Rear Wheel Bearing Vibration?

[OregonLC]

I too have thought about a brand new DS, perhaps even a double cardan. However my joints feel great on the ground. Limber but no slop. Post up your results if you do.

 

[joshAUST]

I'm not an mechanic, but thought I'd throw in my two bob, sorry if its of no help...

Could it be the rear brake caliper or the hand brake mechanism playing up, either stuck on, wearing unevenly, etc?

I know its unlikely, and I'll admit I've read a lot of the messages on your post but not all of them, so I may have missed some of the details.

It may only come out when the rear wheels are under load perhaps, so when you had the drive shaft off you didn't feel it.

My 2003 LC100 had a seized left hand side hand brake mechanism - it was stuck on for over 2000KM!, and I didn't notice it, but I did notice a bit of vibration coming from the rear end. I had just picked up the car second hand, and I had never driven it before, nor driven any other LC, so I didn't know what to expect re vibrations, noise, etc.

Mine was caused by rust, as the car must have spent a lot of time at the beach with a previous owner.

 

[OregonLC]

It could be that. The vibration does go away with either foot or handbrake application. However it also goes away when the rear DS is removed.

 

[joshAUST]

It could be worth temporarily disabling the hand brake drum brake, and, if not that, then removing one of the calipers at the rear and then CAREFULLY test it.

You don't need to disconnect the brake lines to remove the calipers, just remove the two bolts that hold the calipers onto the wheel hub.

I'd recommend placing a piece of wood between the pistons once you've removed the caliper from the rotor, a piece thicker than the width of the rotors, and cable tying it in place to stop the caliper pistons from extending too far while your testing the car, and it'll make it easier to get it back on the rotor too, without having to resort to clamps, etc to retract the pistons.
Then cable tie or wire the caliper up out of the way so its not going to bang into anything or fall off.

 

[joshAUST]

And yes, its all less likely as you don't hear the noise when the DS is removed, but if the issue only happens under load, then it could still be the brakes.

 

[guerasfj60]

And yes, its all less likely as you don't hear the noise when the DS is removed, but if the issue only happens under load, then it could still be the brakes.

Two steps forward, one step back. This may be related to the drone for me.
I did a few things and documented the results as they were performed but need more miles. I will report back after I finish a decent road trip starting tomorrow.

 

[OregonLC]

Alright, so a few updates: used the Harbor Freight angle finder tool and dialed in the pinion angle a tiny bit more. When you're looking at a degree resolution of 0.1 degrees even hand pressure on the tool can affect the measurement. Overall it was 0.5 - 1.0 degrees out. Was able to bring it as close to zero as possible by adjusting one upper link by half a turn. This is really splitting hairs. No difference at all was measured in the vibration/resonance. 55-60 mph it vibrates. At 65 it's smooth and below 50 it's smooth.

Next I tried adding the harmonic balancer back onto the vehicle. If anything this amplified the vibrations. To be fair, the MT sliders block the OEM attachment points from being used. The PS torsion adjuster bracket, however, has hole centers that match with the balancer and I was able to attach it there. It's less than a foot south of the factory point and maybe 1-1/4" inboard of frame center. It is a very solid mount, however, and I feel that the damper should have had a similar effect.

I'm starting to wonder if there isn't something in the cut of the Nitro gears that creates a vibration. The 4.88 harmonic seems to be a common occurrence (and not just with the TLC, Jeeps seem to have a similar effect). Although the 100 does seem extra susceptible to vibrations (the factory, after all, did put a funky damper on the frame). For whatever reason the system creates a resonance right at that 2,700-3,000 shaft rpm range. The only head scratcher is why it didn't create the vibration immediately upon re-gearing. It could be that it was on the tipping point of vibrating and the degradation of other components pushed it over the top over time. Body mounts, trans mounts, engine mounts, suspension bushings, shock wear all contribute to what is felt in the cab. That it goes away when the rear propeller shaft is pulled and that the same shaft doesn't vibrate when installed in our 2004 indicates to me that the problem is downstream.

So... that's all great, but what to do? I'm very confident that nothing is broken (or about to break). I'd drive this truck to the moon right now without worry. It has become a bit annoying. I could go back to 4.30s. If gear cut were the culprit, this would be a fix. It's a $1K job, no guarantee, and my 8,000 lbs weight we suffer a performance hit. Honestly, power has become a big issue for me. At 8,000 lbs, 34s, and high drag accessories, the 230 hp 2UZ is not happy with highway climbs. Lash the trailer to her and I'm 9,500 lbs. Last trip I achieved 181 miles on a full tank with a headwind (but with a 4,000 ft elevation drop). So 4.30s weren't high on my list of desirable solutions. Although in looking at ratios I could run as a 3-spd on the highway (OD off) when loaded: 4.30 x 3rd gear = 2,800 rpm at 65 vs 4.88 x 4th = 2,400 rpm. Hill climbs in 2nd would also be better: 4.30 x 2nd = 3,660 rpm at 55mph vs 4.88 x 3rd =2,700 rpm or 4.88 x 2nd at 4,200 rpm. Right now, I know I can't hold 4.88 x 3rd = 2,700 rpm on climbs. Downshifting to 2nd feels like I'm whipping the truck; don't really like to hang out at 4,200 rpm for long durations. Maybe 4.30s wouldn't be that bad after all if I view it as a 3spd. Off the line performance in 1st as well as 4Lo performance would suffer. See attached gearing matrix for the available options. All area measured with 34.25" tires. Orange shading are vibration zones for 4.88s. Going down to a 33 would help a bit in both gearing and drag, however it's nowhere near as substantial as a final ratio change.

Another option would be to move over all of my equipment to our 2004. The A750F with 4.30s is probably the best overall ratios available.

Or I could cut bait and go with a 200. 381 hp would forgive a multitude of sins...

 

[nemisonic]

Alright, so a few updates: used the Harbor Freight angle finder tool and dialed in the pinion angle a tiny bit more. When you're looking at a degree resolution of 0.1 degrees even hand pressure on the tool can affect the measurement. Overall it was 0.5 - 1.0 degrees out. Was able to bring it as close to zero as possible by adjusting one upper link by half a turn. This is really splitting hairs. No difference at all was measured in the vibration/resonance. 55-60 mph it vibrates. At 65 it's smooth and below 50 it's smooth.

Next I tried adding the harmonic balancer back onto the vehicle. If anything this amplified the vibrations. To be fair, the MT sliders block the OEM attachment points from being used. The PS torsion adjuster bracket, however, has hole centers that match with the balancer and I was able to attach it there. It's less than a foot south of the factory point and maybe 1-1/4" inboard of frame center. It is a very solid mount, however, and I feel that the damper should have had a similar effect.

I'm starting to wonder if there isn't something in the cut of the Nitro gears that creates a vibration. The 4.88 harmonic seems to be a common occurrence (and not just with the TLC, Jeeps seem to have a similar effect). Although the 100 does seem extra susceptible to vibrations (the factory, after all, did put a funky damper on the frame). For whatever reason the system creates a resonance right at that 2,700-3,000 shaft rpm range. The only head scratcher is why it didn't create the vibration immediately upon re-gearing. It could be that it was on the tipping point of vibrating and the degradation of other components pushed it over the top over time. Body mounts, trans mounts, engine mounts, suspension bushings, shock wear all contribute to what is felt in the cab. That it goes away when the rear propeller shaft is pulled and that the same shaft doesn't vibrate when installed in our 2004 indicates to me that the problem is downstream.

So... that's all great, but what to do? I'm very confident that nothing is broken (or about to break). I'd drive this truck to the moon right now without worry. It has become a bit annoying. I could go back to 4.30s. If gear cut were the culprit, this would be a fix. It's a $1K job, no guarantee, and my 8,000 lbs weight we suffer a performance hit. Honestly, power has become a big issue for me. At 8,000 lbs, 34s, and high drag accessories, the 230 hp 2UZ is not happy with highway climbs. Lash the trailer to her and I'm 9,500 lbs. Last trip I achieved 181 miles on a full tank with a headwind (but with a 4,000 ft elevation drop). So 4.30s weren't high on my list of desirable solutions. Although in looking at ratios I could run as a 3-spd on the highway (OD off) when loaded: 4.30 x 3rd gear = 2,800 rpm at 65 vs 4.88 x 4th = 2,400 rpm. Hill climbs in 2nd would also be better: 4.30 x 2nd = 3,660 rpm at 55mph vs 4.88 x 3rd =2,700 rpm or 4.88 x 2nd at 4,200 rpm. Right now, I know I can't hold 4.88 x 3rd = 2,700 rpm on climbs. Downshifting to 2nd feels like I'm whipping the truck; don't really like to hang out at 4,200 rpm for long durations. Maybe 4.30s wouldn't be that bad after all if I view it as a 3spd. Off the line performance in 1st as well as 4Lo performance would suffer. See attached gearing matrix for the available options. All area measured with 34.25" tires. Orange shading are vibration zones for 4.88s. Going down to a 33 would help a bit in both gearing and drag, however it's nowhere near as substantial as a final ratio change.

Another option would be to move over all of my equipment to our 2004. The A750F with 4.30s is probably the best overall ratios available.

Or I could cut bait and go with a 200. 381 hp would forgive a multitude of sins...


View attachment 1516059

Any update on this? We have a 2001 LX470 did 182k (fully baselined in 2016 in SoCal) to 275k (1 year in New England in 2020) including lots of Sierra-Nevada trips and also a cross-country from California to New England. The vibration showed up for us in the past 20k miles (4 oil changes, 2 years). In 2019, I did a new OEM rim set off ebay (TX seller) + new tires (2nd set of Pirelli Scorpions, OEM size, that did not vibrate previously), Spring 2020: replaced brake calipers+pads, disabled parking brakes, checked U-joints in drive-shaft / propeller-shaft (which I grease every 5-10k miles). Summer 2020: Also swapped rear-to-front on the tires myself. Still have passenger-side rear vibration. No leaks on the hydraulic suspension (new pump and oil also for 4 years prior to vibration). Good swaybar links only 1 year old (rubber out back, poly out front) - so, no axle wrap, right... No-rust California vehicle.... Also whether I had a shop replace the brakepads and rotors (2019) or myself (2020 brakepads, rotors, and calipers, using Lexus dealer parts) showed no difference.

Looking at other LX470's, I sit about 1-2" higher at Neutral height (1st owner did the SoCal OHV trails), and I figured out how to adjust that- would that affect pinon angle?

Any ideas? Did this ever get resolved?