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post #1 of (permalink) Old 01-07-2005, 06:51 PM Thread Starter
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Closed knuckle D70

A buddy is planning to put a flat-fender Power Wagon back into service - make it safe and functional but not historically correct.

Among other things he's worried about the reliability of the D70 front axel, particularly the closed knuckles which he fears will trap mud and wear out the U-joints. Also he would like to put disk brakes on it.

Until he mentioned the disk brakes I was steering him towards replacing the seals around the knuckle balls and letting it go. Doing a brake conversion makes me think that he might be better off looking for a newer axel, off something like a power company bucket truck.

So, what's so bad about the closed knuckle axels? How often does a D70 or Rockwell passenger-side drop front axel turn up? And how pricey are they when you can find one?

I spent several weeks prowling junk yards around here and never saw anything heavier than a 44. But then I didn't go to any yards specializing in heavy trucks.
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post #2 of (permalink) Old 01-08-2005, 04:39 PM
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Re: Closed knuckle D70

Jim are you sure it is a D70. I dont think that would be orginal to the truck if it is. I am 99% sure they used the early dodge pumpkin style rear. Either way, closed knuckles really dont hurt anything. Other then they can be a pain. Fresh seals, and keep grease on the balls when the truck is sitting, will keep any mud and water out.

[img]images/graemlins/40BEER.gif[/img]
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post #3 of (permalink) Old 01-09-2005, 12:08 AM
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Re: Closed knuckle D70

The closed knuckles are designed to be filled with either grease or 140W oil to lube both the u-joint (remove the u-joint's seals) and the knuckle pivot bearings. There should not be any mud in the closed knuckle. With good seals, it would be better for mud than an open knuckle.
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post #4 of (permalink) Old 01-09-2005, 06:46 AM Thread Starter
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Re: Closed knuckle D70

I'm only taking his word that they're D70s, and he probably doesn't really know. I haven't seen the truck myself.

Will, that's what I thought about the closed knuckles. So why do they always get such a put down here?
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post #5 of (permalink) Old 01-09-2005, 09:41 AM
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Re: Closed knuckle D70

Some of the closed knuckles such as found in the M715 are designed like the toyota birfield joint and are considered weaker than the spicer u-joint type design. Most people also consider the knuckle itself a weaker design. I don't know if it is actually weaker but if you break the knuckle the axle is trash wheras a open knuckle design the c's are replaceable (not an easy task on the inner but doable).

The M37's i have seen at auctions all had the weird 9" looking front axle in them. The civilian powerwagons with the fixed roof came with the dana 70 closed knuckle design sometimes. The M37 is a 3/4 ton truck and not a 1 1/4 ton.

There is a book available to those that want to restore them to stock.
http://www.swapmeetdave.com/Ahl/M37.htm
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post #6 of (permalink) Old 01-09-2005, 10:48 AM
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Re: Closed knuckle D70

The ones that could be used in jeeps are the ones that get put down. They are the dana 25 and 27 for the obvious reason that they are light duty axles. The other is the closed knuckle dana 44. The reason for it is it uses the 260 size u-joints same as the cj dana 30. It is not the closed knuckle itself that is bad but the housings and shafts that went with it.
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post #7 of (permalink) Old 01-09-2005, 11:08 AM Thread Starter
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Re: Closed knuckle D70

[ QUOTE ]
It is not the closed knuckle itself that is bad but the housings and shafts that went with it.

[/ QUOTE ]

That's what I suspected. Thanks.
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post #8 of (permalink) Old 01-09-2005, 08:15 PM
 
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Re: Closed knuckle D70

Actually there is a standard u-joint in there. I would presume that they thought that was a better idea than the "C" found on the end of most axles. I would bet the "strength of the sphere" came into play in that design??? JMO
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