Probably a grenaded transfer case

60wag

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BTW a cell phone with a vibration analysis app makes a cool tool for diagnosing stuff like this
 

DouglasVB

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what is the frequency of the vibration? does it match tire RPM or driveshaft RPM?
Hmm that's a good question. It started up around 45 mph and increased in severity around 55-60 mph and then pretty much smoothed out above 65 mph although I felt like it was still lurking just under the surface. But it didn't feel like an rpm-related issue necessarily? Not really sure how to describe the feeling.

The closest things it reminded me of are 1) when I was having tire balance issues on my front axle (solved by using balancing disks) and 2) previous driveshaft issues or differential issues. But it didn't strongly feel of any one of those in particular.

I didn't get to where my truck is stored yesterday so at this point I won't be able to work on it until late next week. At least I have a very accommodating friend who is letting me store it on her property but it sucks not having the truck at my house so I can work on it incrementally and easily.

The good news is I am going to get to see my parents for the first time in over a year in person! The doctors cleared my mom for the first dose of Moderna a couple weeks ago so now that her body has had time to start working on antibodies I'll be going to visit them and do some heavy equipment maintenance with my dad. With my mom's ongoing cancer treatments, we've all had to live like hermits for over a year now to protect her (I'm the backup caregiver if anything happens to my dad). So I think that's a pretty good reason to delay working on the truck more 🥰
 

Telly

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Rotate the tires give it a test run. Sure sounds like a tire vibration to me.
 

DaveInDenver

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I also wonder if the vibration is consistent regardless of throttle or varies with how hard you accelerate. I think you did say it continued to vibrate coasting, though.
 

DouglasVB

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I also wonder if the vibration is consistent regardless of throttle or varies with how hard you accelerate. I think you did say it continued to vibrate coasting, though.

It was continuous with acceleration, coasting, clutch pushed in or not, different gears, rear t-case put in neutral, going uphill or downhill. It reminds me a bit of head shake on a motorcycle.
 

rover67

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so the frequency matched the RPM of the tires?
 

DouglasVB

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so the frequency matched the RPM of the tires?

Sort of but not perfectly. It felt more or less like the below:

1619561288946.png


The period of the vibration (that I could detect anyway) didn't change between 45mph and 65mph. Just the intensity. Above 65mph or there abouts, it still felt like it was lurking just under the surface.

Now that I think about it, it also came with a bit of a rumble or noise.

When I test drive again, I'm going to strap a GoPro on the bottom of the frame so I can see what's going on after the fact.
 

DouglasVB

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No updates on the 4runner over the last month. There have been a lot of things going on and I've just been too tired to dig into the rear axle. We've got two sick geriatric cats one of which has spent some time in the kitty hospital, the dishwasher decided it was time to go out, a family member's ongoing cancer treatments, unstable stuff at work, etc. etc. Lots of stress and whatnot so I haven't had the energy to dig into the truck more.

I've been contemplating again if it might be time to get something more reliable and comfortable to drive that has at least a couple air bags and safety features. The last few years I've been working on the truck much more than wheeling it. I'd rather it be the reverse! I could go for the trailer approach with a tow pig and trailer to put the 4runner on but I've got nowhere to park a truck and trailer.

I'd like to have 35" or bigger tires, manual trans, lockers, and probably a dual t-case setup or at least a crawler gear. So if I stay with Toyota that limits me to a 1998 or later Tacoma. I think I would want to retain ABS which doesn't seem easy with a SAS setup. So probably long travel? Otherwise if there were an ABS solution for a SASed taco, then I would think a 3 link setup and a Dana 60 front axle would be pretty reasonable. At that point, then I could find a 2WD taco and throw an Atlas 4 speed t-case behind it for less than buying a 4x4 taco.

Beyond Toyota I guess there are Jeep Wranglers and the new Ford Bronco that would theoretically check all the boxes.

Since I live in California and don't see that changing anytime soon, whatever I hypothetically end up with will need to be Cali emissions compliant so ideally the truck is already registered in a county that does smog testing in Cali.

Whatever I would do, I know I don't have the skills or the time to do any welding or fab work. I'd need to hire a shop to build a truck or find a built truck that's actually good.

Mainly I just want something that works and that gets us out more often. I'm exhausted even thinking about finishing diagnosing and then fixing my 4runner. I know there are new and exciting things waiting to break after I get the vibration problem solved.
 

Notyourmomslx450

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When wheeling is your hobby you’ll always be working on it.
 

DouglasVB

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When wheeling is your hobby you’ll always be working on it.

Yup 100% agree with that statement 😂 I just wish it wasn't a maintenance hobby with a little wheeling and more of a wheeling hobby with some maintenance. I was thinking this morning about all the trips we've missed in the last year because the truck has been down for maintenance more than it's been running. We didn’t get to Death Valley this winter. We didn’t get to do Cruise Moab. We aren’t going to the train run next weekend. We didn’t even get to the local OHV park. We basically haven't gotten out and done anything for quite some time because any time I've got I'm working on fixing whatever the latest thing to break is.

I feel tired just thinking about it haha!
 

DaveInDenver

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Going 35" tires and anything mini truck or Tacoma is going to put you right back where you're at now break stuff. Tick-tick-tick. You need to have reasonable expectations.

If you want something you can 'wheel hard and not break too much on 35" you need 1 ton running gear and if you want actual safe and comfortable on the highway the best way for that is have that stuff under a 1 ton truck. Or at least something full size. But that's not going to be nimble in rocks.

Anyway, you can do plenty of stuff on IFS and 33" tires. If you're sympathetic to the machine you won't break it too much either.
 

AimCOTaco

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Sounds like you need an 80. :devilish:

With low gears in the t-case. :hill: :hill:
Yeah, those 80's never break anything and always pass emissions :ROFLMAO:..

Can you put 35's on a Rivian?

I've used audio and FFT to find vibrations in machinery but didn't know there were vibration sensor apps... cool!
 

Notyourmomslx450

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Going 35" tires and anything mini truck or Tacoma is going to put you right back where you're at now break stuff. Tick-tick-tick. You need to have reasonable expectations.

If you want something you can 'wheel hard and not break too much on 35" you need 1 ton running gear and if you want actual safe and comfortable on the highway the best way for that is have that stuff under a 1 ton truck. Or at least something full size. But that's not going to be nimble in rocks.

Anyway, you can do plenty of stuff on IFS and 33" tires. If you're sympathetic to the machine you won't break it too much either.
You definitely don’t need one tons to run 35’s on a Toyota.
I’ve run 37’s on multiple Toyota’s. All on Toyota axles. Ran stock rear axles on all of them. Never broke a rear. Fronts I’ve only broken one Longfield birf in 15+ years of hard wheeling.
To say you need tons to run 35’s is crazy talk.
 

DaveInDenver

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You definitely don’t need one tons to run 35’s on a Toyota.
I’ve run 37’s on multiple Toyota’s. All on Toyota axles. Ran stock rear axles on all of them. Never broke a rear. Fronts I’ve only broken one Longfield birf in 15+ years of hard wheeling.
To say you need tons to run 35’s is crazy talk.
I wasn't speaking colloquially "you" but formally "you" as in specifically Douglas here. He's the one with the t-case (a Marlin at that) that shattered with "only" 35x12.5 Grabbers IIRC after all. There's people (conversionally) who wheel 33" and sometimes even 35" with IFS and don't even blow all that many CV axles, much less transfer cases. How punishing one is to their junk seems to be kind of a spectrum.
 
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Notyourmomslx450

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I wasn't speaking colloquially "you" but formally "you" as in specifically Douglas here. He's the one with the t-case (a Marlin at that) that shattered with "only" 35x12.5 Grabbers IIRC after all. There's people (conversionally) who wheel 33" and sometimes even 35" with IFS and don't even blow all that many CV axles, much less transfer cases. How punishing one is to their junk seems to be kind of a spectrum.
Crazier things have happened.
If I remember correctly Douglas had a very early tcase adapter (not that that’s the issue), but they’ve been known to have lubrication issues from time to time.
 

DaveInDenver

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Crazier things have happened.
If I remember correctly Douglas had a very early tcase adapter (not that that’s the issue), but they’ve been known to have lubrication issues from time to time.
If memory serves his 4Runner also has had issues with rear axle bearings, both driveshafts and the steering box. It's not a knock just that I get the sense he's hard on the truck and might benefit from Dana 60s and an Orion.
 
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