it this weekend.

I wouldn't throw parts yet. A pressure test beats staring at a dry driveway if the 1970 Datsun 240Z is losing coolant with no puddle. If the cheap test changes it, stop and reassess. This is from a 1970 Datsun 240Z in Westchester. Stop there until you know. Worth doing even if the car feels fine right now. I'm keeping receipts and dates in one folder.

If it were in my driveway, swap the cheap/easy piece first on the 1970 Datsun 240Z and see if the fault moves. That's the branch I'd chase this week. This is from a 1970 Datsun 240Z in Westchester. Run the total, not the monthly, before you commit. I'm in no rush to be a hero on it.

Log the conditions before you spend. Capture voltage while the 1970 Datsun 240Z is actually failing — after it restarts you've lost the clue. Save the big job until that test fails. On “steering wheel vibration only at one highway,” that was the fork that mattered for me. This is from a 1970 Datsun 240Z in Westchester. I'd want a dollar figure or a measured spec, not 'should be fine.' If your situation is the opposite, ignore me. I'd rather look cautious in this thread than stuck later.

I'd want a measurement, not a hunch. A pressure test beats staring at a dry driveway if the 1970 Datsun 240Z is losing coolant with no puddle. Save the big job until that test fails. Write the result down so the next test isn't a repeat of the last one. If this is nothing, great. I want that in data.

Ask what changed right before it started. Write temp, speed, and in-gear vs coast when the 1970 Datsun 240Z does it — then decide on parts. If the cheap test changes it, stop and reassess. Was this after sitting overnight? Not driving it hard until I know more.

This is usually cheaper to test than to guess. A pressure test beats staring at a dry driveway if the 1970 Datsun 240Z is losing coolant with no puddle. Save the big job until that test fails. Had a similar mess a couple years ago and that's what finally sorted it. Checking again after work.

Log the conditions before you spend. Loaded-suspension checks on the 1970 Datsun 240Z catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. On “steering wheel vibration only at one highway,” that was the fork that mattered for me. Run the total, not the monthly, before you commit. No warning lights, which is why I'm documenting it.

Log the conditions before you spend. Swap the cheap/easy piece first on the 1970 Datsun 240Z and see if the fault moves. That's the branch I'd chase this week. On “steering wheel vibration only at one highway,” that was the fork that mattered for me. Have you gotten a second quote in writing? If your situation is the opposite, ignore me. If this is nothing, great. I want that in data.