Opinions needed: shortening half shaft

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Hey all!I'm in need of some opinions about a project I'm working on.  I've got a front wheel drive car that needs a shorter half shaft on the passenger side.  I've looked into alternative OEM replacements but I can't really get specs of other models to find out if they are the length I need.Anyway, I'm REALLY tempted to cut this puppy in half and remove a chunk to shorten it but at the same time, I want to make sure it's going to be structural and hold.  The car is stock making ~200hp and ~150lb/ft torque just for reference so it's not a monster.I did some interweb searching and there are really 3 methods people use for shortening these half shafts.1.  send them off to a company to get cut down, spun on a lathe, and re-splined2.  chop, bevel, and reweld3.  chop, fit a sleve, and reweld.Option 1:I'm not really sure how much I need to cut off of it because it's currently too long.  I'd estimate 1-1.5" but I'd like to have the opportunity to fit it and make sure it won't bind or be too short.  Therefore, I'd like to not have to send it off to only have to redo it if it doesn't work.Option 2:I'd have to cut it down and do something like this:The problem is that I don't have a lathe or some way to make sure it's "true".Option 3:I could cut it and put a tight fitting sleeve around it like this:I'm leaning towards option 3 because it's something I could do and make work.  The question for y'all is, do you see any issues with strength or longevity of taking this approach?  I measured the outside diameter of the axle and it's 1.08".  I can get some .156" wall tube that's turned to 1.00" inside diameter and press the stubs into the tube and weld it up.What do you guys/gals think?  See any issues with it?Last edited by kjlindgr; 07-30-2008 at 12:45 PM.www.lindgrensupercars.comMiller Dynasty 350Miller Dynasty 200DX - retiredMiller Millermatic 210Miller Spectrum 3080Miller "Power of Blue" stool  Miller Syncrowave 180SD - retired
Reply:I'd say 3 but be careful cutting it. U joints, or at least the one's I've seen, have a sleeve that goes inside the tubing much like any other tube end fitting. So you don't wanna cut through that. But if you could order the U joints and some tubing and built it from scratch if ya can.Miller Syncrowave 180SDMillermatic 175
Reply:I do not really see any options but #3. Consider #2 - weld is stong but brittle, so, without proper afterwelding heat treatment it will develop cracks very soon.With option #3 without analogs it is hard to say about proper tube size. For me - calculations would be a must...
Reply:If you give more details about the project and the kind of car, someone here might be able to tell you what OEM shaft might fit. Otherwise, I'd wait for some information from people on this site who work with those situations and understand what is involved. That said,.....Unlike a driveshaft which runs at a higher speed but has lower torque because of the differential gearing, the halfshaft runs at wheel speed but transmits the full driving torque so needs the full strength of the original axle. For option 3, you need to calculate what strength tubing will do the job, and be sure the welds are as strong/stronger, considering fatigue factors too I expect.  Just the 'worries' of a non-engineer.
Reply:Thanks for the comments all.  I've got the same concerns.  The axel is solid stock, and not sleeved.  The engine set came with one torch cut in half so I know what I'm working with.The car is a Honda Civic EK with an F20B engine.  People say to use 90-93 Integra axels with Prelude input shafts swapped out.  That's what I was doing when I ran into this length issue which nobody seems to have an answer to.  I posted up on Honda-Tech but the ratio of people that know what they are talking about to those that don't are like 1:11,000,000.  Here was my idea path:1.  Get opinions from the experts on if it's a good idea or not2.  Get opinions from the experts on the best way to make it holdThe pipe I was looking at is A513 Type 5 DOM tubing with .156" wall thickness.  It's got an ID of 1.063" so I'm sure I can heat the tube and slide the axels in with no issues and then weld around the lap joints.  I can get technical specs for the materials and that goodness too if that would help.www.lindgrensupercars.comMiller Dynasty 350Miller Dynasty 200DX - retiredMiller Millermatic 210Miller Spectrum 3080Miller "Power of Blue" stool  Miller Syncrowave 180SD - retired
Reply:Can you be more specific - what kind of experts you are looking for?
Reply:Originally Posted by NomandCan you be more specific - what kind of experts you are looking for?
Reply:Just go to a good boneyard that uses Hollanders manuals (any good yard should have them)...it's an interchange manual and will tell you what swaps out with what.Anything worth doing is worth doing RIGHT
Reply:Originally Posted by olddadJust go to a good boneyard that uses Hollanders manuals (any good yard should have them)...it's an interchange manual and will tell you what swaps out with what.
Reply:Originally Posted by kjlindgrTempting, except the F20B is a Japanese only motor which never saw a use in any US production car.  They are all imported.
Reply:You might take a look at the following thread, and see if you can find someone nearby you with a lathe who is interested in modifications like these to help you.  There are more people like that around than you'd guess. A local fellow built a number of full size working copies of early Wright Bros. engines in his back-yard shop, including the patterns for the castings he had made.What part of the world are you in?http://weldingweb.com/vbb/showthread.php...ight=halfshaft
Reply:are the axles solid or hollow?  The hollow ones are usually friction welded, and much easier to shorten. The splined diameter should be larger than the shaft, so you cant just cut a bit off the end.  Search the formula SAE forums  www.fsae.com for more info
Reply:A sleeve is fine. "Tight fitting" is an understatement though. It should be machined as a shrink fit with a few thou of crush- ie it needs to be warm and the axle halves need to be frozen for it to go together.Then weld and enjoy. Also, obviously you need to not warp it when you weld it.
Reply:You could grind off the weld on one end.  Cut the tube the proper amount and make it square on the end.  Trim up the yoke with a grinder.  It has a lip the tube slips on tight.  The U-joints have to line up, so both ends have to be the same.  You can use a level.  Make them true the best way you can on all 3 planes and weld it.  I have done a few.  If this is high speed stuff, don't even think about doing it your self.If the yokes are not true, it will vibrate.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Thanks for the input guys.  I'm going to attempt it.  I purchased some 1.06" ID tubing.  I'll post up pictures once it's done  www.lindgrensupercars.comMiller Dynasty 350Miller Dynasty 200DX - retiredMiller Millermatic 210Miller Spectrum 3080Miller "Power of Blue" stool  Miller Syncrowave 180SD - retired
Reply:Originally Posted by David RIf the yokes are not true, it will vibrate.David
Reply:I make them like in your option #3I use 4130 seamless tube and I interference press fit .001-.005 freeze one heat the other and press them then weld.Phasing is important as is runout I chuck them in my lathe and check runout and tack GTAW then check again tack some more, then weld.I have several sets in race cars and no failures yet.
Reply:Originally Posted by CapnbondoThis is why I suggest the sleeve made on a lathe and shink-fit. This gives everything no real option but to go together straight.
Reply:The pipe I ordered is .002" undersized so it should expand enough when heated to shrink fit it.  I like the idea of puting a 90 degree tube notch in it to make sure to distribute the heat across a wider area versus a straight cut.  I'll do that and the rosettes.www.lindgrensupercars.comMiller Dynasty 350Miller Dynasty 200DX - retiredMiller Millermatic 210Miller Spectrum 3080Miller "Power of Blue" stool  Miller Syncrowave 180SD - retired
Reply:I (and past members) have made custom half shafts for our Formula SAE cars a couple of different ways and you MUST BE CAREFUL WITH THISKeep in mind our car only makes 50 hp, weighs 392 lbs + driverWe tried to cut the splined ends off of a set of axles, and made a sleeve, bored and pressed in the cut ends.  It was 4340 solid round, with 4340 splined ends.We tried it two ways, one was to straight cut the ends, and those broke in half of a lapthen we cut the sleeve at a 45 degree angle and then welded it up and those are still in service.  Both done with a heat treatment to 130 ksi afterwards.  I am still kinda scratching my head on the cutting at a 45 degree angle because a torsion failure in a hard material always happens along a perfect 45 degree planeFood for thought, the sleeve MUST BE vacuum melted 4340, welding must be top notch and the heat treatment is keygood luckMechanical Engineer