Rear Tires Suddenly Lock Up Going 65

RedFish said
I know where a 69 GTX sits today with the same problem. Last time it hit the 1/4 mile track it got into 3rd gear and locked up both rear wheels and slid to a stop. Driver backed it off the track and drove it up on the trailer.
That was years ago and the car hasn't been driven since. Owner has a Dana 60 rear to put under it but really doesn't know if the rear is the problem.
I've heard of times when a floor shifter combined with a broken left ( bisquit type ) motor support changed gears. From drive to reverse is a stretch though.
Bottom line, I've tagged this thread so when yall figure out where the problem is I can call ronnie and tell him. Good luck

Wow! This seem to be more common than I had thought. I see how it could be a motor mount jumping gears, and you're right, that is a long stretch.

cudamark said
I'm thinking it's a valve body problem or temporarily plugged oil passage. In a race car, a transmission brake applies reverse and forward at the same time to keep the output shaft from turning. Maybe something went haywire to cause the same sort of thing. It would also explain the "loss of power" as the engine would be working against the converter like you were bringing the RPM up to stall speed. I can't see the brakes or rear axle doing that, and then just as suddenly, curing themselves, although the loose pinion nut/shaft may have some legs. You'd think there would be a bad leak if that was the case though....

This is what I think happened.

Whatever it was, it had to of initially absorbed a LOT of energy to lock up both tires as violently as it did on a 3200ish lb vehicle going 65 mph while a strong 360 is also applying torque at 3000rpm in the same direction.

Brakes seem to be the only logical thing that could malfunction and absorb this amount of energy and could possibly show little/no signs of damage. But I just can't see brakes as the problem (although they will certainly be checked), to instantly lock both tires due to a collapsed or damaged hose or master cylinder. Where would the energy come from to apply that much brake pressure?

You'd think the ring and pinion or anything in the transmission would just explode if told to put up with that much stress. Or like mentioned, leak, vibrate, make noise. Anything besides magically fixing itself. Haha

If the tranny somehow went into "trans brake mode" I may have felt it as the loss of power (the friction of the forward and reverse band slipping), then as soon as I let off the gas there wasn't anymore torque (probably negative torque) from the engine and it could actually lock up the output shaft now and that would have locked the tires.