Re: Truck stumbles and shakes in overdrive?

What Is a Transmission Shudder?

Also known as a torque converter shudder, a transmission shudder refers to =
when your vehicle=E2=80=99s transmission begins to noticeably shake or trem=
ble 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.=20
Common Causes of a Transmission Shudder

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

When the fluid in a transmission becomes dirty and contaminated, the partic=
les in the fluid prevent it from building up enough pressure in the transmi=
ssion lines. In turn, this will prevent proper pressure contact between tra=
nsmission 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 c=
lean, fresh fluid. If the cause of your shuddering transmission is low flui=
d 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 w=
orking properly again. By practicing proper vehicle maintenance, such as ge=
tting regular transmission fluid changes, you will likely never have to exp=
erience a shuddering transmission ever again.