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I need some help from the L Series "lifers" here .

I've had an annoying clonk develop in the rear drivers side of my RX L I had though it was some sort of rear strut issue . It's a metallic almost rattle sound but it only does it over slightly larger bumps .
I de junked my boot and the sound was still there .
Today I had it parked up a gutter on one side and crawled around underneath it looking for lose bushes or A arm and rear diff mounting bolts . Tail shaft and center bearing seems all good as did everything I could get at under there .
I grabbed the rear corners and reefed them up and down , bounced up and down on the tow bar and - nothing .
Drove it home and pulled out the offside rear strut and found nothing obvious there .

What I did find was more backlash that I like in the rear inner and outer DOJs . What I had though was wear and backlash in the rear diff is actually in the drive shaft joints themselves . There seems to be more clearance on the diff and stub axle splined shafts themselves than I would have thought good . On the drivers side you can hold the inner joint housing and move the hub and disk meaning worn DOJs and maybe the inner splines .
I think the clonk noise may be the outer DOJs because you can give them a light thump with your hand from underneath and get a buggered shock absorber like clonk noise .

So long term L lifers , do often ignored high mileage rear joints do these things ?
Oh and BTW my gearbox is an AWD one so that's why I can feel and hear the backlash if I am not gentle on the clutch when taking off from rest .

Cheers A .

Yeah most L series owners pay very little attention to their rear shafts and most people still run the original ones. Simply cause you don't notice how crappy they are when you driving 2wd, and when you engage 4x4 you are usually on loose ground and there are too many other factors involved to notice the clunks.
People with AWD of sorts in their L series have the problem you have, naturally because you are actually using them on the road when it's most noticeable.
I think you've already covered the above in your post anyway so the obvious/simple answer would be;

If your rear shafts are worn and causing you a problem - renew them.

Yep will be looking at getting that mob in Rydalmere to do the joints for me .

Cheers A .

Disco are you sure the noise you hear is from the rear drive shafts? Most of the noise in my RX is from the rear diff hanger bushings.

The bushings are different for AWD models. The part time 4WD bushes were not designed for power to be sent through the rear diff all the time.

I assume the AWD bushes would be stiffer and allow for less movement under acceleration.

Just a thought...

Lee

Its not a noise like a stuffed front CV makes .

I KNOW they're rooted because when I had one of the back wheels off I grabbed the drive shafts at each end and twisted in opposite directions . Neither CV or DOJ's are supposed to have that much radial free play .
Jeez when you can hold the inner joint bell and rock the hub/disc assembly back and forth you know they've had the Richard .
I also held that inner joint and rocked the tail shaft and there is bugger all backlash between the diffs crown wheel and pinion .

Anyway today's update is that 5 Star CV and Power Steering at Rydalmere dont have any OE manufactured joints though they can get the "Great Wall" made ones at short notice - noo thankyou .
I like the reman'd OE ones because they have a greater depth of hardening on them and are made of better material .
5 Star said original early Subaru rear joints are getting thin on the ground and only about 3 out of 10 are good enough to re manufacture nowadays .

They are trying to put a set of good ones together for me by the end of the week and they should see this car out , I think ATM it has the original 24 yr 349K old ones in it so not a bad run ...

A .

How old are your rear shocks? I had a thumping in the rear for ages until my rear shocks completely failed and I replaced them... That's what I'll be putting my money on. I've still got my original rear shafts, even though they don't have power through them most of the time, I've had them work with a welded diff for a few months and they've done 42x,xxxkms without an issue so far... There's plenty of slop in them too.

Swap out your rear shocks for another set and see how the noise goes...

Cheers

Bennie

PS - lifer as L series owners, or were you meaning lifters?

Have you checked the play between the inner joint and the diff spline? when you go AWD, they usually clunk. Easily fixed by pulling the shaft off the diff stub, cleaning the splines, coating the stub with epoxy, re-fit the shaft, leave overnight - no more clunk. Not a problem to remove later, as epoxy doesn't stivk to rust, it is just to take up the slack in the worn, previously lazy splines.

My rear dampers are late MX5 Konis and not that old .
Like I mentioned earlier I've been under my car and swung off everything that could have been a problem .
Since I've had this car the diffs been out , trailing arms out for wheel bearings , tail shaft rebuilt with renewable unis . We know the bushings are all ok and there's nothing else that could cause backlash in the drive line .

The joints have some movement on the splines either end but the free play is in the joints themselves , if you grab the axle shaft and the bell section of each joint and can feel movement it has to be wear between the balls and their races . The reason it makes a slight thump as you take off , unless babying the clutch , is because it has to drive all the slop out of each joint by four and it feeds back through an AWD transmissions center diff .

Anyway my mind is made up and I intent to get my joints opened up to see how bad they were . The CV people I use reckon most of them by now are throw aways and few are rebuild able . Gotta be a reason for that .

A .

still say diff carrier and centre bearing myself. mine does the same thing if I stand on it then back off.

Well I tell you what , jack the back of your car up on one side and rotate the raised wheel as much as possible to take up any slop in the rear DOJ/CV joints . Then rock the diffs pinion shaft and note almost no movement , there can't be very much backlash between the crown wheel and pinion if the rear companion flange doesn't move much at all . Yes I know how to check differential backlash .
Tail shaft is fine , spent a stack of cash having that rebuilt with three replaceable yoke type uni joints . Bearing is fine .
All three bushes the diff is suspended off are also fine .

When you can grab a DOJ/CV by the bell and rotate the guts via the shaft going into the joint then that's where the excessive movement has to be .
I can see it I can hear it .

Busy with other things like turbos and radiators ATM but I will get to those rear joints soon enough .

A .