Why more splines?

[nagal]

I have read lots about more splines are better. Is this simply due to the fact that to get more splines on an axle shaft, the diameter of the shaft has to be bigger resulting in a strong shaft or is there something else?

Yes, I am bored at work posting silly questions.

[Elusive]

the more splines an axle shaft has, the more surface area in contact at the junction.
...and... 30 spline axles are usually 1.31" diameter while 35 spline are 1.5"
a notable exception to this is the 14 bolt with 30 spline 1.5" (at the splines) shafts.

[Comrade Andy]

The SAE actually have standards to which US auto manufacturers (OEM and Aftermarket) work by and the spline dimensions are one of those standards hence larger diameter axle = more splines. Its really only for comparing aples to apples, I've got a 19 spline Landrover axle at my dad's in England that measures 1.5" that just for the record is a Salisbury axle that's really a HD dana 60!! it's just made in the UK not US!

[blackZZR]

I often wonder if the spline copunt is a regulated thing, you read about axles on d44s out of the 50s and 60s having 19 splines, were the slines bigger in that day?
do splines diferate between manufacturers?
I know with modern Danas, the count is a factor on the same axle, but does the cut size difer on different axles?
bigger cut would mean less splines would it not?
would wider cuts mean more strenght per spline?
where woiuld you get the engineering info on this?

[MendoZJ]

Ive got a 19 spline D44 from I belive the early 60's in my YJ. Does anyone know anything about these axles and their strenth. Im running 33's now and havent had any problems but want to go bigger soon. Do you think the 19 splines can handle it? Its locked btw.

[Comrade Andy]

Do you think the 19 splines can handle it?

That 19 spline 44 shaft should have the same diameter as a newer 30 spline model, one of the main moves towards mores splines seems to have been two fold, 1 to standardize amongst US manufacturers and 2 the higher number of splines an axle has, the tighter the tolerances and less slop in the diff, but the latter doesn't nessasarily equal higher strength, imagine the splines are mountains it takes a lot more work to move the one big one than a few small ones. Make sure if you do upgrade you get axles with rolled splines, rolling cokpresses and harderns the splines, where as cutting obiously removes material.

[MendoZJ]

Well I guess I answered my own question today when I broke my driver side shaft.

[Comrade Andy]

Well I guess I answered my own question today when I broke my driver side shaft.

Sound like it's time to go 30 spline! Unless you have an expensive locker...