good gears for mountain driving

Too many variables, particularly gross weight. a 1% difference in grade can make a huge difference, a 10,000 lb gross change can make a huge difference. Even high winds can affect a decent on a steep, long grade. Engine braking effectiveness varies with every trucks. Might be gear 7, might be gear 6, might be gear 8. Start conservative, if you find you need to brake in the first 1/4 mile to keep speed in check, brake some more, then carefully drop a gear. But not all grades are consistent from top to bottom and this adds all sorts of other potential issues

Experience is the best tool to have here. Experience with trucks and weight and experience with the particular grade in question. Better to err on the side of over-cautious until you gain experience and learn the grade, but remember, going down with no need to stop mid-way, and going down with the ABILITY to stop mid-way down are two different things. Too many assume the best and go down much faster than would be safe if they had to stop inside of a quarter mile due to a crash around a curve.

 

As STexan said, there's too many variables to answer that correctly. Your rear end ratio, engine and transmission all play in to this. As well as weight, grade, and even road conditions.

Take Big Savage mountain in Maryland on I-68. My old truck had a 13 speed with 3.36 rears. I'd go down at 80k in 8th, and hardly ever touch the brakes, and maintain 45mph. This new one has a 10 speed with 3.73 rears. At 80k, I'm going down in 7th, never using the brakes, and actually having to accelerate on the flat spots of the hill.

Unfortunately, Only experience will answer your question.

 

In my experience any gearing at 3.42 or lower is terrible for a 60 series on down grades you will never hold speed unless brakes are used with Jakes.
ISX Jakes hold much better.
DD engines hold nice on grades with 2.38 gearing and direct 10 speeds.

 

Never mind. I erased my comment.

I've been trucking all day and I'm tired.
I thunk he meant for climbing... til I read it again.

I'm going to bed

 

If you are gaining speed when the service brake is off and your engine brake is on, downshift. Use service brake to bring RPM low enough to get in the lower gear.

Continue process until the fire is out on the trailer brakes.

 

It what ever gear will hold the truck back with 10psi or less of brake pressure. If your truck has applied brake Aire pressure gauge.

You use the bakes to get you down the hill because in the winter you don't want to use the engine brake or if the engine brakes goes out you still want to be able to go downhill.

You use the engine brake to go downhill faster ! Using the engine brake and the regular brakes you can go faster then just using regular brakes.

 

Rear end gears are irrelevant uphill or downhill on steep grades if you have transmission in proper gear to maintain desired rpm .. some are a bit better than others but mainly in top gear

 

My Pete has a eaton 13, rears at 3:55, I run loaded at 79500 to 80000 never have a problem going up or down