1. Explain a wimpy Toyota 8" axle running 37 stickies
2. A 44 is a step up from a S35. I've not denied that. But, a S35 or 44jr is a good viable option for people who can't get a 44 easily. But I still maintain the 8.8 is not a step up from the 44. D44 = 8.8 = S35.
3. Theres not enough change in strength to justify the expense. Now, moving to 60's or 9" is the next class up.
4. Your confusing me here. In one sentence you say the 35 axle has the same tube as a TJ44. Then you say to upgrade the tube to .250" It's .250 from the factory.
1. Toyota's third member style axles are different that the fully cast housing design of an 8.8, D44, D35 or even the D60. Its more like a 9", and third member housings are notoriously stronger. This is because most often, they are tapered from the center outward, inherently creating a big truss, made of steel, not cast. A third member axle is definitely a better design (for strength anyway) than the standard cast center section with tubes. Plus theres just the fact that Toyota has made better drivetrain components than Dana for a long time. Toyota's 8" third members are pretty cool...high pinion, and can be swaped front to rear, plus the strength of a D60, definitely awesome for field servicability. Lots of big semi-truck axles, including Rockwell 2.5 ton axles, are third member style designs.
2. If a D44 is a step up from a S35, but a 8.8 is not a step up from a S35, then shouldn't it read D44 > 8.8 = S35?
3. hhhmmmm 9"...third members...Spidertrax housing's are sexy
I ment .500, reading to much axle specs to keep crap straight. And, TJ D44's tubes are still prone to the same flexing a S35 would be, but the larger center section and larger gears add to strength and lessen the chance of breaking something inside that center section vs a S35.
For future reference - thanks to Google and my trusty calculator:
Dana 30 - 2.5" x 0.250" wall - Moment of Inertia: .65941 in^4
Dana 35 - 2.5" x 0.250" wall - Moment of Inertia: .65941 in^4
Dana 44 1/2 ton - 3.0" x 0.250" wall - Moment of Inertia: 1.16870 in^4
GM 10-bolt - 3.0" x 0.250" wall - Moment of Inertia: 1.16870 in^4
GM 12-bolt - 3.0" x 0.250" wall - Moment of Inertia: 1.16870 in^4
Ford 8.8 inch - 3.25" x 0.188" wall - Moment of Inertia: 1.1614 in^4 (some say .250", but I've never measured one so I'll stick with never_monday's spec)
Ford 9-inch - 3.0" x 0.250" wall - Moment of Inertia: 1.16870 in^4
Dana 44 front 3/4 ton - 2.75" x 0.500" wall - Moment of Inertia: 1.5493 in^4
Dana 60 rear - 3.125" x 0.313" wall - Moment of Inertia: 1.61209 in^4
Dana 60 front - 3.125" x 0.500" wall - Moment of Inertia: 2.3506 in^4
Dana 70 rear - 3.625" x 0.563" wall - Moment of Inertia: 4.1611 in^4
The higher the moment of inertia, the more cross sectional area of material to absorb stress, the stronger the tube.