I have a 70 Cuda, 440, 727, 3.23 SG, power front disc brakes. When I drive the car the initial movement forward or reverse is very stiff, and I have to give it a fair amount of gas to move. Car will not idle forward if I take my foot off the brake when it is in gear. Something is holding it back. It is as if the brakes were on, however the wheels rotate smoothly when I lift it off the ground and the brakes are not hot after driving it for a while. So I do not not think it is a brake issue. Same with transmission as it is in both forward and reverse gear. Although I could be wrong. Any suggestions as to what this can be. Appreciate it.

Check and see how easy the driveshaft turns when the rear tires are off the ground, and trans out of gear, motor turned off. Maybe the rear end gears, or bearings, are too tight. And check the rearend temp after driving it awhile. For the heck of it, also check the transmission's temp after driving it for awhile.

If the driveshaft turns hard, remove it from the car. Then check how easy the rearend yoke turns, and how easy the transmission output shaft turns, and go from there.

Thanks. I will give that a try.

A little more back ground is needed, did you just buy the car? Was anything swapped out ? engine , trans , drive shaft or rear? How about the converter?

I had it for a while and did a complete rebuild. So everything has been replaced from front to back. Engine, torque converter, trany, drive shaft, rear end, disc brakes, etc. So no one change that I can pin it to.

Bias ply tires? They do have more rolling resistance compared to radials. Don't think it could be that much difference though.

Perhaps overinflating the tires and seeing what happens could shed some light.

Also, sounds like yo may have just done a couple shake downs drives, has the front end been aligned yet? Out of spec toe can add lots of drag.

What is accurate engine rpm speed in drive, in neutral, not just what dash tach says. What are torque converter specs? Linkage to carb all ok?

When driving on level, place trans in neutral and let coast down. Does deceleration appear normal?

Place on very slight incline in neutral, no emergency brake. Will car begin to move on its own when you release foot brake?

Maybe the brakes are sticking a bit.

If you've eliminated the wheels and brakes as the frictional source, can you push/move the vehicle freely with it in neutral/engine not running?

If not then I'd be looking at driveshaft/rear diff/axle as the source, if you can confirm these rotate freely and the condition is only when the engine is running and or in gear, then I'd be looking at either the brake booster to master pushrod adjustment as that may be inducing front residual brake drag, if that has been eliminated, my next suspect would be that the transmission band adjustment may be too "tight", I'd start with the 1st/rev band and re-torque/adjust to factory/mfg recommended specs, check the 2-3 band as well, you'll need to drop the pan for 1st/rev band adjustment...

Mike

Another suggestion to check alignment. As mentioned, if toe is off that can make a lot of drag. You can rough check with a carpenters rule. Pick a consistent tread feature on the tires. Measure distance across front of the front tires and back of the front tires. Front should be about 1/8" less.

Also, when you jack it up to check for freewheel keep the engine running. If something is off with the booster, engine vacuum alone could be applying the brakes.