1979 FJ40 Pinion Help Needed

[Azrocks]

Hello all! I was formerly on this site as Azrocks but my account was tied to an email I no longer have access to. Bummer. Anyway, I have a 79 FJ40 that last year I completely tore down to do a full rebuild. I’m working on the rear differential. I ordered a rebuild kit from Cruiser Outfitters but I’m running into a few issues. I have reached out to them and of course they were very responsive. Because of the holiday I won’t be able to get a reply until next week. I thought I would run my issue by you all.

The pinion but I received doesn’t fit the pinion shaft. I have a 27 spline shaft. I have a castle but that I think came off the shaft when I took it apart last year which I don’t think ever came OEM. It does fit though. With my cheap calipers the old nut inside diameter that fits is about 25.5mm. The new is very close to 24mm. Were there different size shafts?

 

[Azrocks]

This is the kit I’m using.

 

[Azrocks]

Ttt

 

[pb4ugo]

I dont think i've ever seen a castle nut used on a 40's pinion. They usually have a high collar that gets staked to the notched in the pinion. I think cruiser outfitters will have your answer. If the new nut doesnt fit, you'll need find one that does thatccsn be staked.

 

[timmyisinthewell]

Sorry, these pics are the best I could provide. It appears Toyota used the same rear pinion shaft, p/n 41342-55010, from 03/69 to 07/80. There are a couple different p/n's for the nut, but I couldn't tell you why the change.

 

[timmyisinthewell]

Hard to see in the pic, but it seems to show a cotter pin in an inset for a 5 month period in '69 and the fiche shows a different p/n for the castle nut

 

[peesalot]

If I read that right March of 69 thru Aug of 69 had castle nut, as to the different dia. thats a ?, IIRC the castle and the stake are same size on the 9.5 in the 40's.

 

[timmyisinthewell]

See my post above. The pinion shaft p/n was the same from '69 to '80. Even a thread change would have created a different p/n.

 

[cruiseroutfit]

Toyota did use a castle nut on the early diffs, but never on a 1979 FJ40

The OE pinion castle nut is 90171-19010 (our part# PN19010) is 19x1.50mm thread with a 26mm drive.

The nut in the IKTOYLC is 90179-20001 (our part# PN20001) and is 20x1.50mm thread with a 30mm drive. Stake Nut. Some will come with an integrated washer (which is a plus) but the thread diameter/pitch is the same 20x1.50mm

For posterity there is also a 90179-20061 used for output shafts and some pinion kits, it's also 20x1.50mm thread with a 27mm drive. Stake Nut.

(Note color can vary from Zinc Silver to Cad Gold)

You may have an aftermarket ring/pinion that uses as castle-nut, not common but a possibility. If the old castle nut fits the pinion and the pinion is cross-drilled for a cotter-pin, no reason not to reuse it. Otherwise we (Cruiser Outfitters) just need to know what diameter/pitch nut you are looking for and we can attempt to find an OE solution.

 

[timmyisinthewell]

Not that it really matters if it works. See part identified as 41204B (nut for drive pinion)

 

[cruiseroutfit]

Not that it really matters if it works. See part identified as 41204B (nut for drive pinion)

View attachment 3642074

All distractions fwiw.

90171-19012 & 90171-19035 supersede to the 90171-19010 I have listed above. They are 19x1.50mm castle nuts and never used on the later stake style pinions, so they won't fit a stock pinion or the larger pinion the OP has.