Advice on making transmission shafts - Page 3
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  1. #41
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    Quote Originally Posted by 10 fingers View Post
    Interesting thread regarding a subject we have a bit of experience and now avoid. Few automotive enthusiasts and hack machinists are familiar with transmission shaft design and manufacture. As an addendum, the aftermarket is plagued with parts that do not interchange.
    I couldn't have said it better.

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    Kopf,I don't have the time to go back and parse all of you comments but I'll make it simple -

    1) You can buy input shafts for a variety of transmissions that are hell-for-stout (much better than OEM). If you don't believe me, go look up Powerglide or TH400 input shafts and you'll see there are a dozen brands all for under $200. These are shafts specifically produced to handle much higher HP than stock. Yes, they make them in quantity but the volume isn't nearly as large as you might like to think.

    2) The entire point of 'Practical Machinist' is people who want to get things done properly and efficiently. It's not called "Have Gladys in Purchasing Get Bids From The Top 3 Most Expensive Vendors Machinist".

    3) The point of this thread- as I stated - was to learn if the skills needed to do the above still exist, and in this region of the world. I expected the usual peacocks to join in and they have. It's never hard to find someone who is overly proud of their abilities...and the first sign of that is someone who can do a good job if they charge enough. Money is the easiest way to cover a lot of deficiencies. Let's not forget ...I can make these myself if I throw enough money at it. The entire driving force behind business is the concept that a company can realize benefits of economy and scale.

    What would I expect to pay? There's no reason a shaft like the one I've shown should be more than $1000 when bought in small quantities.

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    Quote Originally Posted by Rob F. View Post
    These guys ought to have it if it is such a common part:
    Used Auto Parts Houston | Salvage yards | LKQ Pick Your Part

    Stupidest comment of all, thanks.

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    Quote Originally Posted by GregSY View Post
    I first need to make a good (or at least coherent) drawing then I plan to start asking around.
    Do you know enough to make a 'coherant' drawing? Do you know what the spline is, how to specify the splines including tolerances? Do you know what material you want to use and the specific heat treat callouts required? Do you know the tolerances required for the grinding etc?

    -------------------------------------

    I used to work for a UAV company in So Cal. We had a lot of gears and shafts with splines made for the UAV transmission.

    We would go to the gear vendor and ask him if what we wanted to have made was viable. He would tell us what we wanted, and would type out what we should put on the drawing, because we didn't know, at least well enough to make a coherant drawing.

    Your average machinist is not going to know any of this, but somebody who runs a shop making shafts, gear/spline cutting, grinding, heat treating etc will know all of this. Whether you like it or not your going to be paying for years of expertise, which you will need to get a shaft that will work.

    ------------------------------------

    Anybody who takes this on will deserve a grand steak dinner at a fine restaurant, rather than the McD's value deal you think their worth.

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    Quote Originally Posted by GregSY View Post
    1) You can buy input shafts for a variety of transmissions that are hell-for-stout (much better than OEM). If you don't believe me, go look up Powerglide or TH400 input shafts and you'll see there are a dozen brands all for under $200. These are shafts specifically produced to handle much higher HP than stock. Yes, they make them in quantity but the volume isn't nearly as large as you might like to think.
    Oh, there's no need to blindly believe you. I'm familiar. I simply asked how you have come to verify and accept the assertion. I ask because I am also familiar enough to know that there is great variation between the various offerings. That inconsistency leading to the question - Which one is actually correct? You might be surprised to discover just how many are actually poorly done. But hey, marketing is truth. Right?

    I am personally aware of ( at least ) three forum members that make and sell them, themselves. As in, it's a core part of their business. You might ask yourself why they are not weighing in right now.

    Quote Originally Posted by GregSY View Post
    3) The point of this thread- as I stated - was to learn if the skills needed to do the above still exist, and in this region of the world. I expected the usual peacocks to join in and they have. It's never hard to find someone who is overly proud of their abilities...and the first sign of that is someone who can do a good job if they charge enough. Money is the easiest way to cover a lot of deficiencies. Let's not forget ...I can make these myself if I throw enough money at it.
    Just a heads up - To be clear, any monkey with half a brain cell can push the power button of a machine. Making Gears & Splines is not brain surgery. It's just Math, materials, and experience. You can find and purchase any old Hob, Shaper, & Grinder today. Thinking that you'll be making quality parts from provided samples in short order is a fantasy.


    Quote Originally Posted by GregSY View Post
    The entire driving force behind business is the concept that a company can realize benefits of economy and scale.
    "...entire driving force..."...?

    I'll disagree with the broad flatness of that statement, but have to wonder just how it pertains to your desired result, lacking the scale part of the equation. ( not to mention the relationships )

    Some times, price is not the player you make it out to be. Over the last two years, we have done a fair amount of work for a specific sector that we had previously not. We price the work honestly and fairly, but are not the least expensive. Not by a long shot. Yet, we keep getting the contracts. I have asked several of the people overseeing the contracts about the "why" of it. It turns out that ( I am told ) in an industry sector widely known for "lowest bidder wins", quality and service do actually matter. At least, in our experience and in regard to Gears & Splines.

    ( personal anecdote - I was actually very surprised to learn this, as I had fully prepared to quote and never hear back from any of them, and frankly couldn't care less. )

    Quote Originally Posted by GregSY View Post
    What would I expect to pay? There's no reason a shaft like the one I've shown should be more than $1000 when bought in small quantities.
    We firmly agree.

    In fact, I am glad to learn that the way your text reads on the page is not how it actually is. So, having said that I am a little surprised that you can not find someone competent to do it. Is it possible that my previous cautions about your delivery is contributing to your lack of success?

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    Quote Originally Posted by GregSY View Post
    Stupidest comment of all, thanks.
    Quote Originally Posted by Rob F. View Post
    These guys ought to have it if it is such a common part:
    Used Auto Parts Houston | Salvage yards | LKQ Pick Your Part
    Quote Originally Posted by GregSY View Post

    The part I want made is very, very common part that was produced in the millions over a 25 year span. I'll bet there are ten sitting within a 5 mile radius of anyone in a populated region of the USA. There should be very little mystery behind the splines for anyone who has been in the business. A company that is good at making shafts should be able to look at this shaft and realize their skills and tools allow them to make one without a lot of fuss. A company that has lots of fat and incompetence may still be able to make one - as long as they can find a market that will pay for their inefficiencies.
    Why is my comment stupid? If it is as YOU say: :"The part I want made is very, very common part that was produced in the millions over a 25 year span. I'll bet there are ten sitting within a 5 mile radius of anyone in a populated region of the USA" then just go to any salvage yard in USA and get one. Why is this a problem? As YOU said, there were millions of them made....

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    Quote Originally Posted by Zahnrad Kopf View Post
    Oh, there's no need to blindly believe you. I'm familiar. I simply asked how you have come to verify and accept the assertion. I ask because I am also familiar enough to know that there is great variation between the various offerings. That inconsistency leading to the question - Which one is actually correct? You might be surprised to discover just how many are actually poorly done. But hey, marketing is truth. Right?
    Just a heads up - To be clear, any monkey with half a brain cell can push the power button of a machine. Making Gears & Splines is not brain surgery. It's just Math, materials, and experience. You can find and purchase any old Hob, Shaper, & Grinder today. Thinking that you'll be making quality parts from provided samples in short order is a fantasy.
    The lack of a standard is a huge problem. All manufacturers make a 1-1/4" pro mod input shaft. But half the time the torque converter hub doesn't fit the input spline. It is really neat when you pay $200 for next day shipping and the splines don't fit. I have a rockwell hardness tester and you wouldn't believe variations in hardness.

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    Quote Originally Posted by GregSY View Post
    You can buy input shafts for a variety of transmissions that are hell-for-stout (much better than OEM). If you don't believe me, go look up Powerglide or TH400 input shafts and you'll see there are a dozen brands all for under $200. These are shafts specifically produced to handle much higher HP than stock. Yes, they make them in quantity but the volume isn't nearly as large as you might like to think.
    That's mostly marketing BS bud.

    I've been a manufacturer of automotive products since 2006. Before and simultaneous to that I owned a transmission rebuilding business. I can attest first hand to most aftermarket "much stronger than stock" stuff being just a bunch of marketing fluff and BS.

    I recall the first time I needed some custom splines made and had a meeting with Kieth the original owner of Dutchmans. Not so different from your same kind of parts. I got an education and overall my take away from that experience is that I should lower my expectations and I could do better doing it myself.

    I'm not the guy to make your parts.

    I am curious though what the hell do you need a custom input for a 904 for? Is this a converterless dirt track deal or?

    I bet you could simplify that shaft a lot depending on what you're doing.

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    Quote Originally Posted by converterking View Post
    The lack of a standard is a huge problem. All manufacturers make a 1-1/4" pro mod input shaft. But half the time the torque converter hub doesn't fit the input spline. It is really neat when you pay $200 for next day shipping and the splines don't fit. I have a rockwell hardness tester and you wouldn't believe variations in hardness.
    I love reverse engineering automotive stuff that must certainly be made from some kind of super metal one would think only to discover it's carburized 1018.

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    I agree very much with the most expert members here who say "itīs not that easy".

    They look at things like stress risers, longevity, ability to make root angles, etc.
    Accuracy, longevity, strength vs failure in short-term-use (typical) // liability, etc.

    I also agree with the guys who think "itīs not that hard".
    This is true.
    And in most cases a spline that fits is good enough.
    And if it fails 4 years later itīs still "good enough" for typical motorsports etc.

    But sometimes legal challenges get put on the parts makers, for reasons that may have nothing to do with the parts.

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    Quote Originally Posted by hanermo View Post
    I agree very much with the most expert members here who say "itīs not that easy".

    They look at things like stress risers, longevity, ability to make root angles, etc.
    Accuracy, longevity, strength vs failure in short-term-use (typical) // liability, etc.
    And in most cases a spline that fits is good enough.
    And if it fails 4 years later itīs still "good enough" for typical motorsports etc.
    How many 4,000 horsepower cars have you built?

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    I also need a transmission shaft - 727 output shaft. At 3500 lbs car weight, a factory output shaft is known to be good to about 800 hp - drag racing. After that it is a crap shoot depending on how hard it hooks. New motor going in over the winter will be 1000 hp+. The only aftermarket shaft that is made is not available at this time. The shop that was making them at this time is shut down and whether or not they restart is questionable. They moved and I guess it has not gone well. So got my fingers crossed but not sure what will happen......

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    RE: in most cases a spline that fits is good enough."

    You do know the functional difference between an involute spline and serration, and why the involute profiles must be accurate?

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    Quote Originally Posted by 10 fingers View Post
    RE: in most cases a spline that fits is good enough."

    You do know the functional difference between an involute spline and serration, and why the involute profiles must be accurate?
    Well, I don't, but would love to learn.

    Sent from my SM-G973U using Tapatalk

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    Quote Originally Posted by 10 fingers View Post
    RE: Gear cutting is not that big a deal.

    Please look me up at the AGMA trade show next month. I'm eager to have you introduce me to all the industry professionals that solicit your services. Deal?
    I actually toned that post down a bit because it was too harsh, but what the heck. You asked for it ...

    Nobody at AGMA is gonna ask me nuthin' because I am old and don't give a shit no more. With the exception of Liebherr, they are fucking idiots. The people we worked with exhibited at AGMA and IMTS shows for twenty years, and they were one of the biggies. Not only that but I made gear hobbers, some of which are spread around the US today. Nice ones, fucked up by greedy people trying to make obscene (and unreasonable) profits.

    Our head guy had a background selling pots and pans, and his second in command was a maitre d' in a steak house on probation for small-time dope dealing. He's now doing real well working at a big name gear machinery company. I've dealt with a president of AGMA and he is a moron. This is the one who totally screwed up AGMA standards because he doesn't have a clue. We've made two million dollar sales then had to deal with the stupidest, greediest, most dishonest people on the planet, from some of the biggest names in the gear industry (and the riggers, truckers, and freight forwarders.)

    I'm sick of the whole fucking mess. I'd rather be homeless sleeping under newspapers than deal with those assholes again. People who don't know shit running off at the mouth about silly crap such as "Well, we'll need six hours to mae a CAD drawing" ... of a circle. As I pointed out earlier, in less time than you took to blab about how special you are, Dan from Oakland made the parts - at 1/10th of what you wanted. There's guys who know their shit out there, but no. Gears are not that special. They are a little special but not like you make it. No wonder the US is going noplace fast.

    (And I've owned and run hobbing machines that you've never even heard of, so nanner nanner, my dick is bigger than yours.)

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    Quote Originally Posted by Cole2534 View Post
    Well, I don't, but would love to learn.

    Sent from my SM-G973U using Tapatalk
    Involute spline members are self centering under torsional load. But only if the profiles and index spacing are accurate.

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    I would have thought there was a standard definition for splines by now. like gears or threads. where a designer could spec a 15 tooth spline with 1 5/8 fathom diameter grade h? I guess I never really looked at splines that much.
    I had to look up involute spline... would a rough forged or even rough knurl make it stronger by removing grain stressors?

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    Quote Originally Posted by memphisjed View Post
    I would have thought there was a standard definition for splines by now. like gears or threads.
    There is. It's not difficult. The main problem would be that in the past, people have done all sorts of weird things, so reverse engineering an existing part can be a headache. But generally speaking, splines are pretty straightforward.

    The difference between an involute spline and a serration is that involutes are curves, serrations are straight-sided. So they have different uses.

    where a designer could spec a 15 tooth spline with 1 5/8 fathom diameter grade h? I guess I never really looked at splines that much.
    In general there are two types of splines - involute and straight-sided. (Not serrations, straight-sided splines. Serrations would be used more on the handles of microscope focus dials and stuff like that.) Involute splines work the same as gears. The metric ones can be a pain because they started out as translations of existing inch splines. I haven't looked recently to see if they still do that. Metric gears suck ass, so I avoid them.

    The only other thing is, for involutes, there can be a flat root or a fillet root. That's what it sounds like. Fillet is stronger but sometimes wall thickness is so small you have to use flat root.

    The other type is straight-sided. Transmissions would be a common place to see them. They come in two varieties - major diameter fit and minor diameter fit - that should be self-explanatory ? For major dia fit the o.d. of the shaft locates on the larger diameter of the part, the remaining dimensions have clearance. Minor diameter fit is the opposite, root of the spline shaft locates on the small diameter of the mating part. Major diameter is more common, because it is easier to grind the o.d. of the shaft. Grinding the roots requires specialized equipment. Older Italian cars seem to like minor diameter fit, grrr.

    Then there's three "classes" - A, B and C. One is tight, non-moving. One is snug, can move but not supposed to. And the last is easy sliding fit, supposed to move under load.

    There are standards for all of the above. Maybe they are now in Machinery's Handbook ? Otherwise, you can buy the standards or just look at an Ash Gear catalog for the basic dimensions. It's pretty straightforward.

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    Gears engage on line at a time. All power is transmitted though that contact line at any point in time.
    Splines are so different which is why they can be smaller and hold up to much higher power levels.
    Both are not easy to make but splines add a level.
    ....and then there is rolled vs cut and the stess/strain and resulting strength.
    Not to mention how the heat treat is done on such a shaft. Is hard all over and lengthwise good? Or do you want the shaft to spring or wind up in the middle under high load?
    It sure looks easy until your parts have to pass that 1/4 million mile high cycle duty test day in and out.
    Worse yet is when one fails and your last 8-24 hours worth of production is red tagged and quarantined. No smaller shop can ever hope to do this type fatigue testing.
    Bob

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    Quote Originally Posted by CarbideBob View Post
    No smaller shop can ever hope to do this type fatigue testing.
    No smaller shop is asked to We're talking uses of 100 hours a year ? Totally different situation, no small shop will be rolling anything, and you can make up for under-engineering by over-materialling (I just made that word up ) But it's a simple concept and it works - use 9310 where detroit would use 1045 and you'll get as good or better performance for the kind of use the part will see.

    Works at Indy

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