Engine brake when raining? Yes or no?

[ascdds]

The instructions for the engine brake states not to use it when raining or slippery roads.

"Using the retarder on wet or slippery roads may cause loss of traction on the drive wheels—your vehicle may slide out of control. To help avoid injury or property damage, turn the retarder enable to OFF when driving on wet or slippery roads."


Several people have told me that's BS and it's just lawyers being overly cautious to cover their butts. It seems to me that it would be more dangerous to go down a steep grade without the engine brake than it would be to use it if it's raining. This will be my first time in the mountains so I would love expert opinions on this.

[palehorse89]

You will be just fine using it on wet roads .....

[paddler1954]

I can see where it could be a problem. If you are driving on a road that hasn't seen any rain in a while then oil from passing vehicles can film over the road. Here you come charging down the hill, the brake retarder causes the transmission to downshift and the rear end locks up and skids. Remember your anti-lock brakes can't correct for the transmission/engine locking up the rear wheels. Course a quick stab of the go pedal would straighten you right up but most would hit the brake and compound the problem. Personally, I'd still use the retarder but your driving experiences may be different than mine.

[C.Martin]

I like your spirit!!!

But, as an operator...it’s my duty to follow the prescribed guidance. All my years as a bus test engineer (zero years, zilch, nada) prompts me NOT to stick out my neck.

You pose an interesting point...given the choice, wouldn’t it be safer to run thru the Mountains in the rain using the engine brake??? I ask better than what??? How about putting on the Captain hat for a minute and go with...if you think the grade requires engine braking to be safe...AND...the Engine Brake can lead to control loss in wet and slippery conditions...maybe park the rig, have some coffee...and wait for the weather to change...or find an alternate route with less grade. That would be my recommendation. But..you can still wave a tight fist in the air at all those lawyers!!! Grief!!!

I know I might sound like a fraidy cat...no, not really —— just someone that has had pretty good luck by following the safety guidance. When I was in the Military...we often felt it more important to “mission hack” than follow 100% of the written guidance if in wartime conditions and lives depended on getting supplies. I have to remind myself...driving a motor home...there is no “mission”. Just have fun, be conservative, and everyone will respect you for taking their safety into consideration.

I implore you as a friend...please don’t test the limits. If you by some slim possibility misjudge, the cost could be so much greater than a few hours or days of your time.

[palehorse89]

Most Coaches have close to 20k on the drive axle .........a 3 stage engine brake won't slide 4 big tire's with that much weight on them on just wet roads , ice....yes.

[Sweetbriar]

I think I would place that in the same column as cruise control in slippery, questionable or difficult driving conditions. At those times my preference is the coach changes speed at my command or intentional action. An example would be if I feel the coach hydroplaning and I let off on the throttle and I want to coach to just coast and bleed off speed and not do anything that could potentially complicate the problem.

[96 Wideglide]

Only time I leave mine off is snow or ice.

[ftodaro]

I am not an expert but my opinion is that the engine brake is likely softer on the overall degree of speed change than hitting the brakes. Its the amount or degree of your change in speed that upsets the control of your rig. so if your slowing gradually, all is good. if you begin your dissent at a lower speed to start you should be in good shape.

[Nellybelle]

I have no experience with a engine break. However I do tend to follow owners manuals.

[Domo]

Funny how the amateur drivers (less than 50K miles on the same rig) want to believe they have better experiences and knowledge than the design teams and engineers that built and tested our equipment under adverse conditions and published guidelines to keep us alive, the gear in one piece and themselves from being sued.

I like the recommendation that if you think the conditions warrant some change in operation, then maybe you should stop, have a cup of coffee and wait.

I've no desire to cruise down a 6% grade in pouring rain and "hope" I've made the correct decision...

[docj]

My engine brake is set to drop the transmission to 4th at the same time the brake is engaged. This can create a bit of "shudder" which, I presume, could possibly cause the rear axle to slip. My solution to this is to manually drop the transmission to 4th; that way one can hardly notice when the engine brake engages. My MH is geared so that I can easily maintain ~65mph in 4th which is faster than I would want to drive in a rain, anyway.

[Crasher]

Let me tell you what can happen when you drive on a rain slick road with the exhaust brake engaged. I was going south out of Corpus Christi in our then new 1996 36' Discovery just after a heavy downpour that had let up to a light mist. It was on a two lane asphalt road and I had just crossed a bridge over a canal. I was going 40 mph and let off the power for a slight curve after the bridge. The EB engaged and immediately shifted to a lower gear. When that happened, the rear wheels broke loose and I found myself sliding broadside taking up half of the other lane with an oncoming car. I instinctively turned into the slide and applied a little power which disengaged the EB and shifted up a gear. The coach came back into my lane and the car went past. It scared the cra* out of me, my wife and 14 year old grandson. That was 12 years ago and all of us remember it like it was last week. Now whenever we're driving in the rain, my wife reminds me to turn the EB off along with the cruise control. We like safety better than stupidity. So the next time some unknowing expert tells you that running with the EB on when the roads are wet is not a problem, tell him he doesn't have a clue as to what can happen.

[Superburban]

A good friend of mine drove over 20 years for SEPTA (Phliiy area) transit. If they were caught with the engine brake switch turned on in the rain, it was automatic dismissal.



Compared to the foot brake? 1 axle providing braking force, compared to all the axles with the foot brake. With the power of todays engine brakes, I think the chance of braking traction, is greater then engine brakes of the past.



If you have a tag axle, one could argue that even with the drive axle locked up, the tag axle will provide some traction, and help maintain control.



Plenty of arguments either way, but are you willing to bet your life, and others on the factory manual being wrong? I don't think there is a vehicle manual written that does not say to turn off the engine brake in bad weather. Thats lots of lawyers talking, I would bet they have some experience in why its written that way. Its one of those things that others could get away with it a million times, But that does not make it any safer for you.



The biggest issue with the Jake brake, is when you do loose traction, you immediately start sliding in the direction of the road crown, or outward on a turn. But your first reaction is to hit the brakes, and not think of the engine brake causing the spin, so you will just keep on spinning. If you are prepared, and looking for the traction loss, you could think quickly, and turn the engine brake off, and maybe regain control. But will you think quick enough?


My opinion, the best jake brake setup, is with many of the military trucks, the jake is activated by the driver Via a pedal on the left side. Something starts going wrong, the first instinct may be to lift your foot off the Jake brake pedal. Took me a long time to get used to the Jake brake coming on when you lift your foot off the throttle.


At least do everyone else on the road a favor, and set the Jake to the lowest setting. Also be prepared on how you are going to explain to the insurance company how you lost control, by doing something that is not written anywhere is a safe thing to do. That will also just feed the righteous warriors that think RV drivers should be licensed like truck drivers.

[FIRE UP]

Well Gang,
Every situation, every rig, every set of tires, every road, and more, ARE ALL DIFFERENT. How one rig handles a given situation with any of the three brakes mentioned, Exhaust brake, 3-stage Jake Brake, and Retarder, is gonna be different than just about any other rig with either the same auxiliary braking system or another version. Tire age, rubber resilience, loading of the rear axle and or even tandem, will act differently. It's a standard instruction for any heavy chassis maker to post warnings of use of auxiliary braking in inclement weather conditions.

We had the same warnings on the dash of all our fire trucks. One of the important factors here is EXPERIENCE. The more one drove in ugly weather and, used available auxiliary braking systems, the more one got used to what to expect.

The answer to the OPs questions is, if you're not comfortable with the use of whatever kind of auxiliary braking you have, in inclement weather, DON'T USE IT, it's not rocket science. But, if you've got plenty of time behind the wheel of heavier coaches with different kinds of auxiliary braking and, have used them in various weather conditions with positive results, well, then the "engineers" are not the only ones on the planet with education and experience with these kinds of conditions. Your choice.
Scott