Odd deceleration grind/noise (2 Viewers)

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I got a part time kit on my rig and have the same grind mainly on the rear.... When loaded for a long trip the noise is gone when running around town unloaded .. i can hear the grinding noise....
I think it is a drive line angle issue on the rear.. at least for me....
I read some where that adding a 3/4" longer than stock, lower control arm will take care of the problem....

I learned t live with it and will not worry until the noise gets worse.....
 
I'm bringing this thread back. Has anybody solved there grinding noise problem? My buddy's 91 landcruiser has the same noise he has 4 inch lift with castor plates rebalanced driveshafts, he changed the transfer case and transmission with a known good one. The truck also has arb air lockers front and rear with lower gearing. It makes a grinding noise if you are at highway speeds and slowly take ur foot off the accelerator, the noise is there when you let off but it begins right between the transition of engine putting power to drivetrain and deceleration. It has been to many shops and many people have tried to diagnose it but to no avail. Last thing left to try is to hook up a chassis ear system and help further diagnose. Anybody have any suggestions or ideas of what it can be?
 
Has he removed the front drive shaft, locked the center diff, and tried driving the truck? Has he done the same thing with the rear drive shaft? I'd be willing to bet its a simple drive shaft issue. Until that's done you shouldn't waste time or money on replacing anything else.
 
According to him, it has been removed and tested. But in willing to try it again. Does anybody know if it would be ok to try and run the car with no front driveshaft and drive flange hubs removed? Will that fling bearing grease everywhere?
 
BlackLS1 said:
According to him, it has been removed and tested. But in willing to try it again. Does anybody know if it would be ok to try and run the car with no front driveshaft and drive flange hubs removed? Will that fling bearing grease everywhere?
Click to expand...

It probably would fling grease. You could try stretching latex gloves over the hubs to try to catch some of it, condoms might work also.
I'm sure someone on mud could take a ride in the truck and get a better idea of what the noise is. I live in Castaic, if you're buddy is ever in the area I would be more than happy to take a ride in the truck to see if it was the same kind of noise I was experiencing. I only have a 2.5" lift, I used caster plates to get 3* castor and in doing so it created a drive shaft vibration. I blew a bunch of money and time trying to get rid of the noise. I bought a DC shaft and now my truck runs smooth and quiet.
 
Xs2 to above! I spent about a year chasing the "grind noise" exactly as you describe - new u-joints front and rear, wheel bearings, spindles (part of my front axle rebuild) etc, etc. it really got under my skin..... Had several very mechanically incline friends (one who builds drag cars for a living and knows his way around cars so I figured he could figure it out...... Nope). Microphones on transmissions, transfer cases, yada yada. All this time I've heard over and over about the DC driveshaft swap but none of my friends were familiar so I kept searching - all the time getting more pissed. Last year I moved to Boulder and first thing I did ( well, about two weeks later....) was take it to Robbie (one of the top LC mechanics you'll ever find) He gets under my truck, measures the angles of the front driveshaft (have a 3" lift) and tells me they are off by several degrees - he says " try this, this is out of my wife's 94 cruiser - a DC shaft I built for it" - slaps it in and........
Perfect.
Nothing.
No noise - nothing.
I go to YodaJims in Denver and pick a Gen 3 Four Runner rear shaft and he builds me a beefy new front dc shaft - all together about $400 installed.
Best $ spent in a long time.
You can get the specs from him for the measurements and have it measured - I bet they are beyond normal angle range (sorry for such a long post but this was a huge victory for my truck I had to share!)
 
Crashdix says it all. I went through everything listed in this thread. The grrr is from the front driveshaft angle whether you have new u joints or not. The dc shaft fixes it. At a coast you hear theis grrrr metal grind noise that makes you cringe!
*** Now the quick and easy way to fix if no money for the dc. Make 1.5 inch spacers ( we used thick walled heavy duty pipe that we cut up.) The inner diameter was barely larger than the tcase crossmember bolts. Use these spacers to drop your tcase crossmember thereby reducing the front ds angle. On taller lifts we have found both the dc shaft and small .75 inch drop to eliminate 100%. On my 80 with 3.5 lift the dc was all that was needed. You will need longer bolts - get hardened ones though...
From the side of the truck you barely even notice the small drop.

It was a happy day when we figured how to get rid of this bothersome noise - esp after chasing it for a while.
 
Good tip on a cheaper fix. If you want to be absolute sure this is the way to go, remove the front shaft then drive it, or better yet, borrow a dc shaft and swap it for a quick drive - you will happily surprised.....
 
itbrokeagain said:
So I have a question. I have a 4 inch lift stock shafts and no noise. What is the difference?
Click to expand...

You got lucky. Some people never develop the DS vibrations, and some develop bad vibes with minimal lifts. I have a friend that put a 4" on his truck and is using the stock shaft with no vibrations.
 
Hey guys, thanks for all the replys. I will show them to my friend. Were going to try and remove the hub and front drive shaft. I will keep you guys updated when we figure it out.
 
I have J springs, 315, and 5.29 gearing. I have grr sound on de-acceleration. I was fearfull that I had a front diff issue after I installed the gears. I am thinking DC shaft is the only way to go. I don't know if anyone has tried before or not but a FJ60 has a DC shaft in front. Can that be altered to work??? I also just installed sliders last night and the noise seemed less on the way to work this morning. I am thinking a little more wait changed the driveline angle enough. What are your guy's thoughts
 
Just replaced all the air lines and went to check lockers, the rear locker or front wouldn't engage checked everything for leaks it was coming out of the rear breather all the air pressure. So I'm guessing the metal air line is broken hitting the gears hopefully. I will know tomorrow.
 
Hello Guys I've been trying to find a solution to the noise as well. After checking the front end, greasing the bearing and U joints I decided to get a front DC drive shaft. After installing the shaft the noise went away when going under 60 mph, but it is still there when going above 60-65 mph. It won't do the noise all the time, but it does it often enough to where it bothers me. Has anybody thought of anything else? I am planing on loading the back of the truck with some sand bags and see if anything changes by changing the rear angle of the truck like some suggested.
 
My truck still does this. I am still worried about it but I am not going to throw money at it. Does any one have documented failures from not replacing the front shaft with a DC shaft?
 
neal0124 said:
Has he removed the front drive shaft, locked the center diff, and tried driving the truck? Has he done the same thing with the rear drive shaft? I'd be willing to bet its a simple drive shaft issue. Until that's done you shouldn't waste time or money on replacing anything else.
Click to expand...
bringing back this thread as I'm experiencing what sounds like the same thing. Sending you a pm as I'm not too far and want to see if you're still around and willing to take a listen.
 
How do you measure the driveshaft angles and what should the correct angle be? I have some slop in a rear u-joint that I'm pretty sure is making my noise. I'm only on a 2.5" lift.
 
I’m no pro, but generally speaking, you remove the shaft and put an angle-finder vertically on each flange at diff & tcase to see the difference. With a standard shaft, you want it as close to equal angle as possible, whether // or \ /

I think (?) front stock shaft from factory is \ / while rear should be parallel // (?)

To see if it’s the culprit, you can lock the center diff, remove the shaft in question, and drive around.
 
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