Driveline Vibe/Binding - Only in Accelerator Pedal - Tacoma Quirk?

First off, yes, another driveline vibe question, but I've been searching for a week without getting anywhere.

Background:

Truck was stock, had the usual 5 MPH vibe, went for the TSB, got denied for the ARB, said forget getting anywhere with the dealer, added my own set of TSB 4-leafs + Icon AAL in the rear with 5100's and did the Eibach 620 / 5100 @ 0.85 up front.

Took the truck out for about a week and had the "rumbling" effect up front on cold days that went away in 4HI. Installed the ECGS bearing two weeks ago with the help of a member on here (thanks again BostonBilly!). Cured those vibes and had a smooth truck. I've got the initial shudder common with lifting the rear, which I will deal with in the future.

I now notice an almost imperceptible vibration in the gas pedal during say 10-25% throttle up to about 50 mph. Truck floorboard and steering wheel are basically complete smooth. I don't hear any audible noises. Shifting the truck into neutral or taking my foot off the gas will eliminate the issue basically. Shifting into 4HI doesn't cure anything and goosing the gas eliminates the issue. I notice if I shift out of OD it typically gets a lot better as well. I can occasionally feel it in the brake coming to a stop, but again, it is very minor. The only way to describe it is almost something binding.

The truck only has 34K on it, so wheel bearings seems unlikely. I lost a small amount of fluid during the ECGS install, but it was just the overflow amount, which I've read is actually a greater capacity than what the truck needs.

I've also read that Tacoma transmissions are just quirky, so I'm not ruling out that it's just something in the truck that has always been there, I just only focused in on it because I'm looking for it. I was toying with doing the OME / Toytec carrier drop, but it seems like that's more if the truck has more pronounced vibes. It's almost like if you were in a MT and were a gear too high and lugging the engine, but not to the degree you'd feel it in the wheel. It really feels like the motor is just being thrashy and it's not smooth.

I dunno, I know there are a million in one vibration threads, so I apologize for that, but having already done the ECGS bushing, I'm a bit stumped.

 

this is driveline phasing.

You likely have a front u joint and rearmost u joint at closeish but opposing angles and a center carrier bearing u joint angle at close to 0ish deg. Problem with this is that puts the driveline 90* out of phase, and it seems that the harmonics of this vibe spawn right around those speeds. My truck is the same as far as the very light vibes, and i have a similar rear lift as you do on yours.

Idealy you would have the first u joint (out of the trasfercase) at a close to 0* then the center and rear joints at opposing same angles. I have managed to get this and crusing at speed was the smoothest i felt. PROBLEM is that now there is a relative much bigger angle at the center u joint, this puts a larger side load on the weak ass floppy dick center carrier bearing rubber and you get the driveline take off shudder around 10-20mph or so.

At this point just leave it. Dont buy an OME / Toytec CB drop... you are wasting your money, get some big fender washer and you will have more of a degree of tuneability as far as your cb. I have 4 washers per side on my cb netting me ~ 1/2in drop, this has made all the different speed vibes the least. Cost, 8-10 washers at 20 cents a piece and 2 longer bolts at 1.50 a piece.

And thats god damn BS that the dealer denied you for a FRONT bumper when dealing with REAR driveline vibes.

 

Thanks for the reply. That makes a lot of sense. Since I don't have the typical vibes, I figured it might be something else, but that makes a ton of sense.

As far as the bumper, I don't know if I got too greedy asking for the spring TSB too early on in the deal or what. The dealer I bought the truck from refuses to acknowledge the vibes existed and blamed it on my "very aggressive tires" (rofl) and the "TRD Off-Road Package" (funny, I don't remember that being a feature in he brochure. The second dealer had it a couple of days and were starting to work on the TSB, only to deny me halfway through. I'm not sure if it was that I maybe pushed too hard for the TSB or whether it was the warranty claims person that denied me. I was told I'd be getting cleared fora rental car by some woman at the dealership and then I got a call a few hours later that my bumper was why they denied me. Knowing that warranty work pays less, I wonder if she took a look at my truck with a reason to deny me. I didn't even have my AT's on at the time.

It's moot now, but at least I have my answer. I do know I'm being insanely critical of the truck right now, but unfortunately, that's just my nature.

 

Dude i am right there with you. SUPER critical of just about everything. The vibes i have had to learn to live with. If i get a wild hair up my ass at some point ill end up filling the rubber of the center CB with some permatex ultrablack to stiffen it up a bunch and getting the driveline angles proper. That should get rid of takeoff vibe and higher speed vibes as well.