Driveline whine at 55-60 mph

[SIZZLE]

Hey all. I've searched this issue but didn't find any conclusions. I get a noticable whine when accelerating between 55 and 60 mph, but at no other time. If i feather the throttle at that speed, right between coasting and accelerating, I can get a small virbration. It sounds like it is coming from the front end, but hard to tell (my hearing is not very good). It doesn't do it at all when the truck is loaded and the back end sits a little lower, which makes me think it might be related to the rear drive shaft.

I don't recall it doing this before i lifted it, but i lifted it pretty quickly after i got it and wasn't quite in tune with the truck before throwing mods on. It's been this way for the last 8k miles with no change. It's a '94 with 203k miles. OME heavy lift, 315s and 4.88 gears. All these mods were done at the same time and the front axle was rebuilt at that time too, all by a reputable LC mechanic (Mudrak). I'm guessing they are the original U-joints.

My questions are:

What do you guys think would cause this whine?

Has anyone successfully diagnosed and/or solved this problem?

Any harm in letting it go? It's slightly annoying, but livable and as long as you are not going that speed or are loaded down, you wouldn't think anything was wrong. I only get that slight vibration if i try. Naturally i don't want to cause damage if avoidable.

I'll start dropping driveshafts and throwing parts at it, but i wanted to get the opinion of the board first. Thanks for your input

 

[smug01]

I have had basically the same issue for the last 3k miles. Started just after getting 4:88's, but I did go to a reputable shop and used Nitro components. The shop was so concerned that they re-did both front and rear (a few weeks apart), but there was no change and all the R&P tolerances were within spec.

I'm starting to supect the output shaft area of the Transfer Case, as the whine has slowly gotten worse over the past 1k miles and is now there even when at constant speed. On the lift, with the tires spinning freely, the only noise that sounds suspect is coming from the T-case when using a stethoscope, but it is not a whine...more of a gear meshing/grinding noise...but I am not sure if that is normal or not. Maybe it was going out before, and now that the output operates in a much higher speed band, it is more noticable and/or increased wear on already worn out components.

Unfortunalely, I am having trouble finding a mechanic that can even diagnose, let alone want to rebuild thie T-Case should it prove to be bad.

 

[kbahus]

Pull your front drive shaft, lock the center diff, and go for a drive. Takes 15 minutes to do.

 

[tatcape]

Man I have same problem....also have it at 35 mph ...after 4.88's... all nitro components including front axle rebuild kit...I have had both dc shafts out re-packed balanced checked....alighment checked ...35's balanced ..going to have a reputable mechanic specializing in 4x4 take a look at her on fri ...I will post up result ...will be keeping close eye on threat

 

[smug01]

Pull your front drive shaft, lock the center diff, and go for a drive. Takes 15 minutes to do.

I did that. Whine is still there. I am suspecting the rear output. I just bought a chassis ear to connect to the components underneath. Will be investigating this weekend.

 

[SIZZLE]

I haven't pulled my shaft yet, but will try to do it this weekend. A lot of guys have tried this and got false results, so i was hoping that someone who's posted on this problem before found a solution. If it still whines I can at least eliminate U-joints and unbalanced shafts from the list. I hope its not a transfercase output. At least my noise has not gotten worse over 8k miles. I'll post up after the weekend.

Thanks!

 

[john_eckels]

There are a number of threads on this like the one below. Mine does the same thing and the noise comes from the rear endl AKA the ring and pinion. Mine quieted down some by using synthetic in the diffrentials. I use 1/2 140 and 1/2 75W90 in the rear. From what I have read here, this seems to be pretty common espeially in the 96 and 97 models with lockers. I was concerned about when I first got my LX. After 80K more miles it's about the same.

https://forum.ih8mud.com/80-series-tech/152284-what-noise.html

 

[jynx]

I was going to suggest diff too. I had my gears set up by a "reputable" guy too and when I tore mine down to install the locker I found there was ZERO pinion preload and the carrier bearing have a strange wear pattern that suggests no preload also. I had a slight whine but thought the same thing "well I had somebody do it for me"

Backlash is most likely off. Given what I had when I tore it down it had to have been super tight when it went together initially.

Also, in my pickup I had a similar whine and pulled the chunk, adjusted backlash and put some preload on the carrier bearing and it quietened it right down. Gear set up is not rocket science but it is a skill that must be mastered, and there are few that really have it down.

 

[SIZZLE]

Thanks for the input guys. I think the diff makes sense based on the lack of any other symptoms. Probably the front based on where the sound seems to be coming from. Though, it seems weird that it doesn't do it when the back is loaded down. I'll drop the front drive shaft to try and isolate it to that end. Unfortunately i'm not experienced with adjusting R&P. So if that is the case, i'll need to take it back to Mudrak.

Can you remove the front third member without fully disasembling the front axel?

Thanks!

 

[john_eckels]

As the third poster said, you have to lock the center diffrential if you remove the front drive shaft.

Thanks for the input guys. I think the diff makes sense based on the lack of any other symptoms. Probably the front based on where the sound seems to be coming from. Though, it seems weird that it doesn't do it when the back is loaded down. I'll drop the front drive shaft to try and isolate it to that end. Unfortunately i'm not experienced with adjusting R&P. So if that is the case, i'll need to take it back to Mudrak.

Can you remove the front third member without fully disasembling the front axel?

Thanks!

 

[smug01]

So today I did some investigation into my whining noise. I had put some 85W-140 into the T-case some time back to see if it reduced the noise. To me it was inconclusive, since for the last 3k miles the sound has been changing. First only on light acceleration, then it seemed to be only when transitioning from drive to coast torque in the driveline, to now...anytime above 40 MPH, but seems to lessen to some degree around 70 MPH. It is still more prevalent on the drive to coast transition, but can be heard all the time now above 40 MPH. You can even feel it through the body of the vehicle...very slight, but it is ther in the footwell.

That being said, the 85W-140 had been in there about 500 miles, so today I changed it back to 75W-90 Mobil 1. Now the whine seems to have increased slightly, but again, hard to tell.

Finally, I hooked up a Chassis Ear (Steelman Wireless) to 4 locations:

1) T-Case rear output area (on case)
2) rear Diff case
3) front Diff case
4) T-Case front output area (on case)

The microphone/clamps were attached to the metal of the case directly. Then I went for a drive, going through all speed zones. The front and read diffs were very smooth and quiet...you could hear a slight change in pitch on the drive-coast transition, and the volume of the sound was proportional to speed. I'd say the rear was slightly louder than the front, but not by much.

Then I switched to the T-Case rear...wow, the sound was so much louder than the diffs. So much louder, that i has to turn the earphone volume down. The sound was a combination of gear meshing and a whining/humming that changed drastically in pitch on the drive-coast transition. Although the front t-case was noisy as well, it was much quieter than the rear.

So to make a long story short, I am highly suspicious of the T-Case for this noise. So now, I guess it is off to find someone who is willing to work on the Transfer Cases.

 

[neal0124]

So today I did some investigation into my whining noise. I had put some 85W-140 into the T-case some time back to see if it reduced the noise. To me it was inconclusive, since for the last 3k miles the sound has been changing. First only on light acceleration, then it seemed to be only when transitioning from drive to coast torque in the driveline, to now...anytime above 40 MPH, but seems to lessen to some degree around 70 MPH. It is still more prevalent on the drive to coast transition, but can be heard all the time now above 40 MPH. You can even feel it through the body of the vehicle...very slight, but it is ther in the footwell.

That being said, the 85W-140 had been in there about 500 miles, so today I changed it back to 75W-90 Mobil 1. Now the whine seems to have increased slightly, but again, hard to tell.

Finally, I hooked up a Chassis Ear (Steelman Wireless) to 4 locations:

1) T-Case rear output area (on case)
2) rear Diff case
3) front Diff case
4) T-Case front output area (on case)

The microphone/clamps were attached to the metal of the case directly. Then I went for a drive, going through all speed zones. The front and read diffs were very smooth and quiet...you could hear a slight change in pitch on the drive-coast transition, and the volume of the sound was proportional to speed. I'd say the rear was slightly louder than the front, but not by much.

Then I switched to the T-Case rear...wow, the sound was so much louder than the diffs. So much louder, that i has to turn the earphone volume down. The sound was a combination of gear meshing and a whining/humming that changed drastically in pitch on the drive-coast transition. Although the front t-case was noisy as well, it was much quieter than the rear.

So to make a long story short, I am highly suspicious of the T-Case for this noise. So now, I guess it is off to find someone who is willing to work on the Transfer Cases.

I'd imagine that the TC gears would be louder because the gear profiles are much more aggressive than The RP gears.

 

[hudyhue]

See my 92 makes ( I'm guessing the same noise) a little about 20-25... And louder when I let off the gas pedal coasting....

 

[1303]

In light of that, I'd pay some attention to the rear output bearing...

 

[tatcape]

We had mine up on rack today.. checked over all nuts bolts bushings ..ran in it while center diff lock switch engaged ....in low ....lockers no reproducing it ... but on test drive noise there ...checked both drive shafts .again ....alignment specs again ....panhards ....brake system and nothing ....all in great shape
Ran out of time to hook up monitoring ears ....hope to do that soon
Took on quik trail run this eve put in low and the whine was loud ..seemed louder then norm ....
Find myself listening to radio little more !!!!!

 

[SIZZLE]

I was going to drop the DS this weekend, but took it for a drive first and couldn't get it to make the noise. Can't fix what aint there. Maybe it has something to do with temperature? I don't know, seemed to be doing it in all situations (except loaded) before. I'll see if I can pin down when it is making that noise and post back up. That might help pin it down.

 

[smug01]

In light of that, I'd pay some attention to the rear output bearing...

I was thinking the same thing. Now, I just need to find someone who is willing to work on these components.

Does anyone know of a mechanic in the SoCal area that would be willing to tear into one of these transfer cases (and has experience doing so)? It is a little more than I am willing to tackle on my own. Yotamasters suggested that I find a transmission specialist, but didn't have a recomendation for the 80-series.

 

[BradAT]

I'm definitely gonna be following this thread, mine started the mysterious whine and howl last week. Changed all diff and transfer case fluid. No change in sound, next is to check the grease in the birfs. Just a note, 95 with factory gears and lockers. Anxious to see what the out come or solution is.

 

[sct11]

I have a whine when letting off the throttle at highway speed. I am almost positive that its the 5.29s, as I don't know who set them up. All this talk about the t-case has me wondering though. I have actually learned to drive it with just not letting completely off the throttle until I have to for sure hit the brakes. I hate to pull the mid section without replacing all the bearings and grease on the birfs. Would like to know what other people are finding.

 

[neal0124]

I was thinking the same thing. Now, I just need to find someone who is willing to work on these components.

Does anyone know of a mechanic in the SoCal area that would be willing to tear into one of these transfer cases (and has experience doing so)? It is a little more than I am willing to tackle on my own. Yotamasters suggested that I find a transmission specialist, but didn't have a recomendation for the 80-series.

Try TLC4x4. I'm pretty sure marlin crawler will do it also but they are in Fresno I believe.