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Chatter / shudder in low RPM's...(FIXED!) u-joint


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After searching this forum thoroughly I've decided to post since I couldn't find another user with my car's problem.

 

Its a 1995 Legacy LS automatic with the 2.2 L engine. It has a chatter or shudder that feels like its coming from the front of the car when you first take off, but it doesnt' have anything to do with the way you turn the wheels. It doesn't happen except when the car is in gear, and it goes away completely when the FWD fuse is in place.

 

The torque bind could be at play here since there was a tire size issue that I discovered--the inside edge of one tire that was badly worn, but the outside and middle were within spec of the other 4 tires. I replaced the two rear tires since then so all tires are within 1/16" tread of each other (all are same brand). I've read that torque bind symptoms occur when you turn hard in the car, but mine happens mostly when going straight.

 

I've checked the front and rear differential fluid levels and both are good, with good clarity in the fluid. Would it help this problem if I replaced the fluid with synth?

 

The chugging/chattering/shuddering seems only to occurr at low rpms, when headed in a straight line, when starting out in 1st or in very low rpms (and much weaker) in 2nd gear. The car also has a hard shift from 1st into 2nd gear, but not always. This symptom is very intermittant and seems very arbitrary; I've tried easy accelleration and aggressive, and both ways seem to return random results. The shift from 1st to 2nd is late and it kicks into 2nd when it happens.

 

Any help appreciated!

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After searching this forum thoroughly I've decided to post since I couldn't find another user with my car's problem.

 

Its a 1995 Legacy LS automatic with the 2.2 L engine. It has a chatter or shudder that feels like its coming from the front of the car when you first take off, but it doesnt' have anything to do with the way you turn the wheels. It doesn't happen except when the car is in gear, and it goes away completely when the FWD fuse is in place.

 

The torque bind could be at play here since there was a tire size issue that I discovered--the inside edge of one tire that was badly worn, but the outside and middle were within spec of the other 4 tires. I replaced the two rear tires since then so all tires are within 1/16" tread of each other (all are same brand). I've read that torque bind symptoms occur when you turn hard in the car, but mine happens mostly when going straight.

 

I've checked the front and rear differential fluid levels and both are good, with good clarity in the fluid. Would it help this problem if I replaced the fluid with synth?

 

The chugging/chattering/shuddering seems only to occurr at low rpms, when headed in a straight line, when starting out in 1st or in very low rpms (and much weaker) in 2nd gear. The car also has a hard shift from 1st into 2nd gear, but not always. This symptom is very intermittant and seems very arbitrary; I've tried easy accelleration and aggressive, and both ways seem to return random results. The shift from 1st to 2nd is late and it kicks into 2nd when it happens.

 

Any help appreciated!

 

Well, even though your symptoms are a little odd, putting the FWD fuse and having the problem quit pretty much nails down the center diff clutch pack area as the problem. I also think '95 falls into the MY range that gets a steel sleeve to fix some aluminum wear issues. probably couldn't hurt to try a tranny flush and conditioner additive since the alternative is expensive and at least 1-2 people have had luck with it.

 

Carl

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Well, even though your symptoms are a little odd, putting the FWD fuse and having the problem quit pretty much nails down the center diff clutch pack area as the problem. I also think '95 falls into the MY range that gets a steel sleeve to fix some aluminum wear issues. probably couldn't hurt to try a tranny flush and conditioner additive since the alternative is expensive and at least 1-2 people have had luck with it.

 

Carl

 

I did do the tranny flush, and didn't help much if at all for the shuddering issue, but seemed to help a bit with the kicking from 1st gear into 2nd quite well.

 

What kind of tranny conditioner? can you recommend the best one?

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Heres a thought ....

Is it possible that the driveshaft going from the rear of the transmission to the rear axle has a bad Universal Joint in it. The torque bind going straight ahead is puzling, as it shouldnt be happening then, even if the car is locked in 4wd. Torque bind develops when one wheel is spinning faster then the others. Also check all the cv joints to make sure you dont have a riped boot or a seized joint.

Try to rule out all the cheaper things first.

 

nipper

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Heres a thought ....

Is it possible that the driveshaft going from the rear of the transmission to the rear axle has a bad Universal Joint in it. The torque bind going straight ahead is puzling, as it shouldnt be happening then, even if the car is locked in 4wd. Torque bind develops when one wheel is spinning faster then the others. Also check all the cv joints to make sure you dont have a riped boot or a seized joint.

Try to rule out all the cheaper things first.

 

nipper

 

I just replaced the 2 front CV joints & axles, I checked the rear CV boots and all looks good. Could this possibly be a transmission mount? or maybe a clutch/flywheel problem?

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They have clutches inside the transmission, but you cant have a clutch replaced unless you have the entire transmission replaced.

 

 

Heres a thought, does it make any noise? Maybe its the flex plate or fly wheel that has a crack in it.

 

nipper

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They have clutches inside the transmission, but you cant have a clutch replaced unless you have the entire transmission replaced.

 

 

Heres a thought, does it make any noise? Maybe its the flex plate or fly wheel that has a crack in it.

 

nipper

 

It doesn't make any noise, and in fact it couldn't be a clutch or flex plate because the symptom goes away when you put in the FWD fuse to disable the AWD.

 

I guess its' most likely a U-Joint or clutch pack or maybe a trans mount. I wish somebody else had this happen as I'm just not sure yet. I'll probably take it in to have it properly diagnosed next week. If I do, I'll post the actual diagnosis here afterwords.

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I had something close to it, and it was the U Joint on the driveshaft that goes to the rear wheels. If it turns out to be that, have the driveshaft taken to a driveshaft shop and let them rebuild it (they put in a forduniversal joint), as the sooby part is unreasonably expensive.

Remeber by putting in the fuse, you are shutting down half the drivetrain, and removing half the load (if its not the driveshaft). Also this is a bit wierd so sometimes a fishing expedition is needed. Driveline vibrations are hard to diagnose without being there.

 

good luck

 

nipper

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I had something close to it, and it was the U Joint on the driveshaft that goes to the rear wheels. If it turns out to be that, have the driveshaft taken to a driveshaft shop and let them rebuild it (they put in a forduniversal joint), as the sooby part is unreasonably expensive.

Remeber by putting in the fuse, you are shutting down half the drivetrain, and removing half the load (if its not the driveshaft). Also this is a bit wierd so sometimes a fishing expedition is needed. Driveline vibrations are hard to diagnose without being there.

 

good luck

 

nipper

 

Ok, I took it to the shop today. I told them what's up, and they said they had a guy in recently with the same kind of symptoms and it turned out to be the clutch pack.

 

Not sure though because when he said "clutch pack" he had $$$ in his eyes and gave me a sort of grin.

 

Yesterday I was accelerating somewhat aggressively off the line, then I quickly let off and heard a distinct sound. It was a knock of metal on metal like something big was rattling (I only heard one or two knocks though).

 

This would seem to indicate that something is loose, like a tranny mount or a motor mount. Still weird though as the problem is 100% gone with FWD fuse put in.

 

I've got it lined up to be looked at in the shop this Wed, depending on how fast they troubleshoot they may not charge me. I'd really hate to drop $800 for the clutchpack, especially and even worse if that was not the problem. Any thoughts??

 

...one other thing, is the problem is totally gone when I drive in Reverse.

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On the bright side, thats about what that job seems to be going for. You may want to price an entire tranny rebuild and see what it goes for.

 

I am facing the same issue, only mine does it in turns, but oddly not when backing up.

 

nipper

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On the bright side, thats about what that job seems to be going for. You may want to price an entire tranny rebuild and see what it goes for.

 

I am facing the same issue, only mine does it in turns, but oddly not when backing up.

 

nipper

 

I took my car to the shop yesterday, and sure enough it was the U-Joint, the front one where it connects to the transaxle. One of the swivels is badly rusted and is hanging by a thread. So I'll be driving it in FWD mode untill I can figure out how to fix it. I've read somewhere here that you can replace the u-joints with a ford part that actually allows service. Otherwise its a whole new driveshaft.

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Heres a thought ....

Is it possible that the driveshaft going from the rear of the transmission to the rear axle has a bad Universal Joint in it. The torque bind going straight ahead is puzling, as it shouldnt be happening then, even if the car is locked in 4wd. Torque bind develops when one wheel is spinning faster then the others. Also check all the cv joints to make sure you dont have a riped boot or a seized joint.

Try to rule out all the cheaper things first.

 

nipper

 

Good call!

 

And, should be cheaper/easier to fix than cent diff.

 

Carl

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heheh see i get them right once ina while :)

 

When i had mine done i think the it cost me all of 125.00 to fix (not including the labor to install it as i did that myself). They installed a uni from a small ford truck that had a grease fitting. I would recomend removing the offending part from the car, as eventually the vibration will come back again. Call around to some local drive shaft palces in the phone book, im sure you will find somone. What helped me was searching the threads here, especially on the older subaru list, as people there knew about it.

 

 

nipper

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