Painful low frequency drone/pressure in cabin (1 Viewer)
- Thread starter LJE
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- Thread starter
- #182
I actually did do a drain/fill back when I was overhauling this vehicle (it was dead when I bought it). Since then it's only had, uh, ~ 1000 miles on the fluid? Guess it might be worth seeing if it lost a tooth in that interval, hahaha. I already have a cheap borescope.
As previously mentioned, I remember one of the gear oils I drained on this vehicle having more than average gunk on the magnet - no chunk, but more build up than I've seen on other Toyota's. I can't for the life of me remember which one that was though!
We'll see if I'm feeling froggy or not once I get back from this trip...
DOH, I "knew" that.....just not in that moment! 
I have been following this one like a hawk. Huge thanks @LJE for taking us on your journey here. Given the number of comments and also the other posts on this topic it seems that you are not alone. I have a very similar thing on my 2001 with 255k.
I recently put in a new OEM rear drive shaft hoping it would fix my issue, but so far it doesn’t seem to be the magic bullet just like you found. I even took out the slip yolk and hand greased it before installing. (And yes, I’m 99% sure I put it back on correctly. There is a page in the service manual to show you how in case you didn’t mark it.)
At least in my experience part of what makes this so mysterious is that it is transient. Some days it seems way worse than others. Which just makes this even more maddening. Last night on the highway it was driving me crazy, but today it seemed far more reasonable. Maybe it is just me? Who knows!
Things I've done (all OEM parts):
Things I haven’t done:
Before installing the new rear driveshaft I did a test run with it out (and the CDL engaged) and man was it smooth. It even got rid of the throttle re-application clunk. Which of course is making me think it is something in the rear.
I really hate to say this, but could it really be related to the rear diff?
I recently put in a new OEM rear drive shaft hoping it would fix my issue, but so far it doesn’t seem to be the magic bullet just like you found. I even took out the slip yolk and hand greased it before installing. (And yes, I’m 99% sure I put it back on correctly. There is a page in the service manual to show you how in case you didn’t mark it.)
At least in my experience part of what makes this so mysterious is that it is transient. Some days it seems way worse than others. Which just makes this even more maddening. Last night on the highway it was driving me crazy, but today it seemed far more reasonable. Maybe it is just me? Who knows!
Things I've done (all OEM parts):
- Front CVs
- Front Flanges
- All new Front UCAs
- All new Front LCAs
- New No2 LCA Bushing
- All three front diff housing bushings
- New Motor Mounts
- New Trans Mount
- New Mobil 1 Syn 75-90 in front, center, and rear diff
- Repacked front bearings
- Repacked front needle carrier bearings
- Rear Driveshaft
- And yes, I still have my frame weight
Things I haven’t done:
- Front driveshaft (front transfer to front diff)
- Rear Axle Bearings
- Transfer case Bearings
- Rear Suspension Arms
- 7 Year old Michelin LTX (but still look good)
- Rear Diff?!?!?
Before installing the new rear driveshaft I did a test run with it out (and the CDL engaged) and man was it smooth. It even got rid of the throttle re-application clunk. Which of course is making me think it is something in the rear.
I really hate to say this, but could it really be related to the rear diff?
- Thread starter
- #185
Thanks for the kind words!
I think that's where I'm at with the last of the 'waaaah.... waaaah.... waaaah' noise that I have. I would say that the pressure/pain is 95% gone, but the waaaaah remains.
I blew up my front diff out at Windrock, so my front driveshaft & drive flanges are pulled out - so nothing is spinning up front. That means whatever is making that noise is either in the T-case or the rear diff.
I actually recently recorded this - rear is up on jackstands, wife has the tires spinning at 50mph. It's hard to hear on a cell phone, but if you played this on a computer it's super obvious that there's this tapping/clunking noise that's oddly rhythmic. I put a stethoscope on it, and it sounds like 'da da da da... Dadadadada.... Da da da da.... Dadadadada', again, overtop of the gear meshing/unmeshing noise.
I found a front/rear diff out of a 2001 (so 4.30 gears vs my 4.10) that I'm going to take a pattern on, strip down those diffs (the housings are super crusty, but insides look great & backlash is still in spec), and then transplant those gears into my housings + ARB lockers & new bearings. Marlin Crawler was backordered on the lockers though, so I'm waiting on those (and to get some time!).
I think that's where I'm at with the last of the 'waaaah.... waaaah.... waaaah' noise that I have. I would say that the pressure/pain is 95% gone, but the waaaaah remains.
I blew up my front diff out at Windrock, so my front driveshaft & drive flanges are pulled out - so nothing is spinning up front. That means whatever is making that noise is either in the T-case or the rear diff.
I actually recently recorded this - rear is up on jackstands, wife has the tires spinning at 50mph. It's hard to hear on a cell phone, but if you played this on a computer it's super obvious that there's this tapping/clunking noise that's oddly rhythmic. I put a stethoscope on it, and it sounds like 'da da da da... Dadadadada.... Da da da da.... Dadadadada', again, overtop of the gear meshing/unmeshing noise.
I found a front/rear diff out of a 2001 (so 4.30 gears vs my 4.10) that I'm going to take a pattern on, strip down those diffs (the housings are super crusty, but insides look great & backlash is still in spec), and then transplant those gears into my housings + ARB lockers & new bearings. Marlin Crawler was backordered on the lockers though, so I'm waiting on those (and to get some time!).
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Wow, you can really hear some sort of teeth engagement sound in that video! Hmmm.....
Oh man, that is def one unique way to diagnose this problem! Best of luck there...
So just to confirm, it seems like you got rid of most of the original 50-55 mph booming noise vibration with the replacement of the transfer case rear bearing and with the new rear driveshaft?
And since then, you now have a new-ish in and out, cyclical " 'waaaah.... waaaah" sound that is different-ish from the original vibration?
Oh man, that is def one unique way to diagnose this problem! Best of luck there...
So just to confirm, it seems like you got rid of most of the original 50-55 mph booming noise vibration with the replacement of the transfer case rear bearing and with the new rear driveshaft?
And since then, you now have a new-ish in and out, cyclical " 'waaaah.... waaaah" sound that is different-ish from the original vibration?
- Thread starter
- #187
Yessir! That's correct. I'm also playing with cracking the rear vent windows JUST BARELY. I mean, a TINY amount. I open them, and then close them, but letting off the button before they bottom all the way out. I was looking at the D-pillar rubber flap pressure vents on the wrecked LX that I was yanking the 4.30 geared diffs out of, and those pressure vent rubber flaps looked like they stayed pretty shut - I seem to remember mine sorta stayed just a little open even with no airflow (AC) on in the car with it parked. I might look at those here again soon if I get around to pulling the rear upper trims off again. If those pressure vents were allowing more air than designed to get sucked out of the car (via the low pressure zones created by external air moving over them) then that might cause some issues. I have no idea what would cause those to permanently deform to a slightly 'open' state though.
But, like I said, it's SO MUCH BETTER than it was. I drove it to and from Windrock (5.5 hours each way) without much trouble. Before I couldn't drive it more than 15 minutes without my ear hurting for the rest of the day.
The majority of that seemed to have been the rear output bearing on the T-case - I could noticeably move that around by hand by pushing on the rear driveshaft. There's a video earlier in the thread IIRC. My front bearing is fine though (at least, not sloppy).
The new vibration is very different - the 'pitch' of it stays the same no matter the speed (seems to start to be noticeable around 50mph), but the 'spacing' between 'waaaaaahs' shortens the faster you go, eventually getting to a constant waaaaaaaaaah/brrrrrrrrrrr vibration at around 75-80 mph.
Diff issues seem rare in these trucks, but, at the same time, they're all getting older. I'm curious to see if I find anything sloppy when I pull this one apart.
Yeah I'm feeling like this might be in the cards for me soon. I'm sitting here reading @nissanh 's great post on this topic right now. The interesting thing about the posts in that thread is that most people did this job because of a bad rear seal. And most folks said their bearing was fine. It was wild to watch your video though. Clearly not a happy bearing.
That is good to hear! I feel like mine has improved somewhat with all the stuff I've done, but still not 100% fixed. Just like "the clunk" that so many of us chase, it seems like it isn't a single thing. Often a cocktail of parts.
Yeah, I mean this sure sounds like tires, but I know you have already tried multiple things there. Waiting on pins and needles to see how your rear diff exploration goes.
I'm guessing you have already seen this other mega thread on that topic. One person even claimed the had a highway pulsing vibration because of a fuel pump! :O
- Thread starter
- #189
I'm curious if my bearing was taken out by a poor job of replacing that exact seal - I could tell (by non-OEM sealer) that the tail housing had been off before. Between the residual orange FIPG that had not been scraped off the mating surfaces, and the fact that the T-Case is missing all the wire mounting/support brackets, it didn't give me great confidence that whoever had been in there before had done a good job. I'm curious if they damaged the bearing while removing it to get to the seal, and just re-used it? That's the only thing I could think of.
One other thing that would help eliminate tires (other than me having swapped wheels/tires, had both sets roadforce balanced, etc) is the fact that when the rear axle was up on jackstands & the tires spinning at 50mph, you could feel a pretty rough vibration. Even the wife (who was in the driver seat) was like 'wow, that's can't be right!', so I'm pretty confident it's not tires. I guess I could have taken off my tires & left the BORA spacers on to keep the rotors in place, but meh, that diff is coming down anyways.
The one other thing is that I swear the pinion angles between the rear diff & the T-case don't match well - which is bizarre, considering I'm running at a stock height. Nothing is bent/damaged, but I need to measure them to be sure at some point.
I'm not sure when I'll get around to tearing into the rear diff - like I said, waiting on the ARB lockers still. Which is fine, because I have to study for a test this weekend/first half of next week anyways. Why did I decide to get a masters in mechanical engineering? Oh, that's right, because I hate myself...
If I recall, when you did a drive with your rear driveshaft removed you said you still had some vibration? I wonder if given the fact your transfer case had been opened up before if you might have bigger issues internal to the transfer case? I think based on your other thread you have a bore scope, I wonder if you could bore scope inside the transfer case? Or maybe you could borescope the rear diff? Given you are about to yank the rear diff probably no need, but just brainstorming here...
Ha, I'm also a Mech E. Problems like this can clearly drive us crazy.
- Thread starter
- #191
You have to remember that the rear diff is still going to spin even without the driveshaft in place - now, it's sorta just free spinning at that point, but it's all still rotating. When I'm driving it doesn't matter if I'm accelerating or decelerating - I still get the waaaah waaaah waaaah noise. However, if I'm just coasting down a hill, maintaining the exact same speed due to gravity, the noise will go away.
So it's whenever there is any load (accel, decel, maintaining speed on level ground) on the driveline that the noise comes in.
Sticking a stethoscope on the T-case, it feels/sounds great. But, that's not under any real load, so that could make a difference too.
I did actually get the transfer case out of the same 2001 LX I yanked the diffs from too - all for $400. I figured if regearing & putting lockers in didn't fix the issue, I'd at least have a transfer case to swap in and give it a whirl.
Whats even more embarrassing is that I do vibration stuff as part of my job... Hahaha. More focused on ultra high frequency pyroshock than lownfreq vibe stuff though.
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- #193
Hahah, actually out ON TOP of the far part of Panther rock with Huey. Things went south & I was stuck for 30 minutes or so before blowing my diff... Managed to get off of it & back off the trail though. I call this 'my really expensive photo', hahaha:
First time ever wheeling, so at least I got that out of my system early.
Most fun I've had in a long time though - will absolutely be back for more.
- Thread starter
- #194
Sorry - had another thought. When I was at my in-laws with the LX up on a lift, the shakiness/vibration got way better when we pulled the rear drive shaft, locked the TC, and let only the front wheels spin. Now, again, not much of an actual load on the T-case at that point, but that was another thing that I felt like pointed to the rear diff (in my case).
Blowing a diff at an event like COTR is actually great because there are so many guys around to help make it seem to your wife like it's totally cool and she shouldn't be mad at you for breaking your only transportation home.
I know this isn’t your issue, but I immediately thought of this thread when watching this video. Goes to show you it can be the little things that you can’t imagine causing such a major vibration.
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- #198
I've been meaning to come back to this thread!
So I went to COTR in October, waaaaaaah waaaaaah sound and all. Had an absolute blast. Blew my front diff, so hadn't been driving the truck much. But, can confirm my waaaaah sound was still present without the front diff spinning at all (no drive shaft, no hub flanges) on the drive back.
I put the rear up in the air, and with the tires spinning at 50mph, there was a weird rhythmic tapping sound you could hear with a stethoscope, and even without the stethoscope, the rear diff sounded *rough*. Sorta sounded like some rocks bouncing around in there. Again, when I changed the diff fluid a 1k miles ago when rebuilding the truck, the rear magnet had a lot of smoo on it - significantly more than usual. No chunks of teeth, just a whole bunch of paste.
Fast forward to now. I just finished rebuilding two 'new' diffs with ARB lockers, new bearings, and used 4.30 gears. Swapped them in over Christmas, and have done a couple drives since.
'Waaaaaaah.... Waaaaaaah' sound (I think) is gone, but haven't done much highway driving during break in. Hoping that we've solved this one though. If it's not solved, then it must be the T-case. I have a spare one of those too now, so if that's the case I can swap.
However... The 'ear pressure' thing is still definitely around. Not nearly as bad as it was when I started this thread, but still there at lower speeds/back roads. I'm highly suspicious of my AHC at this point - despite ALL suspension bushings being new OEM (front/rear upper and lower control arms, and upper/lower AHC 'shock' bushings), AHC globes and fluid being new, and neutral pressures being correct, the ride over small bumps/expansion joints/sealer joints in the road is TERRIBLE. Let me repeat that. IT IS TERRIBLE.
My 2003 Sequoia with a somewhat sporty Eibach suspension and ALL polyurethane bushings in the front rides SO MUCH BETTER. I know I'm shouting here, but I'm just trying to communicate how rough it is.
Big bumps/dips are absorbed super nice, but all the little stuff feels as if I'm riding on concrete (have I mentioned how bad it is?). I *believe* the overly stiff AHC is exciting resonance in the cabin (imagine hitting a drum with a stick) that's causing this problem. It's really bad driving down my gravel driveway (very bumpy), paved roads seem to vary, so I definitely think it's suspension related.
This is something I've noticed this entire time, but I've been focused on the higher speed highway type driving. There's a number of threads dating back a decade on this exact AHC problem with no resolution, so I've got my work cutout for myself to figure it out. We've currently got a ton of snow on the ground here in Indiana, so I need to undercoat the vehicle before I start driving again.
Thanks for following up!
OMG YES. SAME HERE! It also drives me crazy. Not quite as crazy as the vibration, but right up there.
Exactly like you say, big bumps are fine, but the small little cracks and such send quite the shock through the body. None of my other cars are near as bad.
I've also done the same things on your list except for the "shock" bushings. I had read somewhere that was supposed to be the big thing that makes this much better. Very sad to hear that didn't work for you.
I have also wondered if it is related to the body to frame bushings, but for the few folks that have changed them out, they said it didn't change much.
I will of course be following if you decide to go down this path. It is really surprising to me how bad it is. There is no way it was like this when it was new off the dealer floor right?!?! Interesting to hear this was a topic a decade ago on these forums.
I really want to go try a Land Cruiser to see if it has the same thing.
