wolfe10

The simple answer is "not enough harm to be concerned about it". Certainly, repeated high RPM downshifts will shorten engine, transmission and drive shift life. BUT, all these components are well over-designed. Also, be aware that you are going to burn more fuel doing this, as exhaust brakes on, then throttle to re-accelerate does take extra fuel, particularly since this eliminates coasting (my favorite "gear"). Personally, it would drive me crazy to have the transmission downshift, engine RPM's go way up and rapid deceleration every time the throttle is closed. And, with your Caterpillar C7, you have other options that can be programmed by a Caterpillar dealer including "Latch Mode" in which the exhaust brake is applied when the service brake is applied and stays on until you go back on the throttle. Were I to be inclined to drive with the exhaust brake on, I would pay a Cat dealer to reprogram to this options. Latch Mode allows full use of the exhaust brake in emergency stops (applies instantly when you step on the brakes) and allows the exhaust brake to stay on for long descents without coming on every time you let off the throttle. Brett Wolfe

Wayne, You are correct. Just as in your car, or other vehicle, if you downshift the Allison (using the down arrow), it will not shift above the gear you select until you up-arrow OR if you want all 6 speeds available, by pushing "D". The exception is if you try to take speed in that gear to above design perimeters either with the throttle or steepness of the grade. Said another way, the transmission will not allow the engine speed to go high enough to harm the engine-- it will up-shift. And you are correct in how you descend a grade. With any heavy vehicle, the service brakes (brake pedal) is NOT to be used to maintain a safe speed of descent. Using the exhaust or engine brake in combination with the transmission down arrow to choose a condition where your speed of descent is in EQUILIBRIUM. The equilibrium speed is one where you are neither accelerating nor decelerating. It varies with slope of the grade and your total weight. (GCW). As a guide, physics dictates that your equilibrium in a motorhome will be faster than a loaded 18 wheeler and slower than an empty one. If you do have to use the service brakes, do so in one reasonable application (no pumping), slowing down enough to down-shift to the next lower gear. Repeat until you find a gear that keeps speed in equilibrium. At first, it may seem strange that your speed of descent is much more related to this equilibrium speed than to road conditions. Said another way, on a given grade, your safe speed is the same on a straight road and a curvy one (assuming curves can safely be driven at or above your equilibrium speed). We were on a 10+% grade coming out of the Green Mountains in VT in 2nd gear with the exhaust brake on-- no use of service brakes at all. Dianne was concerned that someone would run over us (we were going about 15 MPH). We came around a corner, and a loaded logging truck was descending at around 5 MPH-- his equilibrium speed. Brett Wolfe

Here is an ongoing discussion on just that subject: http://community.fmca.com/index.php?showtopic=289 Brett Wolfe

There are TWO TOTALLY DIFFERENT "LET THE TRANSMISSION CHOOSE THE CORRECT GEAR" MODES/PROGRAMS in the Allison ECU which is the "electronic brain" controlling shifting and other functions. In ECONOMY MODE, the transmission will not downshift even at WOT (Wide Open Throttle) until the engine pulls down to peak torque RPM in some application and 200 RPM lower that "regular mode" in others. In REGULAR MODE, the transmission WILL downshift much earlier (to maintain higher engine RPM). ONLY at higher throttle positions is there any difference, so on flat ground you will NOT notice any difference (except accelerating from a stop IF you are at or close to wide open throttle). It can make a BIG difference in rolling hills. If you are in rolling hills and regular mode (particularly with the cruise control on), it is common for the transmission to shift down to 5th on the uphill and back to 6th on the downhill. Repeat this process hundreds of times. In economy mode, you will stay in 6th gear unless the hill is so steep or so long that the engine can not pull it without dropping below peak torque RPM. If you can pull a hill in a higher gear (lower engine RPM) AND the engine does not overheat, THAT IS WHAT CATERPILLAR RECOMMENDATIONS FOR THE MOST ECONOMICAL WAY TO CLIMB A HILL with a modern turbo, after-cooled diesel engine. If you know you will need a lower gear because of the steepness of the grade and/or are engine temperature is rising higher than thermostatically controlled temperature, if driving in economy mode, use the down arrow to drop a gear (this is what I do) or switch out of economy mode. Be sure to switch back into economy mode when past the steep section, or agree to pump extra fuel in the tank. IF your engine begins to overheat, your HP/weight ratio is low OR if it irritates you to loose a few mph on a hill in the name of saving fuel, in the hills, by all means drive in regular mode. It confuses me to hear people advocate driving in economy mode only on flat ground, as there is not 1% difference in shift RPM's between regular and economy mode on flat ground, excepting accelerating from a stop if you use WOT. Every time you start the coach, the transmission is in regular mode. This is the default setting. IF you push the mode button, it goes to "economy mode" AND the light illuminates. There is no "absolute" on how much difference in fuel economy driving in economy mode will have. On flat ground where you will be in 6th gear irrespective of what mode you are in, there will be ZERO difference. The MOST difference in mileage will be in rolling hills, where in regular mode, particularly if on cruise control you will start up a hill in 6th gear, go to WOT in 6th gear, downshift of 5th gear still at WOT (WHERE IT IS USING A LOT MORE FUEL). After the hill is crested, the transmission will up-shift to 6th, then likely coast a little in 6th gear (unless you are driving with the exhaust brake on-- if you are it then applies the exhaust brake AND downshifts TOWARD the pre-select gear which is generally either 2nd or 4th).And so on 6-5-6-5-6-5-6-5....... A modern turbo inter-cooled diesel is much more efficient at low RPM high throttle settings. This is NOT my opinion. It is stated in just those words in the Cat Owner's Manual. Note: In either mode, you are free (and welcome) to use the up and down arrows to PRO-ACTIVELY choose the correct gear. You can not screw anything up-- even if you down-arrow to 1st gear at 70mph, the transmission understands that you meant "please downshift to the next lower gear as soon as the engine RPM will not exceed the pre-set amount. Then downshift again when safe....." By the same token, you can shift between regular and economy mode as often as you want with the transmission in any gear when you make the change. OPINION: I drive in economy mode 99% of the time, including in REAL mountains, but use the up and down arrows to choose the proper gear. I use regular mode ONLY when I am willing to say, "I am willing to throw a lot of fuel away to gain a little performance." When passing on 2 lane roads, THIS IS the case. Brett Wolfe

Let's start with the first question: Is your toad plus dolly within the towing rating and GCWR of your coach? Before considering lengthening the interval I would visit with Demco and get a feel for both what you are checking (real details) and the reason for the 50 mile recommendation. Sometimes these recommendation ARE based on solid engineering/mechanical reasoning, sometimes on "lawyer speak". You deviate from the recommendations, you do assume some additional responsibility/liability. And if you choose to deviate from the recommended safety check, I would only do it after repeated 50 mile checks show no issues and then perhaps start slowly lengthening the intervals. Note, I am not suggesting that you do extended the check intervals, only suggesting that it only be considered IF repeated 50 mile checks reveal no issues. Sometimes asking other for advice on "what can I get away with" gets you just that "examples of what others have gotten away with". Not sure that is a reasonable basis for your doing it. For example, others may have different toads, are able to tension the straps tighter, only travel smooth roads, etc Brett Wolfe

Sounds like a mall parking lot has your name on it early on a Sunday morning! Bring those jack stands/wood blocks for safety stands. Brett Wolfe

A relay achieves the same thing (battery voltage to the bulbs and no heavy load on the switch while retaining all original switch operation. Brett

Generally speaking, a leak that takes overnight to drain the pressure is within commercially acceptable standards. But it is also large enough that you should be able to find it with a trusty soapy spray bottle. Brett Wolfe

Wayne, Get one of your more agile neighbors to crawl around (not under the coach unless blocked up) and determine exactly what is leaking. Most likely sources are a chafed area on the air line or a fitting that is loose. We can't give you advice on whether it is safe to drive -- it depends on what line it is AND whether it could "blow out" and lock up the brakes. Best answer is to repair where it is. Will send you a Private Message. Brett Wolfe

The inverter/charger should be connected to the HOUSE battery bank. Therefore most remotes display house battery voltage. But once you have the digital voltmeter (Santa can find them starting under $20 at Radio Shack, Sears, etc) tracing can be very easy. If only the house battery bank is charged by your charger, the voltage of the remote display will be very close (assuming minimal 12 VDC things are running and inverter off) to that you find at the house batteries and different from chassis battery. If both banks are charged by the charger, just leave it unplugged from shore power with some 120 VAC items on in the coach running from the inverter. Go back a couple of hours later and check voltage at the batteries. The one supplying the inverter will be lower than the one that has been "at rest". Brett Wolfe

Tom, The dealer may be correct, but you also might want to confirm this with Tiffin directly. The dealer's statement could mean "committed to a dealer or it could mean committed to a retail customer". Big difference. If an engine is built before 1/1/10, it doesn't have to meet the new standards, since they go into effect for engines produces on or after 1/1/10. I have no idea what supply of engines Tiffin has or if Cummins has already ceased production of "old style" engines, but certainly worth a call or two. Brett Wolfe

Put a digital voltmeter on the house battery. See if voltage varies when this occurs. Some converters and chargers do cycle on and off. When off, battery voltage falls from charging levels until it comes back on. If no variance in voltage at the battery and no variance in brightness of other incandescent lights, look for what else is powered on the same circuit as the bathroom lights. If no wiring schematic, pull the fuse and see what else doesn't work. Brett Wolfe

Welcome to the FMCA Forum. Best source for a good beginning point is your engine owners manual. And most RV'ers end up changing once a year, not based on miles. If you feel your use of the motorhome is unusual (i.e. pull a 7,000 pound trailer, all very short trips, etc) let us know the unusual circumstances and perhaps we can fine tune the recommendations. Also, call Allison (800 252 5283) with our transmission serial number. Until recently, they called for a main filter initial change at 5,000 miles. On very recent transmissions, that requirement has been eliminated. Brett Wolfe

Consider using a HD relay with hot coming from battery, with the switch only providing the "signal" to close the relay. It leaves all functions the same, but allows a high-amp relay (still under $8) to give full voltage to headlights.

A call to a friend with a National DP and some digging has revealed this list of dealers who are reported to have purchased parts from National. I have not verified any of it, but it should give you a good starting place. Good hunting: Giant RV Corona, CA 888-564-5247 Ortega Manufacturing (he suggests you start here) 3960 Industrial Ave Hemet, CA 92545 951-766-9363 Temecula Valley RV Murrieat, CA 951-894-2347 Walt's RV Surplus 16616 Valley Rd Fontana, CA 92335 909-823-0563 Brett Wolfe

Gary, Best answer is to call Rexhall on Monday for a wiring diagram. Using a relay is the best way to power the headlights, as there is a voltage drop across the light switches at high amp loads/a limit to how many amps the switch can reliably handle. By using a relay, headlights will be brighter and the head light switch will last longer. So, hopefully that IS how yours is wired. Have you verified that all the wires are still on the head light switch and that the one to the headlights has power when the switch is in that position? Any way to trace back wiring from driver's side head light to relay? Brett Wolfe

Tom, You are correct. There IS reciprocity of licensing requirements for drivers. So if you are licensed in your home state, you are OK in other states and Canada. But, as you suggest, each state has its own weight, length., speed limits, etc. One is subject to the laws of the state one is driving in for these issues. Brett Wolfe

For those of you wanting to have your individual wheel position weights so you can know the proper PSI for your tires (and indeed if a corner is overweight and you need to move stuff around), I just got the 2010 Weighing Schedule from Walter C. Cannon, Executive Director, RV Safety & Education Foundation. This is from their Website: http://www.rvsafety.com/custompage7509.html?pg=weighing Start Date End Date Location Event/Place 1/6/2010 1/10/2010 FMCA WMHA Indio CA 1/25/2010 1/26/2010 Escapees Boot Camp Quartzite AZ 3/3/2010 3/6/2010 AZ Good Sams Yuma AZ 3/8/2010 3/12/2010 Gypsy Journal Yuma AZ 3/11/2010 3/14/2010 FL Winnie Gator Orlando FL 3/21/2010 3/25/2010 FMCA Winter Convention Albuquerque NM 4/13/2010 4/18/2010 NM Good Sams Hobbs NM 4/19/2010 4/23/2010 Freightliner Haulers Kerrville TX 5/15/2010 5/15/2010 Pikes Peak Traveland Rally Pikes Peak CO 5/27/2010 5/30/2010 FMCA GLASS Rally Berrien Springs MI 6/3/2010 6/6/2010 RVSEF Lifestyle, Education & Safety Conference Bowling Green KY 7/15/2010 7/18/2010 Heartland Owners Rally Nashville TN 7/22/2010 7/25/2010 The Rally Louisville KY 8/11/2010 8/14/2010 FMCA Summer Convention Redmond OR 8/30/2010 9/2/2010 Gypsy Journal Elkhart IN 9/8/2010 9/17/2010 Escapade Goshen IN 9/15/2010 9/19/2010 PA RV & Camping Show Hershey PA 10/14/2010 10/17/2010 Kings on the Road Rally Stone Mountain GA Brett Wolfe

What kind of "heating problem"? I will be doing the Maintenance Seminars at the Cat RV Club Rally in Amarillo in March (before FMCA Albuquerque). Look forward to meeting you if you are able to attend. Brett Wolfe

The only factual data I am aware of is from a survey of C15 Caterpillar owners on the Caterpillar RV Engine Owners Website (an FMCA Chapter). Club Website: http://catrvclub.org/ Club Technical Website: http://autos.groups.yahoo.com/group/CATRVCLUB/ Survey results: http://autos.groups.yahoo.com/group/CATRVC...veys?id=1992366 This is one of the Yahoo Group sites, so you must register, but no cost and no junk e-mails from it. There were only three respondants. One reported 7.1-7.5, one reported 7.5-8.0 and one reported 8.0-8.5 MPG. Brett Wolfe

OK, if tires are different than those on the GVWR tag, to come up with the recommended PSI based on each axle carrying its GAWR, take that axle weight rating and go to your tire manufacturer's inflation chart for the NEW tires. For example, if Michelins, go to: http://www.michelinrvtires.com/michelinrv/...tion-tables.jsp Again, this should be viewed as a TEMPORARY ANSWER until you actually weigh the coach. Brett Wolfe

The 95 PSI on the sidewall is the correct pressure IF the tire is carrying its maximum allowable load. Until you weigh it, another source for PSI is the GVWR tag near the driver's area. It will give PSI for axles loaded to their GAWR (Gross Axle Weight Rating), And many truck stops, moving companies, grain elevators, etc all allow for axle weighing. But that assumes perfect left/right weight distribution, so individual wheel position weighing is far better. Then, using the heavier wheel position on each axle, go to the tire manufacturer's PSI/weight chart to determine the minimum PSI for all tires on that axle. I recommended adding 5 PSI as a safety margin to that minimum. Brett Wolfe

Sam, Welcome to the FMCA Forum. Best advice on towing is to start by reading the owners manual towing section very carefully. If questions, call Toyota. Though someone may have a similar model, running changes are made that may make advice less than accurate for yours. As an example, Ford changed the steering column in the Ford Focus between 2007 and 2008 . In 2007, you could/should tow with the key in the OFF position. Do that with a 2008 and the steering locks up! Another option, particularly if you will be using an auxiliary brake in the toad is to run one additional wire from coach to toad to keep the battery charged while towing. Be sure BOTH ends of the wire are fused, as both ends will be hot. And if you will be leaving the coach to toad wiring connected overnight, a diode so the car battery does not try to charge the coach battery if you are boondocking. Brett Wolfe

Replace shocks if: 1 They are leaking (not just damp with oil, but leaking). 2. If the bushings (top and bottom) have any wear or play. 3. They are bent or otherwise physically damaged. 4. They do not control coach motion-- in addition to Tom's excellent advice, I find the easiest place to "test" shocks is over speed bumps at regular (slow) speeds. You can easily tell how many times the front and then the rear go up and down before stabilizing. Anything over 2 oscillations means they are shot. I like them to give better control-- so 1.5 is my maximum. If they are OK per the above, I don't have any great expectations for the shocks to control side to side motion. YES, the help, but were you to make a shock stiff enough to substitute for HD sway bars, they would be VERY stiff (read that "uncomfortably stiff") in normal driving conditions. So, for excessive sway, start by verifying that all 8 of the sway bar end link bushings and main bushings are in good shape. Also, some shocks (older pre-FSD Koni shocks) are adjustable. So adjusting them may be an alternative to replacement if everything but dampening is OK. Brett Wolfe

Welcome to the FMCA Forum. What kind of coach/chassis do you have? Does it have an on-board air system? And, as a side note, is the 95 PSI in all tires based on the tire manufacturer's recommendation for your actual weight? It is unusual that the fronts and rears would work out to the same PSI. Brett Wolfe