Retarder and rain..

Topic: Retarder and rain.. (Read 2135 times) previous topic - next topic

Retarder and rain..

July 05, 2015, 07:50:07 pm

The book says turn the retarder off in the rain.
The book says gear down on the down grade.

While the weather is what God gives you, a saying among the cruising folks is "The worst thing you can have is a schedule".

Well, I have one that takes me down Fish Creek Pass on US 30. about 5-6% for almost 5 miles with a 30-40% chance of rain.

I would like some discussion re: Why turn the retarder off in the rain.
what type of moisture conditions ?
When I turn the windshield wipers on I turn the retarder off. Back on when the pavement looks relatively dry.

thanks

Re: Retarder and rain..

Reply #1 – July 05, 2015, 07:56:22 pm

I know is says that but I have rarely turned it off in the rain. I turn it off in the winter and slippery stuff if I get caught in it but not in the rain yet unless the rain is super heavy. I slow down in the rain though so maybe that makes a difference. Carried me well for 370K miles driving Foretravels so far. I do understand why you should but I try to figure out the road conditions and not just turn it off in the rain. I have delayed leaving if it is heavy rain or I have run ahead of it too. It is much better then driving in it.

Re: Retarder and rain..

Reply #2 – July 05, 2015, 08:02:36 pm

Elliott,

"Absolute" statements are more for lawyers than for drivers.

The reason for not using the retarder in wet conditions is the danger of locking the rear wheels.

If you keep your speed low enough that two things can happen: 1. retarder on light application and 2. rear wheels do not have the ability to lock up THEN absolutely use it.

Said another way: On dry pavement, at, say, 40 MPH you need to generate XX braking HP to keep your speed in equilibrium.

Applying that same braking HP on a wet road may lead to the rear wheels locking up (and the subsequent loss of effective steering). But, if the speed is reduced to, say 30 MPH, quite a lot less braking HP is needed. Not enough to lock up the rear wheels.

Re: Retarder and rain..

Reply #3 – July 05, 2015, 08:34:29 pm

I would agree with the two statements as well as a good dose of common goes a long way, When in doubt slow down!!

Re: Retarder and rain..

Reply #4 – July 06, 2015, 06:41:02 pm

Remember, its that first 15 minutes of rain, when the oils from the center of the road combine with the other pollutants and water to make soap - that's when its the most dangerous.
After that gets washed off the crown, things get a lot less slippery.

Re: Retarder and rain..

Reply #5 – July 06, 2015, 08:25:08 pm

And to add to my first comment, I also use the brake pedal when I want to slow or stop. That prevents just the back wheels from slowing but both the back, tag and fronts. If it is down hill I will slow down as Brett said, and use the retarder even if it dry.

Re: Retarder and rain..

Reply #6 – July 07, 2015, 12:18:50 pm

Has anyone here experienced rear wheel skids while using the retarder?

It seems to me, while using the retarder , the road surface would need to be much more slippery (ice) for the rear to break loose under retarder alone. If it were to break loose while also applying the service brakes, the ABS system would still release the disc brakes as needed when an individual wheel begins up slow too quickly. It's just that the residual retarder effect would still be there if we're a rear wheel. Front wheels would be ok.

Re: Retarder and rain..

Reply #7 – July 07, 2015, 12:59:44 pm

Quote from: Tom Lang – July 07, 2015, 12:18:50 pm

Has anyone here experienced rear wheel skids while using the retarder?

Great question Tom. There is alot of talk of this but I cannot remember anyone relating an actual occurance. Anyone? I understand the physics but have not yet read about an actual experience.

Re: Retarder and rain..

Reply #8 – July 07, 2015, 02:05:22 pm

If you have the rear end start to come around heading downhill in the rain, even the best driver will never catch it. Lots of YouTube videos of trucks losing the rear. Rain, early morning ice require more caution, especially braking.

Pierce

Re: Retarder and rain..

Reply #9 – July 07, 2015, 02:15:01 pm

Anytime the rear breaks loose and it starts sideways, being heavier than the front, the rear will try to beat the front end to the bottom of the hill or what ever, every time, just picture where the toad winds up in this sperience

Re: Retarder and rain..

Reply #10 – July 07, 2015, 03:02:46 pm

But will the rear break loose in rain where only the retarder is applying braking?

Re: Retarder and rain..

Reply #11 – July 07, 2015, 03:13:43 pm

The retarder will decrease rear wheel/tire revolutions quickly enough for the tires to loose traction in wet conditions. The effect will be similar to applying the emergency brake real quick in an automobile. You'll just have a lot more weight trying to pass you.
Raymond

Re: Retarder and rain..

Reply #12 – July 07, 2015, 03:27:39 pm

Quote from: Raymond Jordan – July 07, 2015, 03:13:43 pm

The retarder will decrease rear wheel/tire revolutions quickly enough for the tires to loose traction in wet conditions. The effect will be similar to applying the emergency brake real quick in an automobile. You'll just have a lot more weight trying to pass you.
Raymond

Is this based on experience?

I've been driven my coach for seven years, always with the retarder on, rain or shine. I've never had any issues. I've managed to stay away from ice and snow, and slow down considerably in rain.

Re: Retarder and rain..

Reply #13 – July 07, 2015, 03:50:09 pm

Quote from: Tom Lang – July 07, 2015, 03:27:39 pm

I've been driven my coach for seven years, always with the retarder on, rain or shine. I've never had any issues. I've managed to stay away from ice and snow, and slow down considerably in rain.

Operative words "slow down considerably,".

Roland

Re: Retarder and rain..

Reply #14 – July 07, 2015, 04:01:31 pm

This is one of those "use reasonable sense" situations. In the rain more caution is needed--including retarder use. I use the retarder in the rain, but I pay close attention and don't use it as aggressively as I would under dry conditions.

Re: Retarder and rain..

Reply #15 – July 07, 2015, 04:34:06 pm

There is a lot more to this than just the retarder, the condition & age of the tires plays big in this game, take old hard rubber tires vs fresher softer tires. Huge difference in traction on water, snow or ice. With some sense one can get along very well. But get it sliding and watch the rear & toad pass the front. Bad way to aquire an education.

Re: Retarder and rain..

Reply #16 – July 07, 2015, 04:44:25 pm

I believe on the newer coaches, [at least on my 97 and 99] retarder effect is directly proportional to the amount of
braking you are using, by means of pressure switches on the brake air system. A small amount of brake pressure
produces a small amount of retarding, and increases as brake pressure increases. My air schematic shows 3
pressure switches, thus 3 stages of retarding. As you brake, all wheels brake, with the retarder assisting the rear
wheels. In the event of the rear wheels locking up first, the front wheels will continue turning and abs should
relieve some of the rear pressure but does not appear to affect retarder operation.
If you have a joystick 6 stage retarder, it is not linked to the brake system and operates anytime the lever is
not is the off position.
I drove to Canada in the rain and the snow last year, and did not ever turn the brake operated portion of
the retarder off.

Re: Retarder and rain..

Reply #17 – July 07, 2015, 07:15:58 pm

Quote from: jcus – July 07, 2015, 04:44:25 pm

If you have a joystick 6 stage retarder, it is not linked to the brake system and operates anytime the lever is not is the off position.

Actually, the joystick operation is in addition to the three pressure switches. The joystick can be left in the off position, and the three stages of retarding will commence based on braking pressure. After full retarding, more brake pressure will apply the service brakes plus full retarding. Without using the service brakes, the joystick applies 6 stages of retarding when your foot is off the throttle. Only the master retard switch completely disables the retarder.

Re: Retarder and rain..

Reply #18 – July 08, 2015, 08:43:58 pm

Last year we got caught in Colorado and was holed up for 4 days waiting for the snow to quit and melt off the roads. We saw an opening and took off for Arizona. The snow caught us again and while headed down a hill I lightly engaged just the retarder. I could feel it trying to get a little squirrelly so I quickly turned it off. I think that if I had applied the retarder thru the brake pedal it wouldn't have been as bad since you would be slowing the front down as well.

I'm trying to recall the physics behind it all but all I would do is confuse myself. Linear momentum and all that good stuff...been too long.

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Retarder and rain..

July 05, 2015, 07:50:07 pm

Re: Retarder and rain..

Reply #1 – July 05, 2015, 07:56:22 pm

Re: Retarder and rain..

Reply #2 – July 05, 2015, 08:02:36 pm

Re: Retarder and rain..

Reply #3 – July 05, 2015, 08:34:29 pm

Re: Retarder and rain..

Reply #4 – July 06, 2015, 06:41:02 pm

Re: Retarder and rain..

Reply #5 – July 06, 2015, 08:25:08 pm

Re: Retarder and rain..

Reply #6 – July 07, 2015, 12:18:50 pm

Re: Retarder and rain..

Reply #7 – July 07, 2015, 12:59:44 pm

Re: Retarder and rain..

Reply #8 – July 07, 2015, 02:05:22 pm

Re: Retarder and rain..

Reply #9 – July 07, 2015, 02:15:01 pm

Re: Retarder and rain..

Reply #10 – July 07, 2015, 03:02:46 pm

Re: Retarder and rain..

Reply #11 – July 07, 2015, 03:13:43 pm

Re: Retarder and rain..

Reply #12 – July 07, 2015, 03:27:39 pm

Re: Retarder and rain..

Reply #13 – July 07, 2015, 03:50:09 pm

Re: Retarder and rain..

Reply #14 – July 07, 2015, 04:01:31 pm

Re: Retarder and rain..

Reply #15 – July 07, 2015, 04:34:06 pm

Re: Retarder and rain..

Reply #16 – July 07, 2015, 04:44:25 pm

Re: Retarder and rain..

Reply #17 – July 07, 2015, 07:15:58 pm

Re: Retarder and rain..

Reply #18 – July 08, 2015, 08:43:58 pm

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