I was told that this is the forum to put this in, first it was the V10 now here. I need help, so please read my post, I'm looking for advice here.

I have a 2003 F250 SC Super duty V10 with 4R100 transmission and 3.73 gears, 83,000 miles, owned since new. I tow my race car with an open trailer and my nearest track is 88 miles one way. With the open trailer I'll towed to the gate of the track and will consume only a 1/4 of a tank and I can cruise at 70-75 easy. Now I own a new trailer, is an enclosed V nose 24ft dual 5200lbs axles etc. I went to the same track, it takes a bit to get moving and them gears (3.73) makes it feel like the motor is working harder to get up hills etc. I take it off the over drive for hills and slight hills in the highway. I can get it to tow in overdrive at 65mph with cross wins etc. When I got to the track it consume half a tank. By my calculations this joker gave me 6.65 mph to the gallon!!! I don't like it how it tows it does not have the hump like when I tow it with the open trailer due to is lighter and less win to deal with. I installed air bags to help not to sag at the back.

I went to Randy's ring and pinion and did the calculation with the OEM tires etc and compare it to 4.30 gears. The results are that with 4.30 gears and .071 overdrive it will cruise on 70mph at 2240 which I think is not bad. Anyone here has the same truck and tranny and 4.30? How does it ride? I just hate this going up hills and have to drop gear to 3rd and sometime to second. Any info I'll appreciated. By the way I search this but all I can find was 4.30 with 5 and 6 speed.


Edgar

 

i dont have the V10 but i have the 5.4, same ballpark basically for a F350 my truck for some odd reason came with 3.73 gears. Test drive i was fine (new truck fever) after the first week i realized i made a huge mistake with only getting 3,73 gears, i didnt like how i didnt have the grunt i was use to down low....... weeks turn into months etc and five years later i had enough and had 4.30 gears installed. As soon as i left the shop i could feel how the truck was grunting down low, making the tire slip slightly from the added gear ratio, towing a trailer i didnt have to put my foot through the floor anymore. Empty on the highway with the 4.30 gears and 285 75R16 tires at 70mph i turn around 2100rpm, personally if i were to do this again id jump to 4.56 gears with the slightly larger tire im running. $.30 are great but for the same jump in rpm at 70mph id take 4.56 to get even more grunt. And besides i wouldnt tow this kind of weight over 65mph anyways so again jumping to 4.56 gears and slowing down to 65mph is no problem for me

 

Awsome, I'm leaning more and more to the 4.30 gears. Thanks for the respons:

Edgar

 

You don't state the new weighting with car when hauling but with the dual 5200 lb axles, I'd expect over 10k. That a bunch when using OD. You might be lugging it, reducing your mpg.
I'd go back and review your torque curves and determine what rpm is idea first before deciding on the ratio.
I've pulled my son's 10k toy trailer with my brother's 99, v-10 with 3.73's and I can't be in any hurry going up hills. Nothing compared to my 6.0.

 

I order the trailer with those 5200lbs axles. But by the plate it says 3500lbs but is heavier than that and my car weights 3016 so I say combine I think is around 7k.

Edgar

 

I responded to your post in the mighty V-10 forum with a lot of info and data from my situation, but here's the important part.

I'm very pleased with my current situation, the new TT is 10' longer and 1500 lbs heavier. The EX is lifted 4" over where I started, went from 31.5" 265 tires up to 35.25" 305 s, 3.73 gears to 4.88s, now running tunes AND we are enjoying a 30%+ towing MPG increase. Lovin my V-10!

 

Thanks for the info I read it. Definitely going with 4.30 gears.

Thank:

Edgar

 

Hi Edgar.

My Excursion had that configuration; V10 and 4.30 gears. I used it to tow a 28' enclosed car hauler between 9-15,000 lbs. It towed it well with 4.30s, and I was able to spend the majority of my time on the interstate in overdrive. That was around 1,980 RPMs at 61 MPH. I've never towed 70 MPH before and I don't think I ever will; the fuel economy penalty is HUGE.

I averaged over 8 MPG towing at 62 MPH. If I were doing 70 I would have been fortunate to see 7. The problem isn't weight, but wind resistance. Empty or loaded you aren't going to see 8 MPG if you tow at 70 MPH.

That's a huge myth that's just not true. I did some comparisons when I was towing my trailer on the way out east. Total gross trailer weight was just north of 15,000 lbs. On flat ground at 62 MPH I was turning right around 2,000 RPMs at ~80-95% engine load and 7.5-9 MPG. Switch off overdrive, RPMs go up, engine load goes down to 65-75% and fuel economy goes down to 6-7 MPG.

I would have burned an additional $130 in gas had I locked out overdrive on that trip. She's most efficient pulling as hard as possible in the highest gear because pumping losses are cut to almost nothing.

 

I guess it depends on the vehicle, tranny, engine, ect. Hear's a quote out my Expedition manual.

"When towing a trailer:
• Use a lower gear when towing up or down steep hills. This will eliminate excessive downshifting and upshifting for optimum fuel economy and transmission cooling."

I'm sure we all have our own ideas. I find I do get better performance, better mileage, and a tranny that runs cooler when avoiding OD when towing.

You might save a few bucks in fuel in your case, just not sure how long that tranny will hold up, developing more heat. Now at 320k on my tranny, but as always, holding my breath after 15 yrs.

 

The 4R100 in the OP's truck (as well as in my EX) is designed and intended to be in OD when towing up to the CGVWR, it only needs to be taken out of OD if it starts hunting when climbing grades, as that up/down shifting will build heat.
When towing my 12k TT the trans runs cooler in OD than in D and the mileage is better in OD also obviously. When I upgraded from the factory 3.73 gears to 4.88s the V-10 was turning higher RPM as expected but the better torque in that RPM range allowed the trans to stay in OD much more resulting in an MPG increase from 7 to 9 MPG. That comparison was made over the same route (Philly to/from Savannah), with the same trailer (31' toyhauler), at the same weight (9500lbs) and at the same speeds (60-63 MPH). Seeing the same results with the new larger and heavier TT.

 

I was measuring both, and it ran noticeably cooler in overdrive by about 5-10° if I remember right. Here's a shot of the warmest I was able to get it:

 

Here's a page out of your Excursion owners manual. It specifically states the use of the OD button use when conditions cause excessive shifting such as "heavy loads, trailer towing" to avoid overheating. I guess we could discuss that it's only a suggestion. Again, many opinions here.

"Drive is activated when the transmission control switch is pressed.
• This position allows for all forward gears except overdrive.
• O/D OFF lamp is illuminated.
• Provides engine braking.
• Use when driving conditions cause excessive shifting from O/D to other gears. Examples: city traffic, hilly terrain, heavy loads, trailer towing and when engine braking is required.
• To return to O/D (overdrive mode), press the transmission control switch. The O/D OFF lamp will not be illuminated.
• O/D (Overdrive) is automatically returned each time the key is turned off regardless of last mode of operation.
2 (Second)
This position allows for second gear only.
• Provides engine braking.
• Use to start-up on slippery roads.
• To return to (Overdrive), move the gearshift lever into the
(Overdrive) position.
178
2005 Excursion (hdw)
Owners Guide (post-2002-fmt) USA (fus)"

 

Excessive shifting. With 16,000 lbs behind my Excursion I stayed locked in 4th gear for >90% of the time. It would go tens of miles without downshifting. I would hardly consider that excessive shifting.

 

Thanks for all the good information. I'm about to order the gears. The next question, do I have to take the truck to the Ford dealer to correct the speedometer once the 4.30 gears are installed.

Edgar

 

I thought that was what I said, only needs to be out of OD if it's hunting gears while towing.

Like Tom I tow heavy and leave it in OD, where it stays except on the bigger hills (both going up and coming down), And I too see about +10 degrees higher trans temp when in Drive as opposed to OD in similar conditions. And thanks for providing the info from the manual that confirms what we are saying.