Deceleration Moan...what I've done.

[Safado]

Raven...Thanks for the pic...that's the one I looked at last night, but thought that Dan and B were talking about the U-joints themselves...I now see that you're talking about the 2 flange yokes. I'll check that when I get home.

Sean...there are several shops that can attach a remote ear to your diff and other parts so that as you drive you can "hear" what noise they might be making. Might be worth the diagnostic fee before you tear into it again.

 

[montocr]

How much lift do you have? Do you have adjustable control arms, to set your pinion angle? When I had mine with J's and spacers, I had this exact noise. I took the rear shaft to the drive shaft shop 3 times. Each time the upper u-joint would become slightly sloppy after very few miles and the noise would come back. I bought a new OEM driveshaft, which helped, but still was barely there. It drove me crazy and I couldn't simply drive without trying to create the noise to see if it was still there. I had my angles all dialed in perfect, and even tried pointing the pinion up or down. Finally I took the 1.5" spacers out and just ran the J's. This cured the noise. As of recently I have added a lot of wieght to the vehicle so I switched to the 864 xtra hd springs, which give less lift, but I put my spacers back in. Overall it sits between the two previous hieghts. I have heard the noise very faintly, just a couple of times. I think some trucks can benifit from a cv shaft for the rear, and pointing the pinion up. Slee does this on some of the taller trucks that they do. However, the best thing to do first is replace your U-joint, because they are cheap and should not have slop.
Carl

 

[sleeoffroad]

99.9% it is the rear driveshaft. Add weight to the truck and see if it changes the noise. If it does, most likely driveshaft angle. With 6" of lift (MTRAT) it is on the verge of needing a rear CV shaft and turning the pinion up instead of trying t keep it parallel. Sean, you might have to go to a CV.

 

[cruiserdan]

99.9% it is the rear driveshaft. Add weight to the truck and see if it changes the noise. If it does, most likely driveshaft angle. With 6" of lift (MTRAT) it is on the verge of needing a rear CV shaft and turning the pinion up instead of trying t keep it parallel. Sean, you might have to go to a CV.

Excelent point, Sean DOES have a lot more lift than many of us. Extreme dirveshaft angles are problematic.

 

[MTNRAT]

Hmmm, it still makes the noise with the rear driveshaft out, just not as much. Even less with only the front driveshaft out, but still there.
Cheers,
Sean

 

[Jim_Phillips]

I have been discussing a similar problem on the 60s list. I also have a moaning noise coming from the rear diff / propshaft. Problem started after I fitted new springs which gave me a 3 inch lift.

Consensus is on the 60s list is that the UJs bed in at a certain angle - when you change that angle the UJs don't like it. Just to prove this theory I loaded up the 60 so that the back end sagged - the noise and vibration went away. I am hoping my solution will be to fit new UJs.

You never know...

Cheers, Jim (where's that beer smiley gone?)

 

[Safado]

Christo....I'm glad you chimed in. I wanted to ask you what solution, if any, you use on vehicles that have been buying the 6 inch lift?

Part of the "dancing u-joints" in my head last night showed that the more lift you have, the more shake/wobble there will be. One of my problems is I really don't know how much lift I have. I never spoke to the PO and Alan P. doesn't remember what springs he used. But there is a large spacer on top of the springs as well that is about 3-4 inches. There are a few old tags on the springs, I'll try and post the numbers to see if they tell anyone anything.

The front pinion is turned up and as I mentioned before the drive shaft has a CV. That may be what I need in the rear then. Plus I've noticed that the rear t-case support has been dropped about 3/4 of an inch using 2 nuts as spacers...probably to help in this area.

Any stock measurement I can make from the axle housing to some part of the vehicle to see where it sits now? Thanks

 

[sleeoffroad]

Doesn't really matter that you know how much lift you have, just add 400 lbs to the rear, see if it sags and if the noise changes. If so, pretty sure it is driveshaft.

 

[Pskhaat]

I hate noises. I am going to change out the gear oil bact to dino to see if there is any difference.

It's not the oil. I've run everything trying to get rid of my hum (it's not really that load) but I know the noise to which you are all referring. Don't worry about the oil unless it of course needs a change

 

[MTNRAT]

I will load mine up. See what happens. Another thing I noticed, the noise is almost gone when I drive the truck for the first 1/2 mile and the gets louder the more it is driven.
Cheers,
Sean.

 

[Safado]

Doesn't really matter that you know how much lift you have, just add 400 lbs to the rear, see if it sags and if the noise changes. If so, pretty sure it is driveshaft.

Ok, I'll try that out.

Christo...what have other people done with the rear diff and Drive shaft when buying the 6 inch lift? I know Sean has it, and has a moan...anyone else report it?

 

[MoJ]

I will load mine up. See what happens. Another thing I noticed, the noise is almost gone when I drive the truck for the first 1/2 mile and the gets louder the more it is driven.
Cheers,
Sean.

Something worn. Doesn't show up until lube warms up.

 

[Safado]

Ok, finally got the chance to check things out. Front drive shaft with CV joint is 90 degrees out of phase at the flanges....rear seems to be in phase. Reason I say that is it appears that it may be slightly out of phase...I'll have to check it out more when I pull it again.

Haven't done the 400# test yet, just trying to think of what to use.

 

[MTNRAT]

I put 700lbs in the rear and the noise virtually disappeared. I had prieviously taken out my double carden front shaft and put the stock one back in for reference. I then weighted the truck down with the 700lbs and the front really made the noise. Put the double carden front back in, kept the weight in, and virtually no noise. Conclusion: like Christo figured - rear drive shaft. Quiet now, but the brakes don't work as well .

 

[AmabilisCruiser]

What was the resolution to this? This noise just appeared on my 80 after full front Birfield replacements with bearings etc.... Had a little noise like this for years very minor and short in duration, but after a 600 mile drive on highway now noise is very noticeable. I had both drive lines rebuilt with OEM joints and installed/balanced by Drivelines NW in Seattle a couple years ago. I suspect something in the transfer case. I'm trying to add a very quick 4 second video of the sound but having trouble with that.

 

[joshespdx]

What was the resolution to this? This noise just appeared on my 80 after full front Birfield replacements with bearings etc.... Had a little noise like this for years very minor and short in duration, but after a 600 mile drive on highway now noise is very noticeable. I had both drive lines rebuilt with OEM joints and installed/balanced by Drivelines NW in Seattle a couple years ago. I suspect something in the transfer case. I'm trying to add a very quick 4 second video of the sound but having trouble with that.

I’m so glad you revived this. This is “driving” me nuts. A lot of good info here. At 288,000 miles, a recently completed Birf job and a lift, it seems that my UJ’s are a logical next step.

Who has CVJ’s on their driveshaft? Sources? Cost?

Thank you!

 

[BILT4ME]

I’m so glad you revived this. This is “driving” me nuts. A lot of good info here. At 288,000 miles, a recently completed Birf job and a lift, it seems that my UJ’s are a logical next step.

Who has CVJ’s on their driveshaft? Sources? Cost?

Thank you!

They are referred to as "Double Cardan" or "DC" U-Joints on here. Tatton has one with mixed reviews and others have pulled a Taco shaft and had it reworked to fit.

 

[bwakeling]

I just live with it....

 

[AmabilisCruiser]

What was the resolution to this? This noise just appeared on my 80 after full front Birfield replacements with bearings etc.... Had a little noise like this for years very minor and short in duration, but after a 600 mile drive on highway now noise is very noticeable. I had both drive lines rebuilt with OEM joints and installed/balanced by Drivelines NW in Seattle a couple years ago. I suspect something in the transfer case. I'm trying to add a very quick 4 second video of the sound but having trouble with that.

Alright - got my issue fixed! I didn't replace the brass spindle bushing when I rebuilt the knuckles. Bad bushings - new bushing/roller bearings installed. Runs and sounds fantastic!

 

[Malleus]

I do not know if it can be "adjusted out" it may be a case where you just need to live with the noise or replace the gearset. It is indeed possible that a noisy gearset will last many, many miles and it is not necessarily a "bad" gearset.

^ this

Way back when I used to get paid to build axles, the single most common reason for customer returns was "noise". This is so prevalent in the industry that it's led to the birth of a separate engineering discipline (No Sh*t), called NVH (noise, vibration and harshness).

Our standard remediation in cases where customers reported "noise" and nothing else was
1. open the differential carrier and inspect the case and gears.
a. If wear, or particulate was found, replace the gearset, and eat the loss
b. if no immediately apparent cause, replace the gearset and carrier, and eat the loss