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Long Roadtrip on New Transmission?

I recently got a rebuilt transmission put in my 2001 Pathfinder. I have to take a roadtrip up to Fresno / San Fran (from LA), and I’m wondering if there’s any problem taking the new tranny on such a long roadtrip. My mechanic said it wasn’t a great idea, but that it wasn’t necessarily a bad idea either. Apparently it has more to do with the “nonstop driving” more than putting so many miles on this. I’m trying to wrap my head around this more, but in your eyes, is it not a good idea for a new tranny to go on a long trip?

Worst case is we use my girlfriend’s car. Thanks in advance.

If the car has a new transmission, what’s the problem?
You may not want to drive it like you stole it at first but you do want to shake the bugs out to make sure you don’t get stuck. Who knows, maybe he forgot to tighten a line or the transmission has an infant mortality issue…
But, once you’ve driven it around for a bit and are fairly confident it won’t leave you stranded, why not take it out and blow the spiders out of the exhaust?
What good is a car that you can’t rely on?

As long as you are going to worry, you need to worry about the engine holding together for your trip without spinning a bearing, the electrical system giving out and leaving you beside the road, a tire blowing out on the highway, the brakes giving out when you need to stop in a hurry, or unseen undercarriage rust causing the floorboard to give way and dumping you out on the road. California is the most likely state to be invaded by aliens from another planet. The transmission has been rebuilt and is the least likely component of the car to give you a problem.
If, as you drive around before making the trip, the transmission is functioning properly, then you can scratch off one worry. Highway driving is the easiest miles you can put on a car, so you can scratch the other car worries off your list. Military drones, as we speak, are searching out the aliens, so you will be safe there. In fact, your only worry now is not having something to worry about. Enjoy your trip.

Triedag is right. Make sure you do enough driving locally to be confident the fix is secure. Otherwise, expect it to give less trouble then components that haven’t been replaced. I am wondering though, if this is the mechanic who changed out the transmision, why he would have so little confidence ihis work.

Btw, isn’t it more reliable now then before it was in need of being replaced ?

And, hasn’t California been visited by “aliens” already…many times over ?

“And, hasn’t California been visited by “aliens” already…many times over ?”

Funny you mention that…

My Aunt Zora claimed to be kidnapped by aliens that took her away on a spaceship - while she lived in Los Angeles.

Drive on! Would you stay home if it was a new car? The worst that can happen is that the aliens that abducted my Aunt Zora will hit you with a tractor beam and pipe you up. But that seems just a bit unlikely, doesn’t it?

I wouldn’t pick up the car at the shop and immediately start a long trip. But, if you’ve had a few days with it and all is well, it should be fine. After a big repair I like to check for leaks and put a few miles on a car over a couple of days just be sure all the connections are tight, no leaks, and normal functioning.

I had a trans job on a car, ended up putting a quart of TF every 200 miles, road trip no time to stop for a repair, ended up trading away the problem, but monitor your fluids and u should be ok.

Maybe your mechanic was referring to the REST of the car. Surely he isn’t worried about the transmission he just overhauled. If he is, you need a new mechanic.

A properly rebuilt and installed tranny should have absolutely zero problems with a long trip. You should have many, many thousands of trouble free miles ahead. As a matter of fact, a long trip maintaining relatively constant speed is the easiest thing you can do to a tranny.

Varying speeds to properly break in mechanical things is an old custom that relates to engines. Engines have piston rings that slide up and down the cylinders, and the surfaces of the cylinders are specially prepared with controlled scratching (called “honing”) to allow proper intial wear by the rings to maintain a miniscule level of oil after the wiper rings go by to provide lubrication for the compression rings, which will be pushing against the cylinder walls. Avoiding beating on an engine was to allow that proper initial wear.

Additionally, the piston rings vary in their travel based on engine speed, and there was a concern that pistons always stopping at the same spot would create a “shelf” at the top of the cylinder that would interfere with their travel when you then ran the engine to higher speeds. Engines do, in fact, develop “shelves” over the miles that need to be reamed out to remove the piston/ring/connecting rod assemblages, but I don’t know that such a shelf developed in the first 1000 miles. OK4450 or one of the others here could probably clarify that.

Trannys have no pistons, rings, or honed cylinders. Automatic trannys have only hydraulic solenoids, gears, and frictional “bands”. They can’t wear in a destructive pattern the way cylinders might. The attached document might be a bit “deep”, but it shows that trannys don’t have the “rubbing up against” wear issues that engine cylinders have.

On any complex machine that has been recently assembled there is a chance for a mistake or oversight that can cause a failure. If you are hundreds of miles away from the shop where the work was done, you would have to get a tow back to have the warranty honored or use another shop which might not be able to honor the warranty.

A good 50 mile test drive out I-5 or I-405 towards the Ridge Route or a full speed pass up a long grade might be a good test of the transmission.

Hope this helps.