Rear end vibration other than bearings/u-joints? (1 Viewer)

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Yesterday I suddenly noticed a rear end vibration in my 94.

It felt like the kind of shudder you get under load with a misfire, which I had with a bad fuel injector and a blown spark plug on another vehicle. No CEL though on the LC

Changed the plugs, none were catastrophic. All looked like the had been running on the lean side. Jacked it up and checked the u-joints, no slop. No obvious issues. All had grease. All the u-joints were replaced from the original ones in the last 40,000 miles.

Transfer case fluid was good and correct level. Not mixed with ATF. Auto trans fluid was correct level and still smelled fresh from my last drain/fill about 20k ago.

Checking bearing play on all 4 wheels. None observed by rocking at 9/3 and 12/6. All 4 tires are inflated to exactly 55.0 and all 4 are same tire, put on about 15k ago and have been rotated twice (Nitto Terragrappler E load range)

185k on rig, which is well maintained. What other options should I check? The vibration is most notable at light load on acceleration or constant cruising, especially above 40. Seems to disappear when coasting. Feels like it's coming from the read end. TIA
 
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There is some play but I'm not sure exactly what I'm looking for. Turning the driveshaft with the wheels off the ground in neutral, there's about 1/2 to 3/4" of rotation before anything engages to rotate the tires.
 
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I have actually run into a similar issue on my 80. Happened a few days after I bought new tires. I get a really annoying vibration at 45-50mph, very low frequency tone. My best diagnosis at this point is the transmission mount in the middle of the frame.

-All fluids are fresh and look great, no metal, no discoloring
-all new U-joints in front and rear DS
-all new wheel bearings (F+R)
-new spindle bushings up front
-everything properly lubed and greased
-no play whatsoever in pinion flanges or transfer case output flanges

At first I thought it was a tire out of balance, but it only happens when accelerating within 45-50mph. So definitely not tires.
This vibration then came with new symptoms a few days later. When I put the truck in drive or reverse, I get the same vibration.

I inspected the engine mounts and transmission mount and noticed that the transmission mount was a little compressed. The rubber has very small cracks in it, but otherwise looks OK. The engine mounts look perfect.

I ordered all 3 mounts and they should come tomorrow. Going to start with the suspect transmission mount. I will definitely report back on how it goes.

I have given my 80 a very thorough baselining since I bought it 4 months ago. I honestly can't think of any other wearable mechanical item that I have not replaced yet. The mounts are the only thing that I can think of. And I don't think it is uncommon for bad driveline mounts to cause very strange vibrations.

For reference, I do not have a lift, just OME stock height heavy duty springs. I am running 265/75/R16 Michelin Defender LTX (Load Range E)
 
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Ok so a combination of things definitely helped my problem about 75%, but it's still there a bit.

Changing the transmission mount helped a lot. Less vibration and noticeably quieter inside.

I also upped the air pressures on my tires. Running 40psi up from 32psi, oddly enough that helped a good bit as well. Might pump them up a bit more and see if it helps again.

Hopefully this helps you out a bit.
 
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Look for anything rubber to be a possible culprit. Once I replaced all my panhard and control arm bushings in the rear, many mystery vibes disappeared and handling really tightened up. Replace worn with new OEM rubber: trans, engine, etc.
 
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Look for anything rubber to be a possible culprit. Once I replaced all my panhard and control arm bushings in the rear, many mystery vibes disappeared and handling really tightened up. Replace worn with new OEM rubber: trans, engine, etc.

Agreed. I feel like if I replace all my rear axle bushings a lot of my small vibrations would go away.
nothing wrong right now, just would be better.
At best these trucks are 23 years old so it’s safe to say that at least most of the rubber needs to be replaced.
 
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Were your u-joints replaced with OEM (Toyota)? U-joints can have no slop and still be binding, causing the vibration you are experiencing. Especially if not Toyota joints.
 
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Were your u-joints replaced with OEM (Toyota)? U-joints can have no slop and still be binding, causing the vibration you are experiencing. Especially if not Toyota joints.

U joints are OEM.

Made no difference before/after.

Going to attempt to change the two engine mounts tomorrow and see how that goes.
 
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I just replaced my engine mounts. Old ones were visibly splitting at the metal. Overall, truck just feels a lot smoother. But I still get a tiny vibration at 45-50 mph.

@zapatius, Do you have a tire carrier installed? I feel like I haven't noticed this vibration until I installed my tire carrier. Might be the cause or just a coincidence.

I know you said rear end, but maybe it could be a birfield? I was reading a 100 series post about a very similar issue and new CV shafts fixed the problem.
I just greased my birfields so they are nice a fresh, but maybe one is going bad idk.
 
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It felt like the kind of shudder you get under load with a misfire, which I had with a bad fuel injector and a blown spark plug on another vehicle. No CEL though on the LC

since the 94 is obd I you will not get a check engine light from a misfire. its normal to have backlash in he drive train as there is a lot of slop between all of the different components, but when your checking for pinion play your looking for an up and down or side to side similar to checking for a wheel bearing. if the truck is lifted and the u-joint angles are out that can also cause a vibration
 
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since the 94 is obd I you will not get a check engine light from a misfire. its normal to have backlash in he drive train as there is a lot of slop between all of the different components, but when your checking for pinion play your looking for an up and down or side to side similar to checking for a wheel bearing. if the truck is lifted and the u-joint angles are out that can also cause a vibration

Agreed, backlash is normal. The Land Rovers I used to have had even more backlash than the 80.

I also have no play in either pinion, and no play in the transfer case outputs.

Also stock height (OME 861/862), but I have an ARB bumper, winch, and 4x4Labs tire carrier.
 
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I would check the u-joint angles, there shouldn't be too much lift with that combo but it does lift it over stock height

Didn't think about that. I will check. Also should note that I started noticing the vibration after I went up in tire size, only very slightly though (265/75/R16).

I wouldn't mind putting in a set of Tom Woods drive shafts or something similar just for the standard U-joints alone. I don't think I would need a double cardan at this height but maybe just nice to have bigger U joints.
 
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Sorry, I didn't get an alert that anyone responded to the thread.

I just ended up going down the rabbit hole. It's not a DD, but it has been on 5000 mile trips and pulls our camper, so I don't want to break down anywhere.

I ended up replacing plugs, wires, distributor cap, rotor, distributor o ring, starter, alternator, drive belts, doing the Wit's End cooling elbow for my temp sensor, replaced the radiator hoses. I've got a set of the ProForged tie rods on the way to replace and sway bar bushings. I'll add panhard and control arm bushings to the list. I also bought a front axle/bearing kit from Cruiser Outfitters to go ahead and do that. Ugh.

I drove it again, then took it completely off the ground on jack stands. The rear joint on the front drive shaft has a lot of play. I'm guessing that's the likely culprit. They are either Moog or Spicer, can't remember. I'll replace both u-joints in the front shaft with Toyota (ditto for rear shaft, when it's time). I thought a 1.5-2.5" lift didn't have an issue with drive shaft/u-joint angles? Incorrect?
 

Irish Reiver

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It's unlikely but if the U-Joints have been used to working at a certain angle and you introduce a lift which changes the angle then the U-Joints can throw a hissy fit. Start with new U-Joints and see how you get on.
 
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Sorry, I didn't get an alert that anyone responded to the thread.

I just ended up going down the rabbit hole. It's not a DD, but it has been on 5000 mile trips and pulls our camper, so I don't want to break down anywhere.

I ended up replacing plugs, wires, distributor cap, rotor, distributor o ring, starter, alternator, drive belts, doing the Wit's End cooling elbow for my temp sensor, replaced the radiator hoses. I've got a set of the ProForged tie rods on the way to replace and sway bar bushings. I'll add panhard and control arm bushings to the list. I also bought a front axle/bearing kit from Cruiser Outfitters to go ahead and do that. Ugh.

I drove it again, then took it completely off the ground on jack stands. The rear joint on the front drive shaft has a lot of play. I'm guessing that's the likely culprit. They are either Moog or Spicer, can't remember. I'll replace both u-joints in the front shaft with Toyota (ditto for rear shaft, when it's time). I thought a 1.5-2.5" lift didn't have an issue with drive shaft/u-joint angles? Incorrect?

IIRC in terms of aftermarket UJs, Moog has them for front and rear, Spicer only has the front. I have a full set of Moog joints that I keep in the 80 as spares. They have smaller needle bearings than OEM, but there are a lot more of them. As far as a stock height, 32" tire, low impact use LC like mine goes, I'm sure that the Moog joints are more than good enough.

So far I have replaced all 3 engine mounts and all the rubber exhaust mounts. Also added a hanger for the tailpipe because the 4x4Labs bumper requires the removal of the factory one. The truck feels so smooth now. But I still get the vibration.

I am not really sure what it could be at this point. I feel like everything that is serviceable or perishable has been done.

If it is the UJs would they not vibrate at higher speeds too? The vibration stops at 50mph. Maybe I installed them incorrectly? I replaced them 3k miles ago and only recently started having this issue. No binding and super smooth when I installed them.

I almost feel like maybe something is out of balance but again, the vibration only occurs at a very specific scenario (45-50mph, uphill, accelerating).
@zapatius hopefully we can get to the bottom of this soon.
 

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