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5-bolt axles vs. 6-bolt (3x2) axles?

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  • 5-bolt axles vs. 6-bolt (3x2) axles?

    Just stirring up trouble again...,

    I know the 5-bolt axles use real CV joints vs. the tripod joints for the 6-bolt axles so that's good.

    Now I have some of both in the garage so I measured some other things; The 6-bolt axles are 28mm diameter. The 5-bolt axles are 30mm diameter but they all have a turned-down section about 1-1/2" long near the outboard joint that is only 27mm diameter. Anyone know the purpose of the turndown section? It's outboard of the boot so it's not there as a retaining groove for the CV boot. (?)

    I know I've read questions that others have posted about shortening or lengthening axles by cutting/rewelding. I tend to agree that it tends to introduce a weak area from the heat applied by the welding process. I was watching "Truck U" on Speed at lunch and they were installing a Mopar factory Pre-runner kit on a Ram pickup. Now, I know that turning a full size truck into a pre-runner sounds kinda funny on it's face, but what interested me is that the factory kit included 2" extensions for the front half-axles. The extensions looked something like a 6" tube with a 2" plug inside. It also had 4 plug-weld holes that were welded, along with welding the ends to the original axle. Is the annealing process only a problem if the axle was heat treated to start with? I know from experience cutting/welding mild steel that the torch cut edge or welded joint is generally harder than the adjoining metal. I know that from trying to hand-file the different surfaces. Now, if it's forged and/or made from something like 4130 or other heat-treatable steel there's more to it...,
    Don Johnson (really!)
    Just so you know.

  • #2
    I've done a little research and this is what I've gotten.

    1. On the question of the thinned secton of the larger half-axles; I talked to someone who's drag raced high-horsepower 300ZX's and he said that the first thing to break is that the splined stub that goes through the wheel hub will twist off the ourter CV housing, so the reduces section of the half shaft is of no consequence.

    2. Shortening half-axles. Many opinions and several methods, as I would expect.

    a. This one came from the "Offroad Network"- "The length of your sleeve only needs to be twice the dia of the axle either side of the splice. 1" axle needs 4" of sleeve over the splice, the sleeve ends need to be cut at an angle (45 deg), so when you weld, you don't weld a ring around the axle thats 90 degrees to the axle centerline, that can cause a major stress riser and the axle to crack. Rosette welds are plenty strong . If you can, and have room on the axle to slide the sleeve on and out of the way , splice weld the axle back together, finish grind the weld, then slide the sleeve over the joint and weld it.." This one was unique in advising to cut the sleeve ends at 45 degrees. His instructions didn't mention drilling spot-weld holes in the sleeve, but did comment on the strenght of rossette welds. (?)

    b. This came from the Mercedes Benz hotrodders on (One of their common upgrades is to use Nissan R200 diffs! ;-)) "Disassemble the half shafts, cut the shafts in a lathe to the correct length (in our case we cut 52mm from the middle of the shaft), make a slightly undersized 7.5cm long sleeve, taper the ends of the shaft for welding; clean up the shafts to allow the sleeve to slip on to the cut shafts; heat and slip the sleeve onto one of the cut shafts; weld the cut shafts together in a lathe; machine the welds to the shaft diameter, true the shaft straight, then heat the sleeve and bang it on over the weld and weld the sleeve to the shafts.It sounds like a lot of work but it was an easy two/three hour job at a cooperative machine shop with welding facilities." This one is similar to the first but more descriptive.

    c. Re-splining? "my mate got sleeved ones when we put an h22 into his civic. bust them within a month, ordered more from a different company, same result. Last 2 years he's been using cut and resplined ones with no problems...," No info on how these sleeved axles were sources or how they were built, but they were obviously un-acceptable...,
    Don Johnson (really!)
    Just so you know.


    • #3
      The weld will be plenty strong if done well. Welding the original shaft then welding a sleeve over it sounds good. If you're worried of the strength of the sleeve weld, then fish mouth it to get some more strength in torsion and reduce in plane stresses from being all in the weld direction.

      The hardest part will be keeping it all straight and true, but even that isn't all that difficult with the tools and proper welding procedure.
      '18 Chevrolet Volt - Electric fun hatch for DD duty!

      DefSport Koni Sleeve and Spring Perch Buy!!!