For the people with a 3.55 gearing & 5-speed. What is your RPM at 60 mph in 4th gear? Also 5th? I now have 4.10 with 5-speed. 95% of the time I am not towing anything. When I do tow my trailer weight is 12,000 loaded. Was thinking of going with 3.55 gearing for increased MPG. Also to keep up with trafic with out pushing so many RPM. When towing my trailer I would use 4th gear as final drive.
Jay
-------------------------------------------------------------
97 7.3 350 CC 5-speed 170,000 miles
3"dp 4"ex 40hp tow chip Di pyro
I'm not sure what the rpm is at 60, but I'll check. I tow in 5th gear when I can and keep an eye on the tranny temp. Only gets hot in the summer, but it will get hot in 4th too. My truck will definitely bog down with 10k going up hills. You have to be pretty aggressive attacking the hills. I actually went from the factory 235/85/16 to I believe 245/75/16 to get a little higher rpm for towing. I would try the taller tires first and see how you feel about them. If you don't like it you can just wait till they run out of tread and go back to factory.
__________________
1996 F250 4x4 ext. cab, long bed 5 spd. 3.55ls, Tymar Intake, Tymar 4" downpipe and 4" exhaust. AIC, B&W turnoverball, EBPV brake, tranny temp gauge, boost gauge, and egt gauge. 235k miles and thousands of $$$$ in maintenance and repairs.
My '97 CC F-250 had 3.55 gears and got around 20-21 MPG while being driven in "Geezer" mode. I pulled a 5700 pound RV with no problems. When I went to a 5th wheel, I bought a new 2000 with 3.73 gears. It pulled ok, but not great. I then went to a F-350 with 4.10 and life is good.
IMO, you will not be real happy with 3.55 and a 12,000 pound trailer, particularly in big hills and mountains. I would expect you to to tow that trailer in 4th gear, and 3rd on some hills. Going down big hills would not be happy, I fear.
But I'm a flatlander and tend to get freaked out by big hills and mountains.
Florida Ed
__________________
2001 7.3 F-350 Dually Lariat CC LWB 4X2 Dark Green 4.10 4R100 5'ver Hauler (32' Montana 2 slides 10,500# - 2,000# tongue weight), 106 gal aux tank, 112K miles, nephews arguing over who will inherit it 'cause I'm gonna' drive it 'til I die. Bone stock.
2001 5.4 Gasser F-250 XLT Crewcab SWB 4X2 3.73 4R100 67K miles headed to 150K (wife's vehicle on the "junk-iron" theory of vehicle safety....most junk iron wins in a crash) stock as the day it was made
Before these: '00 F-250 CC PSD, '97 F-250 CC PSD, '94 Ford F-150, '91 Ford E-250, '81 Ford E-150, '66 Ford F-100 (cars not included)
What is wrong with pulling in 4th gear? As long as the rpm is in the sweet spot who cares what gear your in?
OD is exactly that. Meant for no load and cruise conditions.
__________________
1996 F-250 extended cab long box five speed. Home made Tymar, 203 Stat, 60 gal in bed fuel cell, 315/75's, no muffler, ebpv welded open 3" to 3" DP, Babies. 290K, still chugging, and still smoking when cold.
UPDATED 8/1/08 Replace so far. 1 LUK flywheel+clutch, 2 thermostats, 2 set of brakes, 1 set of calipers, 5 CPS, 3 sets of tires, 2 Transfer pumps, 1 Injector modual, 1 Computer, 2 Alt, 2 sets of batteries, 1 Water pump, 6 Belts, 1 PS hose, 2 Sets ball joints, 2 set u-joints, 2 carrier bearing, 2 Speed sensors, 1 oil pres sender, 1 temp sender, 4 sets of e-break cables, 1 front fuel tank, 2 rear fuel tanks, 2 set of glow plugs, 6 Glow plug relays, Oil galley o-rings, Turbo pedistal o-rings, EBPV o-rings, 3 sets of Injector O-rings, 1 Vac-pump, 1 new carpet.Total $$$ in repairs v/s miles driven = 3.0 cents per mile. Add fuel to that it jumps to 14.8 cents per mile over the life of the truck.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MarkEkberg</div><div class="ubbcode-body">What is wrong with pulling in 4th gear? As long as the rpm is in the sweet spot who cares what gear your in?
</div></div>
Agreed. 4th is 1:1 and should create the least heat.
__________________
95 F350 Crew 5spd/4.10, SuperChips tuner, solid flywheel, T444E waterpump, 205° stat, Locked F&R, 9.00R16 Michelin XLs
97 E350 SRW cutaway, E4OD/D70/4.10, 19.5s on the rear, deep trans pan, batteries inside, 1800W inverter, manual glowplugs
84 C30 Suburban, 6.2/4-spd, 3.21s
Other rigs I goof around with regularly:
93 F350 4x4, 7.3 IDI turbo, 5spd, 4.10s
90 F250 4x4, 7.3 IDI, 5spd, 3.55s, D60 swap, straight pipe, turned up fuel screw
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">What is wrong with pulling in 4th gear? As long as the rpm is in the sweet spot who cares what gear your in? </div></div>
Yep, I've towed up and down over the Rockies, western mountain ranges, etc, and with the wide power band, 5 speeds, you couldn't give me 4:10 gears. When I was unsuccessfully looking for a clean used '91 I ran across a log truck driver who had two '91s and wanted to sell either one, one high geared and the other low. He said pulling his trailer, he actually made better time with the 3:55 geared truck in steep mountain country. The reason being, when pulling a steep grade and you have to drop down to 3rd for example(regardless of which rear end), with 3:55's you're against the governor at about 62MPH, but with lower geared differential you're against the governor at way less miles per hour. Plus pulling the REAL steep stuff with a heavy load, I can still get to 35 MPH in 2nd which is helpful. After I bought my truck, I definitely agree with him.
Keep in mind 91 and 97 ZFs have different ratios... S42 ('91) and S47 ('97) respectively. The PSD also won't have an identical power curve to a 7.3IDI.
I had a '94idi w/turbo and 3:55. If I was in OD I was going 70MPH to get 2000RPM. Drop one gear and it was much better. I had 4:10 before the '94 and a 4:10 now . Much happier while towing and not really that much difference in fuel mileage.
I have one truck with the ZF42 and one with the ZF47. I think the ratios in the 42 are more useful. If I'm in a jamb with a heavy trailer i just grab low range until I get straightened out.....probably why I have over 150,000 miles on the stock clutch and DMF flywheel.
__________________
Mine: 91 F250 Reg Cab 4x4 5spd 7.3IDI 4.10LS 145,000 miles. Banks Sidewinder 92 D60 F axle w 97 brakes and Powerlock. Lift: about 4" over stock 250. 33x12.50x16.5 Pro Comp MTs Magnaflow 12" muffler. Sees dirt everyday. Used to haul hay, wood, feed cows, check fence.
Hers: 96F250 CCSB 7.3 PSD 4x4 5spd 3.55 LS 190,000 miles. Puchased 7/03, Looked for a 5spd CCSB for a year!Dana 60 front axle, at stock F350 height (for now) Energy Poly bushings, Bilsteins, 305/70/16 Pro Comps on 16x10 Weld Outbacks, AFE Pro7,TYMAR 3x3.5x4 downpipe,TYMAR 5" straightpipe, gutted EBV, IH Non EBV pedistal,New Alliant AC Injectors,(stage 1)Cal reg kit, SBC Con O clutch, permenent clutch bushing fix, AC mod with a different twist, AMP Powersteps with custom brackets and wiring(one of 2 OBS trucks with them according to AMP) Line of Fire. Sees dirt everyday.
My Company pickup: 86 F250 6.9 C6 320,000 miles Co trucks 5 89 to 94 IDI's, plus about 50 more diesels.
Diesel Mechanic 28 yrs
My dad had a 92 IDI and the rear end went out put 3.55 gears in them and was very unhappy. With the way it pulled. got great mileage unhooked, but it stayed hooked to a 25 foot goose neck with steel side rails a steel box and a steel gate that weighed over two hundred pounds. it hauled at least three zero turn mowers everyday. So i would suggest going with the 3.73 if your going to pull that much wieght. Just my .02
__________________
Early 99 Super Cab Dually 4x4
TS 6 Postion Chip(Stock, High Idle, 40 Tow, 80Eco,120,140)
Tymar Intake
MBRP 4in Exhaust
Phatom II Gauges (Boost, Pyro, Trans)
Oh Yeah Only 38,000 Orignal Miles
Linear Mode
