Tundra 1st gear mysterious shudder

Hello Folks,

I have been noticing a shudder in first gear every single time I accelerate from a stop.

I have a 2002 Tundra SR5 RWD 4.7 V8 Access Cab Automatic Transmission.
I bought the truck with 170+K on it and have done a ton of work to it.

There is a very slight shudder/vibration/rumble that only happens in first gear at about 10mph, a few seconds before shifting into 2nd. From a stop, when you hit the gas, it is perfectly smooth about 2 seconds in, then you feel a very slight shudder (almost like it bounces slightly 4-5 times) somewhere along the drivetrain and it goes away after 1 second and then a couple seconds later shifts to 2nd (same time every time). I cannot figure it out.


I went to see two mechanics, one got in the truck and held the brake while putting power to reverse and drive and heard a creak and he said to check the mounts (transmission and engine), he said you find that bad mount I bet you solve the problem. Hard for me to see it though as it happens so consistently at the same speed (10mph about) and instantly goes away. I changed both engine mounts and did not resolve. Have not yet done the Tranny mount (it looked good).


I then spoke to another mechanic who took it for a drive and said it was so small and light of a vibration (yeah to him lol) that he said don't worry about it and just drive the truck, as he said it would be very difficult to figure out where that's coming from as it's so slight and the truck runs excellent. When I dropped the transmission pan and changed the fluid, it looked so clean and the magnets barely had black dust on them. I also replaced the carrier bearing and still have the vibration.

One thing I have noticed. The idle blips ever so slightly (does not even register on gauge but feel and hear it) every 2 - 4 seconds. From idle, I'll put slight pressure on the brakes and do a very slow roll (no gas) and the truck will bounce up and down, I believe at the idle blip points, which kind of makes sense I guess.

There are no CEL lights on and the truck drives excellent. Does anyone have any ideas on what this could be?

Work Done to truck:

Timing belt, Accessory belt, lower ball joints (Toyota), inner outer steering tie rod, suspension (bilstein 5100 on stock springs), all new brakes, exhaust headers, full exhaust, new plugs (Toyota), replaced one coil pack (I thought it may be a coil (when I got the truck, the plug was loose - def heated coil pack), transmission pan, pcv valve and hose, and I'm sure I'm missing some things.

**HUGE shootout to 'Shifty', thanks man for getting me through this build with my many questions!

 

Grease your drive train yet? Search for zerk locations if you haven’t.

 

2wd has no zerks on the driveline.


Check the trans mount for missing/loose bolts or cracking of the crossmember. There's a TSB about it.

 

Shame you did the motor mounts instead of the transmission crossmember mount. The motor mounts rarely / never fail on these. The transmission mount in 2wd trucks has a tsb as listed above by @assassin10000 . The crossmember can be cracked and often bolts are missing. Do you have the LSD rear end? Common for those to shudder when the fluid needs to be changed, or the clutches get worn.

 

There are no ZERK fittings, I had to remove driveshaft for carrier bearing and replaced two u-joints and the others had no play. I don't see any cracking on crossmember. As far as LSD, I cannot figure out if I have it or not, so I removed 24mm fill bolt and snapped pictures, hopefully you folks can tell by the pics. I should add, the only fluid I have not changed is the Diff bc I could figure out which Diff I had (LSD or not) and which fluid to use. Sorry for the many pictures, not sure which angle will help you best.

Tranny mount + cross member:




Differential Fill Plug:

 

Drive 5-10 miles and do your best to only use the e-brake, then feel the front wheels & see if you have a dragging caliper.

 

Open diff. Can see cross pin and spider gears.

Possible cracks:

 

Yup - those black lines next to the bolts may be cracks. I would remove the crossmember to better inspect it.