Join Date: Mar 2005
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Re: 700R4 troubles
I would like to start by saying that I am by no means a professonal...... but I have experienced the demise of a 700r4 and watched the rebuild (and asked a lot of annoying questions while doing so)
The passages in the valve-body of a 700r4 are really small(not too much larger that an ink cartrige in a cheap bic pen) when you start to burn a clutch (usually the overdrive) the debris from the clutch can easily gunk up the valves to the point that they will not work. The first one in the sequence, between 1st and 2nd gear, goes first. (to further back up Dirt Dog's statement; the passages in a 400 are about the size of the outer diameter of the cheap bic pen itself....in exaggeration (a turd could pass through the valve-body of a 400.
Since shifting primarily relies on the pressure of the transmisson fluid passing through the valve-body, I could see how reving, and slamming into drive would produce enough pressure to open your gunked up #1 valve.
From what the guy that rebult my transmisson said, the three most common reasons that people kill 700s:
1) running really big tires w/o regearing (my problem)
2) towing w/o being really anal about maintenance (flush an fill w/ new filter)
3) plowing... period (that is about the meanist thing you can do to a transmisson)
most of the time all that really needs to be done to function properly is cleaning the valve system.... but if you have to pull the transmisson why not rebuild it (and besides the clutch that already started burning is not going to last that long.)
one of the things to look for if you suspect a burnt clutch is cloudy transmisson fluid that smells kinda burnt.