Front differential problem

[r6speed]

bought a cheap subaru, needing some help with it. I have read a ton on the forums and still have not found anyone explain my problem.

 

93 2.2 NT A/T AWD Legacy wagon, paid $800 has 166K (was "supposedly" rebuilt motor and tranny 20K ago)

 

When I bought it the guy said it needed tires badly and drove very messed up due to this. I arrived and all tires had good tread, one (rear) had a plug. Car drove like crap as expected, ran great, but jerked, wobble, and bounced.

 

Took car in and had both front tires balanced, made a huge difference, car no longer jerked from side to side and vibration/wobble/bouncing was much much better, problem still not cured though. So I took it to a mechanic, they replaced both front cv axles and it didn't change a thing. They stated they looked over brakes, rotors, hubs, ect and found no problems.

The problem seems to be coming more from the passenger side or middle. When driving the car it has a "bounce" type "vibration" (?thump?) that is consistent with the wheel spin, like at the same velocity of the tire, like something happens once per rotation of the tire. It feels like a separated tire on the front passenger, but I had them checked and also switched them out with some others I bought just to make sure and no difference, still did it.

I put the FWD fuse in and that didn't make any difference either, but I was able to jack up the front on stands and slowly run the car. This is where I noticed the front pass tire is not getting any power, its pretty much all on the driver side (I could stop the pass tire with my hand). So I'm guessing something in the diff is messed up, but what would go wrong inside the diff to cause this?

Also when the front was on stands and it was in drive I could NOT hear, feel, or see any vibrating thump...

Any and all help is greatly appreciated!

 

EDIT: also this thumping occurs starting at about 10mph all the way up to 45 (won't drive it over that), it also doesn't matter weather your on the gas or off, straight or turned, its a very consistent thumping...

Edited May 11, 2011 by r6speed

[idosubaru]

differential is fine. that's how diffs work - they only send power to one wheel. all FWD vehicles are really only ONE wheel drive. go get one stuck in mud and watch how many tires spin - only one every single time.

 

same with 4WD vehicles - they're really only "2WD"...i mean there's lots of variations but basically they are 2WD unless you have a locking or limited slip differential in place.

 

so - sounds like your differential is fine. they usually make nice groaning, grinding, whining noises when failing too.

 

thumb with wheel is probably an axle. if any of the axles are new or recently replaced then it's probably got a bad axle. aftermarket axles are junk unfortuantely, new axles that fall apart or have all sorts of issues are really common. reboot a used subaru axle or use MWE only, anything else is a waste of time.

 

could also be a wheel bearing or a really bad brake issue - clump or rock or bent backing plate rubbing, etc.

 

here's to hopefully a really easy fix!?!?!

[r6speed]

I read about some bad aftermarket axles but after the mechanic already put autozone specials on That being said, I still am not convinced its a cv axle issue, here is why. I put the car on stands and ran it, I know the axles are at different angles but I think odds are I would be able to see the bad cv axle when running on stands. Also if it where a bad cv axle than unless the new cv axles are bad in "The Exact Same" way than I don't see how it could be cause it feels the exact same as before the axles were replaced.

I know open diffs only spin one tire when no traction is present, but I thought when I stopped the tire with my hand it would or should have put some power to it, guess I'm wrong there.

I will pull the brakes and hub apart myself and check them out. I already checked wheel bearings and they are solid. I really really don't want to spend any more $ on things that are not going to fix it...I understand thats hard to do and probably impossible but I'm hoping

One more note on the cv axles I'm just thinking...maybe it had the same cheaso aftermarket axles before they got changed and they just got changed with the same...

[Fairtax4me]

My moneys on a bad U joint.

 

But this got my attention

93 2.2 NT A/T AWD Legacy wagon, paid $800 has 166K (was "supposedly" rebuilt motor and tranny 20K ago)

 

At 146k an Ej22 is just getting broken in. What the hell did they do to warrant rebuilding an Ej22 at that mileage? 2 Options:

1.They never maintained the car, ever.

2. They were BSing you trying to get more money.

 

 

Now down to brass tacks. If the differential was at fault, holding one wheel still would make it knock and click and carry on like a popcorn machine.

 

When you had the car on jack stands, did you have all 4 wheels off the ground? Were the rear wheels spinning when the trans was in gear? They should, if not, check the FWD fuse holder on the passenger strut tower. Small black box, 3/8" x ~1" . Open it, there should NOT be a fuse in it. If there is, remove it. The fuse gives power to the duty solenoid "C" that controls the fluid pressure on the center transfer unit clutches. When the fuse is in place, it disables the AWD, so the rear wheels will not get power from the transmission. With the fuse removed, the AWD works normally, the rear wheels get power. This will cause the whole driveline to spin, a four wheels, all four axles and the driveshaft. The driveshaft consists of 2 sections, has 3 U-joints, and is supported in the middle by a carrier bearing. Any of which can go bad and cause exactly what you describe.

[r6speed]

Ok Thank You for the information FairTax4Me, I will check out the driveline and u joints and bearing, but I don't think they are my culprits either since I drove it in FWD with NO difference in feeling.

As far as your questions, please read my first post, it answers all of them except what they did to the car before and I don't know who knows. They fed me a story about how her mom had it all rebuilt for her to drive to my state (she's from a couple states away) and then after 20K on it her dad gave her a new jeep and blah blah blah. (I have no idea) haha

Edited May 12, 2011 by r6speed

[Fairtax4me]

but I don't think they are my culprits either since I drove it in FWD with NO difference in feeling.

\

Doesn't matter. The ENTIRE driveline spins when the car moves, regardless of FWD or AWD mode. The driveshaft still turns whenever the car rolls.

The difference in FWD mode, the rears wheels will not BE DRIVEN by the transmission. If you were in a situation where AWD was needed, where the front wheels were able to slip, the rear wheels would not kick in to help move the car, they will sit there like dead weight.