Driveline howling like The Black Keys

I like to think that I am familiar with most of the common traits and flaws of the 2G Tacos, including all of the wonderful noises and vibration they can create. This issue, however, has my head down on the desk (and I've been to two reputable shops for help with it).

The first shop stated "take your truck back to whoever regeared your rear end... immediately." The 2nd shop that regeared my rear end tore it all apart, found nothing, set it back up again and the issue remained unchained. After this, they concluded that it was my input shaft bearing failing in my 6-speed (RA60F) manual transmission. I'm not so sure.

The issue:
The truck has a very audible driveline howl seemingly in the front. It can be heard at all speeds, but absolutely waaaaaaaaails at 50-60km/hr (31-37mph). It occurs in all gears (including neutral), 2wd, 4wd, clutch in, clutch out, driving straight, driving corners -- essentially it's there all the time. No vibrations in the seat, pedals or steering wheel. I've had it for a while now and it hasn't really gotten any worse.

Anyone experience this shit?



The truck:
200,000km overall, 25,000km on the Spicer u-joints + Toyota Carrier Bearing + Koyo front wheel bearing assemblies, 15,000km on the 4.56 Yukon gears + rebuild kits, 50,000km on the ECGS front diff bushing, 10,000km on the 315/75r16 Cooper STT Pros, transmission throw-out bearing chirps like a mofo and I need to deal with it but I can't see that making this sort of howl?

 

When you are at the speed where the truck makes the noise , will it also make the noise when you coast with your foot off the gas pedal ?
What happens when you shut the truck off at that speed ? do you still hear the sound ?
Have you popped your serpentine belt off to eliminate everything on the front of the engine ? Noises can travel throughout the truck

 

Those are big ass super aggressive mud tires. I’m sure they howl like a banshee.

 

1) Yes. Technically it exists all the time, but you have to really focus to hear it at parking lot speeds.
2) I can't say I've ever killed the engine at 50km/hr. Is that safe to do...? I worry about locking the brake pedal up or something.
3) I can't say I've done this either. What would that do? And yes finding the source is a real SOB.

 

They aren't bad. High quality MT tires have come a long way. Tire noise and driveline noise is easily separable when you've had them for a while, IMO.

 

Take the beast on a back road run where there is no traffic and shut the truck off when you hear the sound . You can do this safely both for personal health and its not going to damage anything .

Removing the serpentine belt for a 4 minute diagnosis and start the truck .
Eliminates all spinning components on the front of your engine
I do this at least once a week on customer vehicles when I have trouble finding noises . This little technique makes me look like a hero sometimes

 

I will have to try these. Thank you for the suggestions!


EDIT: Still makes the noise with the engine off, rolling at 50km/hr.

 

I experienced a whine/vibration out of my 2nd Gen. At first I thought it was a wheel bearing, then thought it was the carrier bearing…. but the more I listened, the more I could pinpoint it coming from out of my TCase.
After all said and done, it was the Needle Bearing in the TCase. Changed that and the problem was gone.

 

I forgot to mention above that I changed the Needle Bearing to the ECGS one they offer.
https://eastcoastgearsupply.com/i-8536125-toyota-8-clamshell-bushing-eliminates-needle-bearing.html

 

If it's that loud a good shop should be able to find the noise by running the wheels in 4wd up on the rack and listening with a stethoscope

 

Which bearing in the t-case was this? I've got the ECGS bushing for the front diff and it's been great for years.

 

This is what the first shop did, and claimed the rear diff was the culprit. Second shop later said that with the truck in the air, and slight preload on the suspension, you could stand underneath the transmission and hear it coming from there.

From what I'm reading online, my symptoms aren't indicative of a internal gearbox bearing going bad. They may have just heard my near-death throwout bearing.

 

@WormSquirts have you ever encountered my issue with your own truck?

 

Maybe a stupid suggestion but have you checked the heat shields and their bolts?

 

Never encountered it, but my next step would be to pull the rear drive shaft and put it in gear and see if it makes the noise, if yes it's transmission or tcase, if no, its the driveline or rear diff.

If it doesn't make the noise sitting still, I would leave the driveline out, put it in 4wd (front wheel drive) and drive around, see if it makes the sound then.

It's possible it doesn't make the sound of there's no load on the transmission though, but this should isolate some things at least.

 

This is would be my next step as well .
It's only 10 bolts to get the rear shaft off

 

Thanks man. I'll give this a shot! Think I can hit 60km/hr in FWD without rattling to pieces?

And do you have any advice on isolating the front diff? Pull the CV axles? If I remeber right, the front driveshaft doesn't normally rotate, so pulling that wouldn't establish anything.

 

Baby, I’m howlin’ for you!

Da-da, da-da, da
Da-da, da-da, da
Da-da, da-da, da
Da-da, da-da, da
Da-da, da-da, da
Da-da, da-da, da
Da-da, da-da, da
Da-da, da-da, da

 

Is it quiet in 4th gear?

 

Yeah you can drive just fine in fwd. I've even driven on the highway that way, as long as everything else is working properly.

Front diff doesn't spin when it's not in 4wd, just the CV's spin, but they are disconnected by the ADD.