allison tranny

[loghauler191]

well brought our 97 American dream home last night love the way it handles and drives question is going down hill is there a way to lock the tranny in a certain gear to keep it from shifting down to low over reving the motor by the way am using the pac brake to save on brakes

[wolfe10]

loghauler191 wrote:
all this is very helpful and I did not know some of this yet but not to old to learn what I was really after was on a gentle hill that you can safely roll down 60-62 with pac brake on not having to use any brake but keep the tranny from shifting down maybe iam expecting to much

The only way to have the exhaust brake on and NOT downshift TOWARD (not directly TO) the pre-select gear (the one in your left shift window/only shift window) is to have an Allison dealer program in a higher pre-select gear for the exhaust brake.

While 2nd and 4th are popular pre-select gears, I have mine set to 5th-- personal choice.

BTW, some of the information posted here does NOT apply to your Allison 3000 transmission (such as grade brake).

[deadbat]

loghauler191 wrote:
all this is very helpful and I did not know some of this yet but not to old to learn what I was really after was on a gentle hill that you can safely roll down 60-62 with pac brake on not having to use any brake but keep the tranny from shifting down maybe iam expecting to much

JimM68 post is about right on.plus
Does not work like that.Your exhaust brake is an assist device.it can not stop your vehicle.its an aid so u dont overheat your service brakes on long steeper downhill grades.The engine has to see high RPM for the exhaust brake to work most effectivly plus the lower gear assists in holdback.its designed to shift down thats the way the system works.I have never seen or heard of a 3000 allison down shifting by tapping the brake pedal.Not sure what thats all about?
nor have I heard of cruise having to be on?
quote:In order for it to shift down on a downgrade we must have have the cruise control engaged? That just does not make sense to me at all?
If you have a exhaust brake and its switched on as soon as u release the fuel pedal the engine brake will engage and trans will downshift

[loghauler191]

thank you very much very helpful info

[wny_pat1]

I believe OP's coach has a Allison Allison MD3060 six speed overdrive transmission. It can be set up by Allison to operate several different ways to fit the owners preference. A visit to you local Allison dealer should explain all the setup options for the transmission. If you are lucky, the transmission also may have a Allison Retarder. It is a option for that transmission. Much better than any Pac Brake!!!

I believe OP's Coach also has a Pac Brake retarder, which may or may not work, depending. You need to use "Pac Brake Lub" on it frequently to keep it working. You can find at a Pac Brake dealer or on ebay. some use Tri-flow lube. PAC brake's PRXB is the new, much improved verison. In your case, I would opt for the Allison retarder!!!

Your manual, if you don't have one: http://fleetwoodrv.com/partsandservice/manuals/1997_AMERICAN_DREAM.pdf. It covers the transmission and Pac brake operation.

[loghauler191]

all this is very helpful and I did not know some of this yet but not to old to learn what I was really after was on a gentle hill that you can safely roll down 60-62 with pac brake on not having to use any brake but keep the tranny from shifting down maybe iam expecting to much

[JimM68]

there are a few different ways the allison braking can be programmed.

Most common is "with the engine brake (pac brake) switch on, lifting off the throttle will engage the exhaust brake and signal the trans to head for second gear.
The trans will downshift as it can for max braking.
Th rpm limits in this case are much higher than what the engine will achieve accelerating.

It will not let your engine rev too high ever.

[donn0128]

If it is the Allison 1000 transmission then it should have the grade brake feature. To activate it on a down hill tap the brake and you should hear the transmission upshift one gear, and the RPM climb significantly.

[Canadian_Rainbi]

I'm not sure that all Allisons have a Grade Brake as such. Our 2002 DP does not have anything marked as such.

In order for it to shift down on a downgrade we must have have the cruise control engaged. This works well for most gentle hills. We switch on the exhaust brake and if cruise is selected it does add more speed control to the transmission on the hills, but the exhaust brake itself will not engage until we touch the service brake pedal. This of course turns the cruise control off.

You need to use the service brake to get you down to a speed where the exhaust brake and transmission will hold you at steady speed. We have descended many very long 6% grades an not touched the service brake after the first few times.

Our exhaust brake sets the transmission to select 2ng gear (it is a 6 speed Allison) but of course second gear will not engage if we are going too fast for it, which is of course the case at highway speeds. Normally it selects 3rd or 4th. If the speed gets too high for engine RPM the transmission will shift up. Hence the need for using the service brake to find the right speed to descend the hill.

A little practice and it will soon become second nature.

We love our Allion and Exhaust break. So much easier to drive in mountainous country than the gasser we had before.

[Peralko]

Your ECM will keep the engine from overreving. If the RPMs get too high for the good of the engine, the tranny will shift to a higher gear.

[donn0128]

No. The Allison has what is called grade brake. You tap the brakes once going down hill and it sends a signal to downshift. Over revving is perfectly safe and the way the transmission was designed.