Drive line noise mystery? Solved

[5022]

My 2013 389 had the driveline between rearends off about a quarter turn from what I considered in time so I went to dealer and questioned it. They said it was an update from factory to fix a problem they were having new from factory. I guess some drivelines were out of balance with the knuckles running in time. I don't have a vibration or hop but it doesn't look right from what I was always around.

[Chamberpains]

I like the idea of a GoPro for certain things. I've monitored smoke coming out my stack during shifting and accelerating with one before. But the wind noise would overpower the speaker so you couldn't hear anything. Having it up off the ground all you have to compete with is the engine running. You can hear a rear end starting to whine, a tick of a U joint that may be clicking, slight grinding of a bearing at certain speeds, some of those harmonic sounds you get at certain speeds causing loose bolts and body parts to rattle. There are numerous things that you can pick up on as a human walking around hearing it then opposed to a camera picking it up and then trying to hear it or see it. But I like the safety, comfort, and ease of using a camera thats for sure.

I've also gone on rides out side of the cab and on top of the deck of trailers at highway speeds to see, hear and feel what a driver is complaining about. I figure it's no different than riding in the bed of a pickup truck or riding a motorcycle. You just take a couple extra safety measures with a tractor trailer. But I do find this method a bit more nerve-wracking then just having the truck static in a shop. Thinking about it now, I kind of wish I had a GoPro back then (late 90's-early 2000's). Video Technology wasn't that great then. I probably wouldn't have gone on those stupid rides. Even better yet, if I had access to a Pocket Rawze (cellphone with internet connection) life as a Tech. would've been a hell of a lot easier.

[alborz]

A friend of my came over and looked at it. He figured that the rear axles are no in straight line. The rear rear axle is about 1.5 inch toward right side on passenger side and rear forward axle is iabout 1.5 inch toward left side on driver side. They charged me $2000 plus for three axle alignment and rebushing and I have this problem ever since. The bos guy didn’t accept their fualt right after I returned to their shop the next day.

[Chamberpains]

I don't think any of us ever asked what the strange noise your hearing actually sounds like. Rattle? Whine? Pinging? Ticking? Sound like someone stepped on a duck???

It also seems that if your axles are offset by 1.5 inches, are the torsion bars the correct length? Did they replace them instead of just putting new bushings in your original ones? I would think if the alignment shop had a pile of them sitting around, it would be real easy for someone to grab ones that are either both off by .75 inch long or 1 that is 1.5 inches to long. Causing your 1.5 inch offset.

[alborz]

(03-15-2018 )Chamberpains Wrote:  I don't think any of us ever asked what the strange noise your hearing actually sounds like. Rattle? Whine? Pinging? Ticking? Sound like someone stepped on a duck???

It also seems that if your axles are offset by 1.5 inches, are the torsion bars the correct length? Did they replace them instead of just putting new bushings in your original ones? I would think if the alignment shop had a pile of them sitting around, it would be real easy for someone to grab ones that are either both off by .75 inch long or 1 that is 1.5 inches to long. Causing your 1.5 inch offset.

the sound is like grinding gears
the torsion rods are not original
the shop guy replaced welded torsion rods with my originals. I haven't measured the length of each

[Rawze]

(03-15-2018 )alborz Wrote:  the sound is like grinding gears
the torsion rods are not original
the shop guy replaced welded torsion rods with my originals. I haven't measured the length of each

Torsion bars are generally pretty cheap. Measure them on another truck of the same model and Just get some new ones.

[alborz]

Thank you for your advice
What’s the purpose of tortion bars? Do they keep the axles in place from going side to side?

[snailexpress]

(03-16-2018 )alborz Wrote:  Thank you for your advice
What’s the purpose of tortion bars? Do they keep the axles in place from going side to side?

yes the torsion bars keep axle in place from side to side. Grinding noise mostly from u-joints not in proper angle. Could be axle off set or frame height not set to specs.
Cheap shops have no idea how to set suspension they just putting parts how they think is OK.
Some words about laser 3 axle alignment system. Mechanic take measure distance from drive axle to most rear, then from most rear to the middle axle. Left and right should be the same. If front axle not perpendicular to the frame stupid computer user will set rear axles wrong. They trained to do so by Hunter Laser system manufacturer. Computer will print 00-00-00. Everything is good
Differential case angle is important too. If rear springs set not right it will eat u-joints and destroy differential input shaft bearing.
Try to find your truck suspension specs from dealer and check.

[Chamberpains]

When you measure the torsion bar length, be sure to measure the distance from where they mount on the frame to the axle. Not the whole length of the bar.

tor·sion
ˈtôrSHən/Submit
noun
the action of twisting or the state of being twisted, especially of one end of an object relative to the other.

Torsion bars hold the axle from moving left and right. But their main purpose is to control twisting of the axle.