For those of you who know about Auto transmission, please help. I have a 94 Chevy Suburban1500, 350 TBI, 4X4 4L60 E tranny.


I am getting a very bad transmission "thump" between 1500 and 2500 RPM. It does it specifically really bad while cruising down the freeway at about 2000 RPM's. I'll hear and feel back to back thump thump thump. Not while shifting. It shifts beautifully. It also does it while trying to get through an intersection. Mainly between those RPM's. If I gun it and it goes up to 3000 RPM it doesn't do it, and if I take off really slow and it shifts before 1500 rpm it won't do it. I was told it could be a torque converter lock up issue and I was also told it could be something in the valve body where the transmission is trying to shift into 2 gears at one time. The worst it happens though is when I'm on the freeway at cruising rpm. Right around 2000 rpm. Does anybody have any ideas?


P.S. My trucks name is Lucy. She's awesome, accept for this problem. Please help her?

 

Hate to ask a woman's age, but what's Lucy's mileage. I assume original tranny? How has it been serviced?

 

She has 246,000 moles on her and I don't know of its original tranny or not. I just serviced the tranny today. I replaced the torque converter control solenoid located under the tram my pan and while I was down there I did the filter and put new fluid in it. The fluid was gorgeous though. No metal in the oan. Fluid actually looked new. It's still doing the exact same thing though.

 

I've destroyed alot of 4l60's, never heard one thump at highway speeds. Seems even more strange since the trans is functioning properly. I'd be looking at the transfer case, carrier bearing, u joints.