The longest axle combo for EA81s?

[Scott F]

I am curious if there is a convenient way of running longer axles on my 84 BRAT. I don't mean 1/2", but more like 3"+. The long term goal would be to redesign the suspension as an A-arm system, with 10-15" of travel. The rear would also get longer axles and trailing arms.

[zyewdall]

Seems like a driveshaft shop should be able to make whatever length axle you want. At least with driveshafts you just take them the two ends, and tell them the length, and it's easy. I doubt you could get anything stock though.

[4x4_Welder]

That would be sweet, u-joints and a slip shaft. Might kill unsprung weight, but be beefy as hell.

IIRC, Crosslander used u-joints and slip shafts on thier IFS system.

[GeneralDisorder]

You cannot use u-joints on the front of a subaru. Read up on u-joint application and theory and you'll understand why.

 

*hint*: it isn't called a "constant velocity" joint for no reason.

 

GD

[4x4_Welder]

Oh, I understand that. Just commenting-

BUT, if you were to go to a double a-arm/coil system, you could, if you used the proper knuckles and left room for the yokes.

[GeneralDisorder]

Oh, I understand that. Just commenting-

BUT, if you were to go to a double a-arm/coil system, you could, if you used the proper knuckles and left room for the yokes.

Nope - you CANNOT use u-joints on an IFS. It's really that simple. Try it out if you don't beleive the thousands and thousands of vehicles produced without a single one using u-joint IFS. Again - read up on CV and u-joint theory and you'll understand the fundamental differences.

 

They CAN be used on rear independant. There's many examples of that - early Gen 1 Subaru 4WD being one, and early Z-car's being another. Not to mention Jag's, Corvette's, etc.

 

GD

[4x4_Welder]

I know I would have had the pic on my old HD, it's nowhere to be found now. I swear, the Crosslander 244x had U-joints up front, on a coil/ a-arm IFS system. It is doable, the CV is used for reduced vibration, but an outboard universal with either a double cardan cv or Rzeppa cv inner would be a pretty tough setup, with a slip-shaft for the travel. Either that, or set up the a-arms so that the axle length stays the same through the arc of travel, no slip, but you'll scrub your tires to death.

[daeron]

GD: where might one "read up" on said theories? this is something that I believe my elders are all ignorant about, because I always get fuzzy answers from them about it

[GeneralDisorder]

Here's a good start:

 

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

 

Check out the section on angular speed.

 

Basically without two u-joints running at equal and opposite angles, the changes in velocity will rip the joints apart in short order. This manifests itself as "vibration". Or (under larger differences in angle) as joint failure.

 

And I quote from the page above:

 

To prevent the jerky rotation of the axle or driven shaft there usually are two U-joints in a three part shaft assembly. The second U-joint will convert the jerky movement back to an even, uniform speed of the third shaft - if both the driving and the driven shaft are parallel and the two universal joints are correctly aligned with each other.

Obviously this in not possible in a front suspension - not and still allow the wheels to turn. U-joints are simply NOT applicable to IFS, and you won't find anyone useing them for this reason.

 

GD

[GeneralDisorder]

Add to this that u-joints can accomidate at most 15 to 20 degrees of angle (and that's pushing it), and CV's can do upwards of 30 degrees (Porsche 930's can do 28, and the race versions 30 even). You would be losing articulation ability with the u-joints as the stock CV's are easily capable of 20 degrees already.

 

GD

[daeron]

GD: thank you.

 

I have never even looked at a CV axle disassembled before, or blown out, and I hadn't the foggiest exactly what they were.. I couldn't imagine something to do what a U-joint does, that isnt a U-joint...

 

anyone else who doesn't know exactly what a constant velocity axle is, look:

 

 

Wiki says its copyrighted, so I maybe shouldnt use it here.. but it came from a 1972 Saab FSM, so thank you, Saab. At least I gave credit.

 

I understand the three shaft setup, with the first and third parallel to each other (this is the system used on my Zcar, as you already mentioned.) There is a tendency to retrofit later CV axles, ESPECIALLY given the difficulty of rebuilding old halfshafts... parts availability, you know. Now I understand what makes this superior.

[GeneralDisorder]

You like that?

 

Check this out:

 

http://www.drivetechnologies.com/

 

And watch what it can do:

 

http://www.drivetechnologies.com/videos/truck.wmv

 

Now if only anyone could actually afford a set . Maybe when the patent runs out.

 

GD

[thatswhatshesaid]

You like that?

 

Check this out:

 

http://www.drivetechnologies.com/

 

And watch what it can do:

 

http://www.drivetechnologies.com/videos/truck.wmv

 

Now if only anyone could actually afford a set . Maybe when the patent runs out.

 

GD

Utterly amazing.

 

Those angles were ridiculous!

[thatswhatshesaid]

How about these on a Subaru?

[Frank B]

All you would have to do is extend the shaft. You could take it to a machine shop and have them make new ones at your length out of whatever you want. A backyard way to do it would be to cut it in half, bevel the ends that you cut, get a 3" piece of the same metal(from another axle), bevel those edges. Piece it together the way you want it, and weld it up. If your not a good welder, pay somebody that is. If done right, the weld will be stronger than the shaft. You could also slip a piece of pipe over the shaft before you weld it up, then after you grind down the welds you slide the pipe over your welded piece then weld the ends of that pipe(sleeve). You would have your longer axle, but I have no Idea what the angles would be on the joints after that.

[Scott F]

Whoever brought up U-joints, thanks for nothing. What I am talking about is using a complete half shaft from another Subaru or another car. Or, use the DOJ cup, and the axle from another application to make a hybrid half shaft.

 

IOW, a cheap and easy combo that does not require custom components or machining. I am a machinist/welder/fabricator, so I can come up with a custom solution if I need to. For the inner joint, I would cut off the cups and weld on 930 flanges, so I could use 930 CVs and off the shelf axles from SAW.

 

The question is what to do about the front outer joint? Maybe a 930 CV could work there as well.

 

Has anyone made a long travel Subaru yet?

[s'ko]

Scott.

 

Most of the work done on soobs to date are either body lifts w/lift blocks or solid axle conversion.

 

Custom A-arms have been talked about and so have other theories. I don't think there is a lack of ideas, it's mostly time, money or ability.

 

In terms of axles from other subarus to the BRAT, the newer soobs have a larger diameter stub axle, so the DOJ are larger. Also the EA axles use a ball and race set up, while the EJs use a DOJ w/three round bearings. It may be possible to swap out the entire DOJ joint on an EA82 axle to an EJ axle, but I haven't tried it.

 

Another problem when dealing with the EJ axles is that the EJ hubs have a smaller diameter spindle. Converting your front axles to EJ hubs would be possible, similar to an XT6 front hub conversion, but you would have to retain the stock type lower control arm w/radius rod. The EJ a-arms are nicer but you would have to do a lot of custom work to get it mounted to your chassis.

 

Come over sometime and you can take a look at what I have going on in my BRAT.

 

L8TR

 

BW

[stinky]

You like that?

 

Check this out:

 

http://www.drivetechnologies.com/

 

And watch what it can do:

 

http://www.drivetechnologies.com/videos/truck.wmv

 

Now if only anyone could actually afford a set . Maybe when the patent runs out.

 

GD

 

I've been checking up on them for a while now, and they don't seem to have ever done much with them. I'd love to see it in a subaru useable form.

[baccaruda]

those cornay joints have been costing me sleep for a couple of years now

 

They're not widely seen because they're far more than the average CV-joint-using-car needs. Limited applications = limited demand = unlimited price.. tragically.

[subie_newbie]

Jesus friggin christmas, what do you do, GD, that allows you time to find friggin sweet clips like that AND have intricate knowledge of mathamatics and CV/U-joint theory???? NACCO? Freightliner? Pierce? Only an engineer is geeky and cool enough to pull that off!