The Cessna 120-140 Association Forum

I am completing SB95-3B on the Ford-style alternator.
https://www.qaa.com/wp-content/uploads/ ... xpAkPPTlJA

On disassembly the hub (P/N 653983) felt sloppy and easily lifts off the drive shaft revealing a Woodruff key. I am pretty sure these keys are not meant to be reused. Is this a case of finding any engine Woodruff key that works? Or does anyone have a specified part number/spec?

Interestingly I found the nut (P/N 530412) loose, no sleeve at all (P/N 530407), and an old one-piece bushing inside the retainer.

I also have no idea how I am going to reinstall and torque the top 1/4" nut when I reinstall the thing. With the tach drive housing installed I cannot come up with a good wrench solution. Surely someone knows the trick here?

The key is an alternator part. I used to have a parts list, but can't lay my hands on it now. Woodruff keys are a pretty standard item. I am not aware of any requirement to replace it unless it is damaged. That said, if the drive is loose, either the key or the drive is probably worn.

Try Aerotech of Louisville for the key if you can't find it locally.

You're not the first one to find missing parts in the drive...

Thank you John!

I've run into another conundrum with SB95-3B

Figure 1 shows the generator/alternator gear 531325 sliding over sleeve/bushing 530407. Seems there are two different ID gears labeled 531325. Very confusing. This has led to me not being able to complete the SB as my gear 531325 is a much smaller ID and does not allow for installation over sleeve 530407.

For comparison here are the two options for this gear both masquerading under the same part number.

Solution is that I need to buy a very expensive gear. Just putting this out there for info.

Figure 1 from SB95-3B for reference:

Where did you get the two pictures of the gear? Which one is yours? They both look like they have some sort of bushing in them, albeit not the same bushing.

I just grabbed those photos off the internet for convenience. The smaller ID (and smaller photo above) example is identical to mine and is one piece of steel. I should say it's perfectly possible this is a different part number originally but gets wrongly labeled nowadays as 531325? Here is the backside:
The larger ID 531325 gear (photos from Textron) also has a larger OD to accommodate the bushing. It would slide over PN 530407

Comparing now the "OD" of the barrel: