The other day my wife's Forester started having a little off idle shudder, not at all noticeable at driving speeds just at take off.  It seemed to be coming from the rear drivetrain so I put the FWD fuse in and it lessened dramatically, it's still there but not bad.  Got it to the shop today and they diagnosed a bad rear u-joint and explained you need to replace the entire shaft. 

 

How difficult is this to do?  Seems pretty straight forward, any special tools etc? 

 

How long can I leave it in FWD and continue driving it?  I don't want to tear up the rear housing of the trans but need a little time to sort out whether I can do the repair or schedule it with the shop.  Do I have days, weeks?

Edited December 29, 201411 yr by mattri

You can't continue driving it with the u-joint like that. The bad u-joint throws the shaft out of balance and eventually it will break the yoke or the joint and the shaft will whip around and cause a lot of damage, and possibly injury to you or other passengers in the car.

 

The quick thing to do is unbolt and remove the rear section of the shaft. This eliminates any possibility of damage. You can drive the car indefinitely by doing this, though there is a chance that leaving the FWD fuse in for long periods (several months) can cause damage to the duty c solenoid for the AWD transfer clutch. This will safely get you a couple of weeks with no ill effects. Obviously it will not be ideal, especially if you need to drive in snow or off-road, but there won't be any possibility of further damage to the driveshaft or related parts.

 

There are some driveshaft shops that can rebuild Subaru driveshafts (new u-joints and carrier bearing) but they can be almost as costly as ordering a new shaft. (I have this same problem right now with my GFs 95)

I was quoted $425 for a new driveshaft. The same shop said they could rebuild the current shaft (3 new joints, new bearing) for around $300-350.

 

There are sources for new joints that you can install yourself, but you need certain tools to do it, and there is the possibility that the shaft will be out of balance after installing the new joint. (The problem I currently have.)

Good to know, thanks.  I'll look at removing the rear section first. 

New u-joints from rockford drivelines are about $40 each. The only tools I used to install mine were a file, some sandpaper, a punch, vise, and a BFH. Seriously, it's not hard, it's not rocket science. As long as you take it easy and pay attention to detail it comes out balanced and works fine.

 

For some reason shops are terrified of touching staked u-joints and I don't get it. I really do wish I took pics of my repair jobs and documented it... Maybe next time.

Thanks for the heads up.  A local(ish) yard said they have a complete unit they'll sell for $125 but they need to inspect it first.  If it's a direct swap I can do that no problem.  For now my biggest concern is that I'm really not in a position to park the car until I can do the work which will be Thurs at the earliest, maybe the beginning of next week.  I'll look tonight if I can get the rear section out for now. 

how positive are they of the diagnosis?

those can be tricky to diagnose, i'm surprised they caught it that easy.

 

www.car-part.com should have them cheaper than that.

 

ask machine shops (like the ones that do head resurfacing) to replace ujoints.  that's what i've done before.  hand them a ujoint and shaft and it's simple for them.

 

i don't recommend it but i've put some miles on bad ujoints before.  they can cause some serious damage when that thing lets loose and start taking out everything around it, so it's risky.  you've got a good chance of making it until thursday just fine and yet a real possibility of it failing.  if you notice increased vibrations and the rear view mirror shaking....i'd quit driving immediately.  drive easy, light on the gas and brake.  insert FWD fuse if applicable.

If you end up needing a new driveshaft, check out www.wholesaleimportparts.com. They have brand new shafts available. I'll be ordering mine from them shortly.

Sourced a drive shaft, should be able to do this tomorrow or this weekend at the latest.

 

It looks to be pretty straightforward mechanically, unbolt the rear flange, the carrier and the gaurd around the rear diff, slip out the old, in with the new- anything else?

 

Also, it looks to be a tight fit to getthe shaft out past the exhaust and the floor pan, will I need to drop the exhaust, if so how? 

 

Any other tips/suggestions? 

Make sure it's out of another forester, and not an impreza. The center bearing mounts are at different heights between the 2.

You may need to remove the heat shield that's just above the exhaust (if your car has it) but I've never had to remove the exhaust to get a driveshaft out.

 

Just shove the pipe to one side if you need a bit of wiggle room.

Just wrapped it up, thanks to all for the good suggestions. 

 

The bolts on the gouard over the rear diff really didn't want to come out and had to undo the rubber hangers to drop the exhaust a few inches but other than that it went pretty well.  I don't have a good place to work and it's ridiculously cold here but still only took about 2hrs.  Test run in FWD went well so took the AWD fuse out and all is well. 

 

Thanks again, Matt.