WCM ultralite rear axle issues

[RGTorque]

so recently i have had some issues with the driver side axle poping out of the rear as soon as i begin to drive. no real evidence to the issue but here is what i do know.

 

1) i did a big burn out in front of the garage before this happened, but drive through the lot and into the garage no issue. the next time i went to drive the car out of the garage the axle poped out.

 

2) diff fluid has a lot of fine "glitter" in it but does not smell burnt.

 

3) clip that holds the axle in the rear is still in the rear

 

here is what i have done so far.

 

1) stuck the axle in the rear and it was snug (not coming out by pulling)

 

2) drained and replaced the rear fluid (found metal particles, but they were very fine)

 

3) bought a 3 new axles because of weirdness.

#1 bought new subaru axle because outer cv seemed to have play. new axle had the same play on the outside but was tight and smooth on the inside.

#2 bought new faq axle which was nice and smooth on the outside but dry as a bone on the inside

#3 bought new subaru axle which had the same play on the outside but was tight and smooth on the inside.:toetap05:

 

i ended up installing axle #3 thinking it must just be like that...

 

so, now i am about to take the rear out to check bearings and what not and i notice a bit of difference on my axles and im wondering if this is the cause of my problems.

 

the two older axles are my originals. both oem. ALL THREE have the same play in the outer cv. the new axle (middle) was installed in the driver side. i notice that its a slight bit shorter and the face where it mounts on the knuckle is a bit different. also the pass side axle (which has not given me trouble) seems to have some wear on the inner splines *see last pic

 

anyone have ideas before i pull the rear?

 

http://imageshack.us/scaled/medium/801/q318.jpg

http://imageshack.us/scaled/medium/94/l73v.jpg

Edited September 26, 2013 by RGTorque

[RGTorque]

http://imageshack.us/scaled/medium/801/q318.jpg

http://imageshack.us/scaled/medium/94/l73v.jpg

http://imageshack.us/scaled/medium/21/vuzy.jpg

http://imageshack.us/scaled/medium/34/i548.jpg

[RGTorque]

http://imageshack.us/scaled/medium/856/5gcu.jpg

http://imageshack.us/scaled/medium/707/3zpz.jpg

http://imageshack.us/scaled/medium/854/gzwl.jpg

http://imageshack.us/scaled/large/849/pkoh.jpg

Edited September 26, 2013 by RGTorque

[jlumba81]

Found this on NASIOC about rear axles popping out.

[RGTorque]

yea i read that thread ages ago when i had my diff out before. no real answers, just a bunch of people voting on where the circlip stays... guess ill take the rear out today.

[JohnK]

Roman,

When I first got my car I spent more time than I care to think about on the suspension - a bunch of which involved taking fairly accurate measurements of everything in 3 dimensions (Took three attempts before getting to where I trusted my measurements and understood the limits of the accuracy I could deliver) so I could enter reasonably accurate data into my copy of WinGeo3 to understand what the suspension was doing, as well as understand the fundamentals. While this was a ton of work, it's paid off over the years and has proved its worth. In my experience, you just gotta know what it is you're working with, otherwise you're just throwing mud at the wall.

 

"The circlip" is supposed to be on the inboard end of the axle (see below). Normal behaviour is that the axle will resist coming out unless you lever it, just a bit, with a pry bar. When you work with the rear a bit you'll see that the circlip is just a convenience for assembly since it holds the axle in position while you're working on things. The resistance you encounter when removing it lets you know that the axle was seated and the same when you install it back into the diff. My Civic is the same, and I expect this is a common design. What keeps things together is the suspension, and its alignment. When I changed one of the axles on my Civic I nightmare'd about it coming out before I realised that it couldn't - the suspension links kept it from doing so. The same SHOULD be true on our cars, provided everything is aligned correctly. However, these cars have so much adjustment available that you can put things so far out that they might as well be on the Moon. The measuring I did early on allowed me to align the car "perfectly" - when I finally took it to a local shop with the latest Hunter equipment, it came out on the money - shop owner said he couldn't have done it more precisely although "accuracy" is another matter since it's determined by your camber curves, tires, ..... . Getting to that point involved replacing several suspension links. My measurements, mapped onto the floor of my garage allowed me to draw a rectangle that was true to the long axis of the car and which I used to put each wheel exactly (more or less ) at the corner of a rectangle that gave the true long and lateral axes of the car. For my car, to position a wheel pretty exactly at each corner took cutting one of the fwd lower rear suspension links to add 3/4 of an inch in length, and replacing a number of the rear links. I found that, if some of the as-delivered rear links were used, not only was the wheel too far inward re the reference rectangle, when correct camber was set the axle was pressed into the diff causing bind in its travel (and I assume bearing destruction eventually). In the other direction I found (stumbling around more than a little) that what looked like a good adjustment was acting to pull an axle out of the diff. Since we use standard (we hope) axles, the position of the rear wheels is determined by the location of the diff and the lengths of the axles. The links have to be the correct lengths for the wheels to be in the correct positions. "Correct position" is not only at the right width, but also fore and aft - it's real easy to have the rears parallel to each other but off center with respect to the long axis of the car, which gives you weird behaviour coming out of corners and such.

 

 

So, based on my experience and probably obviously true to any mechanical engineer who gave half a thought to it, the only reason axles "pop" out is because the suspension is set incorrectly, or something fundamentally is wrong with the suspension. When the suspension goes through its travel, the axle moves in and out of the diff - hence the length of the splines. This is called 'plunge' and my suspension software calculates a value for it. The problem is that there's not a gauge that I know of that'll tell you where in the range of plunge you are when you align your car. As a general rule, whenever I change anything on the suspension, after it's buttoned down, I grab each axle and push and pull it to make sure there's a little free play. If it's binding, there won't be any movement. I think that the worst (bind) case is when the axle is level with the diff. If there's only a small amount of play, I reason that it's improbably the axle could un-plunge enough to get out of the diff. Along with this I've obsessed about suspension travel, not wanting, ever, to allow things to go solid - silasto deals with full bump wonderfully and the shock maker handles droop. I had my shocks built to allow only 1 1/2" droop because of the ride steer problem in droop with our/my setup.

 

These circlips are a pain. Since they don't really do anything when the car's working (i.e. they don't bear any load) they're not tempered and when an amateur mechanic like me takes one out, it's soft enough that it can't be re-bent properly to seat in its groove in the axle and may go in hard enough to make you worry, or get knocked out (possibly, but maybe not). But they are supposed to be there, the Subaru manual says replace when removed, and they guide assembly for the mechanic. And, they may produce shiny bits when digested by the differential (sorry about that).

[RGTorque]

thanks for the reply.

 

i do understand how some misaligned parts could create a PULL on the axle that would pop it out. im my can just rolling down the driveway will pull the axle out. that being said nothing has changed in my rear suspension in the last 3-4 years short of an added diff brace.

 

in regards to the circlip, my understanding is on the LSD diffs the clip stays inside the diff. my clip is still in its proper slot in the diff. i am wondering if i do need to just remove and bend it back into a better shape to hold the axle. since the rear is still in i may do that.

 

now to figure out how to get the clip out...

[jlumba81]

Here's two more links that might help. Wrxtuner (has link for service manual) and Clubwrx (mentions a tsb)

[JohnK]

Perhaps there's a difference in parts here (there's a mechanical and a hydraulic LSD for instance), however....If everything is intact and connected, where can the axle move to? The diff is fixed in place, and, at the axle's other end the upright is located laterally by the lateral links, the radius rod (runs fore and aft) keeps the upright from twisting (more than a small amount), and the shock limits the vertical travel of the upright. If one were to plot a view of the axle pivoting about the diff through a bump-droop of +/- 3" I don't think you'll see a change in the hypotenuse that's enough to equal a distance sufficient to get the axle free of the diff. However I look at the assembly, I keep coming to the fact that the axle is trapped - unless there's too much room for motion in plunge, which indicates that something's moved.

Again, possible part differences, but both of my axles have circlips, and every time I pulled either, it took no more than a modest levering with a large screwdriver to pop the axle out. I've never seen an assembly that was retained in place against any kind of operating force with so insubstantial a restraining element.

Actually, with regrets that you're having problems, the prospect that something else is happening is intriguing. If I'm mistaken, it'll be really interesting to learn of another property of this system.