Rear End Thump Noise
 

I recently discovered an odd sound and feeling in my rear end. It seems when im in reverse or forward and my wheel is turned far (as in turning into a parking space or out), my back tires seem to have a thud and a kind of jumpy noise. it happens on both sides depending on which way im turning. My mechanic told my that he believes that a clutch pack is catching and it should be slipping and its common with subarus. He is calling for a flush with a new pan and external filter and refill with dextron 6 synthetic and use trans tune in it. Has anyone else had this problem? and any other solutions as college starts back up monday and my bank account cant afford anything major.

Re: Rear End Thump Noise
 

Sounds about right, classic transfer clutch binding. If you're lucky that fix should do it.
Try putting the FWD fuse in and see if it stops doing it. If it stops then your mechanic is on the right track.

Re: Rear End Thump Noise
 

So i can drive the car with the fwd fuse? sorry im mechanically not very smart. And is the fwd fuse under the hood

Re: Rear End Thump Noise
 

I agree that it's probably an issue related to your transfer clutches. I had a similar problem with my 92. SVXFiles did some transfer clutch work to the car, and it made the problem go away. You can diagnose it by putting in the FWD fuse. If the problem goes away, then it's probably related to the transfer clutches, or the Duty Solenoid C (which controls the transfer clutches).

It is not recommended to drive the car for any long distance with the FWD fuse in place. It could cause damage to your transmission - especially the front differential.

Re: Rear End Thump Noise
 

Yes you can drive with the fuse in, just don't drive 1,000miles. The FWD fuse is in the underhood fuse box near the battery.

Re: Rear End Thump Noise
 

I drove for a year with a bad transfer clutch. Didn't swap out the trans until after that, but the trans was working perfectly fine. Just be careful not to launch the car hard.

Re: Rear End Thump Noise
 

Do you think that this flush will be a pretty decent fix if it happens to just be a binding clutch, Or does it look like im doomed to have some serious transmission problems?

Re: Rear End Thump Noise
 

It's possible, but unlikely, that a transmission flush will solve your problem. Most AWD transfer issues are usually not major problems. Most can be solved without removing the transmission, and can be done pretty quickly by someone who knows these cars.

Re: Rear End Thump Noise
 

Thanks for all the input. I was curious if it would be damaging to continue driving the car with the transfer clutches the way they are. Im going to have the flush done sometime next week and hopefully that helps it enough, can i do any other serious damage if i decide to drive it?

Re: Rear End Thump Noise
 

Please keep us posted if you do have a flush. At the dealership I worked at a few years ago, they would not perform a flush on a car with high mileage if it had not had regular flushes (every 60,000mi iirc). One mechanic told me this was because after many miles without a flush, performing one would almost certainly result in the car coming back a couple weeks later with a bad transmission. His explanation was that there were tiny pieces of metal that are floating around in the atf that somehow form a "cushion" and flushing would remove these particles and cause rapid wearing of the internals. I have always wondered if this is fact or complete bs.

Re: Rear End Thump Noise
 

Partially accurate.. The particles tend to settle. A flush usually rustles them up and can cause them to get lodged where you don't want them which can cause clogs.

Tom

Re: Rear End Thump Noise
 

I doubt the flush will fix it. Your problem is not that you have a hydraulic or a friction problem. Both of those aspects are fine or you would have slipping clutches and this would not give you these symptoms.

In normal use the clutches are jammed on hard by oil pressure and the solenoid bleeds off the pressure and then lets it back on intermittently so that some slippage can occur between the front and rear wheels.

If you have checked for trouble codes and there are none, then I reckon you have a defective solenoid.
In your case the solenoid is not working. Putting the fuse in is supposed ro feed power directly to the solenoid, opening it to allow the pressure to escape from the clutch, and thereby over-riding the ecu's attempts to allow intermittent pressure build up, but it only works if the solenoid is working and can allow the pressure to escape.

Re: Rear End Thump Noise
 

I believe my mechanic said he was going to take the pan off and put a new pan filter and change the external filter on the transmission as well. Im debating on the flush or not. He states that he has flushed many subarus with the same type of binding situation and it has worked. There are no trouble codes coming up and when i put the fwd fuse in the sound went away. Im not very technically savvy and now am wondering if a flush is dangerous, i know that if the tranny goes im not going to be able to afford to fix it.

Re: Rear End Thump Noise
 

I know this is everyone's favorite quick fix, but if there are any other indications like hard shifts, revving during cruise, gear hunting, etc. you may want to check the Throttle Position Sensor. I agree with the diagnosis of mechanical problems, but my car showed this same problem combined with the others and was fixed entirely by replacing the TPS. It's a costly part, but it really turned mine around, and was a cinch to test (check the how-to). I was convinced it was in my transmission as well, and my fluid is a gritty, smelly mess. Turns out a bad TPS seems to lock it into 50/50 so it lurches like a 4WD in tight turns, and wreaks havoc on the rear end.

I was on the fence about the flush as well, and still am not sure if that's something I need. What else would folks recommend for someone with nasty ATF that may not have ever been flushed (I have no previous records on the car)?

Re: Rear End Thump Noise
 

Woody, at post thirteen you said that putting the fuse in made it stop. That means that the clutches are fine and it does not need the flush. Since it let's the pressure off the clutch when the fuse is in, but the ecu is not letting the pressure off under normal circumstances, it means that the ecu or it's associated wiring and sensors are playing up.
I would be visualy looking at the internals of the ecu, (with a magnifying glass), for capacitor, resistor, transistor or printed circuit board breaks. It might pay to check the resistor under the bonnet too.
Save the flush money for the repair you really need.