offroad axle braking remedie discusion

[Scott in Bellingham]

I remember as a kid my uncle would have what he called "shear pins" it was a pin that under high stress would brake or shear to prevent either the outboard motor or a winch from breaking, the pin on the outboard would fit next to the prop and the one on the winch was on the shaft that entered the winch gear housing, theese "pins" where no more then a soft bolt that would give befor the machine would break , now if we were to incorperate something like this into the soobie drive maybe it would save a few axles and prevent being stranded out in the abyss

lets discuss our options

[GeneralDisorder]

Well - my system seems to work well (for me - YMMV).

 

I've swtiched to using EA82 DOJ's on both ends of my EA81 rear axle shafts. They are about 1/2" deeper each, and that gives me enough extra stretch with the EA82 rear coils, in combination with 1" spacer blocks on my diff hanger to prevent them from over-extending. On the EA82 there are two types of rear axles - one with two DOJ's, and one with a CV on the outer end. Get the double DOJ axles for better stretch.

 

On the front - there is a company in CA by the name of GCK that makes some pretty serious EA81 front axles. They are "beyond" 4WD spec for the EA81, and the joints are amazingly strong. They are not remanned in ANY way - even the shaft is brand new. I have not been able to break one no matter how hard I've tried. Possibly with bigger tires and more gearing you could, but even GCK claims they are "optimized for off-road performance". I have to say I'm impressed with them, and I don't say that often. Sadly, they make nothing similar to this for the EA82. Perhaps if you gave them a call.....

 

The next weakest link is definately the rear diff stub axles. I would like to find a way to make some out of a stronger material, or make them from standard steel but not hollow - use a different method to keep them in place. Maybe a cir-clip or a bolt over flange or something. Perhaps move up to the R180 diff, or the R200 in the STi.... need more info on them tho.

 

GD

[Numbchux]

I like where you're going with this.....but I have no idea how you would do it.

 

And, as QMan has said, the axles really are the shear pins in our case. they are the weak link. if you're putting too much force on the system, they will break before the diff does etc. And if you're careful with your driving style, and have the car setup well, you won't even break them all that much.

[GeneralDisorder]

That's true - same with H1 Hummers. The axles are like fuses that protect the rest of the drivetrain. Except in the case of the H1, they are flange bolted in place and easily changed out anywhere, anytime. I had to do a few in weeds and grass - at least you dont need to jack them up.

 

I would love a flange bolt style axle that is easy to change. A little more beefy than stock, with a 4 or 6 bolt flange would be perfect in my opinion. And remedy the weak stub axle design. Personally I don't care if I destroy a diff once every 5 years.

 

GD

[Mike W]

Back when I was planning my next project I was thinking of using some Nissan rear end components. 280ZX stuff would offer the flange mount axles and R180 diff. You can get spools for the R180 but then the weak link might be the diff stubs again. 300ZX stuff gives R200 diff and you could theoretically put a ARB air locker in that (I was gonna run a R200a up front too.) I guess some 300zx also had rear steering, perhaps for those seeking to further complicate matters. Maybe with the Nissan setup, you could use the outer stub as the "fuse" by turning a groove into it to weaken it a bit? Maybe this doesn't help, just thought I'd toss it out there. Whatever's gonna break most often, you want it to be easily swapped out. And whatever's the biggest pita to fix out in the woods, you want to protect it.

[4x4_Welder]

I don't think those systems would flex enough, though-

The real problem comes from the fact that nothing on the rear of these cars was designed to be fixed in the middle of nowhere, and is the only spot I really think they dropped the ball on an otherwise decent 4wd system (other than making it primarily front drive). There really isn't a way to fuse the system without redoing most of the rear end. The only off-hand solution I can give is to figure out how to use a spindle and stubshaft arrangement with outer locking hubs, like on the front of most 4x4 trucks. That way, you can have the hub as the fuse, six small allen bolts and a snap ring, and you're back to wheeling.

The other option would be to replace the rear system with a different style, re-worked to provide approriate lift and flex.

Kind of an idea to think over. Anybody want to donate a car for experiments?

[Andyjo]

A little side note on using a solid rod opposed to a hollow one... a tube (hollow rod) will take torsion/torque much better than a solid rod, it has to do w/ moments of inertia, and crap like that.. if you really want to math i can bust it out.. but i don't think you want a completely solid axle....

[bushbasher]

if you use the complete front hubs, axles, and diff from a nissan 720 4x4, make a custom subframe and a-arms, you can use the longside axles from the nissan truck on both sides of the diff, and it will end up within an inch of the subarus stock width. Stock subarus are about 61" wms to wms vs the nissans 55". I've done the measurements in the junkyard. You would gain locking hubs, beefier axles with a flange mount, a larger diff with more aftermarket than the r160, and bigger brakes too which is important if you want to go beyond 30" tires.

 

Andyjo, I am currently studying mechanical engineering, and I can definitely say a tube does not take a higher load than a solid shaft for a given diameter, however it does give more strength for a given weight. Over 90% of the load on a shaft is distributed on the outer 1/2 of the cross section.

[tailgatewagon]

No thank you,,,

 

ive thought about sending the rear stubs to be heat treated...

you could make a steel coller for the rear doj and weld them on and then get them heat treated... but then you will probably start brakeing things in the trany......

 

i would rather change axles....

 

axels are easy to rebuild... easy to change and cheep.

[Mike W]

Hows about a VW buggy style rear suspension setup with 930 high angle CVs mated up to a R200 or Dana diff with locker? A Quattro diff might work if it's stout enough.

[dustyrider]

It's a great thought but.....

 

We should run with a cheap extra axle, its just that easy of a solution and here's why...

 

I bought one reman. front axle w/ lifetime warranty two years ago.

its blown up three times now.

I go to the store I bought the axle from, buy another one, go home and in an hour I bring back the busted one, and get my money back its not the same axle everytime either!

They even told me, this time how good of a time I had on the replace.

Im really tempted to not leave the parking lot next time.

Lifetime warranties are great and you only need to buy one cause whats the chances of both going at the same time.

This is how the extra one when your wheeling comes into play you won't find yourself stranded anywhere and switching an axle is alot easier of a fix on the trail than say an axle stub.

You can't get any better and cheaper than that.... Which is the real reason we should all be driving subaru's cause their CHEAP and way too easy to fix.

 

As far as making a setup that doesnt break well I think your asking for a harder internal problem further up your driveline which has already been discussed to great length.

As far as making a setup thats easier to fix well sounds like easier to break to me.

Sure you could sink time and MONEY into making and building custom this and that and have a really nice indestructable Subaru.....

But what would you do with all that spare time if you weren't fixing what you broke on the trail?

 

[Numbchux]

I have to disagree with dustyriders reman'd argument....I've had reman'd axles fail so quickly offroad, that I wouldn't feel safe on them every again. I'd want to have at least 2 front and 2 rear spare reman'd axles to feel confident that I could make it home! I think they're too weak. the stock ones are plenty weak. the big problems with diff stubs come when you're running a welded spool, where you have lots of torque on one side, at normal axle angles. running an open diff, or even LSD greatly reduces that risk (it also does reduce your capability, but for my uses anyway, it works better).

[NoahDL88]

There is a small helpfully hint on the fronts at least. When you go in for axles, ask for the 2wd version, they're more stout, at least they are at the stealership, don't know after 10 rebuilds if they differentiate between 2 and 4wd anymore.

[GeneralDisorder]

Yeah - that's one reason I don't go for rebuilds. On the EA81's it's just the opposite. The 2WD uses a smaller shaft diameter and smaller diameter joints. Parts counters do not differentiate at all, so you get what you get. The GCK ones I mentioned for the EA81 are totally BEEF - they are beyond 4WD spec.

 

GD