retroxt Posted October 31, 2011 Share Posted October 31, 2011 First off. I drive a 1986 XT Turbo GL-10 3 Speed Automatic. I have a crazy and unnerving thumping noise coming from my car when I am at low speeds (8-15 mph) after I take my foot off the gas. It feels like something is coming apart under my feet. Here is a youtube video of a recording of the sound: A little back story now: I recently went on a road trip and on my way back I changed fluids. When I left the spot I was at, I didn't realize I had a little too much diff oil (just a notch or two over the fill line). Well for the 4 hr first part of my drive back it drove like crap, with a loud thumping noise (much louder, but consistent with what I am experiencing now). Before I left out, I fixed the too much diff oil problem and drove back and the noise was nowhere near as bad. After about a day of being back here I heard the thumping noise come back intermittently, then it went away for a few days. Well, today I was driving back to my apartment and the noise came back and hasn't left since. Now I am kind of afraid to drive it... I am not sure if the diff is the issue. It accelerates alright (as you can hear in the video) but once I take my foot off the gas, the thumping comes back full steam. Any thoughts? Help is appreciated. Thanks, -t Quote Link to comment Share on other sites More sharing options...
idosubaru Posted November 1, 2011 Share Posted November 1, 2011 same reply i just typed on subaruxt.com: i can't watch the video from here... you sound convinced it's related to the diff oil? when you say "changed my fluids" - do you mean ATF and diff oil or only one of those? does the 3AT have both like other auto's? the 3AT's have some very specific issues - a governor or modulator or something? i'm not familiar with them but wondering if too much fluid will hose them up in some way. they are often easy fixes.... are you sure you used the proper fluids - gear oil in the diff and ATF in the trans? subaru automatic transmissions typically receive gear oil in the front diff and ATF in the transmission - folks have been known to dump the wrong fluid in the wrong one. if it's not transmission/fluid related then i would suspect one of the DOJ's on the cv axle is bad (have the axles ever been replaced or boots busted?). aftermarket axles are notoriously problematic, offering a wide range of issues - one being vibration on accel/decel. or the ujoints in the rear driveshaft if it's a 4WD version, they can thumb on accel or decel as well. Quote Link to comment Share on other sites More sharing options...
naru Posted November 1, 2011 Share Posted November 1, 2011 I would check the steady bearing if you have 4wd. Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted November 1, 2011 Share Posted November 1, 2011 Take the midget out of your trunk? Quote Link to comment Share on other sites More sharing options...
l75eya Posted November 1, 2011 Share Posted November 1, 2011 does it go away if you apply the brakes? Quote Link to comment Share on other sites More sharing options...
retroxt Posted November 1, 2011 Author Share Posted November 1, 2011 Here is the post I just put on the XT board: "Ok, so I definitely put the right fluids in my transmission and front dif, so the wrong fluid is not the issue. After the responses I have received, I think I can rule out the fluid issue entirely. I just had my front wheel bearings, ball joints and tie rod ends replaced about four months ago, and my suspension feels solid in the front (in terms of bounce), so I am pretty sure it is not any of those parts. In terms of the DOJ on the cv, please allow me to express my novice knowledge of my car and ask exactly what that is? The sound appears to source more from the front left side and possible from my axle. The boots have been an ongoing pain in the rump roast. They were totally busted before I bought the car (not sure for how long) and both my fronts have had issues with keeping the boots on since I replaced them (meaning, there is a slight possibility of limited cv grease in the front) On my long drive, I heard the traditional squeaking of the cv on the left side. Could this more pronounced noise be an advanced product of that? Now, on to the U-joint: I went under my car (after putting it in neutral and applying the e-brake) and checked the tightness. When I turned it back and forth, there was a very subtle amount of play in the joints, specifically the one connecting the front and middle pieces together. I also heard a pinging noise, which was sourced at the u-joints3, as if there were two pieces of metal taping each other as I moved the drive shaft back and forth. I am not sure what a healthy drive shaft sounds like, so this could be a typical sound for a healthy u-joint to make..." Naru, could you explain more on the steady bearing? I have selectable 4WD, however, it was not engaged. The sound does not go away when I apply the brakes. No midget in the trunk these days, so that shouldn't be the issue Quote Link to comment Share on other sites More sharing options...
MilesFox Posted November 1, 2011 Share Posted November 1, 2011 (what i replied to dirty impreza) V V V IT reminds me more of the inner side of the axle wobbling. The sound is conducive to driving around with no boot or grease in the inner axle for 10,000 miles. is it jerking the steering wheel at all? also, the stub shafts on the transmission just plug into the diff on an AT, I know this is true on a 4eat, and presume so on a 3at, but is not true with 5mt. I wonder if the axle stub shaft has popped off its circlip that holds it in place. It could have popped out with the romoval of the alxle. you can check this just by separating the bal joint and pulling out the roll pin, enough to slide the axle off the stub, without having to remove the outer end of the axle or the nut. a driveshaft would have a vibration throughout all speeds and rotation, accel, and decel. The brown wagon i am drivng has a bad driveshaft, vibrating because of loose or lost pin bearings in the caps on the u-joints, or an imbalance. The driveshaft will have a little lash as you described. you will find that same amont of lash at all points of the driveline. IT's possible that the axle was just too worn at the time of rebuild I guess the only way to confirm s to mic the inner parts. I dont think you will break anything by continuing to drive. Did this just start, or did it happen right away after rebuilding the axles? Quote Link to comment Share on other sites More sharing options...
retroxt Posted November 1, 2011 Author Share Posted November 1, 2011 There is not any direct jerking of the wheel, other than the vibration made from the thumping noise. About the circle clip, is that the ring that goes on the inner side of the vc axle that goes into the dif (about 4" in diameter)? If so, I know we forgot to put one of those back on when we rebuilt. I thought that ring was only there so the axle didn't come apart when uninstalling, but I could be wrong... The noise just started (well, it started on my drive back from Sheboygan last weekend). The boot on the left side did come loose a while back and all the grease came out. I thought I did a good enough job repacking it though. I did notice recently on the front left wheel and significant amount of what looks like cv grease looking to be exuding from the axel coming from where the hex looking nut and pin meet on the wheel in the center of the rim. That is the same side the thumping noise is originating from. About the drive-shaft, I think you may be right, because I only hear the thump consistently at lower speeds during decel. The noise goes away/is greatly minimized when I hit the gas. All in all I think a swap of cv's might be in order. As you well know, that car saw some ruff treatment before I bought it.... Thanks Fox! Quote Link to comment Share on other sites More sharing options...
MilesFox Posted November 1, 2011 Share Posted November 1, 2011 rebuilding axles is a PITA, mainly because it is so messy of a job. do some reading/searching around here on replacement axles as far as what brands are best, and what is worst. be armed with a SOA part number to compare to what was originally on the car (3at turbo, 23 splines) any other non turbo axle will work, though. Quote Link to comment Share on other sites More sharing options...
retroxt Posted November 1, 2011 Author Share Posted November 1, 2011 I imagine the swap is a little easier when you are doing a full replacement rather than a rebuild.... Thanks! Quote Link to comment Share on other sites More sharing options...
MilesFox Posted November 1, 2011 Share Posted November 1, 2011 It's quite easy if you understand the procedure. It's easy enough that the average joe can accomplish it as their first ever auto repair, given you have at least a 36mm socket, and some sort of long pipe. eventually(soon) axles and bearings will be part of my subaru maintenance videos, as i have shot the tapes, but just need to edit them. Let me know if you are still coming out this way to do more suspension work. It may be easiest for me to come to sheboygan to work on the car there. Quote Link to comment Share on other sites More sharing options...
naru Posted November 1, 2011 Share Posted November 1, 2011 Here is the post I just put on the XT board: Naru, could you explain more on the steady bearing? I have selectable 4WD, however, it was not engaged. The sound does not go away when I apply the brakes. No midget in the trunk these days, so that shouldn't be the issue I would check the steady bearing by grabbing the driveshaft beside the bearing and attempting to move it up and down.This will show play in the bearing or (more likely) its rubber mount. I`ve heard bad steady bearings(the rubber actually) make a similar non-metallic thumping sound. Hard to say for sure,but,it sounds to me like the sound repeats at driveshaft RPM rather than axle/wheel RPM. Quote Link to comment Share on other sites More sharing options...
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