tc

Yep. It's a little above the molecular level. The atoms in metals arrange into crystalline, ordered structures. For instance, a cube with atoms on the corners and in the center. Then these cubes stack together. Occasionally, an atom is missing, and the "stack" kind of changes direction. Each LITTLE area where the cubes are stacked all nice and neat is a grain. The next grain is very similar, but at a slightly different angle.

Cast materials are dependent on how quick and evenly you can get the heat out as the part cools. If you cool it too slow, the atoms have time/energy to "move" around - generally to be near other atoms like them (they're a cliqueish bunch!) - and to get those cubes to stack up all nice and neat, leading to alloy segregation and large grainsizes.

Forged material starts as cast, but is then mechanically "squished" to physically break up these structures and refine both the segregation and the grain size. You can achieve similar effects through heat treatment, but it's not quite as effective.

William

[QUOTE=Albuquerque Jim]
Products on the market:
Warn makes the hub fuses http://products.warn.com/truck/axles/hub_fuse.shtml.
Four Wheeler Mag just put drive shaft fuses in their project Titan. They are made by www.powertrainsavers.com
QUOTE]
I don't like the idea of hub fuses, at least on a locker equipped vehicle, and here's why.

One of the 4wd magazines was testing them and actually broke a Detroit Locker because of a hub fuse. I can't remember the exact reason they gave, but I think it had something to do with the shock load on the side of the locker opposite the fuse, which occured as the fuse broke.

The driveshaft mounted fuse sounds like a much better idea, and there are shear pins for the fuse device that are rated for different torques. They are easy to replace, and you could experiment, starting at a lower torque rating and go higher until you find a rating that will break the shear pins without breaking the CV joints.

This won't cause front locker breakage. However, I wonder about how the potential shock load on the rear could affect the rear axle/driveshaft, or transfer case.

I would rather break something up front than break the transfer case or something in the rear, and be stranded as a result.

On a side note, doesn't anybody make CV joints/shafts that are stronger than stock? I would rather install stronger parts to prevent breakage than weaker ones.

tc

Yes, several people do. CV Unlimited being one. There are mods to use Porsche CV's too. The problem is that at ~$500/ea, you're well on your way to a SAS!

I don't buy the whole "hub fuse broke and took out the locker" story. Gonna need a whole lot more explanation on that one.

FredTJ

Yes, that's not an uncommon occurrance.
Coming from a Jeep background, braking a u-joint (front axle) or an axle with the front under stress does break Detriots.
It's certainly not rare for those that run JV and some of the other more extreme trails with Jeeps running 35's and larger.
The sudden release in tension when an axle u-joint gives up really plays havok with Detriots. Any locker with backlash can be totally destroyed by a hub fuse blowing, axle breaking, etc.
When I had the Jeep I was running Detroits, front and rear, and ran CTM ujoints in the front axles.



Fred

FredTJ

Now, several people have said that the outers break, or rather pull apart due to overextension.
Sounds like Downey may have the right idea with their slip yoke axle shafts.
Now several have also said that they've broken those.
What exactly broke ?




Fred

chadbobb

What is full lock? I kept hearing full lock on the first page. I really don't understand what CV's are. Is there a guide or something anywyere? I hear about people breaking them all the time, but havn't found any kind of guide when i search or anything.

FredTJ

Full lock is when you have your steering wheel turned completely to either the left or right, as far as it'll go.

CV's, a simply google search will show you everything that you need to know about them, what they are, the different kinds, how they work, etc.

http://www.samarins.com/glossary/cv_joint.html

http://autorepair.about.com/cs/gener...bldef_089b.htm

http://en.wikipedia.org/wiki/Constant_velocity_joint

Any many, many, many, many more links can be found.





Well, it appears that "people breaking them all the time" is basically a bunch of bull:

https://www.yotatech.com/forums/f116/those-who-have-broken-front-axles-gen-ii-4-runner-95992/

I posted the exact same question over on POR and got pretty much the same results.
Breakage appears not to be common, at least not as common as the internet hype would lead one to believe




Fred