6.4L Power Stroke Engine and DrivetrainDiscussion of the 6.4L Power Stroke diesel engine and drivetrain in the 2008 Super-Duty trucks. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.4L Power Stroke engine.
I ordered a new 450 yesterday with the 4:88 rear. I am concerned that maybe it was an overkill. I think 19,000-20,000 lbs would be pushing my topside towing. Now I thinking maybe I should switch to the 4:30's.
I have the 4.30 gears in my 05. I would order them again. The engine doesn't scream on the highway, and gets better highway mileage. The 4.30's are rated for 26,000 GCVW too. Lloyd
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2005 F450 XLT Super cab tow truck 6.0, 87K mile, POS Soon to be traded for 09 F550 Lariat Super cab V10
2003 F450 rollback, with V10 power, 141K and still running great.
I've been going over the specs and am thinking that likely, on the 450, the 4.30 is best compromise for towing/mileage with the calculated over all diameter of the 19.5 tires.
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'03, F-350 Lariet, CC, DRW, 5sp torquemaster, 4X4, 4.10ls, Sonic Blue monotone. Hijacker 16K full pivot/slider 5th wh hitch. One PRETTY truck [img]/ubbthreads/images/graemlins/wink.gif[/img] UPDATE: Truck is still performing poorly, though it is better since the last reflash that removed the EBP sensor inputs. Has definately been the worst truck I've owned in my 30 years driving Fords.
I ordered one with the 4.88 because I will be occasionally maxing the truck's 24,000 trailer towing rating and with the hilly nature of the Pacific NW. If I don't like the lower gears I'll simply add an overdrive unit.
DieselGem,
I replied to your PM. Please post my reply here so others can read. I can not seem to find my reply. After reading that you will be towing 19000 to 20000, I personally would stick with the 4.88's, especially if pulling anything over 18000 lbs is going to be on long trips or a regular thing. I was towing 19000 lbs yesterday and it was a lot easier on the truck (Engine/Transmission) with the 4.88's. I have towed this same load with an F350 tow boss with 4.30's and it was harder on the transmission for sure. As I stated in my PM I like to stick with the 80% or less of max towing weight if possible. I believe this makes for a more reliable truck in the long run.
Thanks,
Marc
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2008 King Ranch F450 - 4.30 Gears
2008 XT F550 - 4.88 Gears
2006 Caterpillar 420D Backhoe
1957 Wife - Not a diesel burner, but sometimes does a Regen
What do you consider "screaming" RPM? What rpm was the engine turning at 70mph?
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2008 F-450 Lariat Dark Stone Metallic over Pueblo Gold 4x4(manual shift transfer case, manual hubs), High capacity tow 4:88s, Off Road, Camper packages, Sirius Sat, Upfitter switches, DVD entertainment, tailgate step, traction control, Audiophile 6-disc, PTC Supplemental heat and heated seats(warm buns), rear sensors, traction control, tailgate step. Built May 8, delivered May 24
Reese Signature Series 24k fiver hitch, I installed it myself, best hitch I have found yet
Line-X bedliner, heavy duty floor mats
2003 Sunline F281SR(weekend getaways)
SeaRay 215EC http://community.webshots.com/user/C...host=community
I think this is going to be an interesting thread not only now but,in the future. I pull a 5th wheel toyhauler with two full size harleys now. Most of the driving we do is in Pennsylvania and out west. I have always carfully used my isspro guages and towed most of the major passes without any problem. I have never been the first guy up the hill. The 07 350 with the tow boss was touted as the truck to have and the only reason I don't have one is because the salesmen sold mine while I was on vaction. Thank God! looking at this 450, I think it is one heck of a truck. These engines will pull all day long! It's the brakes I'm after. I think this has been a weak link.
I made the change to the 4:30 and intend to put the guages in when the truck comes in. The truck will be used mainly for towing but I intend to use it as a driver on occasion. Now, I just hope it gets here soon. Thanks again to all of you for your input.
We don't have a choice. Our rig and truck weigh nearly 31,000# GCWR so we need the 33,000# high capacity tow package option which automatically selects the 4.88.
The noise doesn't bother me but filling up the 40 gallon tank at nearly $3.00 gallon twice a month can make my knees buckle a bit.
The 2600 RPM @70 w/19.5" tires is what we get out of our '99 also. After driving the "beast" for 8 years this month as both our tow and around town vehicle, I found I can come pretty close to how fast we're goin' by listening to the engine/tire noise. [img]/ubbthreads/images/graemlins/wink.gif[/img]
You also need to take into account overall tire diameter when comparing the your two trucks. A small difference in diameter makes a substantial difference in actual overall drive ratio.
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'03, F-350 Lariet, CC, DRW, 5sp torquemaster, 4X4, 4.10ls, Sonic Blue monotone. Hijacker 16K full pivot/slider 5th wh hitch. One PRETTY truck [img]/ubbthreads/images/graemlins/wink.gif[/img] UPDATE: Truck is still performing poorly, though it is better since the last reflash that removed the EBP sensor inputs. Has definately been the worst truck I've owned in my 30 years driving Fords.
'04 F-250 Harley-Davidson 6.0L CC SB 
Linear Mode
