Drive shafts strength?

[white433]

I have finally got to work on my cut-down frame. Its mostly put back together. A friend said he pulled a rear drive-shaft from a Ford truck that is the right length I need (33 to 34 inches) , I`ve not seen it yet. My question is, are the stock drive-shafts and u-joints considered fairly stout? I don`t remember anybody ever say anything about breaking one and was just wondering? I`m not planning on getting to wild, but I do have a twenty year old boy.

[Barrman]

All the u-joints on a stock truck are the 1310 size. This is pretty much as small as you can get in a truck. That being said, a stock engined truck will be hard pressed to break them. But, a V8 truck in the right situation can break just about anything you put in there. Which leads to the "great debate."

Axle strength: The D60 and D70 on your M715 have the "big" name, but are 40 years old and comprable to a modern D44 in strength. Except, the D44 today has better metal in it. Many members have broken front axle u-joints and rear axle shafts in mud. Stock everything you should be fine. But, you add lockers, big tires and get in a situation where the front wheels are turned at full lock against a big rock or something and you punch it. Or even just ease into it. "BOOOM!" goes the front axle u-joint.

Stone stock, these trucks will do amazing things. Start adding stuff and the weak parts will show themselves and the money chase will begin. Because once you break one component, replace it with something bigger and better, the next weakest one in line will go soon after. It is an endless cycle. I know of a guy drag racing Super Duty Power Stroke Ford trucks. He bought a complete lot of M35's off GL for the axles. He is out of axles now and thinking of ways to make a 5 ton axle fit under his Ford. I haven't seen him in a while, but he will probably get around to breaking axles again once he finds a stronger transmission, u-joint, driveshaft, etc... You get the point.

[white433]

Thanks for the memories! I had a 67 Bronco in my youth, added V8. big tires, lift, headers etc.,etc. Like you said everything over stock , bought a new headache. When Garrett was about 14, I tried to educate him about the evils which will follow heavy modifications, I failed and he has further corrupted me! In the midst of this freefall from reason, I remain unrepentant. Would any, thus afflicted soul confess knowledge of a stronger type of drive-shaft that might keep one safe from a plunge of mud? Thanks, I gotta go make some coffee.

[gimpyrobb]

Upgrade to a deuce driveline.

[Barrman]

Yeah, 2 common paths have developed over the years.

1) M35 axles front and rear, NP205 t-case, engine/transmission of choice and 42-44 inch tires.

2) CUCV axles (D60 open knuckle front/14 bolt rear with Detroit) NP205 tcase, engine/transmission of choice and 36-38 inch tires.

Or, you could do like a bunch of us have. Stock axles, rear locker, front lock outs, no bigger than 38" tall tires and an awareness of what you are doing so you don't grenade stuff. Engine/transmission/t-case choices and examples are too numerous to list out.

While we are discussing bigger parts. I have a BBC in mine with a NV4500 behind it. For the money, I would recommend a 3053a OD from a M35 over a NV4500. I would still pick the 3053A over the NV4500 if they cost the same too. I have about 10K miles on my engine/transmission and don't have any troubles. But. when you need a gallon of special fluid at $35/quart, those finiky cellulous or something spacers and the 5th gear problems inherent with the design, the 3053A gets looking better and better. 3053A's survived many, many miles being driven by "soldier A" who might have actually been shown how to drive a standard before being put behind the wheel of a vehicle he didn't own and didn't care about the maintenance cost of. In other words, they are stout and will take regular GL-5 lube.

Oh, I think the 3053A is a .78???? OD while the NV4500 is a .73??? OD. So, you don't get exactly the same reduction, but within a hundred rpm at speed is close enough to not matter.

[Doug]

I pound the heck out of my stock jointed drive shafts and have yet to break one....not saying they can't be broke, just saying they can put up with a little abuse prior to doing so. My truck is the short one with 39.5 TSLs on it, 400SBC, SM420, Locked front and rear.


I'd not get in a big hurry to spend money on new yokes and such, run it like it is and replace/upgrade if/when you need to.