rear drive axle play

[bosango]

Hello all,

 

For some time, I've had a heavy metallic rattle/clunk from the rear of my 1993 Legacy LS. I've finally been able to get the car off the ground and check for any apparent looseness. The only thing I've been able to find after extensive banging and shaking is some play in the drive axles. When I tap on one with a mallet, they both vibrate and there is a bit of a clunking. Also, the inner CV joints wiggle a bit when I pull down on the axles. Since I've never had a vehicle with these slip in axles, how much play, if any, is normal? Is there likely to be any damage to the splined mating surfaces inside the differential from driving around with loose axles or is all the damage/wear usually confined to the CV joint?

 

As always, thanks a million!

[nipper]

That sounds like a lot. Before you condm them, check your universal joints and carrier bearing. It is rare that the rears go bad since they have a really easy life.

 

 

nipper

[Gloyale]

Check the U-joint on the center driveline. the front one right out of the trans.

[nipper]

Check the U-joint on the center driveline. the front one right out of the trans.

 

copycat

[bosango]

That's the first place I looked - U-joints and center bearing are fine!

[nipper]

Transmission mount, exhaust pipe, then i will agree.

 

 

 

nipper

[94Loyale]

How did you check the u-joint? The only way to really check it is to drop the driveshaft out and feel it's range of movement. That may just be my opinion, but that's the way I do it. From my experience, I always felt the carrier bearing while making tight turns and hitting the gas, that will make a real loud clunking. The axles will have a little play. Wiggle you're front axles where they go onto the trans shafts and you'll feel some play there too. I've only had to do it once, but you can check the mounts for the diff too, where the two studs go into the rear crossmember, there are rubber mounts. Try to move the whole thing and see if you have a clunk? As stated, I'd def check the trans mount too, I've replaced a number of them.

[bosango]

Hmmm... I like those mount ideas. I'll drive it up on some ramps tomorrow and put a jack under the transmission, differential, and anyplace else that I can to see what kind of movement there is.

 

The clunkation is definitely coming from somewhere more or less between the rear wheels. All the exhaust hangers, clamps, mounts etc. appear to be solid, so I've ruled that out. I checked the U-joints by jamming some long skinny tools in the joints and rotating the shafts in opposite directions - no play. I checked the front axles and they do have a little left-to-right play, but no front-to-back play like the rear ones do. Also, driving in FWD mode (with the fuse in) doesn't seem to change anything (though it sure felt like it accelerated faster).

[nipper]

Just take a prybar to the tranny. Any seperation (it wil be obvious) the mount is shot.

 

the diffentive way to find out is all 4 wheels off the ground, parking brake set, and have someone shift the car. it should clunk. If the PB doesnt work just a foot in the brake.

Another way is to get back of the car on jack stands, and rotate the wheel frwd and bckwrd by hand, it may clunk that way if it is the shafts.

[tcspeer]

How many miles are on your Subaru? I have one that has been on a postal route for 14 years, it now has 424,000 miles. Around 300,000 miles I also had a clunking sound coming from the rear, I could not find it and neither could the people at Midas.

 

I replaced bushing and other things on the rear trying to get it quite. Nothing worked.

 

Trying to fix the shimmy in the front I replaced the tie rods, when this did not fix the shimmy I looked again and noticed the part where the tie rods screwed on to had play in them. I replaced the whole unit to get the shimmy out, to my suprise the clunking that had appeared to be coming from the rear was gone. Check and see if you have play in the rack itself not the tie rods.

Edited April 26, 2010 by tcspeer

[bosango]

Well, I've tried all your suggestions and still the only thing I can find with any questionable play is the drive axles. The far end of the inner CV joint at the boot has about 4 mm of deflection. Also, when I bang on the differential support cross arms (the ones about a foot in front of the rear wheels, with the big rubber bushings), the drive axles vibrate freely. Now I'm thinking that the play might actually be coming more from the differential side bearings then from the axles. The differential seals are still doing their job as it's all clean on the outside. So here's my questions:

 

1. Does my diagnosis make any sense?

2. Are these bearings replaceable; the Rock Auto website lists a Timken differential bearing #30208M - is this the side bearing?

3. Would it make sense to replace the axles at the same time? The car has 172,000 on all the original parts.

4. Anything else I should consider replacing while I'm at it?

 

I gotta say how impressed I am at how solid everything is on this 17-year-old car. This is my first Subie (I got it last year) and I will never again drive anything else.

[nipper]

Rear axles rarely go bad. Diffs may go bad, but yours is young. If the axle turns with the wheel with no play it is not the axle. Use a stethascope to listen for the noise. If it is the diff just replace it.

 

 

nipper