Darn, I am stumped

[punkncat]

My truck has developed quite a shudder between 40-60. In the course of looking after it I discovered a bad midshaft bearing. Went ahead and replaced that, had the drive shaft rebuilt and balanced by a very good local company that has been in business a long time. Shudder is still there.
I replaced the brakes and rotors. It was due anyway. Didn't really think that was it anyway, but that isn't it now, for sure. Still shuddering.
Went to the tire shop and had two new tires put on, everything balanced and checked. The balance machine and our eyes cannot discern anything going on out of the ordinary and the tires balanced with a "small" amount of weight in relation to the tire size (I worked here for over a year).

I have no codes or anything. The truck is running fine, shifting fine, no strange noises above and beyond normal for a vehicle of it's age. I cannot 'feel' a bad bearing when turning the wheels. I don't think my motor or transmission mounts are broken. I can grab the back of the trans and anywhere along the drive line and shake with all my weight to no movement.
As a last ditch thing I have been attempting to take the truck out of gear and coast. Obviously this isn't exactly eliminating the transmission as a culprit, but I cannot tell a difference when coasting in or out of gear. I do note that it seems to lessen a bit under load, but I could be imagining it.

My mechanic (a friend) was convinced that the mid shaft bearing was the culprit and at this point he is a bit stumped as well. Real PITA trying to fix something when you don't know what is wrong.

[martix_agent]

Any chance this could be a driveshaft that is not balanced? It's improbable because I imagine you would notice it even at slow speeds, but you know.. I'm pretty sure some of them have attached weights.

Maybe it's stuck in 4x4?

[punkncat]

Any chance this could be a driveshaft that is not balanced?

I would imagine it is possible. I did have it rebuilt and balanced while they replaced the midshaft bearing. I can see where the new weight was tac welded, but they could have goofed....I guess...

[RuleOfSines]

Gone on a drive with someone watching your wheels to see if there is any wobble?

[punkncat]

Gone on a drive with someone watching your wheels to see if there is any wobble?

Yes, you cannot see it going on, but you can certainly feel it.

[ghilliesuit]

Torque convertor lockup clutch/solenoid???

Take it off of O/D and see if it goes away. Or, when it happens put the throttle down to floor and see if it goes way.

This is more common on trucks that spend a lot of time towing in OD and trucks with a lot of highway miles.

If you list make, model, year, engine, trans specs it would help.

[Jordan]

4x4?

[punkncat]

Torque convertor lockup clutch/solenoid???

Take it off of O/D and see if it goes away. Or, when it happens put the throttle down to floor and see if it goes way.

Yes, as above I 'think' it lessens when I put it under load by throttle or weight (down a hill). It is worse (seeming) when the vehicle is free rolling under no load. Unfortunately the manual shift aspect of my gear selector doesn't work any longer. IE, it's a Titan and it only goes to D, then you have a button to press to put it in a manual shift mode. That button quit working some years back, along with the cruise control. Common issue to these.

[punkncat]

4x4?

Negative. 2x '06 Nissan Titan 4D

[punkncat]

Yes, vehicle is outfitted with the towing package and has a cooler for trans. My coolant is good. The trans fluid is red still, probably could use a flush and a new filter TBH. I can monitor trans temps from the cabin by gauge and with the towing pack have only gotten it above 1/3 of the way while towing a trailer up Blood Mountain with a full truck. Pulling a car on a trailer is like nothing is back there, normally.

[ghilliesuit]

Is the shutter worse while towing?

[punkncat]

I did not note a specific difference when loaded or not aside from throttle load.

[ghilliesuit]

If it gets better down hill off throttle and you see engine rpms rise (aka torque convertor lockup is disengaged) that could be an indicator.

If traveling at highway speeds under light to moderate throttle maintaining constant speed makes it worse that can be an indicator as well.

Either way good luck.

[Rolling Thunder 67]

might be a a broken or cracked flywheel where it mounts to the crankshaft or trashed torque converter. not sure what type of inspection plate is on your transmission,might be able to get a snake camera in there and at least look for cracks around the bolts,if you have a pan that can be removed then you could visually inspect the crank bolts and the torque converter bolts. worth a shot.

[ghilliesuit]

True, loose torque convertor bolts can exhibit these symptoms too. Though, usually all the time and not speed specific. You would be able to put bbn in neutral and rev engine and tell. But it is possible.

[flyweightnate]

My car would shudder from bad control arms. The rubber bushings tore, and the shudder would be absent, until I put in the slightest steering input, then it would begin in earnest.

Non-issue except over 60.

[Mr. Hick]

Do me a favor and run it at that speed with tow/haul on. That will force the transmission into a lower gear and help us discern if the problem is in unsprung weight or driveline.

[VonBraun63]

Since we are all throwing crap at a ceiling fan I’ll join in. Different truck but similar issue. 2005 ford 5.4. Shutter between 40-60. Changed everything up front. Put on new tires. No drive shaft issues. No codes. Chased for a long time.it ended up being a faulty coil. Between 40 and 60 the ecu would change the characteristics of the timing and the coil would fault it didn’t quit it was just an intermittent misfire. Again not a hard fault to throw a code. I later talked to a ford engineer ( for a different 5.4 issue because it’s plagued with them) and he chuckled when I told him that. His words “ bad design with bad coils. We built an over ride into the ecu” Replaced all the coils and it’s been great since.

[punkncat]

Just for shits and giggles I will likely throw some plugs and wires at it this weekend and see if anything changes. They have been a while.

[Tarsun2]

my rav4 tc would not unlock on deceleration. and it would shudder. but that was on decel only.