Not to repeat another driveline vibe thread... but WTF

Suffice to say, things have gone from OK (my old tires, stock wheels, 1” spacers) had some vibes but knew several front end components were shot.

replaced EVERYTHING suspension-wise up front. Got new wheels/tires (ditched the spacers) Truck was smooth as glass. Well... 5500 miles in, my vibes are worse than ever. Just drove to MN for work and it was so bad, I dropped the rear DS when I got to town (Minnesota Driveline) They replaced all the universals and the carrier bearing, serviced the slip yoke and balanced it.

smoother, but still shakes bad at 55ish and again (the worst) at about 73. Goes smooth at 75-80 which is good... at least I won’t go completely insane.

headed back Monday and have an appointment in the AM to have my wheels balance checked. Can’t imagine why they would be out in 5k miles though.

driveline angles- while not *perfect* are acceptable... and haven’t changed in the last 5 years. I pulled things apart in back and inspected the leafs, spring perches, torqued my U bolts, all good.

I’ve still got to check my engine mounts, I’ll do that tomorrow- I’ve got some assistance.

torque converter?? What’s a symptom of a bad one? Seems fine but do they go out of balance?

pulling my hair out.

 

Try post here
Brake test for TQ Converter

https://www.tacomaworld.com/threads/shudder-vibration-at-40mph.686268/#post-24215732

 

Yeah, I should have mentioned that- did the brake test as well. TC locks/unlocks as expected but doesn’t have an effect on the vibes.

I should take a video. When I say vibes, I mean my passenger seat is PARTYING

FULL DISCLOSURE- I should mention- I’ve got a few posts floating around indicating a bad rear wheel bearing (it’s still bad, haven’t found a shop yet) and the fronts- even though they pass all of the typical tests... I’m still leery of them... almost 200k. So I ordered
(yesterday) a pair from 05Taco4x4 (awesome guy to do business with btw)

maybe I should just keep my mouth shut till I get the new front and rear bearings done. I’ve definitely got a noisy rear (drivers side) but I’ll be damned if it doesn’t sound like I’ve got a roar from the front too, but like I said- gonna do it all. This truck has asked for almost zero in 200k. Time to treat her like the fancy bitch she deserves to be

 

It is probably not the needle bearing.
But it can’t hurt to put it in 4WD and see what happens?

 

Yeah, sorry... my brain is shot from a 5 hour drive shaking like a drunk on Saturday morning.

4wd (up to the problem speeds) makes no difference. I’ve had the ECGS bushing in since about 20k miles.

couple weeks back I removed the rear shaft and drove like that. Smoother, not perfect. Changed the front/rear/transfer case gear oil at that time (M1 75/90 synthetic- same as what came out) The old oil had a LOT of miles on it but all looked great.

 

My hopes are that a combo of worn out wheel bearings are causing some harmonic issues.

 

I get a pretty good vibration after about 7-10k miles go by. Then I go get my tires rotated and balanced and its good for another 7-10k then the vibes creep back. I do an almost daily drive down a long beat to shit dirt road and I don't go slow, so I always attributed it to that. I almost always have weights missing by the time I go in for tire balance. Speed tape can fix that though if you find that to be a problem. When I had mud terrains the problem came back much faster.

I'd personally take it in for another wheel balance before going any further just to eliminate that possibility.

 

I always wonder with these post about people and vibrations if it is a serious problem or just overthinking something normal for a truck.

 

I have rather limited experience but Tacoma's do seem to have a trend of vibration issues. Many seem to occur even in stock form. That being said a lot of people might be used to driving vehicles that have a more luxurious ride hahah.

 

I’m pretty realistic about how much vibration I expect on a light truck with relatively big/aggressive tires... but my passenger seat shaking so bad that it’s basically a blur is too much.

I’ve had Duratracs before and they got a little loud/rough as they got up there in age (I put almost 100k on them) but they never gave me any issues like this.

I’ll have the balance checked Monday AM and get them rotated. After that I’ll have my alignment double checked (just had it done by a small reputable shop known for their work on suspension specifically and had them hit the specs I found posted here... can’t remember exactly but 4° caster etc etc.) I’m kind of doubting anything has changed up front as it steers/handles great and tracks well.

I’m sure I’ll get it figured out. Just a frustrating road to success.

 

Ok, turns out 3 of my new wheels/tires were out by over 3/4oz. Visited a brand new Discount Tire (opened 17 days ago) and they got me all road force balanced and back on the road. It’s better for sure. Baby steps. I need to look hard at driveline angles.

 

This was the cause of my steering wheel shake, a broken tpms. At about 68 mph, then went away, and then again at 72ish mph. The shake was just enough to be annoying. It was found after the three quick flashes then solid tpms light.

 

What tires are you running? During a road force balance the wheel can show balanced but may not be "balanced" enough if that makes sense. I have found that Tacomas are VERY sensitive when it comes to wheel balance. Your truck might need to have the wheels rebalanced to a lower threshold level.

 

Its good that it helped somewhat. Yeah dude it is kind of a crapshoot on what kind of balance you're gonna get. Discounts by me generally do good, but sometimes I go in and it comes out worse than it was before but fortunately they never have issues doing a rebalance. I can't really complain when it is free though.

I see you removed your spacers on the front end, do you have any suspension mods done to the rear? If you do, you could always try shimming the axle to change the pinion angle or easier yet, some washers under the carrier bearing mount or a combination of both. You can take one of the bolts out from the carrier bearing mount, measure the shank diameter and you know what size washers to get, run into a hardware store and pick up some of those washers that fit and you can experiment a little. good news is that it is incredibly simple to do and takes minutes.

My experience was this: I replaced my OEM leaf packs with Dakar Mediums. Initially the ass end sat very high, I experienced a decent amount of vibrations from 55-65. My lift actually came with an OME carrier bearing drop (all it was is some machined shims, the washers I mentioned would do the same thing) I installed the shims (they where maybe 5mm-.2" thick) and the vibes almost completely went away at all speeds.

Then after about 6 months when my rear end settled, the vibes came back to about the same they where initially. I removed the spacer shims and my vibes went away again. It has been smooth sailing since.

EDIT: this was the kit I was talking about

It looks like it came with different bolts so you may or may not need to get longer bolts depending on how much washers you put underneath if you decide to do this. Good luck.

 

Tires are Duratracs, my second set. I’m sure the remaining vibes are driveline related... the truck is very smooth at *most* speeds now (75ish shakes the passenger seat) but noticeably smoother all around.

Rear springs are a mashup of a full length leaf from a Chevy blazer added to my Tacoma pack (2015 so it had the heavier pack) and I left the overload in. Added a 1” steel block after it settled and I’ve got 2.5° shims in the rear as well.

I’m pretty sure my driveline math is off. I thought I had it nailed but now I’m looking at it differently. Here’s my new understanding:

From transfer case output flange to first shaft (before carrier bearing) you want minimal working angle (less than .5°, more than 0°) This is due to the first shaft not having a “companion joint” to cancel accel/decel with. Easy enough, and this is getting all thrown out of whack by excessive carrier bearing adjustments (I’ve got a shit ton of washers and spacers and 2 lengths of bolts that I experiment with) I’m realizing now- if you want to get it right you’re probably not gonna guess at it and nail it... there’s some science.

Ok, back to school- now the first shaft from the T-case output is situated and under .5°- move to the second portion of driveshaft. Subtract the larger number (shaft one from shaft 2) and you’ve got your working angle of the first universal of the second shaft. Great, now move to the rear pinion flange, subtract whatever is larger, pinion flange or rear driveshaft from one another and you’ve got the second universal (the one by the rear diff) working angle. You want this to be equal to the working angle of the first universal on the second shaft... to do this you’re gonna be shimming the rear pinion to suit.

I think if you look at it scientifically- a carrier bearing drop makes little sense. That really addresses the first portion of driveshaft only, and without a companion joint to cancel accel/decel (each universal accelerates and decelerates TWICE per revolution) you need this one to be almost dead straight (0° is not good as the needles will not turn at all and will not be lubricated)

Does this make sense? It previously didn’t to me, now I’m clear on what I need to do.

Now- carrier bearing drop. I’ve run some drop for years and it’s worked. Why? My theory- but mostly has to be true- it’s definitely manipulating a couple things- 1, the working angle of the first universal with respect to the T case output flange (actually the input shaft of the trans, all the way through the centerline of your crankshaft!) This isn’t great! Your lift didn’t change this angle one bit so it really doesn’t make sense to space it lower... but what you are also experiencing is a change in the working angles of both universals on the second shaft... so inducing some amount of vibration on the first shaft to cancel some out on the second (if you’re lucky) is quite possible- but it’s not a “fix”.

I’d argue that if you’re content with the amount/absence of vibes then leave it alone, as it’s clearly working correctly (at least the butt-dyno says it is) which is an important thing.

BUT- if things aren’t right, a little detective work will get things sorted out. But I can almost promise you at this point- those carrier bearing washers and shims will probably come out.

Feel free to poke holes in my logic

 

I'm no expert on this, but from my past readings people would either go with a single TW drive shaft (if your DS will clear the carrier cross member with load and compression) or go with a double DS with double cardan joints. Some had their original DS modified. Others bought a custom new one. Keeping the double DS would be my preference.

I have driveline vibes on take off and tried carrier drops and all it did was move the vibes to different speeds. Shimming sounded like a different animal that may or may not work since it can be different from truck to truck. At least you solved the major vibes.

 

This it the visual interpretation of what you've said, of course this one only shows two u-joints.


Here's three, the notes in this image are not mine.