Noise when decelerating from freeway speeds

[brownjeans]

My LX450 is making a noise. Your driving on the freeway about 70 mph and lift and it starts a noise. I thought it was a propshaft/U-joint but I've replaced all four U-joints and had both propshafts balanced and it's still doing it. The knuckles were serviced too - so not that.
What's next? Diffs? T-case?

I'm stumped.

 

[NorCalFJ100]

Drivelines not installed in the correct phase or could even be installed backwards. Check it all out.

 

[Kernal]

@brownjeans

More details are needed:

Is your LX450 in stock configuration, no lift?

Miles on the vehicle?

Was any work done to the vehicle just before the noise began?

When did the noise start (miles ago) and did it start out low (volume)
and then get worse?

Any other new symptoms with the noise (vibrations)?

Have you checked the fluid level/condition in the front and rear diffs and the transfer case?

 

[gomie434]

Is it kind of a low hum with some vibration that feels like it's underneath you?

 

[brownjeans]

Okay, more info. The LX450 has 260k miles on it. Mostly stock. Has a 2" Emu lift, longfield gun bore front axles, bumpers and other mods that shouldn't make any difference at all for this situation. For the most part, it's pretty stock. Or it was - but now it has a new front prop shaft (see below)

The noise is a growl and vibration. It started quiet and grew progressively worse. No work on it recently before this started.

I normally do my own work on most things (I've done U-Joints in the past), but I was busy and a neighbor recommended a local shop and I thought I'd try them. They said I had a bad U-Joint on the rear. They replaced it - but only the one U-joint. That they didn't recommend to replace both while they were at it (I would have).
The sound was better, but not gone. So then I replaced the other U-joint. Still there and it got progressively worse again. Now I wondered if it was in the front.

The noise, vibration is not terrible and makes almost no noise at city speeds. Again, it's a growl when I lift of the go pedal, mainly from high speed.

I took it to a place in SLC Utah (I live just outside SLC) where they are known for working on LCs and they've done work on this and my 60 in the past.

They did a knuckle service, replaced the u-joints on the front drive shaft and had a specialty shop balance it (this is more like what I expected the other shop to do). The specialty shop couldn't get the stock prop shaft to balance so they built a new one and put it in.

It's all back together, but the growl is still there.

The slip joints are both on the inside (toward the T-case) so that's good. The front prop shaft ends are aligned together - "in phase" (stock they are 90* out of phase, right? I'm guessing the prop-shaft place built this new prop shaft so that it's aligned instead? Not sure if this is a problem). The rear is also in phase (I think it's like this in stock configuration, right?).

I'm not convinced the rear was indexed and installed correctly after the other shop did their work. If they put the slip joint on wrong, it might be out of balance. I'll try flipping it 180* and see if there's a difference.

If the noise was there at lower speeds I'd take off the rear prop shaft, put it in 4Low (to lock the center diff) and drive it to see if the noise goes away, but it's mainly at higher speeds. I may try that anyway just to see if I can detect the noise. The thought of this just caused me to go online and buy a center diff switch so I can lock the center diff in 4High. It will be here early next week.

 

[LongDuck]

First off;

Secondly, and more to the point, I was talking to a Toyota Service Director years ago and when I mentioned symptoms of the decel growl like yours, he mentioned that his own 80 did the same thing and he'd done just about everything to try to fix it. His interim solution was to vary his road speed when his wife-unit was onboard to avoid the whine and or growl, and learn to live with it. His eventual solution was a double-Carden front prop shaft.

Me, I just live with it. I've added Moly grease to the front Birfs and thought it got quieter, but it was back within a week.

A man could spend a lot of $$$ trying to fix this. It takes a better man than me...

 

[ZetheGSD]

My LX450 is making a noise. Your driving on the freeway about 70 mph and lift and it starts a noise. I thought it was a propshaft/U-joint but I've replaced all four U-joints and had both propshafts balanced and it's still doing it. The knuckles were serviced too - so not that.
What's next? Diffs? T-case?

I'm stumped.

Well your timing is great as I have been dealing with this for a couple years and just fixed it on my 80 last night.

Most of the 80's that I have worked on with this noise is either caused by bad rear control arms/not adjusted for a lift or front driveline vibrations. Most 80 owners let it slide and don't worry about it. You can search this condition by searching "Slack Throttle" as that brought up most of the issues for when I was looking. I have a Dobinsons 3.5" VT coils front and rear with adjustable rear upper and lower control arms. Front and rear drive shafts are new. Rear is a new OEM shaft as my splines had play from 300k and the front is a double carndan shaft. Even though you are only lifted 2" I have seen this issue with stock 80's.

To fix this I would start at looking at your rear control arms. Most times the bushings have a slight rip which will let the axle move all over making bad pinion angles or just causing vibrations under slack throttle conditions. This may not look bad to the eye, but I promise it's bad while your driving. Replace bushings at minimum but I would recommend you get adjustable arms top and bottom to re-align the rear pinion. This noise always echo's like it's coming from the front driveline but is usually caused by the rear driveline angles. Second, I would install a double Carndan front driveshaft and I recommend @landtank as his shafts are super quality and normally in stock. Please don't buy Tatton on eBay like I did and regret saving some coin just to curse his crap quality. Tom Woods is a decent option, but uses the same junk u-joints as Tatton which fail frequently. Landtank's shaft is built with OEM joints making them last for many years.

Because I am lifted higher than you I had replaced all of these components and still had a minor growl (even though it had gotten much better...). I just installed a set of @Delta VS front radius arms last night and now my slight growl at highway speed under light decel is finally GONE!!!!!!!!!!

To my knowledge not many have actually posted a fix to this, so use my experience in fixing this on multiple 80's to your advantage.

 

[brownjeans]

Well your timing is great as I have been dealing with this for a couple years and just fixed it on my 80 last night.

Most of the 80's that I have worked on with this noise is either caused by bad rear control arms/not adjusted for a lift or front driveline vibrations. Most 80 owners let it slide and don't worry about it. You can search this condition by searching "Slack Throttle" as that brought up most of the issues for when I was looking. I have a Dobinsons 3.5" VT coils front and rear with adjustable rear upper and lower control arms. Front and rear drive shafts are new. Rear is a new OEM shaft as my splines had play from 300k and the front is a double carndan shaft. Even though you are only lifted 2" I have seen this issue with stock 80's.

To fix this I would start at looking at your rear control arms. Most times the bushings have a slight rip which will let the axle move all over making bad pinion angles or just causing vibrations under slack throttle conditions. This may not look bad to the eye, but I promise it's bad while your driving. Replace bushings at minimum but I would recommend you get adjustable arms top and bottom to re-align the rear pinion. This noise always echo's like it's coming from the front driveline but is usually caused by the rear driveline angles. Second, I would install a double Carndan front driveshaft and I recommend @landtank as his shafts are super quality and normally in stock. Please don't buy Tatton on eBay like I did and regret saving some coin just to curse his crap quality. Tom Woods is a decent option, but uses the same junk u-joints as Tatton which fail frequently. Landtank's shaft is built with OEM joints making them last for many years.

Because I am lifted higher than you I had replaced all of these components and still had a minor growl (even though it had gotten much better...). I just installed a set of @Delta VS front radius arms last night and now my slight growl at highway speed under light decel is finally GONE!!!!!!!!!!

To my knowledge not many have actually posted a fix to this, so use my experience in fixing this on multiple 80's to your advantage.

On adjustable control arms - I see OME makes some, Dobinsons... recommendations?

 

[ZetheGSD]

On adjustable control arms - I see OME makes some, Dobinsons... recommendations?

I am using Jason’s “@trailtailor” arms as they are beefy DOM tube with Currie joints on one end and Poly on the other. Metal tech also has similar arms that work great. There are good options you listed as well.

 

[landtank]

In my experience lifts under 4” usually run cleans with stock rear links. At 4 and above installing an extended lower arm will take care of any vibrations due to lifting the truck.

Links with threaded sections have stripped out leaving owners in a bad way. I avoid y to hem.

A front DC shaft is not a cure all. It has a very specific application and if considering one of mine I like to first confirm it’s a good fit for your truck before you purchase.

 

[BILT4ME]

Okay, more info. The LX450 has 260k miles on it. Mostly stock. Has a 2" Emu lift, longfield gun bore front axles, bumpers and other mods that shouldn't make any difference at all for this situation. For the most part, it's pretty stock. Or it was - but now it has a new front prop shaft (see below)

The noise is a growl and vibration. It started quiet and grew progressively worse. No work on it recently before this started.

I normally do my own work on most things (I've done U-Joints in the past), but I was busy and a neighbor recommended a local shop and I thought I'd try them. They said I had a bad U-Joint on the rear. They replaced it - but only the one U-joint. That they didn't recommend to replace both while they were at it (I would have).
The sound was better, but not gone. So then I replaced the other U-joint. Still there and it got progressively worse again. Now I wondered if it was in the front.

The noise, vibration is not terrible and makes almost no noise at city speeds. Again, it's a growl when I lift of the go pedal, mainly from high speed.

I took it to a place in SLC Utah (I live just outside SLC) where they are known for working on LCs and they've done work on this and my 60 in the past.

They did a knuckle service, replaced the u-joints on the front drive shaft and had a specialty shop balance it (this is more like what I expected the other shop to do). The specialty shop couldn't get the stock prop shaft to balance so they built a new one and put it in.

It's all back together, but the growl is still there.

The slip joints are both on the inside (toward the T-case) so that's good. The front prop shaft ends are aligned together - "in phase" (stock they are 90* out of phase, right? I'm guessing the prop-shaft place built this new prop shaft so that it's aligned instead? Not sure if this is a problem). The rear is also in phase (I think it's like this in stock configuration, right?).

I'm not convinced the rear was indexed and installed correctly after the other shop did their work. If they put the slip joint on wrong, it might be out of balance. I'll try flipping it 180* and see if there's a difference.

If the noise was there at lower speeds I'd take off the rear prop shaft, put it in 4Low (to lock the center diff) and drive it to see if the noise goes away, but it's mainly at higher speeds. I may try that anyway just to see if I can detect the noise. The thought of this just caused me to go online and buy a center diff switch so I can lock the center diff in 4High. It will be here early next week.

1) Both driveshafts are supposed to have the slip yoke towards the FRONT of the truck. (Front is at the differential, rear is at the transfer case)

2) The front driveshaft is supposed to be 90°out of phase on your truck. Apparently, the shop you had do the work is not LX 80 series savvy.

Decel noise or vibration are typically related to:
A) u-joints
B) pinion bearings
C) transfer case output shaft bearings.

You're at 260K, and depending on use, you could have worn bearings on the pinion.

Don't replace your rear control with adjustable units. You'll just be introducing more problems and uncertainty into your equation. This is why it's always important to do a PROPER diagnosis and not just fire the parts cannon at it. No, most shops can't do this either because they make more money firing the parts cannon.

I would check fluid levels and types in differentials and transfer case. Make sure they are correct.

Then get the driveshafts correct.

Grease your driveshafts to see if it changes the noise frequency or how bad it is.

Do those, then report back in detail what you did.

 

[jonheld]

Decel noise or vibration are typically related tgo:
A) u-joints
B) pinion bearings
C) transfer case output shaft bearings.

Don't forget worn slip yokes. There should be zero torsional play in the yokes. Any play will cause both halves of the driveshaft to flog around under a "no load at speed" situation, causing vibrations.

 

[brownjeans]

First, thanks all for the responses. Some updates:
I think it's unlikely that the lift is causing the problem. It's the 2.3 OME lift and it was done by the PO many years ago. I don't know if the PO did a geometry correction or not, but I've been driving it for years and not hearing this noise. This noise is new.
I bought a center diff lock switch and installed it on Monday of this week.
I locked the center diff, removed the rear drive shaft and drove it in 4H on just the front - noise gone. Someone tell me if I'm wrong, but I that eliminates the front of the vehicle. So it could be the rear drive shaft, or the rear pinion bearings.
I took the rear drive shaft to an axle/drive-shaft specialty shop and had them check it for balance and such. I'm picking it up this morning.
Before I drive to pick it up I'm going to reorient the front drive shaft to the stock position and phase - and make certain that correcting this doesn't cause any issues. If it does I'll take the front drive shaft to the axle/drive-shaft specialty shop to have them check it with everything positioned properly.
After I do these things, I'll come and let you all know if the noise is going and everything's happy with these things.

On a super sad, but separate note... I have a knock in my engine I'm going to get this sorted first.

 

[landtank]

Sounds like it’s the rear shaft. I offer brand new rear shafts with longer splines and thicker wall tubing.

 

[brownjeans]

Okay, got the front driveshaft installed per FSM and it's happy.
I got the rear drive shaft back from the specialist, put it in and... no vibration!

Probably should have started with the $75 rebalance with the specialist and saved me a bunch of headaches.

Next, figure out the knock in the engine.

@landtank - thanks for the info. I've got my eye on the e-locker rebuild kit. My front locker is stuck. I've bookmarked that for the future!

 

[Box Rocket]

If your noise comes back, you might be dealing with a worn output bearing in the t-case. I've been dealing with the same noise for years now. I've done everything short of a t-case rebuild to fix it. Just waiting for the time when I do reduction gears in the t-case and I'll take care of it then. I think the output bearing is the culprit for many with this issue.