My car is not street worthy yet after new engine, tranny, shaft, and rear. Can I put it up on jack stands and test drive to break in? Only for 50 miles.

I wouldn't

Me either. If something happens, and car goes off the stands, you're back to step one or worse.

Fight the urge.

I have done that a couple of times to make sure that things worked properly, but only for a few minutes. Didn't really feel safe though, but I guess it depends on how it's propped up, and taking wheels and drums off would be one way to make it safer. I remember one time I was checking the balance in a driveshaft, doing about 100 mph in the garage... :D

Pretty hard on new motor to run like that without a load on it,just another opinion.:beers:

You can't really properly break in drivetrain parts, especially the engine rings, without putting a load on it.

Also, What about cooling it going 60mph & no air flow?

LK

Why not finish getting it road worthy and then break it in. Just a thought.

No, no, no, no, no! Please use JYags suggestion.

I wouldn't either

Thanks. It's not going to happen.

You can't really properly break in drivetrain parts, especially the engine rings, without putting a load on it.

bingo!

ever seen Ferris Bueller's Day off?

Ya my wife would shoot me if that happened.

I know I will probably catch hell for saying this and so be it.

If your car is safe and secure the PROPER way of using real jackstands in the proper locations, it is not a big deal to run a car in drive sitting on all 4 stands. Its not as unsafe as it sounds if everything is done in the proper manner prepairing for doing this.

Mechanics like myself do this all the time in a shop environment usually on hoists. Its not really all that different. I would not hesitate feeling safe doing this practice. Its not that big of a deal. Its not like you would need to keep going on and off the gas rocking the car back and fourth on the stands. A car running at one constant speed is not going to shake itself off a set of properly placed jack stands. The key is common sence and caution. There is no point in goosing a throttle when doing this. I would recommend the highest rated stands when doing this. But in the end, I cant think of any real reason for someone to run a car in drive with all 4 wheels off the ground unless diagnosing for a noise in gear.

I just figured I would mention the procedure can possibly be done in a safe manner this way. Now.... That does not make it the best way to break in parts or test drive. The key is all in the load it needs after the usual 20 minute break in. So I will agree with everyone else. You need to drive the car.

The worst part is there is no joy in it. Get the dang thing roadworthy, that maiden voyage is a trip to remember!

Mechanics like myself do this all the time in a shop environment usually on hoists. Its not really all that different. I would not hesitate feeling safe doing this practice.

I like to think of myself as a mechanic but I'm probably not in the same league as you are Chris. I agree that if done properly it is probably really quite safe. However, for most of us I think doing things like that are best left to folks like you (read that as professional) and in a shop environment as opposed to someones garage.
:beers:

i have done it many times making sure there are jackstands under the rear axle to properly align the driveshaft. also removed the rear wheels and put lugnuts back on to secure the drums. i have seen an out of balance rear tire shake badly.

if you do run it on the stands, make sure the rear brakes work, otherwise when you put it back in park, you will hear a grinding like you've never heard before.

I like to think of myself as a mechanic but I'm probably not in the same league as you are Chris. I agree that if done properly it is probably really quite safe. However, for most of us I think doing things like that are best left to folks like you (read that as professional) and in a shop environment as opposed to someones garage.
:beers:

Exactly, I just wanted to iterate the fact that this can be done safely at home by someone that does not make his living doing what I do every day. Its all about precautions.

if you do run it on the stands, make sure the rear brakes work, otherwise when you put it back in park, you will hear a grinding like you've never heard before.

I forgot about that. Its not hard to forget that since the car isnt moving. There is no sence of momentum of a vehicle moving and one could easily forget that the rear wheels are moving and the vehicle is not. Thus slamming it into park with an auto trans will be the same is driving down the street and doing the same thing. Grinds worse then one of those coffee makers with the grinding of real coffee beans.

ever seen Ferris Bueller's Day off?

I had exactly the same thought! :)