[Archived]

Jake Brake use has no effect on fuel mileage.

The only time I don’t use my Jake is on very slick roadways, like snow and ice. Engaging the Jake on slick roads can result in skid.

[Andy]

Very good point about the use of supplemental braking. Avoid its use on slippery surfaces. Both types of supplemental systems can apply the equivalent of a lot of horsepower of braking force to the drive axle which can result in an unintended skid. Using your foot to modulate the braking force or allowing the ABS to control the brake application is your best option. Of course the way to avoid those situations where you risk a skid is to keep a long stopping distance between you and the car ahead.

I think you do lose some mileage from the use of supplemental braking but only if you use it to maintain your cruise control set speed. There are times I leave it off and allow the coach to build up speed by itself on the downhill side so as I approach the next uphill I am carrying a little extra speed which allows me to delay getting back on the gas. But that is nit picking, because if the hills are steep I don’t do that often, but instead rely on the retarder and the cruise control to function in concert with one another.

[Archived]

Remember, ABS should be deactivated if there is ice about. The best way to stop on ice is to lock up the wheels and wait. If you use ABS, it will just keep releasing the brake when it senses it locking and on ice, this is a never ending feedback loop. The same applies on gravel but I doubt that anyone driving a bus is likely to be doing more that a few mph.

[Archived]

Andy, that is contrary to everything I have read about ABS.

First a disclaimer…….I seriously doubt anyone will ever be driving on solid ice. I have a lot of years of experience living and driving in the snow belt of Western NY state in a county that had annual smow fall averages of 240″ Despite the never ending crappy weather I have never encountered glare ice other than in very short or limited sections, usually bridges. Anything other than glare ice will allow some form of braking.

Since 1987 my vehicles had ABS. When attempting to stop on slippery surfaces the owners manual said do not pump the brakes, but to apply a hard steady braking force. Ideally I could modulate my braking force on the pedal and avoid hearing and feeling the pulsing of the ABS, but there were times I knew it was functioning.

Our coaches employ a similar ABS system so like our cars we can modulate the pedal pressure to prevent lock up, but it one wheel slows more than the others the ABS modulating valve is going to release air pressure to that brake and as soon as the wheel speed matches the others air pressure will be re-applied.

I know of no ABS system on our cars or coaches that can be over ridden by a manual swich. Stability systems on some cars can be disabled, but that is to regulate slipping and sliding during turns at excessive speeds. Maybe owners of newer coaches with stability control can post if the stability control system can be turned off.

It is true an ABS system disables the braking force on a wheel that is experiencing impending lock-up, but the ABS is not really reducing the total braking ability of a vehicle. If there were no ABS and a wheel did lock up its braking force is almost zero anyway. What the ABS is trying to do is regulate the braking to create a braking force just short of wheel lock up which is the most efficient way of maximizing braking force.

[Archived]

Jon,

Agree ABS is unlikely to be able to be deactivated unlike stability systems. (I can deactivate on my BMW Adventure for gravel riding). However, what I have read and just re-read to double check, is that on ice or more likely compacted snow, ABS does increase braking distance. ABS also releases the brake (per wheel) after it has locked up, albeit milliseconds after, rather than just before lock-up.

That said, I bow to your many years of bus-driving experience in worse conditions than we generally get over here.

Back to Jake brakes……

[joel]

As I think ahead to the day I have my Coach I think about the stretch of Interstate from Flagstaff to Sedona where the drop is from 7K to 4k in 20 miles. This is is 6% grade on parts of the route. From what I am gathering; if you are driving on snowy roads with 6% drop grades is it best to not travel down if the Jake or Retard brake is not to be used in Snow or Icy conditions. I feel a little pucker everytime I go down that grade with a van and small trailer on day dry roads thinking all that can go wrong with that degree of decent and road curves, I would need Depends if I took the Coach down at night or when it was raining, snowy or icy and not have the benefits of the brake assist. Not much room for error and lots of fatal dropoff points along the way. Now my question: when mountain driving; is the recommendation to drive only in ideal condition when you can use the Jake or Retard Brakes?

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1999 XLV X-6872,  liberty #440

[Jim/Chris]

Just go slow and get in the right gear for the down hill, if it is real icy just the Allison Trans shifting down on its own or with u doing it can cause it to slide on ice, the Trans has a lot of power behind it , sometimes in real bad roads coming up to a stop light I put the Trans in neutral so it does not shift down and cause it to slip on the ice

[orren]

Andy,

The reason I mentioned how few times the ABS kicked in when I was driving in the Miami of the north (western NY) is because I modulated the brakes in the same fashion you learn to modulate the gas pedal to get moving. The reason ABS and stability control underperform is because skilled drivers (I’m not claiming to be one) can push their vehicles to the ragged edge, and like highly skilled aerobatic pilots and race car drivers they get a sense of what is happening with the vehicle. Some use the term “seat of the pants” to describe their feel for what is happening. But for people who rarely push their cars to the limit and thus lack a sense of what is happening ABS is ideal because it is far better than a poke in the eye with a sharp stick. All they have to do is stomp hard on the brakes and let the ABS do the best it can which is probably a lot better than locking the brakes, losing not only the ability to stop quickly, but at the same time losing the ability to steer.

There was a time in my life when my daily driver was a split window Corvette. I ran that all year long in shitty conditions, deep snow, slippery highway surfaces and with the exception of one 360 degree spin I was always able to get where I needed to go. When I spun it I was just lucky because I entered a turn too fast, it snapped around and I ended up exiting the turn pointed in the right direction without ever leaving the road. The key was and is to not overdrive the conditions and plan way way ahead.

[Archived]

Peter,

I think the fumes at Jeff’s might have got to ya, putting the tranny in neutral while stopping in icy conditions make no sense to me. In all my winter trucking in upstate NY, we measured snow by the foot, bumping the tranny to neutral trying to slow for a stop would be worse than staying in gear.

This should be an interesting thread, your turn big boy.

[AL]

In some of are big trucks when the Trans down shifts if its icy it will lock up the wheels on the drive axle for a bit then catch up because of torque from the Trans , I am talking about the Allison Trans your turn buddy

[Archived]

Until we moved to TN we never had an automatic so if you are driving a big truck with an automatic and it drops a gear without any input from you to a gear low enough to make the tires slip I can understand putting it in neutral. But in the winter, in my driving experience you were always lugging the engine to maintain pulling traction because if the gear was too low, even a slight push on the gas pedal spun the tires, and if you lifted from the gas the drag caused by engine compression combined with the low gearing would allow the rear tires to break free.

Tom is right on the money about never putting it in neutral because in the event of an impending slide or skid, lifting off the gas allowed a slight drag on the rear wheels which kept the car pointed straight. With trucks extra special care was required, including speeds much lower than what cars might want to do because the trailer often had a mind of its own and traction was needed on every axle. It is pretty scary seeing the trailer swing sideways filling your mirror and sometimes the only way to save the whole rig was to try to accelerate.

We opted for manual transmissions while we lived in NY because we could exercise better control. There were many times we watched the two foot automatic drivers have their front brakes locked, while the rears were still spinning. I’ll bet Tom has seen that a lot, and it is because of those drivers that ABS was invented.

[Bruce]

I disagree I am not talking about trucks with trailers , I am talking about single axle deck trucks not tandem wheels the deck trucks are light and will do that when empty coming up to a light that everybody has spun there tires to get going and is very icy

[Archived]

We’ll have to either disagree or qualify our comments. I put a lot of miles on single axle flatbed trucks both manual and the occasional automatic. I never put the automatic in neutral, and I never pushed in the clutch until I was down to idle speed. I do not think the one automatic we owned pushed the rear wheels like the bus with its Allison does. However I had about 200,000 miles of driving our first coach in western NY, probably 1/3 to 1/2 those miles in the winter and I never put the bus in neutral. I have had a bus break loose on the rear but lifting off the throttle brought it back in line.

[Paul]

I don’t think as far as the bus is concerned the Trans would do that because of the weight , but as far as the deck trucks it will with the Allison Trans , that’s my case and we have 30 deck trucks that run in the worst weather everyday and mountain roads , I am not saying you would do that all the time but if conditions are right u may have too

[Ken]

COME TO FLORIDA and eliminate the whole problem. Ice only in our drinks here.