Why does my automatic transmission shift so hard?

A bent, blocked, or detached vacuum line can alter the pressure in the transmission producing a rough shift. In some cases hard shifting could be caused by a sensor transmitting the wrong data from the engine. A failed speed sensor may signal that the vehicle is traveling at a higher or lower speed than it truly is.

What kind of transmission do I need for a LS swap?

One of the most common transmissions for an LS swap is the 4L60E, and for a few reasons. It’s a proven strong and dependable transmission and it’s also what came as the original automatic transmission backing up a good majority of LS engines out there. If you find a donor vehicle with both, your job just got a lot easier.

What causes hard shifting in an automatic transmission?

Transmission Fluid Check your transmission fluid. If your transmission is low on fluid, or if the fluid is old and discolored, it could be to blame for the hard shifting. Hard shifting can occur due to a lack of lubrication in the transmission. Transmission fluid should be reddish in color and largely transparent.

What are the signs of a transmission problem?

Harsh Shifting. One of the first signs of transmission problems is when your transmission shifts hard. When your transmission slams into gear it can be a sign of abnormal pressures, worn components or even a low fluid level.

What does it mean when your transmission is slow?

Similarly, slow and hanging shifts can be a sign of worn component or abnormal pressures in your transmission. If you’re experiencing slow shifts, consider changing your transmission filter and see if it is clogged and causing the problems you’re having.

What kind of transmission do I need for my LS?

Six the Easy Way If you have your heart set on a six-speed automatic to back your LS, consider TCI’s 6X transmission. Based around the 4L80E (and fitting wherever a 4L80E will fit), the 6X is a true six-speed transmission that TCI rates at 850-plus horsepower.

Can a LS swap be done on an original automatic?

For owners of classic musclecars already equipped with a serviceable, original automatic, this will be the simplest (and least expensive) solution when doing an LS swap.

When did they stop using automatic transmission in cars?

Over time, the demand for a three-speed automatic overran its popularity and the factory applications dwindled to 4- and 6-cylinder cars until it was replaced by the Turbo Hydramatic 250, which we’ll tie into later. This popular and well-known transmission was first used in 1964.

Why does my transmission shift hard when I change fluid?

If you have not changed the fluid and replaced the filter already, do that while changing these parts. Otherwise, just keep the filter in a bag while changing the o-ring or spring and then re-install it. These are the most common reasons for the hard shifting problem.