in the mornings, when im driving usualy at slow speeds, and today while actualy driving 35 MPH, i heard a buzzing sound coming from the front end. i usualy hear this only when accelerating slightly and when going really slowley. i heard that this could be some valve in the tranny, but i thought it only happend in reverse, and the tranny was rebuilt less then 10K ago. and the noise seems to go away when everything is warmed up, and i don't think its the cat since there is nothign in it!

 

Breathe,

Prior to the 4L60E refinements, the pressure relief in the trans could create a buzzing sound in any gear at low input (engine) RPMs, like idle of crusing at very light loads where the RPMs would be low. It was a little worse in the earlier 700-R4s that had the old design pumps, but continued to be a nuisance on the later units as well. There were several TSBs on this "problem". The phenomenon does not cause any damage to the trans, but can be annoying. I had an '88 TH700-R4 that did this for over 180,000 miles, even though I was **** about changing trans oil and "filters". Even with synthetic oil, it made the noise at idle unless I raised the idle speed a bit with my right foot. It wouldn't do it in park, but would in reverse or drive at low speeds and while standing. Even at that high mileage the trans shifted tightly enough to bark the tires into second, , so it was at least surviving the noise.

If that's your problem, it's really nothing to worry about - as long as you're SURE that's your problem.