Shudder at all speeds when warm?

[Krolik]

Hey guys,


Picked up a 99 two door Tahoe with the 5.7 4x4.

Anyway, just got done doing some quick maintenance on the new rig (plugs, cap/rotor, fuel pump, oil change, u joints) and started driving her around a bit. It's been a bit toasty around Chicago lately and I bought the truck when it was a bit cooler so who knows if it's been happening since.

When truck is cold, there is no shaking. If I let the truck sit a bit to heatsoak a bit and start driving I'll start getting vibration/shudder that shakes nearly the whole damn truck. I feel it in the steering wheel, gas pedal, seats and all. Happens only with light throttle! If I let off the gas, no shaking. Throw it in neutral and apply light throttle, no shaking. Give it the beans, it'll go fast and I do not feel the shaking is there. The truck will put you in the seat.

The shaking happens at any speed above 15mph it seems. If I'm sitting at a stop and take off, the shuddering will not happen until I let off the gas and cruise. Light throttle at cruise will cause the truck to shake.


Trans fluid level is correct when cold and hot (engine running when checking level) but it does seem a bit dirty from where I'd like it to be. I think I'll be doing a trans flush with filter in the coming days.


What's getting me is that the shudder most guys talk about is at highway speeds. This is happening to me at like 30mph consistently and at any speed really. Tapping on the brake pedal doesn't get rid of the shudder.

Thoughts? Suggestions? Time for a trans on this rig?

 

[chevync]

I would change tranny filter and fluid and see if that helps before replacing the tranny.

 

[God]

It sounds to me like the Rear U joint ought to be checked

 

[Krolik]

Well, seems like this issue can be put to rest.

I crawled under the truck today to check everything over again and noticed something I hadn't when I was changing the fuel pump and filter. Some bonehead cut the fuel hard line in between the pump and filter and added a "pre filter". Removed it, threw some appropriate sized fuel injection hose in place and tucked everything away.

Took the truck for a spin and we seem to have a truck that was starving for fuel.

Regardless, came back to put the truck in the air again and everything is peachy.

---------- Post added at 02:29 PM ---------- Previous post was at 02:28 PM ----------

I would change tranny filter and fluid and see if that helps before replacing the tranny.

I think I'll be doing this shortly anyhow. Going to be adding a nice trans cooler to the front end as well, for some reason this truck is equipped with a tow package but no trans cooler.

 

[SunlitComet]

i think unless you had the z 82 option you will have had to pay to add them. tho they were highly recommended for towing they were not always included with the trailering packaging for free the builder book would seem to indicate.

 

[Krolik]

i think unless you had the z 82 option you will have had to pay to add them. tho they were highly recommended for towing they were not always included with the trailering packaging for free the builder book would seem to indicate.

Odd.

I'll be cruising around a couple junkyards soon. Maybe I'll be able to score myself a clean OEM set up from a truck there.