Coarse vs Fine-Spline for 35" Tires (1 Viewer)

[JGM]

Hey Yotawheeler - you have confused me a little bit.

I have seen most of the documentation saying that fine splines were 30 count, not 27. I don't know how many splines the coarse are (like 8 or something).

Is one number correct (27 vs 30) or are there 2 flavors of fine splines?

 

[IDave]

There are 2 flavors of fine splines.

Birfields

68-75 Cruiser drum brake birfields, coarse 6-spline outers
76-78 Cruiser birfields - slightly smaller bell and slightly longer stub shaft than later Cruiser and minitruck, fine spline
01/79-01/90 Cruiser birfields (?J40/45/47/55/56/60/61/62) = Minitruck birfields(79-90 mini/hilux/surf)

 

[yotawheeler]

i got my birfs and knuckels are out of a '81+ BJ6X and im 99% sure their 27 spline...i cant tell you for sure because im about 10,000 miles away from my cruiser at the moment, i know 30 spline are available through bobby long....i had thought the 30 spline were somthing that he had made to improve on the 27 spline for extra strength...could be theres 2 different flavors, i cant say i know for sure...i thought there was just the 27 splines maybe idave is correct on this one...

 

[Isotel]

ok let me try and clear this up..
All Inner Axles (non Ball and Claw) are 30 spline at the Differential, 27 spline into the birfield.. this is goes for all the Drum Brake stuff 69ish and up.. all the way to Minitruck stuff..

Stock Birfields are all 27 spline at the Bell..

Drum Birfields are 10 spline at the hub.
76-78 are 30 spline at the hub (and longer than later birfs)

79+ are all 30 spline at the hub, but a bit shorter than the 76-78's

Bobby Long's 30 spline supper set is the only birf thats 30 spline all the way thru.. Diff-Bell-and hub.. This is why they are major pimp, and no one can seem to break them despite how hard they try..

this shows the difference in inner axle size going into the birfield..

i think i got this right

 

[JGM]

Awesome!

That clears up a lot of gaps for me. Thanks. That should be put in the tech section for reference.

 

[Cruiserdrew]

You might talk to Mark Algazy at Mark's offroad. He runs drum fronts with course spline birfields on his main trail truck. The first time I met him was at Rubicon and he told me this, and the very next day broke a birf! He is pretty much the resident expert on the limitations and joys of old-school. I agree with most others-the later fine spline set up is just better.

My advice would be to swap on everything from the knuckle out, using an FJ60 as the donor. Then you get all the good stuff-larger stud pattern, fine spline standard birfields, vented disk brakes, and beefier steering arms.