I have a sbc hooked to a mechanical 700r4. For the past few years, it has performed flawlessly. Now, like in one day, it starts shifting at 3000-3500 rpm. I checked the fluid, made certain the kickdown cable wasn't binding, and I just flushed the tranny fluid changed the filter and gasket, and it still shifts at high rpms. any help would be greatly appreciated. -Josh
mechanical as in its not computer controlled like a 4L60 right?! it could be a sticky valve, when i installed mine two weeks ago it started out that way but worked itself in. Since yours has been in there for a while i would take it some where and have them drop the pan and check out the valve body and your tv cable is set up perfect right?!
700 & 4L60 are the same tranny . 4L60E is electronic control. if the 700 is shifting at high RPM at ALL times. Check the TV cable for adjustment, melted case or something that would cause it to stick. Pull on the cable to check for free movement . IF that is OK...... the TV valve it's self in the valve body may be stuck.... Sometimes at engine idle you pull the TV cable several times to free up a stuck TV valve in the valve body. It is also possible the plastic governor gear is going bad , broken
Check: TV Cable - Binding or not correctly adjusted TV exhaust ball - Stuck or damaged Oil Pump Assembly - Stuck pressure reg valve/TV boost valve Valve body Assembly - Sticky throttle valve or plunger Modulated TV up/down valves sticking TV Limit valve sticking line bias valve sticking dirty governor filter 2-4 servo assembly - damaged servo piston seals/apply pin damaged 2-4 band assembly - burned, anchor pin not engaged
It is probably the cable..... They are pretty apt to slip adjustment at the bracket by throttlebody/carb. The"teeth" of its ratchet assy will allow it to slip loose thus changing the shift points. Sometimes it gets oily or just goes bad and releases the hold. Where I mean is at the part that has the round"button" near the bracket holding it on intake. if this "button" is pushed it releases the cable to move to adjust the setting of cable.
Bump. Same thing happened to me today. Out of the blue it started shifting later and harder. After about 15 miles, in stop and go traffic, it started to slip, no go. Got it off the road, checked fluid, pulled the pan, looks just fine, no burnt fluid, no swarf. Now, if I start it up it shift into drive or reverse as normal and go but after 15-20 seconds it slips again. Shifting from forward to reverse does nothing. Shut it off for a few minutes and it works again briefly. Any ideas?
A 4L60 is a 700R4. GM just renamed the transmissions. A 3L80 is a TH400, too! A 4L60E is computer controlled.
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