Bag Posted November 1, 2016 Share Posted November 1, 2016 (edited) I recently purchased a 92 legacy wagon ls. It's FWD with 4eat. Wasn't running when purchased but after replacing fuel pump and filter, it runs great. Car drives and shifts fine, but has rhythmic thumping sound that increases with speed. Almost sounds like tire but i replaced one tire and it still has noise. Took the spare tire and one at a time put it on each corner to see if noise went away, but didn't. So I don't think it's tires. Next I thought it could possibly be bearing, so I bought new bearings and hubs, but still have noise. The axles were replaced before I bought the car and the boots looked new. Despite feeling that it probably wasn't axles, I thought it was still possible, so I bought more axles and swapped them. Noise still persists. I also had rotors turned so should not be that either. I'm almost to the point of replacing the transmission but don't want to just throw more parts at it...like I have been. It almost seems like there's a spline or tooth missing....don't know for sure. It's a very regular and rhythmic thumping that starts around 10-15mph. I've tried manually starting in 1st, pushing to second, etc. Happens in every gear... acceleration or deceleration. Goes away if I move to neutral...even if I rev motor. Edited November 1, 2016 by Bag Link to comment Share on other sites More sharing options...
Bag Posted November 2, 2016 Author Share Posted November 2, 2016 Seems like a huge mystery to everyone else too huh? ???? Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 2, 2016 Share Posted November 2, 2016 Which bearings did you replace? It goes away completely when you shift to neutral? Does it change if you just coast with it in gear? Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 2, 2016 Share Posted November 2, 2016 have you checked front diff fluid level or pulled the diff's drain plug to inspect the magnet for 'pieces'? kinda wondering if you think it might be happening about 4 times for every tire revolution - or 1 time. any sense of either of those? Link to comment Share on other sites More sharing options...
Bag Posted November 3, 2016 Author Share Posted November 3, 2016 Haven't dropped pan yet, but think it is more like 1 per tire rotation. Link to comment Share on other sites More sharing options...
Bag Posted November 4, 2016 Author Share Posted November 4, 2016 Seems oddly specific question. What were your thoughts on possible failures. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 4, 2016 Share Posted November 4, 2016 (edited) pan? example, pinion turns ~4 times against ring gear in diff. (like 9 teeth on pinion against 37 on ring = 4.11 final drive) I admit to being ignorant of specifics of the FWD transmission but, on my car, the front differential has a separate drain plug with a magnet - maybe inspect it for big pieces? 4 vs 1 time per rev :example, pinion turns ~4 times against ring gear in diff. (like 9 teeth on pinion against 37 on ring = 4.11 final drive) maybe output bearing on side of the diff? that might be 1 time per tire revolution. if you could get the car up to AWD Tuning in Flower Mound, I bet those guys could diagnose it. I just really am throwing out possibilities - fairtax has the experience here. If you rule out bearings and axles - diff/trans is about the only thing left. If it helps, axles can be swapped side-to-side. Edited November 4, 2016 by 1 Lucky Texan Link to comment Share on other sites More sharing options...
Bag Posted November 4, 2016 Author Share Posted November 4, 2016 Thanks. I figured you were suggesting ring gear as possible. The diff and trans are one unit on FWD right? Meaning if I buy another trans it's just whole assembly and not something where I buy trans and it end up being a diff. Link to comment Share on other sites More sharing options...
ferret Posted November 5, 2016 Share Posted November 5, 2016 Don't overlook the driveshaft. I mean what Subaru refers to as the center driveshaft. It could be out of balance, as lost a weight, or the front or rear universal joint could be defective. The joint at the front of the shaft ( transmission rear ) is usually the culprit. IT's difficult to see and diagnose. 1 Link to comment Share on other sites More sharing options...
montana tom Posted November 5, 2016 Share Posted November 5, 2016 I agree with ferret, Inspect drive line carefully. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 5, 2016 Share Posted November 5, 2016 Thanks. I figured you were suggesting ring gear as possible. The diff and trans are one unit on FWD right? Meaning if I buy another trans it's just whole assembly and not something where I buy trans and it end up being a diff. If it's like my 4EAT but just without the tail section then yeah. technically, it's 2 units put together but no one 'rebuilds' the diffs (NOTE, that's not say some kinda seal or bearing at the axle output can't be repaired - but it's still tricky I think getting the bearing preload back to factory setting) - so, you might check LKQ and car-part.com for a used trans. KInda suspect the FWD version might be hard to find but, i haven't looked. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 5, 2016 Share Posted November 5, 2016 I agree with ferret, Inspect drive line carefully. He says it's a FWD trans so, no rear diff or driveshaft. 1 Link to comment Share on other sites More sharing options...
Bag Posted November 6, 2016 Author Share Posted November 6, 2016 I appreciate the info. I pretty much figured it's going to need a trans. Or at least a component inside of it. It actually shifts very well. May just have to pull it and see if I can identify the culprit. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 6, 2016 Share Posted November 6, 2016 destroyed rear bushings on the lower control arms will thump - but not usually in-sync with rolling. Link to comment Share on other sites More sharing options...
Bag Posted December 3, 2016 Author Share Posted December 3, 2016 (edited) So I went ahead and pulled the trans and diff. Suspicion has been confirmed. Missing teeth on ring gear. https://plus.google.com/104985126743244456824/posts/enAZrmUSYb5 Edited December 3, 2016 by Bag Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted December 4, 2016 Share Posted December 4, 2016 dang, too bad Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now