Driving from Tulsa to Phoenix through Flagstaff and south on I-17. Yikes!

Here is where my inexperience shines through. I need advice please. I'm concerned about my drive because I've never had to tackle a 6% downhill grade in my Prevost. The downhill grade from Flagstaff I here is long and steep. Never been there and if its bad then I might just add 200 miles and drive south to I-10 and not worry. I really want to see Flagstaff and not worry. Can someone tell me what gear to put the rig in and do I leave the second stage Jake on the whole way? Rookie question I know, just trying to be prepared.

Michael Faul
98 CC 45'

Michael, I would keep the Jake on high and progressively down shift as you need to in order to maintain a safe speed. As a general rule, whatever gear the bus shifts to when climbing the hill should be used when descending. I've gone down some pretty steep mountains in Wyoming and never had a problem. I'm sure others will give more advice.

I usually slow to about 50 MPH when approaching a down hill grade and then set my Trans. retarder to maintain that speed. I will use my brake as needed tamping on it. The Trans retarder usually takes it down to 5th or 4th gear. I have seen some long downhill runs and not had a problem .

The general rule of thumb is " you go down the mountain in the same gear you went up it in". For example, if you went up in fourth you will come down in fourth gear. I also leave the Jake on. Be careful to not ride the brakes on the way down or you may not have any at the bottom. If you feel you are going too fast drop down another gear. This will increase the RPM and cause the Jake to operate more effectively. The Jake's best performance is at 1800 RPM and above. Don't worry if you are holding up traffic, let them pass you if they can or stay behind you. Just worry about yourself reaching the bottom safely.

if you have to apply the brakes use the stab method. That is apply sufficient brake pressure to drop your speed 5 miles per hour and when it gains that 5 apply brakes again. I have not driven the road you will be on but I have found that with the proper gear and the Jake on I rarely have to apply the brakes going downhill.

All good advise. Only thing I can add is to be aware of your rpm's. Remember your redline. If you have the Country Coach glass dash it also shows what gear you are in. As Denny said the best help from the Jake is around 1800. If you are on a down hill run at 1800 and you are still gaining speed you cant downshift until you slow it down with your brakes or your rpm's would exceed the red line in the next lower gear. With a little practice you will become proficient. If you are in a gear with rpm's that seem good and your road speed seems a little to slow try the low Jake setting before shifting up a gear. You can always toggle between low and high to maintain speed.

Dale Gary and Denny Thank you! I'm not sure i will ever approach the drastic climb as I will be coming from the east on I-40. I could be wrong bu I think from them map ill start descending before I climb. I know I have go up to go down I think it's gradual over many miles. Second stupid question... I don't think I have a transmission retarder or is that the same as my button that reads low jake, high jake? I was worried about overheating my Allison and redline for sure and this all helps. I'll be white knuckle for sure!

Well check it out. Where am I? The truckers forum? Safest bunch on the road that's what's going on here. Give yourselves a pat on the back. All suggestions that a pro would give.

Dales advice is great (same gear going up as going down). I don't have Jakes and never had a single problem out west last summer. Actually, hardly used the brakes at all on most decents. When I did, I used the stab method to drop ~5 mph usually for a switchback corner or to keep the engine below redline.

As a side note - I have a manual transmission and not an automatic - but I suspect the above would apply based the other comments.

Be safe and Have fun!

Mike, Relax first of all. You have a Jake, just leave it on and in high all the time. Your transmission will automatically downshift as needed as you climb. I have found (in our 2000XL that we had) that 4th gear selected with Jake on high worked well on any downgrade. I'm assuming that will work the same on our H, as its the same engine, trans and Jake, unless the added weight changes it.

Corey you are right. I just need to relax. I'm going for it, leaving the Jake high and downshifting to forth or whatever it is, and making the trip. Thanks for the tips, everyone! I love this forum.

Michael, Good advise from all. Best suggestion was relax. Many of us have been all over the country west to east, north to south, some of us have a lot of miles under our belts some not so many but regardless I can't remember the last time a member reported going off a cliff. ;) I have a jake in my bus and have gone up and down some serious grades with very little pucker up factor involved. As stated leave the jake on high and stab the brakes as needed to maintain a comfortable speed and don't worry about holding up cars behind you. They'll get over it. Some of the best scenery in the country are on roads and highways that are not the best suited for our buses. But if your like a lot of us we bought our buses so we could enjoy those areas.

All great advice. I drove some really steep long descents coming from WA to Yellowstone. Start your descent at a reasonably slow speed; 45-50mph. Keep the Jake on high.

After you do this once you will realize it's not too difficult.

Keep an eye on your transmission temperature and you'll be fine. It's doubtful that you have a transmission retarder.

The road is wide, and the turns are not tight. You will be fine in High Jake & 5th Gear. When you get down towards Black Canyon, the turns are a little tighter. If you are not comfortable at 55-60MPH, drop down to 4th, andf it will keep you around 50MPH.

Adding a bit to Steve's advice. When in any lower gear the transmission will shift up at around 2100RPM, use stab breaking to keep it below the shift point (until you're ready to shift up of course). Monitoring RPM as well as speed will allow you to use the Jake to its best advantage and keep you from shifting up before you are ready to. Slowing to about 1500RPM will cause a shift to the next lower gear.

Mike & Cindy, while never a professional driver of any sort, in our 7 yrs with our bus, this past summer we elected to take US30 West from York , PA towards the PA Turnpike, being forwarned about the grades. In Arkansas & Colorado we've gained confidence, but US30 was a good challenge. Result, slow but steady and now feel much more confident that we can go about anywhere we want. Take it easy and you will do well. US 30 was not 4 lane either.

Make sure you downshift at top of hill and don't let the rpms get over 2100 coming down.

One item that has assisted me in navigating the mountain grades is using the elevation graph on the Garmin 770LMT. It uses a quarter of the screen to display a graph that spans 30 miles and shows you the elevation changes. This way you know when a hill or descent is coming and can be prepared for the elevation change.

Hey Andy I bet u r having a blast ain't ya!!

Do u take the bus out of cruise and drive it in the mountians? What have some of the grades and roads been so far?