transmission that bounces

hey..
ive had my jeep for about 2 years, when i first bought it it had 12k miles and it was 2 yrs old. 6cyl, 5 spd. Carfax on it was clean, but i've noticed something weird that i thought might not be normal.

Whenever i go over a speed bump, or any bump thats major like that, as soon as i start accelerating, the acceleration "bounces" with the car's shakes from the bump. Its like maybe the tranny is movin in and out from the engine, and its only catchin when the frame isnt moving.

My friend said maybe motor mounts are missing, because i really dont kno what the previous owner did. Any ideas? also, how would i check to see if its the engine or the tranny thats bouncing?

Is it a tranny shake or a rear end shake?

Sounds like you need to get under and check all the mounting points, starting from the engine, back to trans and then to rear axle. You may also have some Ujoint issues if there's alot of mileage on it.

the car has only about 25k miles,

i would describe the shaking as a transmission shake. It's like, right after a bump, if the car's frame pitches forward a little bit, then i can accelerate, but while it pitches back, the accelerator doesnt do anything. clutch up the whole time.

I'm not a highly technical person so should I basically be looking for missing bolts, broken welds, etc?

How fast are you going over these bumps, and how big are they?

Definitely need to have a look underneath.

How fast are you going over these bumps, and how big are they?

Definitely need to have a look underneath.

these are speed bumps on the private road outside my street. the raod is 15mph, and i brake to about 5 before each bump. if i start accelerating just as the back wheel is past the bump, i get that weird bouncing acceleration....anyway ill take a look when i get the chance. Should a problem be blatantly obvious, liek something hanging off the bottom of the car?

If it's your transmission bumping, they check all the mounting points for it and the engine mounts also. I'd also take a look at the Universal joints. Shocks may be a concern also.

After re reading your posts, this may also be a fuel delivery problem; does your engine quit for a second, or sun smoothly throughout the episode?

If it's your transmission bumping, they check all the mounting points for it and the engine mounts also. I'd also take a look at the Universal joints. Shocks may be a concern also.

After re reading your posts, this may also be a fuel delivery problem; does your engine quit for a second, or sun smoothly throughout the episode?


As a matter of fact, what u just said makes sense, because the tach shows the engine going down between each of the acceleration jumps.
Smart guy. Should i also check all the fuel lines etc over the head, or were you thinking more about the pump?

ill have the time/environment to take a look on wednesday.

With the engine trying to die, I'd check the electrical connections to the pump first. Check to make sure everything is tight. The fuse for the fuel pump could be loose.

Do you have a distributor? If so, you might want to check the coil and wires.