OK, time for another of my [always] dumb questions

[Ed H.]

I managed to lose the wiper bellcrank nut (the one connecting crank to wiper motor). It seems like it should be a 5/16x18 thread, but... when I attempt to put such a nut on, it turns easily a turn or so with fingers, and then stops. I'm loath to take a wrench to it.

Thank you! Ed

[Mike M.]

Re: OK, time for another of my [always] dumb questions

its a 1/4" fine thread hex nut with an integral plate washer. i assume u r referring to a c-2 wiper motor lever to output shaft faster.. mike

[Ed H.]

Re: OK, time for another of my [always] dumb questions

Well I'll check that out, but it doesn't look like a fine thread... But then my vision, despite the current year, ain't so fine, either.

[Ed H.]

Re: OK, time for another of my [always] dumb questions

OK, well it's not a 1/4". I'll check the pitch again.

[Mike M.]

Re: OK, time for another of my [always] dumb questions

ed: i checked the wiper motor out of our 65 , a car we'd owned since 1970 and with 20K miles on it. i am certain its never been off the car till i removed it last week. its definitely a 1/4" fine threaded hex nut with integral flat washer. i can't imagine GM having a wiper motor shaft with anything other than 1/4 fine threaded shaft. but i've been wrong before. mike

[Paul D.]

Re: OK, time for another of my [always] dumb questions

Ed, I noticed your post is tagged 70-72, so my input may be relevant. I just checked the motor from my 71 and the size is 1/4-28 (fine thread) as Mike stated. My motor is not the original, but is a GM replacement from the 80's. Could it be a later replacement or rebuilt unit utilizing metric parts? Hope this helps. Chip.

[Ed H.]

Re: OK, time for another of my [always] dumb questions

OMG, leave it to me...





It's a '70 I've owned since 1976. I do not believe it was replaced during its time in 'The Beauty Parlor', but I can check that, too.

Thank you!

[Paul D.]

Re: OK, time for another of my [always] dumb questions

Ed,I was just tossing out ideas, but may have been dead on. I just measured a metric bolt (M8) and it was .313 by my mic. Also, yours is configured differently to mine. On mine, the threaded area has no "flats" or machined areas. It is completely round, 1/4-28 threaded portion with the larger, more rectangular shaped area behind it where the crank arm would fit. Chip.

[Leonard M.]

Re: OK, time for another of my [always] dumb questions

Ed, I checked 2 1970 motors and they are 1/4" fine as previouly said.

[Paul D.]

Re: OK, time for another of my [always] dumb questions

Thanks, Leonard, for posting the pictures. That is exactly how my 71 appears. Chip.

[Ed H.]

Re: OK, time for another of my [always] dumb questions

Well, um, um, Darned if I know! I would surely have noted if I had to use a metric wrench... Crazy, but a direction to explore.

Thank you! I'll let you know what I discover.

[Ed H.]

Re: OK, time for another of my [always] dumb questions

Ed, I noticed your post is tagged 70-72, so my input may be relevant. I just checked the motor from my 71 and the size is 1/4-28 (fine thread) as Mike stated. My motor is not the original, but is a GM replacement from the 80's. Could it be a later replacement or rebuilt unit utilizing metric parts? Hope this helps. Chip.

I think we have a winner! Thread pitch appears to be 1.25 x 8, using a 13mm nut. A 1/2" or 13mm nut not a noticeable difference.

I'll try a 13mm nut tomorrow.

Thank you!