Finally started...transmission slipping?

[1966stangkid]

I just got my 66 i6 automatic to start.. some of you may know that i bought it two months ago when she wouldnt start for anyone. the guy i bought it from told me the car hadnt been driving well before he parked it and let it sit for two years. .......now two years and two months later it cost me 60 bucks to put a new batt. in and put in feash gas. anyway she starts right up now and sounds really good. the problem is when i put into any gear and press the gas the moter revs for a little and then she jerks foward and starts moving. but if i take my foot back off the car stops and i have to repeat the process again. does anyone know if this is the transmission or the rear-end slipping. and if you could tell me how to go about fxing it. thanks guys.

[stanger66]

I had mine do the same thing when I got mine 3yrs ago. I checked the fluid and there was none so I added about 3-4 quarts and it drove alright and then did a trans filter kit and cleaned the hell out the valvebody as I could without taking it off and drove it about 400 miles and did it again. Its running ever since and I have the cruise-o-matic c4 I-6 in mine but I have had a fuel problem since I have had it. Try that and then go from there. But yes it sounds like the trans.

[1966stangkid]

Thanks, ill try that and post back with what happens. one other thing i thats a little weird about this mustang is that there are alot of wires hanging from under the dash. most of them are conected to themselves with wire caps and all sorts of relays. i was wondering if this is what normal wiring looks like when its falling out of the dash or if the last owner thought he was some sort of electrision and in the end just made things very complicated?

[stanger66]

To tell you the truth mine has the same thing because my friend that owned the car before me tried to fix all the wiring and didnt finish and now Im trying to find a wiring diagram to repair them or Im going to have to buy a actual harness.

[1966stangkid]

put new fluids in works good now. it stopped slipping and runs good. well atleast in and out of my driveway. it was leeking most of its fluids right back out again but then i put leak stopper in and its stopped for now. will the leak stopper hold up or sould i try and rebuild the trans?

[stanger66]

Where do the fluid leak from? Because you might be able to replace a gasket or something. If it is the transpan gasket or the output shaft you can replace it but if coming from the front seal or other have it rebuilt.