Shake or Shudder at 46mph, 58mph and 63mph! I need Help!

[matad311]

Hi everyone I'm new to this forum and need some help! I have 1998 Chevy C1500 with a 4L60E and just had a new rebuilt trans put into it. I do not know if this is something in my drive line (such as drive shaft or tires) but all I know is once I got done installing the trans i noticed there is a Shake/Shudder at these speeds only, 46mph, 58mph and 63mph. I can make this sudder/shake happen when i let the RPM's and MPH even out. But the wired thing is i can make the shake go away as soon as I get on the gas or if I hit the brake lightly. So I dont know if it would be something in the transmission causing this. The Trans has upgraded internals like the corvette servo and Beast sun shell and some other things and It also came with a new stock torque converter. If anyone can help that would be great thanks!

 

[wally]

I'm not tranny expert it sounds like your torque converter lockup I have a 91 gmc work truck that did the same thing so I disabled it (clipped wire) but unfortunately I don't think it's that easy with the later model electronic overdrives ,but that's EXACTLY what mine did till I clipped it