Ring Gear size

[gwalt584]

I have two set of ring & pinion gears that supposedly are for an FJ40. Both ring gears have 37 teeth and the pinion has 9 = 4.11. Both have 12 mounting holes that match each other.
This is the question: one ring gear measures approximately 9.25" side to side and the other measures 9.5".
Was there a difference in ring gears front and back?
Or is one from a different year range than the other?

Gary

 

[too tall]

No difference front to back. Maybe slight changes over the years of production runs. Are they fine spline or coarse?

 

[gwalt584]

No difference front to back. Maybe slight changes over the years of production runs. Are they fine spline or coarse?

I assume your talking about the pinion splines? if so, I'm not sure. How many splines on the course and how many on the fine?

 

[gwalt584]

I just answered my question. I looked on Cruiseroutfitters web site.
these are course spline pinion gears.

 

[B y r o n]

. . . one ring gear measures approximately 9.25" side to side and the other measures 9.5". . . .

Are you measuring the back surface or the face with the teeth? I wish I was at home I could measure mine that I pulled when I rebuilt both axles.

 

[gwalt584]

I’m measuring both in the same place

 

[Cruiserdrew]

Interesting, I've never noted a difference. You have found something new. I don't have any coarse spline pinion gear sets left, so cannot independently measure.

There are slight differences in ring gear diameter based on gear ratio. I believe 4.11 has the largest ring gear by a few mm.

 

[gwalt584]

I just measured the bolt holes. The smaller ring gear has 10.7mm holes
The larger ring gear has 12mm bolt holes.

 

[gwalt584]

Also, the larger ring has no threads in the mounting holes.
The smaller ring gear the holes are threaded.
??

 

[gwalt584]

I have two other 40 diffs and there are no nuts on the back of the mounting service.

 

[Cruiserdrew]

One of yours is OLD. I believe the threaded holes in the ring gear were pre 1969 but I'm not sure.

If you're in an upgrading mood, this is a good time to gear with fine spline ring and pinions which are stronger.

 

[Pin_Head]

The threaded hole one is early to late 60s. I had one like that from a '67.

Of course, the pinion has coarse splines.