Well, I'm driving it like I was told and don't like it. Vehicle is a 36 foot RV pulling a 2000 Honda Civic on a dolly. Previously MPG was 7.6. Even got 8.2 one time. Now, from NOT using OD, I am getting 5.6. Oh well. Better that than blow up a torque converter. I'm leaving for a 600 mile round trip Saturday. I'm going to sneek in some OD along the way. On the flats of course. Anybody have any comments?

 

You sound like a good candidate for a Gearvendors overdrive, but we're talking some bucks. The idea with a Gearvendors is your stock tranny stays out of overdrive but the gearvendors will drop itself down into that range and it can handle the stress. Plus you have double the gears for the hills. If you try it with the regular overdrive, I think you've got to have good auxillary trans cooling or you might get in trouble. There are alot of guys here that know more than me whether the stock trans can handle what your doing.

 

I have a C class 24 ft E350 with a V-10, auto. I tow a Wrangler. At first I would take it out of o/d except on the flat. I would forget quite a bit and it didn't seem to matter so now I don't worry about it. I only take it out when the load is such that it 'hunts' for the right gear on a gradual climb. I get nine mpg towing. 10.5 to 11.5 not towing. No trans overheating no engine overheating regardless of the grade or the ambient temperature.

Since yours is a 36 footer you clearly have a greater load so my 24 foot coach is not a good comparison, but it at least provides a baseline. By the way, mine is a '99 model.

 

How were you told to drive it? Do you mean O/D off all the time?


biz

 

biz, I was told by a Ford tranny tech and a tech at Roadmaster to not use OD while towing because the bands are not strong enough. They say I could smoke the TC. My reman tranny is a Roadmaster and it went out 'cause the planetary blew up. Had nothing to do with the TC. I don't even know if the bands are in the tranny or the TC. I do know the planetary is in the tranny. I also know that I have plenty of aux cooling. The tech that made the change said there wasn't room to add more. I was going to have him add another or bigger cooler. I think I'm going to go back to using OD and try to keep it from hunting since it has a 24/24 warranty.

 

Absolutely use the O/D except for when hunting. The hunting/searching effect generates heat...and that is the killer of the 4R100 tranny.

Keep in mind...that Roadmaster should have replaced your tranny cooler along with the new tranny. This is a FORD SOP (must do) when replacing the 4R100 due to contaminates that may be in the fluid when the original tranny goes. According to FORD...it is impossible to flush the tranny cooler so that no contaminates remain.

Good luck with the new tranny...

biz

 

Thanks for the good wishes biz. Roadmaster did send extra fluid to flush the system. If I remember correctly, the tech told me they sent 10 gallons above the 17 1/2 quarts that my system holds. They were supposed to flush twice and send that fluid back to Roadmaster. I'll just have to take my chances with the warranty. I am definately going to use my OD. I can't stand, put up with or afford that kind of mileage.

 

How it works 101

your V10 powered RV is mated to a 4R100 4 speed auto transmission with a LOCKUP torque Converter

The trany fluid is sent to the front of the truck into a radiator where is is liquid to liquid cooled.

This is NOT an auxiliary trany oil cooler it is the factory design

Early units had an inferior radiator that Ford fixed in MY 2000 to a larger core and larger oil cooler inside the core

A computer controls the lock and unlock of the Torque Converter

IN OD we have a concern that on slight uphill graded the 4R100 auto trans starts to "hunt" before it decides to shift out of OD and maybe even down a gear. The hunting is not good and can increase the heat in the trany. If you pay close attention the Tachometer will show 50 to 175 RPM changes up or down befor shifting out of OD... this is the torque Converter locking and un locking and is NORMAL

Best action the driver can do if you detect the "hunting" is to mash the stem mounts button and lock out OD until you crest the hill then mash her again to set normal mode with OD back in service.


You need to add in an aftermarket Transmission Oil temp gage $65 and a hour or so of your time. You will need 12VDC, mounting location, and place sending unit in the factory provided port on the drivers side up above the shift linkage (you will see it)

You should consider adding on a aftermarket auxiliary Oil cooler on the out bound oil line where the fluid flows out of the trans into the new aux cooler then on to the factory cooler and return to trans.

All the good auto zone type stores sell these in a few different sizes. Get the $79.99 large one

Get 4 $2.99 12DVC 120MM case fans

Get an 18"X22" or similar aluminum cookie baking sheet from the grocery story for $5.79
and bend each end so it will have a 2" to 3" drop and a lip to mount to your passenger floorboard with 8 very short self-tapping sheet metal screws. 4 on each end

Mount the fans to the cooler so they draw air through the cooler and exhaust down and away (no need heating your GF/wife/mothers/passengers feet)

Mount the cooler with spacers (stack of washers works) to the cookie sheet so the two pipes will face the center of the vehicle

Once you are all set up--- find out which steel pipe flows to the front of the vehicle... Hint if you are not certain ---start her up from cold and feel which one of the two steel pipes gets warm first.

Use a tubing cutter to cut that one pipe (only with motor OFF!) ( you will NOT loose more then a cup full of fluid

After pre fitting and cutting the rubber hoses to the right length--- you put them on the cooler with the hose clamps. Fill the cooler and hoses up with fluid. Attach the other ends of the hoses to the cut pipe. Finish mounting the cooler

Run a 14 Gage wire with a fuse on it from the battery POS to the Fan's red leads (all 4 can be tied together) Run a 14 gage wire from the fans Black leads to a on off switch in the cabin. From the switch run a short wire to any good Ground.

If trans temp ever exceeds 20egrees F turn on the fans...

 

Hey Fredvon - you got pictures of that set up??

 

Sorry I do not.... all my "how to" photos on some distant server got dumped and I lost the back up due to HD failure locally..... such is life with 000101001100s :>O :>(

 

I'm back. Just returned from a 632 mile trip. I increased my mileage to 7.4. This is acceptable to me. Now for how I did it and any criticism or suggestions are welcome. Please note that this reman tranny is diferent from the old one. With the old one with OD on and CC set at 62, the engine was running 22/2300 RPM. With this tranny, and things set the same, the engine is running 26/2700 RPM. Lower mileage right off the bat, right? Now, here's what I did. I set CC at 62 with OD on. When approaching a hill, I increased gas until I was doing 65-67 MPH. RPM at that point was 26/2800. The tranny very rarely shifted back to third and I only saw it hunt twice. That was when I first started out. I say rarely shifted but I'm not that good. I would say I missed the "sweet point" maybe 12 times on each leg of the trip. There was a week between the legs and it takes practice to get the timing right. It is a matter of timing. I think I can do better. Comments please.

 

I would say that with a 36ft. RV, towing, you are doing pretty well. And I would also say that you made a good choice with the transmission (ratio.)

 

Alabama RVer; You are doing it about as good as it can be done. Your technique is about exactly how the rest of us in trucks with a heavy trailer on the back do it with that tranny

As good as the 4R100 was I am super glad I now have the 5R110w...it has different quirks --- but tow haul mode completly eliminates all the fussing when driving in hilly terrain

Enjoy your RV I bet you will be able to eek a few more tenth of MPG out of her but you know it is always going to suck gas like it is cheap... price we pay to drag the TV, cold beer, and a flush toilet along grin