Front end grumble in 4WD ... what could it be?

[Rzeppa]

I would do what Andy suggested and tighten the wheel bearing. Sometimes the loosen up a bit. Its maybe 30 minutes and free to at least see if that is the issue. You can still do the rebuild again.

Agreed with Ken and Andy, grumbling in the front is usually wheel bearings, but that doesn't account for 2WD no noise/4WD The noise! The observation that you got some looseness with the 12 o'clock/6 o'clock test goes back to maybe knuckle bearings but still rules out on the 2WD/4WD test. Definitely a head scratcher! You can't know until you verify that the wheel bearings are properly pre-loaded I guess.

 

[rover67]

12/6 oclock is typically where you can feel wheel bearings when you get it rocking. at least it's the easiest. Back to the driveshaft, whats the angle of the shaft itself?

 

[Notyourmomslx450]

I’m thinking it’s the pinion angle. Maybe???

 

[rover67]

I’m thinking it’s the pinion angle. Maybe???

yeah, curious on the DS angle so we can see if the pinion is square with it. Should be pointed right at the t case flange basically.

 

[Cruisertrash]

@rover67 I wrote that down on a prettier diagram, I think it was 15.8* - I'll correct that when I get to the shop and can take a look at it again. Is the theory with a double cardan that you want the diff pointing straight at the t-case, but then point it down 1-3* to accommodate suspension flex and axle wrap? On the rear you've got a shaft with a single u-joint at either end, so you'd want to get the flanges parallel (and maybe minus 1* in the back) - but double cardans are different. I have less experience there.

 

[Cruisertrash]

Agreed with Ken and Andy, grumbling in the front is usually wheel bearings, but that doesn't account for 2WD no noise/4WD The noise! The observation that you got some looseness with the 12 o'clock/6 o'clock test goes back to maybe knuckle bearings but still rules out on the 2WD/4WD test. Definitely a head scratcher! You can't know until you verify that the wheel bearings are properly pre-loaded I guess.

I'm going to check the torque on the knuckle caps while I'm at it. Maybe the top or bottom is just loose enough to cause some play, which is making noise.

But you're right, the 2wd vs 4wd difference is strange. Bad bearing? it should make noise all the time. Really starting to wonder if something in the diff is unhappy, or one of the two birfields.

 

[RDub]

Jim, have you tried locking the hubs with the DS removed? That would possibly help identify if it’s coming from the front axle assembly.

 

[Cruisertrash]

@RDub Yes! No noise.

I pulled things apart this morning and checked the preload on the big spindle nuts. 13ft-lb. The nuts weren’t loose but I went ahead and pulled them off and reinstalled everything per FSM. No more wheel wobble now.

But the noise is still happen in 4hi and 4lo whether or not the hubs are locked. No noise on 2wd regardless of the hubs being locked or not. What I’m learning is that it’s more of a vibration than just a sound.

Neither the pinion or t-case flange had any play last night when I put the DS back in, but I keep coming back to one of those having an issue.

 

[Cruisertrash]

@Crash see above

 

[DaveInDenver]

You said Englewood Driveshaft looked at the shafts, right? If so and you're absolutely sure the joints are good and everything is phased right I'd be leaning towards pinion bearing or t-case output. I wonder, do you have longer than stock shackles and thus could be oil starving a pinion bearing or seal?

 

[Notyourmomslx450]

@RDub Yes! No noise.

I pulled things apart this morning and checked the preload on the big spindle nuts. 13ft-lb. The nuts weren’t loose but I went ahead and pulled them off and reinstalled everything per FSM. No more wheel wobble now.

But the noise is still happen in 4hi and 4lo whether or not the hubs are locked. No noise on 2wd regardless of the hubs being locked or not. What I’m learning is that it’s more of a vibration than just a sound.

Neither the pinion or t-case flange had any play last night when I put the DS back in, but I keep coming back to one of those having an issue.

it might be the tcase itself. have you drained it looking for gold or silver?

 

[Cruisertrash]

it might be the tcase itself. have you drained it looking for gold or silver?

Not since August. My transmission/t-case has the known 60 issue where the t-case oil drains into the transmission, but it takes the better part of a year to show significant change. May as well check it again though.

@DaveInDenver I took the driveshaft to Bill yesterday, he sat it on the counter and we looked at it together. Clean bill of health (no pun intended). I'm not discounting a dry pinion and an overheated bearing, but I've always heard that's an old wive's tale. It's said that there's enough oil moving around in there that the pinion gets lubricated no matter what angle the pinion is at. But you know, internet chatter - hard to confirm or deny. But like I mentioned above, the pinion flange seems tight as can be in all three axes.

 

[DaveInDenver]

Gotcha. I'm out of things I've had happen to me! The one I'm fighting now is a phase issue because of a two-piece shaft and carrier bearing that Toyota went cheap and didn't use a double carden in. It's a low hum and vibration that would be perfect except it doesn't apply to you.

 

[Rzeppa]

Well, you have ruled a lot of stuff out, which is good. FYI, Marlin schooled me that the proper way to measure wheel bearing preload is with the fish scale on the wheel lug, not by the torque on the nut.

At this point I would speculate that the front output bearing of the t-case is the source of the noise. I know you wrote above that pulling DS made the noise go away, as did unlocking the hubs, but being in 4WD w/hubs locked is going to put some load on that output bearing, where having the DS spin but hubs unlocked is very little load. This doesn't rule out the pinion bearing, for the same reasons in the prior sentence.

 

[Cruisertrash]

@Rzeppa Oh, I use the fish scale too. It honestly was a little tight, even with both nuts removed and a little wiggle to the bearing to unseat it. It was registering 12ft-lb with nothing tightened on it. I did the whole process: tighten the first but to 43, spin the hub, loosen the nut, then tighten back down to the lighter torque (I forget offhand, I was looking at the FSM this morning). Then the star washer and 54mm lock nut, crank that to 73ft-lb. Fish scale reads 14 after that but the hub feels hood spinning by hand. I couldn’t get any less than 14 on the fish scale after trying a few times.

I wonder what might be making it too tight inside? Or was the hub still seated real well on the inner bearing despite no clamping force?

*****

What about the “rear engine mount” as Toyota calls it? The one under the transmission? I could see that thing getting damaged when the front left mount was broken - I had to wheel on it for an hour before I ratchet strapped it. Then this vibration started happening 30-60 minutes after that, which was also some heavy wheelin’. Maybe that rear mount got damaged and then another hour of stress on it finally finished the job and tore it completely. Doesn’t really explain why it only happens in 4WD … but maybe.

 

[Notyourmomslx450]

What about the “rear engine mount” as Toyota calls it? The one under the transmission? I could see that thing getting damaged when the front left mount was broken - I had to wheel on it for an hour before I ratchet strapped it. Then this vibration started happening 30-60 minutes after that, which was also some heavy wheelin’. Maybe that rear mount got damaged and then another hour of stress on it finally finished the job and tore it completely. Doesn’t really explain why it only happens in 4WD … but maybe.

I'd definitely look at this before digging into the tcase

 

[Cruisertrash]

I'd definitely look at this before digging into the tcase

If by “look at this” you mean “ratchet strap it for two weeks while I wait on parts” … then yes, I will!

But wouldn’t that make noise in 2wd or even just over bumps? Maybe not.

 

[Rzeppa]

I think the motor mount business is coincidental. And yes, if it had anything to do with a motor mount it would make the noise in 2WD and with the hubs unlocked.

 

[Cruisertrash]

More updates:

Transmission was over full and t-case 1.5qts low. I did not do a full drain and refill on those as I took some fluid samples from the fill plug and it looked good. Both fill plugs had minimal crud on the magnets. I did dump and refill the diff fluid - perfect in quantity and color, no metal.

“rear engine mount” - the one that holds the transmission - is definitely partially separated. In the photo notice the very small gap between the rubber and the metal above it. If I wedge it apart that gap grows. Who knows how much things are moving around under driving load.

Ratchet strap time:

I also found every single bolt on the transfer case loose. Not finger tight but close. The bolts that hold the case together, the output shaft, the input shaft rear cover, etc. I didn’t use a torque wrench but gave them what I thought was appropriate torque for aluminum. Used a 3/8” ratchet choked up a little bit so I didn’t overdo it.

I still suspect the u-joint at the diff (not the double cardan at the t-case) is blown, even if there isn’t any perceptible movement there. It sounds like a bad u-joint, and as the saying goes if it quacks like a duck…

Luckily I have one available to me in town today. I have a press. Might try to learn how to DIY that job later.

 

[Cruisertrash]

I think the motor mount business is coincidental. And yes, if it had anything to do with a motor mount it would make the noise in 2WD and with the hubs unlocked.

If the t-case is experiencing more forces in 4WD it may shake around more than in 2WD, thus there might be something to the mount business. Thoughts?

I guess I went hard this year!