Drive-line vibrations during acceleration

I have a 1997 Toyota Tacoma XtraCab 4x4 3.4L with a 5 speed manual transmission with 98K miles currently. I just bought this truck 3 weeks ago (I've already put on 3K miles)and fairly new to Tacoma's but am mechanically inclined and been working on cars for 15 years. I have a vibration that is mostly prominent in 2nd gear (initial shift into 2nd so RPM's are 1100-2100) during acceleration but vibration is in all gears/speeds during acceleration. Less vibration when I baby it and lightly apply throttle but can't seem to feel a difference if I press in clutch. No difference in 4WD or 2WD and feels like it's more from the middle of the truck to the front. No excess vibration in gear shift and seems to shift smoothly. I have had the propeller shaft completely rebuilt/balanced (u-joints in CV, rear most u-joint and carrier bearing had play), new OEM NGK spark plugs gapped to .044 and cleaned the throttle body (the ones I took out were very worn OEM plugs and t-body was dirty). I haven't checked the front drive shaft, fluid levels in the t-case, trans or diffs yet. I almost feel the engine is slightly under powered but it runs very smooth at idle and the oil after 3K miles is still clean with minimal consumption and no smoke out of tail pipe. I get 17.5mpg if all 55-60mph driving, 15.5 if all highway at 75mph and 15 average city/75mph highway driving. I don't know if the timing belt was done yet and would be willing to bet it hasn't. The clutch grab is at the top of the pedal but not slipping and the tires are BFG A/T's that have weather cracking in between the tread blocks but not on the side walls and approximately 50-75% tread. Brakes seem good and visual inspection underneath reveals no fluid leaks, anywhere.
The possibilities I have come up with:
1.Front drive shaft u-joints.
2.Clutch throwout bearing/pilot bushing
3.Engine timing is off
4.Transmission /T-case/Differential
5.Motor/Trans mounts
6.Fuel pressure/fuel filter issue
I know its a long post but its informative! I'd really appreciate someones help. As you can see, I put on a lot of miles and have minimal time for mechanical repairs so pinpointing this issue minimizes down time and just "throwing parts" at it. Thanks Everyone!!!

 

The carrier bearing was replaced when the rear propeller shaft was fully rebuilt.

 

Speed related vibrations point to a wheel issue. Either bent rim, out of balance wheel, broken belt in tire, out of round tire.

 

Thanks for the reply, skytower
I agree with you but the only argument is that the vibration comes from when throttle is applied...the more throttle the heavier the vibe. Tires would usually exude "typical" vibrations such as vibrations at a specific speed, on/off vibration depending how load is applied (ie: turning at highway speed) or tread patterns (ie: M/T, A/T etc.). Although I have seen some weird issues with tires I just wouldn't bet that that is the cause of this particular issue. Yes, tires do need replacing due to weather cracking and am experiencing a tire/wheel balance issue at approximately 62-68mph currently. These vibrations are too different to be one in the same...its more of a buzz. I will be under the truck next weekend installing new leaf springs, 1" lift shackles (this truck is mostly highway driven...for now!), Bilstein 5100's on all corners and ALL fluids changed so I will be looking for anything/everything that screams a possible problem and update this post if I find something. I know vibrations sometimes are hard to diagnose but strongly feel its engine/trans related. In the meantime...please keep your thinking caps on and replies comin'! Thanks!

 

Why do you suspect the front drive shaft U joints? Shouldn't they be free spinning?

 

Does anyone have the part # for the carrier bearing?
Thanks!

 

I've experienced this vibration during acceleration as well. What could it be?

 

bowyer2002,
Allow Google to be your friend with finding part number for the carrier bearing. To many variables such as year, engine, 4WD, cab, etc. I don't have the part number...had my friend at his driveline specialty shop do all the work. Sorry...Good Luck!

JakeInGreyTacoma,
I think I may have figured it out. When I removed the driveshaft to have it rebuilt, upon reinstalling it I found my right rear leaf spring cracked. Springs sag over time and this aint no spring chicken being a '97 so moderate sag changes suspension/driveline geometry. Well, over the last week I lost one half of one leaf in the leaf pack...vibration got a little more noticeable. Drove it last night and lost the other half plus half of another leaf so it only has 2 out of four leafs...dangerous and now she sits waiting for the new parts to arrive. Anyway, after I heard a chunk of metal fly off while driving I noticed the vibration got worse. I can only come up with one conclusion so if anyone out there reading this correct me if I'm wrong. The damaged/missing/sagging spring(s) is allowing the axle to wrap changing the pinion angle and hence putting load on the driveshaft joints and slip causing vibration under load, up hill or moderate acceleration. The shocks are smoked too so there isn't anything really helping here but in two days I will install the new leaf springs, shackle kit, new bushings, and Bilstein 5100's at all four corners. I will update this post following replacement and let y'all know!

 

I have a 96 taco with an automatic and in the last week, I started noticing this same vibration. It's only during acceleration and seems most active between 52 and 58 ish. I've recently changed fluids in the diff and transfer. Greased the driveshaft, topped off tranny fluid (was low) and changed to some NGK g-power plugs.

I've checked the trans mount, that's good. Shook the u-joints, they seem tight. There's gotta be a solution to this!

also, i put new leaf springs in back around Thanksgiving 2012.

 

What about fuel injectors. An imbalance of flow could cause a rough acceleration. Check your plugs. 3 should look different from the other 3.

 

wouldn't that throw a misfire code? I've got the 4 banger, but I recently put different plugs in it. Seems that the vibration stops (while still accelerating) if I hit a hard bump which momentarily pushes the rear axle up. Like maybe it's a driveline angle problem?

 

If you're lifted it could be the driveline angle.

There are degree shims available online that are fairly easy to install.

Did you check your carrier bearing? That's where it seems most of the problems come from and it's where mine are coming from right now but it doesn't bother me that much.

Yay for a 2 year old thread bump too

 

X2, even with no lift, the crappy "progressive" TRD springs were known for this issue from day one. As load is put on the drive line the rear diff tends to rotate the pinion up. So, no load, pinion angle near OK = smooth, under load, pinion to far "up" = vibration.
In theory the differential pinion should point at the carrier bearing flange. In the real world a slight amount of down bubble ends up being ideal. Not enough to cause vibes in itself but enough to put the pinion angle closer to ideal under load.
I run about 1-2 degrees of down but my springs are very resistant to axle wrap.

 

I pulled my driveline last night and my carrier bearing seems to be ok. I have 1 u-joint that I'll replace and another that was a little stiff cause it woudn't take grease. After I get these issues dealt with, maybe angles are my next problem. Will see... then update

Yes, I know I bumped a 2 year old thread, but I need answers dangit!

 

And we're all here to help

did you center and true your driveline?

If it's clocked correctly it can still be rotating out of round

 

I FIXT IT!

I took my driveshaft out and tore it all down. I replaced a bad grease fitting and put grease in a u-joint that wouldn't previously take grease. Then I replaced the u-joint closest to the rear diff.

But here's what I believe was the culprit.... I put TOO MUCH GREASE in the slip yoke!! I haven't greased a slip yoke in a long time, so I just packed it full of grease. I believe I pushed it out too far and stiffened it up, which affected the angle of the driveline THUS causing my vibration.

So, I also ran all that grease out of the slip yoke and NOW, there's zero vibration. And DUH, I put a reasonable amount of grease back in. Now, I'm just glidin' down the highway.