View Full Version : center drive , shaft size

11-29-2006, 02:20 PM
what is a good diameter for the center shaft for a 600# buggy powered by a honda v30 1" 1 1/4"????

11-29-2006, 03:11 PM
What material are you using? *Are you thinking mild steel?

11-29-2006, 03:18 PM
mild steel would be probable, I can get stainless but would prefer not to because of cost

11-29-2006, 06:44 PM
My ZZR1100 has very slightly twisted my 1-3/8 x 6 spline shaft. I'd say, based on that, that 1-1/4" solid shaft is marginal.

11-29-2006, 06:50 PM
tenaja, wasnt your shaft 1 1/8? i thought thats what you said before, as you were considering what i was using at 1 3/8, maybe i am wrong, cant remember....

11-29-2006, 06:54 PM
Stainless is usually not stronger than mild steel, cromoly is your best bet. *I wouldn't go less than 1.25", and heat treating will increase its strength as well. *What are you using to transmit power, splines?

11-29-2006, 06:59 PM
Assuming about a 4:1 or 5:1 reduction ratio from the engine to the center shaft either 1 1/4" mild steel or 1" stressproof would be plenty strong. *The stressproof will cost about 10% more is all and has about twice the tensile *and yield strength that the mild steel does. *Some specs from the LaSalle steel site are attached. *You can get the mild steel at many places and you can order the stressproof through onlinemetals.com. *Tim


Stressproof® is made by a patented process which consists of drawing the bar through a special die under heavy draft, then stress relieveing it in a precisely controlled
furnace. Stressproof® offers wearability without case hardening, strength without heat treating, plus excellent machinability and tool life. Other benefits include
resistance to fatigue and stress, balanced working, and minimum warpage and distortion. Stressproof® can also be induction hardened but should be watched for
quench cracks, and, being a resulfurized steel, a magnetic particle inspection operation should be performed after heat treating.

Mechanical Properties
Tensile Strength 115,000 psi (Min)
Yield Strength 100,000 psi (Min)
Machining Characteristics 83% of 1212

11-29-2006, 07:33 PM
tenaja, wasnt your shaft 1 1/8? i thought thats what you said before, as you were considering what i was using at 1 3/8, maybe i am wrong, cant remember....
My jackshaft is 1-1/8" 6-spline, and it didn't twist...it didn't have gear reduction on it.
My center shaft and outer shafts are 1-3/8 6-spline, and with the 16-50 gear reduction, they twisted very slightly. So slightley that you don't quite see it at first.

The material, by the way, is 1045.

11-29-2006, 08:45 PM
Mine is 1" keyed 1215. So far no problems, but im sure a cvt reduces shock on the driveline

11-29-2006, 08:47 PM
That Stressproof stuff sounds good, but may fall into the "exotic" category - I don't know, I've never heard of it down here. If you can't find it locally, or have some delivered, I would aim for 1.25" 4340 with heat treatment. It's possibly overkill, but the weight isn't going to make or break your buggy.

11-29-2006, 09:21 PM
The stressproof is readily available here in the US. *If you want more strength you can also go up to fatigue-proof. *It is another 20 % or so stronger than the stressproof but still machines easily and like the stressproof does not require any heat treatment to get the high strength, good toughness and good wear characteristics. *The fatigue proof is a little harder to find ... but not too hard. *Last time I got some was at metalshorts.com I think. *Both types cost a little more than mild steel but you only need a small piece so the cost is still minimal. *For example at *onlinemetals.com it is in stock and only about 5.00 for a foot long chunk of 1" diameter stressproof rod. * So for $5 or $6 bucks you get a shaft that machines easily and yet you do not have to worry about any post treatment, hardening or other secondary operations to get over 100,000 psi tensile and yield with great toughness and wear. * Again copied from LaSalle steel's site ... below are some specs for the fatigue-proof stuff. *Hope that helps a bit... *

Rorty don't get me wrong. * [smilie=bow.gif] * I agree with you 100% that a 4140 or 4340 alloy are an excellent choice for axle/drive shaft service, but the treatment required to get the high strength they offer can be a bit hard (and expensive) for some home builders to come by. *For the lower budget home built guys the stressproof or fatigue-proof are a great and very simple solution and they are only a couple of mouse clicks and less than $10 *away in here in the good old U S of A. * [smilie=boogie.gif] *Tim


Fatigue-Proof® has the high strength properties usually associated only with heat treated steels. It also has excellent machinig characteristics, resistance to fatigue and
wear, and it minimizes distortion. Fatigue-Proof® is produced from a high manganese, resufurized, silicon killed steel. The chemical specification for Fatigue-Proof®
corresponds to AISI Grade 1144. From this special quality hot roll grade Fatigue-Proof® is made by various combinations of mechanical working and thermal treatment
which can include Niagara LaSalle’s e.t.d. ®(elevated temperature drawn) process. This is a high strength steel bar that eliminates heat treating and secondary operations
such as cleaning, straightening, secondary machining and inspections. All this, in combination with free machining and high strength, operates to lower end costs.
Fatigue-Proof® induction hardens satisfactorily, but as with any high sulfur steel it should be watched for quench cracks. Fatigue-Proof® is also electro-magnetically
tested using eddy currents and pre-tested for machinability through Niagara LaSalle’s unique testing procedure.

Mechanical Properties
Tensile Strength 140,000 psi (Min)
Yield Strength 125,000 psi (Min)
Machining Characteristics 80% of 1212

11-29-2006, 10:26 PM
Sorry, 4140 was a typo: it should have read 4340 - I'm so used to typing 4130 and I'm easily confused at the best of times. I'll edit my previous post incase it confuses anyone.

Those two steels you mention sound perfect. I'm sure if I did a comparrison I could find a similar alloy here without the trade name, but it then really would be an exotic. I appreciate not everyone wants to be running off to a heat treater's with a part, but the advice was offered as another alternative if Stressproof couldn't be located. *[smilie=biggrin.gif]

11-29-2006, 10:30 PM
Stressproof is good stuff, but it is NOT weldable! *The sulphur in it make it easy to machine (11xx series steel is resulphurized), but by the same token, the sulphur makes this material very difficult to weld because it forms cracks at the weld bead.

11-29-2006, 10:45 PM
Sorry, 4140 was a typo: it should have read 4340 - I'm so used to typing 4130 and I'm easily confused at the best of times. I'll edit my previous post incase it confuses anyone. [smilie=biggrin.gif]

Yeah I figured the 4140 might have been typo'd (I do it all the time) so I just gently mentioned 4340 as an alternative ... for others who might reference any of this thread * [smilie=blink.gif] . *And for sure the treated 4340 is a more professional solution.

And yes p'buster good point for people to know that I should have mentioned ... the 2 11xx series steels that I mentioned are *sulphurized/resulphurized so they do not weld well. *Also note that the info I copied from LaSalle warns about surface cracking that can result from induction treating if you do decide to bump the strength up even higher with induction treating. *Both can be done but must be done very carefully and are really for experts. *I welded up a hub to shaft joint just for grins and have tested it about 2 or 3 hours and so far so good. *But that was purely just to see if I could do it, not recommended. *A guy should just drive the sprockets, hubs or whatever runs on the shaft with a key or splines, not welds. *No matter what material the shaft is made of I would assume that few builders here weld the sprockets or hubs directly to the shaft ... but I could be wrong on that. *Been wrong many times before.

11-29-2006, 11:32 PM
No matter what material the shaft is made of I would assume that few builders here weld the sprockets or hubs directly to the shaft

I didn't think people would be welding the axles or hubs, but I just wanted to point out that this material is a bitch to weld if they decide to use it as a weldment.

11-30-2006, 12:08 AM
Yep, very good catch. *The total picture makes the threads useful for other readers that come along sometime down the road which is a very good thing. *Thanks for helping to make it complete!

11-30-2006, 09:07 AM
Im looking at running a keyed shaft. * what I have available to me is as follows:

Keyed Drive Shaft Type Fully Keyed
Material Steel
Steel Type AISI 1045 Steel
Finish Plain
Hardness Unhardened
Specifications Met American Iron and Steel Institute (AISI)

11-30-2006, 12:25 PM
I have been using 1" keyed shaft on a 650# car powered by a 600cc F4i driven by chain. *Works good so far. *There is a thread on here, search "keyed shaft".

11-30-2006, 12:28 PM
OK, 1045 will work fine. *It is not as strong as some other options that have been thrown around but that is OK, just go with the 1 1/4" diameter. *The extra diameter makes a huge difference in a shaft's ability to carry a torsional load. *And as Rorty pointed out you can have the shaft hardened sometime in the future if you decide that you want to.