Mountain Driving

[Bigwiz]

I am new to the forum and have a concern about the proper way to drive down steep grades. I have a 2004 Monaco Monarch 36DBD with a Allison 1000 with overdrive and NO grade brake. The previous owner said all he did was take off the overdrive and let the transmission do the work. But I would like some feed back from other owners with similar setups so I don't over use the brakes. Should I keep it in drive and let the transmission do the work or drop it into 3rd and drop the speed at the crest? Any info would be appreciated.

[Petro]

Bigwiz;

Welcome to IRV2. I believe you have found the friendliest site on the Internet. I also have a Allison 5 speed transmission. The procedure I use is to shut off the over drive and shift the transmission to the same gear going down as it used going up. I only have to occasionally brake if the RPMs increase to much. I try to keep the RPMs at or under 4500.

Don

[edgray]

Quote:

Should I keep it in drive and let the transmission do the work or.....

Bigwiz: WELCOME to iRV2.com We are glad you've now posted your first question.

Generally speaking, its a good idea to turn off the OD when driving in mountains, that way you will only achieve 4th gear. The general rule is to go down the slope in the lowest gear used to get up to the crest. BEFORE you begin your descent and start to gain speed, manually put it in 3rd, or even 2nd if the downslope is really steep, to create the maximum engine braking. You can always upshift if the speed is too slow, and another downshift back to a lower gear is also possible, if necessary, because the Allison will not let you do it any harm.

"If" you need to apply the service brakes, do it firmly for brief periods of time and release. Repeat as necessary. Only in case of emergency should you apply the foot operated "parking" brake, which is on the drive shaft, but it can be used to help slow the MH if absolutely necessary.

Again, Welcome!
ED

[Lued]

This winter was my first trip with our 2003 Bounder with the Allison 1000, The gear i used going up is the one I started off with going down, depending on grade. Omaha to Lake Havasu AZ it did just fine, only hit 3rd gear once, Going the southern route.

[max49]

Not only drop it out of overdrive, drop down as many gears as it takes, so you need almost no brakes. Down a 6 / 7% is always 2nd gear for me unless it's snowy/ icy/ sketchy, then it's 1 st gear. Going up a 7% always gets to be a 1st gear before I summit.
These transmissions don't know how long the grade is, you be the boss.

[dieselclacker]

Its a good idea to know how many RPMs your engine turns in each gear at a given speed. I use third gear quite a lot on my Allison 5 speed for decending up to 6% grades, depending on the length of the grade. I try to keep the RPM down to 4000 while decending. Stab the brakes hard and sparingly to keep below the RPM you choose, then as it approaches this set RPM repeat the braking. Works for me. As Ed says above, the Allison won't let you over RPM the engine in the lower gears, also won't let you engage the lower gears if your speed is too great and would cause harm to engine or transmission, so be careful, and be in low enough gear to decend the grade before attaining too much speed.

Dieselclacker

[Clay L]

Using the same gear going down that you used going up only makes sense if you are going back down the same road.
Most of us going from point A to point B and crossing a pass go up a grade and then continue on. The downgrade is rarely the same as the upgrade was and the proper thing to do is use whatever gear keeps you from having to use your brakes much.

[MaverickBBD]

Let me add my welcome. You got some great advice here. Generally, no overdrive, same gear down as up. The only things I would add is to watch your transmission temp if that is a possibility and remember "you can go down a hill a thousand times too slow but only once too fast".

[Bigwiz]

Thank you to all for the great advice. One last question. Will the shift selector show you what gear you are in as you are ascending a grade and the trans. is automatically down shifting? Or will it show you the gear you originally selected? I have only had it on flat land so far and have no idea. Thanks in advance.

[edgray]

Quote:

Will the shift selector show you what gear you are in as you are ascending a grade and the trans. is automatically down shifting?

BIGWIZ: No, only the gear YOU selected will be indicated. One advantage of locking out the OD is that you then have one less downsift to keep track off. Be aware, steep inclines will often require the tranny to auto DS into third, and you'll definitely be aware if it goes down to 2nd. ED

[dieselclacker]

Bigwiz, the shift indicator will NOT indicate what gear the transmission is operating in when you are in Drive position. The Allison in your motorhome has 5 different gears including Overdrive, and will be engaged in one of these at any given time depending on speed, load, engine RPM etc. The transmisssion will NOT however select a lower gear by its self when decending steep grades.


Dieselclacker

[Bigwiz]

Thanks again for all the great advice. It will be extremely helpful.

[CarlaT]

I do not want to hijack the OPs orignal question, but I am still confused. So how do I know what RPM is for what gear in the MH. If my goal is shift it down to what ever gear it used to get up how would I know the gear? I assume I am trying to keep the coach below 4000-4500 RPM.

[DriVer]

Quote:

Originally posted by CarlaT: I assume I am trying to keep the coach below 4000-4500 RPM.

CarlaT, Unless you have a lot of seat time OR if you own a 6 speed Allison transmission you may not know exactly what gear you are in.

Put the pedal to the metal and allow the computers to determine which gear is needed to climb the grade. On the 6 speeds the IP will show you the selected gear and the gear that the transmission is currently in.