Travel through Yosemite National Park

Most all automatic transmissions will force an up shift to protect the engine and thankfully we learned that by accident at Mount Rushmore on the third day of our trip to the Pacific. After one knows the RPM a force up shift will occur you know when to hit the brakes.

Apples and oranges but we went in on 120 by Old Priest Run by accident and when out by 41. In our 454 gas engine we were in 1st or second the entire drive due to speed zones. We never had to use the brakes for speed control.

By the way forced up shifts occur at about 4500 RPM in our 454 TBI gas engine. Actually on our trip to the Pacific out by Yellowstone and back by Grand Canyon we did not find grades that required braking for speed control but gas engines naturally over better engine braking without mods.

Yup, the Allison will upshift rather than over rev and destroy the engine. Every upshift means less exhaust brake action and higher speeds as you speed up going down hill. This is why this type of brake is the least effective of the three types. But it's also the cheapest so a lot of us have this type of brake.

All you have to worry about is if the road is open or not. If it's open you won't be the only motorhome on the road. And everybody else on the road (for the most part) is only on the road to enjoy the scenery and the park. The speed limit is I think 40 on the entire road in the park anyway and there are turnouts. Whenever I've been through there I don't recall having to use the turnouts very often at all as I've generally been able to keep up with the flow of traffic. And the road elevation doesn't go over 10,000.

thebunns....If you're just planning on driving through and not staying, I think I would go around. When you enter Yosemite from the west side, you either go into the Yosemite Valley which is always open, but does not go through to the east side, or you enter Yosemite and drive through Tuoleme (sp) Meadows to Hwy 395. As others stated, it depends on snow fall as to when the road opens. There will be a lot of windy roads, but we drive into Yosemite Valley every year at Thanksgiving with our 36' DP.

Here is what I like to do when climbing into the park from the west side. Once I start climbing and the road gets curvy, I drop down several gears, either into third or fourth and then leave it there. This prevents the coach from shifting/searching so much and losing power.

We drove down the Teton Pass by accident a few years ago and my wife went into the bedroom and prayed....I couldn't help but laugh. She didn't find it funny. My exhaust brake didn't do well and I was towing a 4500 pound truck. The truck had brakes, but you can't activate them like you would on a trailer. I did get my brakes hot, but I also learned something I never knew about the Allison transmission.

If you're using your exhaust brake and it isn't holding you back, the engine will keep increasing in rpm's and the Allison will eventually UPSHIFT. So even if you get all the way down to second gear and you're once again gaining speed, you can't stop the Allison from upshifting.

On the Teton grade, I brought the coach to a complete stop in a turn out to let the brakes cool. Once they cooled, I decided I would start out locked in first and see how far it would go before upshifting. To my surprise, the Allison will upshift out of 2nd, 3rd, 4th and 5th, but not 1st. I was slow, but I made it down without any issues. People will just have to wait.

Usually never go lower than third gear.

I suspect that many RVers are clueless about driving a rig in the mountains. Several years ago I met 5 families in Yellowstone.

They came down the Teton Pass grade into Jackson, WY. At Wilson there was a sign "Free coffee and dounts while we repair your brakes". 3 of the 5 took advantage of that offer and spent $3K each for brake repairs. :o

One of the 5 decided to attend the Jackson video on safe mountain driving. :B

thebunns wrote:
If I decide to use first gear on downgrades will I hold up traffic

First and foremost do what is safe for you and then and only then consider others.

You left out what kind of brake you have and there are 3 basic types. Most rigs have an exhaust brake and there are many variations on that type. I don't know your rig but I doubt that you can downshift to 1st and still use the exaust brake. 2nd is more likely. You definitely want the exaust brake engaged.

If you do have a typical exaust brake then on that grade expect to also be using the service brakes. Most recommend not pumping air brakes if that is what you have as you could significantly lower the air pressure.

Winter snowfall will determine the opening date. I tried to wait it out the spring of 2011. I had to leave before it opened on June 18. Tioga Road opening dates

You better heck road conditions and closings before you go as Tioga pass is not always open in June. I travel 395 frequently and am always amazed some years how late it opens.

Tioga pass is just under 10,000'
Take your time and use turnouts when safe and you will be fine.