The 8.8 31 spline shafts (1.32") should be a tad larger than the 30 spl 60. And they really neck up at the tire end of the shaft. But, as Keith mentions, they need to be big as they are doing double duty as a semi-floating axle, delivering driveline force as well as carrying weight, unlike a FF.Keith_L said:Yeah, it looks like his page is just unclear about that. 30 spline 60s are 1.31" same as 8.8. Of course the full floater aspect makes a 60 superior.
Having thicker tubes I'm sure wouldn't hurt, but the ones I have seen fail all do about the same thing, tube comes free of the too few welded pins and spins and/or gets tweaked right at the pumpkin joint...this then creates other failures. So, the tube welding idea, if done carefully, will help, and instead of a thicker tube, going with an upper axle support should also help. Both of these ideas only requiring ability to weld and some spare steel for a brace, because I agree with you, not worth spending a bunch of money to beef an 8.8 which is marginal in a Bronco offroad with bigger tires. But, if you've already put down the dough for gearing and a locker for the 8.8, would seem foolish not to try and help make them last.Andy351 said:i was also thinking that since the tubes fail from not being thick enough, couldn't you just retube them with 1/2" thick tubing? thats not expensive is it? yeah its still a SF, but it beats spending all the money over again on gears, lockers, and converting to 8 lug.
just my bored ramblings wondering if it can be done.
Well, some more ramblings...I am curious now just how thick the fullsize 8.8 tubing is. I found a site that shows several tubing cross sections, from the D70 with 3.5+ tube size and .5" wall thickness, to the D44/GM10/12 and ford 9" with 2.75" to 3" dia. and .25" wall. so then I find a Jeep builder site that swapped the 8.8 from an explorer, and he has a cross section of the 8.8 at .188" thickness :shocked x 3.25"dia. That is even thinner than the D35! Of course the tube is way bigger, which helps. This site by the way shows his swap to .5" wall tubing. Anyway, my question is...the explorer has the 8.8 with 31 spline, and the explorer weighs less than the Bronc, but the Rangerstation says the Explorer 8.8 has a GAWR of 3200lbs. My GAWR for the 8.8 is rated at 3770.Andy351 said:yeah, i know the tubes spinning is also a problem, but if you're retubing with thicker tubes anyway, welding them would be not a problem either. all the 8.8s i have seen either fail there or at the spring perches. the tubes crack under the perches because they aren't thick enough (just my guess) and the weight of the bronco breaks them. so by doing this, you'd be killing 2 birds with one stone. the only downfall is that they are SF, but spare shafts are a must anyway IMO.
I think you have a valid point, and proper welding of the tube to the pumpkin would be important. Your brace is exactly what I was planning, but I wish I knew the answer to my question concerning the thickness of these tubes for fullsizes. That's my worry. I am hoping that they are thicker than the explorer 8.8 tubes, but my fear is they are not.NOBS! said:I'm no expert, but my understanding of the plug welds and such is different from the guys in that link.
the reason for the plug welds is a method of retention for dis-similar metals. From what I read, they claim its to fuse the metals together. Not so IMO. The plugs are to keep the axles from spinning and walking out, after the factory friction fit up of the tubes. I'd say if they had a method of proper pre heat and post heat for the welding to cast it might stand a chance of holding up. From the pics I see, it looks weaker than OEM. Boogered up welds with cratering and undercut on the cast won't do shit. Duplicate the factory method,add a couple of your own,run a truss from one side to the other(notched and welded)and bolted to the cast housing.
someone set me staight if I'm headed in the wrong direction.