Drive train has a grind only at 20mph?

Hey wondering if anyone has a clue about a definite grinding or grating issue in the drive train that comes on only at 20 mph then disappears at other speeds. I can feel it thru the whole truck. I'm thinkin drive train because tires are new and quiet, and the tranny guy at the shop says tranny (auto) is ok, and the driveshaft mount was just replaced. Could it be differential, or u-joints/ drive shaft? U-joints seem pretty solid, I can't find any play in driveshaft tho I don't know what to look for. But it also makes the tranny do a little bounce or hiccup just after taking foot off the brake to go. It's a mystery. Anyway, pardon the description. I'm new to the forum and glad I found this cool place for these trucks. Looking forward to doing all the stuff I want to do to it, and tinkering with the little stuff after this mystery is fixed.

 

Check the TSB list, I believe Toyota has one out for a grinding sound < 35 Mph. As far as I understand, it isn't a critical problem.

My truck makes a low growl sounding noise at about 25% throttle at 30 Mph, but no vibration. It's done that since I got the truck, but granted, I'm a second gen.

 

I looked at the TSBs. The grind is not really heard, as much as it's felt. It's almost like the road suddenly got gravely and rough under the wheels at 20mph then goes away. Thanks for the info about TSBs I hadn't checked them before.

 

Hello Truckrider, I have the exact same issue on my 03. I changed the front u joint and the center bearing but the noise and vibration remains and I believe getting worse. Continuing my research on this problem. Let us know if you find the solution, please.

 

Is it more pronounced or noticeable while doing a slight turn at that speed? Or can you be turning or driving straight at that speed and it does it on both scenarios?

 

Only get these symptoms after a dead stop and while doing a turn at that speed. More pronounced when going up an incline after a dead stop. Also, the vibrations when turning is new.

 

If get a bounce when start and also when let off it sounds like a U joint. They can also cause vibration after are wore a bunch. To check them block the wheel both directions and place in neutral. Crawl under and shake drive shaft and check all of them. If mount was redone recently check the mount bolts as well. Sometimes the inner fender well on the front comes loose and will make a heck of a racket when rub the wheels.

 

Have you greased the u-joints? That should be part of normal maintenance.

 

I changed the one u joint I thought may have been causing the problem. Planned on greasing all of them. Going to purchase a gun today.
Thanks guys/gals for the input. Will update in the near future.

 

Well I did hear that if the truck (PreRunner) has been even slightly lifted or suspension altered in any way, it'll be prone to this low speed vibration/grind symptom. I've only had the truck a year, and can't see any evidence of lifting, only beefier shocks and slightly bigger tires. The vibe/grind only happens in a narrow window of speed, within 2-4 mph near 22 mph, to be exact. But it sure bugs me. I changed out the center support for driveshaft, greased u-joints, even had the driveshaft removed and inspected, with no improvement. Looked carefully at my steering/alignment/rack etc., I can tell you it's not that either. I'm told that something has slightly changed either in the driveshaft angle or overall specs to make this happen. Was told by one tech to live with it, but let's face it something's "not happy" down there. Just to test completely, I got the truck up to the speed of the vibration, put it in neutral and switched off engine and just rolled. Vibe/grind still happens, so I gotta probably eliminate the tranny as a culprit. It ain't the rear end gears either, they are new and smooth and quiet. You might wanna test like that (safely, of course, remember the brakes need more effort with motor off etc.) Sorry for the blab, just giving you clues. T

 

OP,
One other possible culprit, is an out-of-balance tire.

 

True. Would recommend checking that for sure. But for me it's still there after 2 alignments (front/rear) on 2 different sets of tires.

 

My 98 automatic does the same thing between 20 and 30 mph. I have checked the same suspects as you and it remains a mystery.

 

Just wondering, has your truck been lifted in any way, even slightly? Different or new or aftermarket front struts? And, did it ever have a collision of any kind, even "soft"? My answers to these are unfortunately all yes, I don't know if there may be a clue there. Something making the driveshaft unhappy, even though mine was taken out, found nothing wrong and put back.

 

No lift but I did notice when the noise started.

I bought the truck used and all 4 shocks as well as the leaf springs needed replacing. I had the front shocks replaced but didn't replace the coil springs at that time. Then about a month later I replaced the rear shocks and leafs. Immediately after that I noticed the grind and am 99% sure it wasn't there before any replacements. I kept hearing a loud thunk in the front end and after strapping a GoPro to the underside, I found that both my front coil springs were so worn that they were slapping against themselves when going over bumps.

So my guess is that the grind is related to the angles of the driveshaft assembly. Currently, the front of the truck sits noticeably lower than the rear, even with new front shocks which is due to the worn coil springs. I think if I get the springs replaced it will level the truck and hopefully eliminate the noise.

Just for reference, I've had the u-joints in the main driveshaft replaced and my center shaft bearing is good.

 

My front Diff needle Bearing is shot and it sends a grinding type of vibe through the length of the truck it feels like. Comes on around 25-35mph then disappears. Have you had that bearing replaced?

 

Are you talking about the rear diff? I have not had that bearing replaced. How did you discover yours needed to be replaced?