Serious Plumbing Considerations

[Jon Wehrenberg]

You cannot make a statement like that to apply universally.

High temperature is the enemy of our fluids. If you never expose the fluid to a temperature of (insert your own value here) it is possible the life of the fluid will not be shortened. However, the use of a retarder on our coaches is construed by Allison as a reason to cut fluid change intervals in half.

Now that we have you able to slow the coach down and watch the gauges at the same time, here are two things you can do. First, turn on the retarder, put the lever in the second "on" position and note that it is unlikely that allowing the retarder to function will raise the temperatures beyond 210 to 230.

Then leave the retarder switch on, but move the lever to the off position. Then do an agressive stop using the coach brakes from about 65 MPH. You will note the temperature will rise very fast, and will exceed the 230 degree marking on the gauge. From that it can be seen that if the retarder is engaged where it is needed the most, such as when descending long steep mountain roads fluid temperatures will easily exceed anything you have ever seen. You may be able to peg the transmission temperature gauge.

The retarder system will function proportionately to the amount of braking force so with routine use of the retarder, even with the lever in the "0" position, but the switch on, tranmission fluids will be exposed to high temperatures.

I have found that anticipating a steep descent, slowing to a reasonable speed at the crest of the hill, and descending in a lower gear allows the retarder to function, keeps the temperatures to a reasonable level, and does not require the use of brakes. If the hills are excessivly steep, the use of brakes may be required, at which point you, the driver, need to determione if you wish to supplement the retarder with braking (and the higher fluid temperatures), or to temporarily turn off the retarder and apply heavy braking to slow down below the target speed, and then re-apply the retarder. Either way you are going to spend money. You will shorten the life of the transmission fluid or you will wear out and heat up your brakes.

[Just Plain Jeff]

Gotchya, but I do something a bit differently.

Let's take the Fancy Gap hill on I-77 just as an example. It is several miles of a descent, with I think about a 7% grade with some nifty twists and turns. What I do when approaching the grade is slow down. I mean, really slow down. If the other good folks along the roadway don't like it, they have 2 other lanes to do what they have to do.

I downshift to the point where the camper feels as controllable as possible. This is not freewheeling; but a controlled descent. If my target speed, for example, is say 40, and I am sorry I am watching the road here, not the gauges, and feel that the coach is picking up too much speed for the remainder of the trek toward gravity, I do use the brakes and bring the speed again way down to what feels like a mangeable point. Usually that is only required once.

Figure it this way; assume you are a blue-hair lady in a Focus who isn't sure which parking spot is closest to the IGA. Since you don't/shouldn't want to walk away from it all, maintain complete control.

Somewhere someone posted that if you go down the hill at the same speed you went up the hill, it would be about right. I go slower than that.

[Gary & Peggy Stevens]

Either way you are going to spend money. You will shorten the life of the transmission fluid or you will wear out and heat up your brakes.

That guys is exactly what I have been saying Spend money on brakes and all that come with them, or spend money on twice the number of trans. fluid changes. I'll bet the brakes overhaul cost is more than transmission fluid and filter replacements ?

Thanks Jon, for clearing that up, even though the Thread Police should revoke your typing license, you too Jeff ?

[Petervs]

The general rule of going down a hill at the same speed as you went up is just that, a general rule. Not all hills have the same incline on both sides, nor as long a gradient. In the west, there are many passes on the interstates that start in the high desert at say 2500 feet above sea level and climb to 4500 feet at the pass and then descend down to say 800 feet on the coastal side. The climb may be 3 miles long and the descent could be 8 miles. Or the climb could be at a 6% grade and the descent longer at a steady 4%. Or vice versa if you are going the other way of course. So the guideline is just that, and must not always be adhered to.

And, if you are climbing a steep grade at 40 mph because that is all the horsepower you have then going down at 40 is not required or sensible in all cases. Descending at the posted speed limit of 55 or 60 or 65 may well be perfectly fine, depending on traffic and weather conditions.

Part of the POG Code of Ethics should be an admonition not to drive like a bunch of FuddyDuddys! For that I could join the PrevostProuds , FMCA, or whatever group Liberty promotes.

Peter vS
94 Marathon XLV

My GPS says it went 88 mph at one point down a long straight hill, not towing anything. How fast will it go on a flat straight road?

[Jon Wehrenberg]

Mr. Peter... I think the rule about speed is not to compare what it takes to climb one side of the mountain and descend another, but to adjust the speed going going down to be approximately that of going up the same side. The hill JPJ is talking about is about 8 miles long and has a much lower speed limit for trucks on the descent. Not even the truckers will complain about your speed if you are going slow because it is a nasty hill and it has numerous runaway ramps.

Mr. Gary...I wish we could actually measure the cost of our choices. According to Allison we should expect 800 thousand miles out of our transmissions, but even if we change the fluids as recommended, are we going to get that life? We can't compare costs of brakes or transmission fluids alone because of so many other factors. No matter what the choice it costs us money to go and money to stop.

[Gary & Peggy Stevens]

We can't compare costs of brakes or transmission fluids alone because of so many other factors. No matter what the choice it costs us money to go and money to stop.

ROGER THAT! And hell, it even costs when we are not going or stopping.

$93 a night for Bluewater RV resort campground.

Tuga , Maybe, that's why Peg and I didn't look into staying there more? Be sure and send us pictures where the Big $$$$$ spenders stay!

[JIM CHALOUPKA]

Peter vS
94 Marathon XLV

My GPS says it went 88 mph at one point down a long straight hill, not towing anything. How fast will it go on a flat straight road?[/quote]


OK Peter, I'll be you Old Geezer straight man.
How fast will it go?

As an aside. Your post showed up on my screne as being entered at 11:57AM. If you recal what time did you enter it (your local time)? What time is shown on your computer as the time of entry. Is it the same time you recal for the actual entry?
JIM

[Jon Wehrenberg]

Peter,

I am shocked. Absolutely shocked. First you take a potshot at Liberty owners by lumping us in with Fuddy Duddys, and than you as a pilot IGNORE operating limitations.

My GPS says it went 88 mph at one point down a long straight hill, not towing anything. How fast will it go on a flat straight road?

Check the maximum speed for your tires. This ignores that at 88 you are violating all speed limits in this country. And you have the nerve to publicly proclaim you did so.

[Petervs]

OK Jim,

FYI I posted that previous response at 8:57 am PST. That is what my clock said anyway, and that was the local time here in Washington state. It is now 11:45 am.

As for the question of how fast it goes, well it was just that, a question. I do not have the answer because I have never tried it. I was at Bonneville Salt Flats once, but the lake bed was not hard and dry so I was not tempted. But I bet someone here has tried it and I was just curious.

And Jon, sorry a broke a law. I was not purposely going real fast, it is just that on that particular day I was on an interstate where the speed limit was 75 and when going downhill my cruise control does not invoke the Jake Brake and so it just speeded up. Since the ride is so nice, and the wind noise is essentially nil, I did not notice right away. Excuuuuuse me! I bet I am not the only one who has ever broken a speed limit. And as for the tire rating, well, I am not too concerned about a momentary overspeed. I would not drive for hours on end at an overspeed.

Also, I did not lump Liberty Owners WITH Fuddy Duddys, they are each in their own seperate category in my mind anyway.

Peter VS

[Jon Wehrenberg]

OK, we are going to let it slide this time. I'm going to forgive you because you are a nice guy.

In the meantime I'll stick with my blazing 62 MPH, safely below my tire speed limits.

BTW, a little drift here, but since low sulfur has become the standard I think the increased consumption is much greater than the few tenths being discussed. Not that I am a cynic, but with lower BTU content the very government that shoves this crap down our throats stands to increase our taxes substantially because with the increased use of fuel they collect the tax on many more gallons and have not added a penny to their cost of collecting (stealing) our money. Keep the speed down and you deny the government weenies their unearned income.