Lower speed vibration ideas?

96 Tacoma V6/auto 4x4 extracab with 251k miles. Suspension is basically stock (Moog replacement front springs and Bilstein HD's all around) and stock alloys with 31" tires. I've got an annoying but not major driveline vibration at coast at lower speeds. Above 50 or so it's gone. Under load it's not there. It's slightly noticeable at cruise under 40 mph and noticeable all the time under 50 when coasting. Diff is quiet and tight. Actually that's all new. The rear of the truck does sit quite a bit higher than the front even with new springs up front. But the rear springs are stock. I had the driveshaft out (marked all the mating points so it went back together the same way) and one u-joint was stiff so I replaced it. Now all joints are good, slip joint feels tight, and the center bearing appears OK. I'm actually thinking of dropping the carrier bearing next. I don't think it's hurting anything as it's quite minor but it is annoying. Almost as annoying as the dash rattle I haven't found yet. Any thoughts? This is my 4th 1st gen Tacoma but the only automatic and it's got a lot more miles than the others had. Even with a 4" suspension lift in two of my previous ones I never experienced a driveline vibration like this.

 

My 03 TRD double cab has what appears to be the same problem. Not bad enough to bother anything I don't think but a little bothersome though. And it seems as though a new rattle appears every other day when it starts getting cold and that really pisses me off!

 

What's the driveline angle look like?

Have you tried engaging 4WD and see if anything changes?

I'm thinking, perhaps your springs have sagged and the pitch of the pinion isn't as high as it used to be. Therefore - when you are coasting, the pinion is sitting lower and out of the sweet spot. When you put a load on it - the pinion pitches upward.

You could experiment by lowering your carrier bearing to change the pitch of the driveshaft and see if anything changes. But otherwise - if you come to the conclusion its the drive shaft angle, you'll need axle shims.

Or, think about getting some new stock springs.

 

The odd thing about this truck is that even with the high miles the rear springs haven't sagged a bit. The original owner never used it to haul anything and the rear is probably 2 inches higher than the front. In fact I thought the front springs were sagging a lot so I bought new "off road" spec Moog springs for the front. Which did pick up the front about an inch but the rear is still easily 2 inches higher.

 

Your rear springs are probably not stock springs. And the drive-line angle situation may still apply...... If you go above or below that sweet spot, you'll get vibrations of various ranges.

Is this a newly purchased truck? Have you had these vibrations since you bought it?

Again - if you only get vibes when you're coasting, then the pinion may not be pointed up high enough. When you accelerate, the pinion will always point upward (putting it within the sweet spot).

Just brainstorming...

 

Yes I just bought this truck a month ago. But it's 100 percent stock. It's a 1 owner truck and the guy had it just to have something with 4 wheel drive basically. This is the second Tacoma I have bought used like that. The last one didn't have as much as a footprint in the bed when I bought it. The inside of the bed was waxed! This one has a bedliner but there wasn't a single scuff in it before I crammed it full of scrap metal last weekend. The rear springs are the original 4 leaf Toyota springs. They just haven't sagged at all like most seem to over time. I was under the truck today changing the fluids in the axles & transfer case and I think the problem is the center bearing. I could move the driveshaft up & down in the center mount pretty easily. It had about 3/8" of free play in it. So I loosened the mounting bolts and pushed back on the bearing and tightened the bolts back up. Now it doesn't move up and down freely. I haven't driven it yet though. Maybe tomorrow.

 

The carrier bearing isn't supposed to be rigid and you're supposed to have some 'up & down' movement..... If it were too rigid, those vibrations will transfer directly into the tcase and possibly ruin those seals/bearings.

http://autonews.galanter.net/2012/04/11/whats-the-carrier-bearing-and-what-does-it-do/

 

It still moves up and down a bit but it's not sloppy like it was before. Now it's basically just moving with the rubber surround and not just clunking up and down like before. It's not winter yet so I have a few more weeks to play with it some more before it's my DD till spring. Still need to change valve cover gaskets and do a transmission service before then too!

Well just took it for a ride. That was it. Vibration is gone! Now if I could just silence that dash rattle behind the glovebox....

 

Purchased my vehicle brand new. Drove it from the dealer to my home which is about 5 miles away. Noticed a vibration right away at low speeds. Thought it could be just breaking in, so I left it till my complimentary 600 mile service/check up. The noise is the slightest shudder and it sounded like it was coming from the driveline somewhere. The noise can always be duplicated with the following conditions:

-truck is travelling at approx 20 mph
-off the accelerator with back pressure slowing the truck down
-transmission has downshifted to 2nd gear

Service appointment #1 (Home Dealership). I advised the techs of the problem and the vehicle was inspected. Nothing was located out of place or loose. Drove home and the noise was still there.

Service appointment #2 (Different Dealership). Noise duplicated for technician. They thought it was my after market dealer installed Toyota roof racks. Removed, drove around and noise still there. Roof racks reinstalled.

Service appointment #3 (Home Dealership). Noise duplicated for senior technician. Microphones attached to the undercarriage with headphones on the tech. Could not isolate. Called Toyota Canada and they believed it to be the front differential. Front diff replaced. Noise still there.

Service appointment #4 (Same Dealership as #2 appointment). Noise duplicated for senior technician. Under carriage and all components inspected and passed. Possible low auto transmission fluid, so they topped it off. Noise still there.

Service appointment #5 (Same Dealership as #2 appointment). Noise duplicated for senior technician again. Driveshaft from 2014 installed. Noise still there. Original driveshaft reinstalled.

Service appointment #6 (Same Dealership as #2 appointment). The Truck had approx 12,000 miles on it now. Upon inspection of the rear differential, there were metal shavings present and slight traces of rust. New rear differential installed and finally, the problem is gone.

Good luck. I read all the other forums and was stumped.

 

wrong forum, this is for first gen (older) trucks

your problem has been reported before and check the correct forum for help.

im not sure what the problems are but some trucks have issues with vibration because of poor quality control in the parts supply manufacturers