So I've had a slight grinding/rattling, bad bearing type noise coming from what I think is the drivetrain for a while, happens when coasting with no tension on the driveline with either the clutch in or the transmission in neutral. Noise is directly related to the speed of the vehicle. Louder at higher speeds, non-existant when stopped. Had a new noise pop up and found out it was a u-joint, so I replaced both of them in the driveshaft. I hoped that would fix the grinding noise as well.


It did not fix the noise, so I checked the pinion angle and found that the pinion was not quite parallel with the transfer case output. I measured the flanges, did some quick trigonometry, and then bought and installed some 4 degree shims. measuring the flanges top to top and bottom to bottom, both are now equal at 64 3/4 inches.


The problem is that now the grinding noise is markedly worse and there's now a vibe when accelerating at low speeds that wasn't there before. It seems fixing the pinion angle made things worse and it don't make no sense!


So, I guess to put this in question form....WTF?

 

Have you tried popping it up on jacks and checking the wheel bearings for grinding? I know it sounds obvious, but often we overlook the easy stuff?

 

I didn't notice any abnormal noises when I spun the wheels while installing the shims, but I'll take another look/listen. Would a wheel bearing make noise all the time or just when coasting?

 

Usually wheel bearing will be all the time, but may be easier to hear when in neutral because your exhaust engine sounds are down. Are you only hearing the noise when your in neutral?

 

Definitely only happens when coasting with the clutch in, transmission in neutral, or coasting with no load on the drivetrain (i.e. neither accelerating or engine braking). I can also kind of feel the noise in the floorboard when it happens. I think I might play with the driveshaft, try some different positions, or get it balanced at a shop.

 

Hmm.. I had a ujoint go bad in an old chevy truck once, I was getting vibs under no load, but when under load vibs went away. This was due to the fact all the needle bearing rollers were missing from under 2 of the caps, when under a load it pushed hard in the direction of rotation and kept itself tight, but when coasting and not under load it flopped around in the cap and made a vibrations. Have you checked all your U-joints besides the ones you changed? Possibly bearings not having enough grease and grinding on the shaft of your u-joint?

 

Yeah, that was similar to when the ujoint went bad on mine, starting making a scraping/squeeking noise when coasting or decelerating. The u-joints in the rear driveshaft are good to go now, I just replaced them and checked them yesterday to make sure they were still good.

 

Ok, figured it out and it's fixed now. I went underneath to turn the driveshaft 180 to see if that helped things, and realized that the u-joint yokes were not aligned. Apparently my lack of mindfulness didn't bother to mark the driveshaft before I took it apart, and when I put it together I just guessed. I realigned the u-joints and voila, no more vibrations and it drives smoother and quieter than it ever has.


I post this with humility knowing that I'm an idiot, but hope that somebody else out there who might have made my mistake Google's this and discovers their bone-headedness before posting it on the internet. Thank you bucketofsoupyum for attempting, in vain, to help me. Unfortunately you can't fix stupid, as is my case.

 

Needs more beer! Glad you got it fixed!

 

I have been chasing a very similar noise for almost a year now. Just as you described only when coasting is it present. Going down the highway if I push the clutch in you can hardly even talk over it. It became present after I finished my 2nd build on my runner. I tried 2 entirely different transmissions both out of Tacoma's. I just installed my Tcase after having it rebuilt then looked at again noise is still present. I will half to mess with the rear driveshaft today, it's too the point I don't even enjoy driving it now.
I know this thread is over 2 years old but ill post if I find it anyways.

 

Probably obvious, but as the op figured out, check your u joints and driveshafts. My runner has been making some weird noises lately, I have a clutch set ready to go in, going to assess the noises when I have it torn apart.

 

I did check the u joints and saw zero play but I will replace them anyways to eliminate them from the equation. I also put in a 1 1/2" drive shaft spacer just to make sure my yoke wasn't over extended but had zero affect on the noise. Also this Grinding noise is just that, there is absolutely no vibration with it which I've always felt when my u joints are on there way out in past Toyota's I've owned. My trans guy thinks it maybe my rear end and the noise is traveling up the shaft. I'll get a YouTube video up and post the link. Lol its pretty ridiculous

 

Sounds good, side note, where did you get your driveshaft spacer? I over flexed last year and desplined my extended front shaft, I been meaning to look for a spacer or longer shaft. Since it happened its been a goal of mine to despline it again and I haven't been able to make it happen.

 

is the rear axle rotated up? if the flanges aren't parallel, like parchisi said, it'll cause a vibration.

 

I know what you mean, The drive shaft spacers I have I half to use for the front. I had my front shaft extended years ago but then after I did my motor swap a year or two ago it wasn't long enough anymore. So for now I have a 1inch spacer in it. It still pops out once in awhile.
The Spacers I have both came from Trail Gear.

I did happen to check my angles last night. Between the t case flange and my pinion they are 4degrees out from each other. I'll take care of that by the weekend hopefully. But if that was a factor that imbalance would give me some sort of vibration I would think and not this horindus noise I'm getting.

 

mine wasn't really a grinding sound, it was more a vibration noise only when decelerating under load... i can't remember if it was there when i pushed in the clutch while coasting?

see if any of this is relevant: http://www.4crawler.com/4x4/CheapTri...line-101.shtml

 

Here is the link to my truck and the noise. It's a little long. If anyone has any idea or suggestion, please let me know. Thanks

 

that sounds a lot like what i recall my truck sounding like, before i put a cv joint in the rear driveshaft... it's only happening when decelerating or coasting, right?

what would it take fix the 4 degree difference, just for testing? maybe pull out some shims in the rear axle mounts?

 

Only when coasting, when I decelerate or accelerate it quiets up. I'll replace u joints anyways and shim the cross support for the t case down to angle to R&P better. Lol I would be soooo ecstatic if this whole time that was the problem. I'm contemplating going back to 4inch Springs just to lower my drive eshaft angle.

 

Well just for who ever in counters a noise such as the one in the video. Lol I FINALLY! Found what it was. Somehow in the build my rear diff/locker went bad. The noise was traveling up the driveshaft which made me think it seemed like it was coming directly from the trans/transfer case. I put temporally dropped in a bone stock 4:10 Toyota high pinion in the rear that would eliminate the difference and potential driveshafts angle noise at once. Took down the road at 70mph, Completely smooth and most of all lol Quiet!!!