[Corey]

Bill,

I manually shift on big hills, both up and down, old trucker habits are hard to break. As for the Jake, select the gear for downhill that will control your safe speed, keeping the rpm high (jake works better at high rpm) and you shouldn’t have to touch the brakes if your Jake is in the high position. We’re in Breckenridge and as an example, Jdub used 4th gear on the big hill west bound and never touched his brakes, the same hill that heated up my tranny temp with the retarder. On all the buses I have had, the Jake never needed any braking action to keep the speed under control, providing you select the right gear.

[Archived]

Bill, you can just leave the jake on in either hi or lo, which ever you prefer. If you don’t like it in town then turn it off there. It’s handy on the freeway or interstate because you’re not on the brake all the time. It will work automatically when you are in cruise without your throttle input. I go up and down normal inclines in cruise with jake on. On real steep downhills I usually go down in cruise, jake on in 4th gear and the most I ever have to do is fan the brake pedal possibly. Basically I just leave the jake on, our mufflers are good enough that it’s not obtrusive even outside the bus.

[granvil]

Bill,

Note what your top speed is in each gear. In my coach 4th gear tops at 55 MPH for example. The reason this is important is because if I climb a hill in 4th, then I want to go down the hill in the same gear. So at the top, beginning the descent I slow to a safe speed for 4th gear such as 50 MPH, manually downshift to 4th and then control the speed with my retarder (or jake in your case).

If the speed slides up towards my top speed in gear I apply hard short time duration braking until I am down to a safe speed again (45-50 mph). Do not pump your brakes. Do not drag your brakes. Do not hesitate to apply them to drop your speed back down, firmly if required. Do not exceed the top speed for the gear because you do not want the coach driving the engine.

Pumping brakes causes the loss of valuable air pressure. Dragging the brakes heats them up. Firm brake application and release slows the coach and then allows the brakes to cool before the next application of brakes.

Do not let people behind you intimidate you into going faster downhill than your comfort level allows. Our brakes suck on level ground. Don’t over use them because 50,000 or 60,000 pounds going downhill is a lot of energy that has to be managed. Instead use the jake or retarder in concert with the right transmission gear to help you safely down steep hills.

[Archived]

I have driven just about every hill in the USA and Canada that a big truck or bus can go on and some I should have not been on becarful going down hill do not be afraid of pushing on the brake to slow done to the gear you need it can get away from you quick nothing worse than going to fast down hill I never worry about how fast it goes up hill it’s the down hill that will get you you can always speed up if its to slow going down the hill

[Davy]

Guys,

Thanks for the input… Jon is there a resource somewhere for what is the upper limit for each gear or do you just pick that up from experience…. Honestly I will have to check not sure if the allison displays the gear you are currently in or the highest available… I know on my old coach until I got VMSPC I had no idea what gear I was actually in at any given time.

Thanks again for the input….

Bill

[Archived]

Bill,

I just manually shifted the transmission up through the gears, noting the speed at 2100 RPM in each gear.

The way our engine / transmissions are programmed to work together under normal driving we never see the speed at max RPM so you have to start out in first, and then arrow up through each succeeding gear, noting the MPH.

Or you can do it with math by noting a speed in each gear and the corresponding RPM using those two values to calculate the speed at 2100.

[Bob]

Bill, I will offer one addition to these valuable comments on use of your jake that I learned from a Greyhound driver trainer on another site. NEVER use the jake or retarder when the road is slippery. It risks locking the rear wheels and a possible sideways slide. The other valuable advice I took from that old bus warrior is to moderate speed as reaching the top of the grade, especially in wet or snowy conditions, as you sometimes can’t see what’s on the other side.

[Larry]

Guys,

Sorry to show my ignorance on this one but I am not sure I am totally tracking and I thing this is important that I keep asking quesitons until I understand… I don’t want to end up in the run away ramp or worse….

So first question for those of you who indicate that you are manually shifting… do you have an indication on your bus what gear you are actually in before you manually shift… Unless I am missing something while driving my allison display always shows 6… it might go to 4 when the jake is engaged I will have to check that

Full disclosure here… I haven’t ever manually shifted this bus or any previous coach I have had so I just wanted to make sure I wouldn’t screw it up so I haven’t done it just yet… is it as simple as hitting the up and down arrows on the keypad or is there more to read up on this… I haven’t been able to find the allison manuel yet but I am sure it’s somewhere in this stack of books…

Thanks for your patience guys!

Bill

[Bob]

My transmission selector, like yours, would display the top gear (highest) that the transmission will automatically shift to. That’s why it displays 6 when you first put it in gear.

To the best of my knowledge, the display will always display the top gear available. As you downshift, the display will decrease by one number to indicate the highest available gear. My display did not indicate the actual gear you were in unless you were in the highest gear available.

Just pay attention to the rpm’s, how many times either the tranny has shifted or you have hit the shift button, and you’ll quickly get the “feel” of it.

Once you try it you’ll find it’s much easier than it sounds.

[Archived]

Bill, some displays showed the selected gear and the gear you were in, some only showed the selected gear. As Paul noted if you hit “D” 6 is going to show up. If that is all that is displayed then you have to mentally track which gear you are in, something that becomes intuitive.

Through experience I just know the important number for descending hills is 4th gear tops at 55 at 2100 RPM. Your jake or my retarder work best at higher RPM so for me to descend a steep hill that I probably couldn’t climb at higher than 45 or 50 MPH I just know I need to be in 4th going down.

Perhaps the way I drive helps. As I approach steep hill climbs I build up a little speed to help me with momentum, but at the bottom I hit the down arrow and I drop to 5th. That is what my display shows. As I climb and the revs drop the transmission can not hold my speed in 5th so it eventually drops to 4th. The display still shows 5 but since it downshifted I know I am in 4th. I should mention I press the mode button so the coach will shift more agressively and hold a gear longer before upshifting.

The point is you start noting what speeds and gears you climb hills and the rule of thumb is the same are used for going down hill.

Don’t worry about down shifting too quick or picking too low a gear. Your transmission will not allow you to engage a gear that will over rev the engine. But do respect the fact that when going downhill the engine can be pushed to higher RPMs if you are manually in a low gear.

My first coach transmitted much more sound to the driver’s seat so I could both hear and feel the up and down shifts. Our newer coaches make it difficult for us to hear or sense transmission shifts so if you want to know speeds in gears start out by selecting 1, drive until your engine is at 2100 RPM, note the speed and arrow up one gear, noting the speed in 2 at 2100 RPM and so forth.

[Greg]

Allision transmits the actual gear your in. So, it can be displayed on SilverLeaf’s glass dash or their PC based product. I’m pretty sure it can also be displayed on Ray Davis’ iPad based system.

[Clifford]

The Jake brake in my coach auto-selects 3rd gear whenever it is engaged (speed permitting). I’m told that this “auto-downshift” feature can be reprogrammed be any Detriot Diesel shop.

i do find it a bit aggressive for my taste and may consider disabling it in favor of manual gear selection.

[Archived]

My transmission auto down shifted to 4th when the Jake is on. It takes the Allison techs less than 5 minutes to change it. Mine now down shifts to 5th and I manually down shift from there. Like others, I go down a hill in the lowest gear I went up the hill, unless the up and down grades and distances are a lot different. On long downhill runs is when I don’t like my brake light Jake brake activated as it stays on almost all the way down the hill. I haven’t pulled the relay because I like it all other times.

[Chris]

The problem with leaving the brake light relay in place is it drives traffic behind you nuts.

The brake lights come on every time your retarder or jake is engaged and if you leave them on they engage every time you or the cruise control lift off the throttle. And that is exactly how that causes road rage. Pass someone and pull back in lane. The minute you or cruise control lifts from the throttle to get back to target speed the brake lights are on. Doesn’t that drive you nuts when someone passes and then hits the brakes? They don’t know you haven’t hit the brakes.

I would bet serious money if you had an alarm that sounded in your ear every time that brake light engaged due to the retarder or brake that relay would be out of there in a NY minute.

[Archived]

Guys,

I was traveling from West Virginia to Louisville today and had some nice hills to practice manually shifting. I think I need to practice a bit more but it worked pretty well and the coach seemed to climb much better with me manually down shifting and descended very well too. So thanks for the help…

Couple of follow up questions… when ascending a hill…is there a rule of thumb RPM wise when a downshift is warrented…. I played around with it today and if I stayed in 6 until RPM dropped to around 1500 speed 50-55… if I manually downshifted… I got a 300-400 increase in RPM and the speed maintained or increased a bit when it seemed like it was going to bogg down.

And on the other end is what is the RPM high side that you all try to avoid exceeding?

Thanks for all the help!

Bill