HELP My new 06 F350 6.0L tows like a Yugo - Diesel Forum

07HEMI4ME · 04-30-2006, 03:53 PM

OK maybe not a Yugo but not far off, Please read below.

Just got back from our 2nd trip pulling the travel trailer (10K), and let me tell you this thing is a Piece of CRAP!! in its current form [img]/ubbthreads/images/graemlins/mad.gif[/img] See truck in sig.

My 1st pull, Two weeks ago was at 50-60 mph and I really was not happy than, but this weekend IM PISSED! [img]/ubbthreads/images/graemlins/mad.gif[/img]

We headed out on Friday morning and got on the Florida Turnpike for our trip to Leesburg, FL. Got up to cruising speed, which is 70 MPH, truck would NOT stay in 5th, kept down shifting to 4th and wanted to run at 2600-2800 RPMs Boost was ~28 psi. This truck will not pull at highway speed!

So after ~160 miles we get to our destination, filled truck up on Sat. am and after my hand calculation, Get This... 7.67 MPG [img]/ubbthreads/images/graemlins/eek.gif[/img]

OK so how can I fix this?

I think my problem is the 20" wheels and tires. Truck says it has 3.73 gears, but with the 20" wheels and tires it must me allot higher.

Who can tell me what my current ratio is? tires are 275/65/20 and are 33" tall

Would installing 4.10 gears be the fix? if so what would be an ~ cost?

Any one else have the same truck having this problem?

I need to fix this before our trip to TN on June 1st. Which will be ~1500 miles round trip. at the present MPG IM going to go in the POOR house.

barrelhorses · 04-30-2006, 05:30 PM

Something else must be wrong with your truck. I have the 3.73 rear and I do think the 4.10 would be better, but my truck really has no problems pulling my LQ horse trailer which weighs more than your 5er. My truck does especially well at highway speeds (65 and up). You might have a programming problem or something. Sorry I'm no tech or expert, but IMHO something else is wrong with your truck. I'd find a good dealer with a good tech and have them go over it.

EDIT: On my recent 1600 trip to FL with my trailer, the overall average MPG was 11.13 mpg. Almost every mile was towing...usually at the same speed as the rest of the traffic.

07HEMI4ME · 04-30-2006, 05:38 PM

But arnt the 20" wheels and tire raising the gear ratio?

I need some one who has the same 20" wheels and tires tell me what thay are doing at highway speeds (70mph), if they are fine than something is wrong with the truck.

You have the 18" wheels and tires and are at 3.73, but with the 20" wheels and tires I have to be somewhere around 3.55-3.60.

I would be very happy with 11 mpg towing.

rosspulliam · 04-30-2006, 05:40 PM

As I recall the 20" wheel/tire option lowers the towing capacity of the trucks, does it not?

07HEMI4ME · 04-30-2006, 05:42 PM

I do not see that in the book. shows the same

dirkus · 04-30-2006, 06:48 PM

I just got an 06 F-350 with the 20" wheels and the 3.73 gears. I have only pulled once with it -- when we picked up our new trailer (about 8k). It was about 70 California freeway miles (much more hilly than FL) and I figured I got about 11.5mpg for the trip. I did try to keep the speed to 60 - 65 mph.

One thing that I did notice was that if I put it in Tow/Haul mode it liked to stay in fourth unless going downhill. I took it out of Tow/Haul and it stayed in 5th and towed just fine. I think I'll use T/H just for long or steep downgrades.

Hope this helps!

johnmart · 04-30-2006, 07:03 PM

[ QUOTE ]
But arnt the 20" wheels and tire raising the gear ratio?

I need some one who has the same 20" wheels and tires tell me what thay are doing at highway speeds (70mph), if they are fine than something is wrong with the truck.

You have the 18" wheels and tires and are at 3.73, but with the 20" wheels and tires I have to be somewhere around 3.55-3.60.

I would be very happy with 11 mpg towing.

[/ QUOTE ]

If your tires are 33 inches diameter, you have an effective ratio of 3.50 compared to my 265-75x16s that are 31 inches diameter with a 3.73 rear ratio.

I also think there must be some other issue for your truck to be as gutless as you say.

I had a van with a 460 gas motor and a Gearvendors overdive that gave me an effective 3.20 ratio with the same diameter tires (31) I could tow my trailer (in overdrive) at highway speeds here at 5 - 7000 feet with no problem on rolling interstate. The truck I now have will take the same trailer and loaf along the same interstate at highway speeds with only about 10 pounds of boost.

barrelhorses · 04-30-2006, 07:48 PM

[ QUOTE ]

If your tires are 33 inches diameter, you have an effective ratio of 3.50 compared to my 265-75x16s that are 31 inches diameter with a 3.73 rear ratio.

[/ QUOTE ]

I'm not totally sure that your statement is correct. I would think that the rear end ratio stated from the factory takes into account the diameter of the stock tire. I could be wrong, though. Perhaps someone else can clarify this. FWIW, I think my 18" wheels with stock Continentals are about 33" diameter.

07HEMI4ME · 04-30-2006, 08:03 PM

[ QUOTE ]
I just got an 06 F-350 with the 20" wheels and the 3.73 gears. I have only pulled once with it -- when we picked up our new trailer (about 8k). It was about 70 California freeway miles (much more hilly than FL) and I figured I got about 11.5mpg for the trip. I did try to keep the speed to 60 - 65 mph.

One thing that I did notice was that if I put it in Tow/Haul mode it liked to stay in fourth unless going downhill. I took it out of Tow/Haul and it stayed in 5th and towed just fine. I think I'll use T/H just for long or steep downgrades.

Hope this helps!

[/ QUOTE ]

What RPMs were you turning at that speed? and boots? Mine just will not stay in 5th

I did run it up to 80 mph today and it was seamed to pull better but that is just too fast to tow all the time. it did stay in 5th but it was turning ~2100 rpms.

Rick M · 04-30-2006, 08:12 PM

The rolling circumference of your tires is the issue/question. Computing it by math Pi x Dia or by chalk marks on the tire and ground then driving it for the rolling distance measurement will determine the distance covered and ultimately the final ratio. Personally, I prefer the chalk method measured by 10 revolutions which allows for averaging and takes into account the compression of the tire, though what it does not count for is the centrifugal effect that speed causes on the rolling size of the tires cause I am under the impression they tend to grow a bit in diameter. But, that is just my impression of it.

07HEMI4ME · 04-30-2006, 08:17 PM

[ QUOTE ]
The rolling circumference of your tires is the issue/question. Computing it by math Pi x Dia or by chalk marks on the tire and ground then driving it for the rolling distance measurement will determine the distance covered and ultimately the final ratio. Personally, I prefer the chalk method measured by 10 revolutions which allows for averaging and takes into account the compression of the tire, though what it does not count for is the centrifugal effect that speed causes on the rolling size of the tires cause I am under the impression they tend to grow a bit in diameter. But, that is just my impression of it.

[/ QUOTE ]

OK so if we come to the conclution that it is the tires, how do you fix this problem? is re-gearing the answer? to me that should be cheaper than 4 new rims and tires. and if it is the problem I would think more people than me should be having this problem and Ford should know about it. I mean they are selling these trucks to tow.

barrelhorses · 04-30-2006, 08:30 PM

I still think you've got other issues to rule out first. Perhaps a turbo problem? Or as I stated earlier a programming issue?

The only time my truck shifts down to 4th is on big hills or if I'm just not paying attention on an average hill. When that happens, yes my RPMs go up to 2600-2800 and boost is around 24 psi. But that is really the exception rather than the rule. On flat ground, I can tow at any speed over 62 mph and never downshift out of OD. And my boost levels are around 10 psi. I can also usually pick up speed on flat ground without downshifting out of OD. (This is all while towing...)

BTW, these transmissions are six speeds aren't they? I really paid attention to the shifting yesterday as I pulled my horse trailer home from a barrel race. It starts out in first and shifts 5 times by the time I am up to speed. So that should put me in sixth gear, right?

07HEMI4ME · 04-30-2006, 08:33 PM

You might be right Im going to bring it back to the dealer and see what they say.

barrelhorses · 04-30-2006, 08:37 PM

Good luck. I hope they can get it straightened out for you. Please post whatever you find out.

JimTJr · 04-30-2006, 08:51 PM

I also think you may have another problem,, are the 20" wheels stock? Or if they are not,, how do the tires compare to stock in circumfrence? You may not be far from stock in comparison.

It should tow like a semi!!