Thats a bit low of a speed for the O.D to kick in, usually doesn't even kick in till atleast 55, and if you get it down to 50 its by really babying it and almost tricking it there.

 

Interesting.. the only reason I assumed it was overdrive is that if I push the button to disable the overdrive, no vibration. Does that effect if the TQ locks or when it locks?

 

Ok.. So I am not 100% positive about the things that I am about to say. So take them with a grain of salt and hopefully someone else can help out and correct me if I am wrong.

I believe that the Transfer-case should be filled separately from the transmission. I think that they are 2 separate units with a seal between them. (if the seal leaks, some of the trans fluid will seep into the transfer-case which is fine)

Are you POSITIVE that your transmission is correctly filled to the proper level?
From what I understand, when the truck shifts into overdrive, it completely locks up the torque converter which should be completely full of fluid at the time. If you do not have enough fluid, then the torque converter will not be full and will be off balance which would cause a shutter or vibration.
I had this issue when I got a trans leak. (again, only happened in overdrive)

My truck is the same as yours and overdrive kicks in around 50ish mph depending on how I am driving.

Not too sure on your idle issue. I am pretty certain that it would be separate from your trans issue.

 

Thanks for the response Sauxon,

I will double check the fluid level, but I did change the transmission fluid and filter, it was the same before and after.. I guess it could have been low in both cases. I see there is a mount under the transmission/transfer case. It looks ok, but could that be a possible culprit?

 

I know in my dakota when i didnt have it at the right level in the transmission after i put it in drive it vibrated and shook the whole truck id check that first.

 

What Is a Transmission Shudder?

Also known as a torque converter shudder, a transmission shudder refers to when your vehicle’s transmission begins to noticeably shake or tremble convulsively. In most cases, transmission shudders occur when shifting your vehicle into overdrive or when you drive up an inclined surface while your vehicle is already in overdrive.

Common Causes of a Transmission Shudder

When your vehicle starts to shake convulsively, it may seem like your transmission is significantly damaged and about to shut down completely. However, the primary cause of a shuddering transmission is simply contaminated transmission fluid.

When the fluid in a transmission becomes dirty and contaminated, the particles in the fluid prevent it from building up enough pressure in the transmission lines. In turn, this will prevent proper pressure contact between transmission plates when they are applied. As a result, the transmission will begin to shudder. For the same reason, transmission shudders may also occur when there is not an ample amount of transmission fluid.

How To Fix a Shuddering Transmission

Fortunately, fixing a shuddering transmission is often as simple as getting a transmission flush to replace the contaminated transmission fluid with clean, fresh fluid. If the cause of your shuddering transmission is low fluid rather than contaminated transmission fluid, you may just need to fill up your transmission with more fluid until it has the right amount.

In some cases, however, low transmission fluid may be caused by a leak that will need to be addressed and repaired in order to get your transmission working properly again. By practicing proper vehicle maintenance, such as getting regular transmission fluid changes, you will likely never have to experience a shuddering transmission ever again.