trans slipping into neutral

[Challenger1970]

I've got a 72 challenger with a warmed over 360 and a 727,3000 stall converter.Whether I launch hard or I punch it from cruising speed, the tranny slips into neutral.Light to moderate acceleration is fine as well as cruising speed.The shifter is a stock slapstickand the shifter actually moves to neutral when this happens.If I let of the gas it goes back to drive on its own.If I shift from first to second (gas pedal seems stiff)the shifter almost moves itself to second,second to drive the same thing happens(gas pedal not so stiff),then in drive the shifter moves to neutral(pedal feels normal).As far as I know the shifter is supposed to lock in drive(mine does),but it still is able to move to neutral and when I let off the gas it moves back.The throttle cable is adjusted properly,kickdown is a lokar unit and seems to be fine(slack with no throttle,tight almost maxed at wot) no interference with any linkages.It make no sense.

[Chryco Psycho]

do you have a broken left engine mount or worn out trans mount , something is moving under the car to cause it to shift

[tactransman]

do you have a broken left engine mount or worn out trans mount , something is moving under the car to cause it to shift

 

[Challenger1970]

all mounts look good. I had a buddy watch the motor while I put it in gear with my foot on the brake and loaded it up.

[Challenger1970]

also when shifting from 1st to 2nd and 2nd to drive manually the shifter starts to move on its own even under light accelaration,so the motor trans should not move as much,plus if just in drive under light accelaration the shifter does not move.

[Challenger1970]

Well I solved the problem. It turned out that thr lokar kickdown linkage bolt that connects to the kickdown lever on the trans was sticking down to far,therefore as I accelerated the kickdown lever moved and hit the shift lever,once I pushed the pedal far enough the shift lever moved to neutral.1st gear was the worst because the shift lever is right beside the kickdown.Now the problem is fixed ,a little trim of the bolt and my car is great again.thanks for the help.hopfully this might help someone else from having this problem in the future.

[Chryco Psycho]

Glad you found the problem