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Another Odd Sound Question (Maybe answered somewhere I didn't see...)
I've got a 2008 base model with just under 60,000 miles. It is making a clack (not so deep as a clunk) kind of sound which seems (to my bad hearing) to be coming from the left rear - but could be almost anywhere. Anyway, this is most obvious in lower gears and occurs whenever the engine torque changes direction. So, if I'm on the throttle and come off it, I get a clack. If I'm off the throttle and come back on, I get another clack. It sometimes shows up when shifting, but I think that's just an artifact of the torque changes involved - I don't think this is (directly) related to the clutch or flywheel. It might be something in the gear box, but the direction of the sound doesn't seem to support that. My guess is that it's something in the drive chain - the drive shaft (maybe hangers?), a u-joint, something in the axle, or perhaps something in the differential.
Looking for any help - if there's already a thread about something like this, please let me know!
Could be. I took the hub covers off and took pictures of both of the axle nuts. Here's the driver's side:
And here's the passenger side:
It's hard to say without knowing how the staking was done, but both nuts look to me as though they might have loosened a couple of degrees, bring the staking hard up against the flat area. Anyway, this seems like a worthwhile thing to pursue, even if it doesn't fix the current noise. Of course, I don't have any of the tools required...
I was thinking its the propshaft diff pinion nut. The diff pinion nut is a large nut inside the center of the diff flange that propshaft mounts to (propshaft is the shaft that connects trans to diff).
Remove propshaft at diff connection. Engage parking brake firmly (or better yet, rig up something like angle iron to bolt onto diff flange to use as a counter wrench). Use a torque wrench on the pinion nut. Set torque to 94 lb/ft.
The actual nut tightening procedure is quite a bit more complicated than that, as its intended to crush an internal washer to exactly the correct spacing (a better, but much more costly way would have been to carefully measure and add precise thickness of shims. But crush washer was way cheaper and for a dd works just fine).
Since your crush washer id already crushed, you just want to get the nut properly tight, BUT NO TIGHTER. You don't want to crush the washer any further. That would be bad.
If this nut was loose, that was your issue. If it was still tight, it wasn't. No need to tighten it further if torque wrench clicks before nut moves. In that case this wasn't your issue, and stop before you do any damage to crush washer.
Regarding the driveshaft hub nuts, there is a procedure to retighten those. The factory left them too loose. You should have them retorqued even if the pinion nut was the problem. Otherwise you'll prematurely wear out your hub bearings. That process invooves torqueing to an initial (rather high) set value, then turning an additional 60 degress further. To loosen them, then properly torque them, requires hefty tools. As in 3/4" socket set. You can buy a set fairly cheaply from harbor freight.
I was thinking its the propshaft diff pinion nut. The diff pinion nut is a large nut inside the center of the diff flange that propshaft mounts to (propshaft is the shaft that connects trans to diff).
Perhaps a possibility, though a quick look through (some of) the threads which reference the pinion nut didn't turn up the single clack sound that I hear as the torque changes. There seem to be other sounds and vibrations associated with the diff though I may have missed threads with my kind of noise. Anyway, since redoing the pinion nut seems to be more complex, I don't think it will be my first try.
Originally Posted by Car Analogy
Regarding the driveshaft hub nuts, there is a procedure to retighten those. The factory left them too loose. You should have them retorqued even if the pinion nut was the problem. Otherwise you'll prematurely wear out your hub bearings. That process invooves torqueing to an initial (rather high) set value, then turning an additional 60 degress further. To loosen them, then properly torque them, requires hefty tools. As in 3/4" socket set. You can buy a set fairly cheaply from harbor freight.
Yeah, I found the detailed DIY procedure on the hub nuts. Seems pretty straightforward except I don't have any tools big enough for that much torque. But I've got a car-guy neighbor who might have appropriate wrenches so all I'd need is the big socket.
I agree most of the time a loose pinion nut results in vibes, not clucks. But your description of the noise reminds me of the symptoms associated with a worn U joint on an old school driveshaft. The nearest thing that would seem to equate in our cars would be the pinion nut (since I doubt the issue is with the cv joints that our propshafts have).
I was chatting with my car-guy neighbor who came up with another diagnostic suggestion. Car in 1st gear, engine off, parked on a level surface...we rocked the car back and forth. This produced a not-quite clunk noise pretty regularly (once per rock) which definitely seems to be coming from the driver's side of the axle. We did it with the trunk open and it still seemed to come from the area near the wheel. My neighbor is into old American "hot rod" cars and trucks - not into anything recent or Japanese - but his first thought was something in a universal joint (constant velocity joint?) on the drive shaft on that side.
This is exactly what I was saying, except he is zeroing in on the axle cv, while I was thinking propshaft. But we're both 'hearing' the same thing and thinking the same thing, probably we have similar automotive histories.
It seems like classic u joint symptom, only our cars don't have u joints (well, unless someone replaced your propshaft with the aftermarket u joint based propshaft meant for high hp builds.)
What our cars use in place of u joint is cv joint. But cv joints don't typically fail with that symptom. Which is why I was thinking diff pinion nut, as there have been cases of it coming loose.
My 3/4 36mm socket arrived so I performed the DIY TSB. The driver's side axle nut was extremely loose. I just kinda touched it with the big socket and it spun freely. I followed up with a new nut, tightened about as much as I could using a short 3/4" breaker bar with a cheater over it. Noise went away. I drove around the block...no noise, give the nut one more slight tightening and staked it down. The noise I was hearing when going from engine power to engine braking (to engine power...) seems to be completely gone. Yay!
But, with the car parked, engine off, in gear, I've still got a clack noise when rocking the car back and forth. This seems to be coming from the vicinity of the transmission. Maybe. I do not hear it at all when driving, just when rocking back and forth. Maybe this is the pinion nut, though I think that might be further back? Maybe it's normal (wouldn't that be nice...)? Any other thoughts?
10-14-2019, 06:13 AM
Another Odd Sound Question (Maybe answered somewhere I didn't see...)
