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View Full Version : Splines on automotive gearbox shafts



Neil Jones
01-26-2009, 12:53 AM
How are they made?

barts
01-26-2009, 01:38 AM
Generally external splines either rolled or hobbed.

- Bart

Optics Curmudgeon
01-26-2009, 10:13 AM
Or rotary broached: http://www.slatertools.com/

Joe

Mcruff
01-26-2009, 10:17 AM
This question depends mainly on how old the gear box is. My old GM truck and Jeep transmissions were milled on. The truck transmission was made in 1961 the Jeep one was made in 1971.

ahidley
01-26-2009, 10:20 AM
Are you asking how origonals are made or how the home shop machinest would make his own?

Neil Jones
01-26-2009, 07:01 PM
Or rotary broached: http://www.slatertools.com/

Joe

How would you use a rotary broach on the middle of a long shaft?

Neil Jones
01-26-2009, 07:02 PM
This question depends mainly on how old the gear box is. My old GM truck and Jeep transmissions were milled on. The truck transmission was made in 1961 the Jeep one was made in 1971.

Is there any disadvantage to milling them other than it's slow?

Neil Jones
01-26-2009, 07:05 PM
Are you asking how origonals are made or how the home shop machinest would make his own?

Can a home shop machinist produce a quality spline like the ones needed in a high performance automotive racing gearbox?

BadDog
01-26-2009, 07:13 PM
Can a home shop machinist produce a quality spline like the ones needed in a high performance automotive racing gearbox?
Sure he can! All he needs is the right equipment, training/experience, material, and time... :p Now if you are asking whether a typical home machinist is likely to have all these things, then the answer is "probably not". ;) With some basic minimal equipment (proper cutter, indexer, etc.) and diligence, I'm sure it could be done to some level turning out a very reasonable apearing and somewhat functional example. But then most truly high end, high power, hight stress splines are rolled and then heat treated (usually induction). We ran into this a LOT with rock crawlers...

Neil Jones
01-26-2009, 07:18 PM
Sure he can! All he needs is the right equipment, training/experience, material, and time... :p Now if you are asking whether a typical home machinist is likely to have all these things, then the answer is "probably not". ;) But with some basic minimal equipment (proper cutter, indexer, etc.) and diligence, I'm sure it could be done to some level. But then most truly high end, high power, hight stress splines are rolled and then heat treated (usually induction). We ran into this a LOT with rock crawlers...


What kind of disadvantage does one face when making their own splined shaft with home shop equipment vs. other specialized methods/machines?

Optics Curmudgeon
01-26-2009, 08:12 PM
How would you use a rotary broach on the middle of a long shaft?

Ya got me there, not all fancy solutions are universally useful.

Joe

BadDog
01-26-2009, 08:19 PM
The main disadvantages that can't really be overcome with careful work and (moderate application of machinery/tooling budget) are the additional strength of rolled splines and the induction heat treat properties. Forming the splines by displacement is quite a lot stronger than cutting them. But that requires some serious dedicated hardware in the from of a roll press (I think I recall that's what they are called). And the induction hardening process carried out correctly (such as by Superior, but not including Moser IMO) provides a very strong and resilient spline (and shaft) without producing a fragile shaft. Superior does a GREAT job of this for the 4x4 axles. Moser on the other hand produces a shaft that (in my experience) is too soft, and I've personally seen them twisted up into what is basically a very expensive twizzler. You won't see that with Superior.

Teenage_Machinist
01-26-2009, 08:37 PM
Heat treating is HSM's bane. Few HSMs will be able to evenly heat and quench a shaft more than several inches long. Then there is grinding if it needs to be precise, and that is a problem.

Mcruff
01-26-2009, 09:16 PM
I have machined splines on several shaftss over the last few years.
They worked fine but they were not fora heavily loaded car transmission. They were more for farm use and driveshafts. Heat treating can be sent out if it needs to be hardened. What application are you actually wanting to do, exactly!!

oldtiffie
01-26-2009, 09:34 PM
Without denigrating or detracting from any of the opinion here, I'd suggest a very good read of "Machinery's Hand-book" for starters, just to get a handle on the design processes and parameters.

Then get some very good professional books - and advice - on the subject.

Gear design is a hugely complex topic - and will consider the materials, tooth form and profile, types of gears, stresses as well as heat-treatment and all machining.

"Design" means just that - and not just a list of "rules of thumb" or guess-work or what somebody said or did.

It is no accident that design and development takes so much time and money for high performance machines - including transmissions.

oldtiffie
01-26-2009, 09:48 PM
I seem to sense that there are two current threads by the same OP that may be related.

Is that true?

The other thread is at:
http://bbs.homeshopmachinist.net/showthread.php?t=32946

oldtiffie
01-26-2009, 09:51 PM
Deleted - duplicated post