7.3L Power Stroke Engine and DrivetrainDiscussion of the 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. 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 7.3L Power Stroke engine.
If you are making a tight turn, and you have good traction, you will get some jerking (sometimes it almost feels like wheel hop) from the bind that the front of the truck is in.
Roger
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2002 F350 XLT, CC, SB, 4x4, Auto, AIC, DiabloSport Predator, BD X-Monitor, Kenwood TM-V7A, Pioneer 7400MP3, Infinity 5.25" Components, Infinity 10" Sub in a Q-Logic Box, Heated Mirrors, Gentex/Mito Auto Dimming Mirror, Rear ID Bar, Uniden PC78 Elite CB, Clifford Matrix RS3 Alarm/Remote Start, Keypad Entry, Homemade "Tymar", custom, muffler back exhaust, 6 Whelen LED's in rear window, 6 Whelen Strobes in the Front, Rears still not installed...
Yes that's normal. There's no differential in the front axle so the wheels are driving at the same speed and if you're getting good traction, you will definately feel it when the wheels are turned. You definately don't want to run it in 4 wheel drive on dry pavement.
My bad...This wasn't what I meant to say. It should read "There's no differential between the wheels (meaning front & back)"
I just discovered today that the front end will bind up even with the transfer case in 2wd. Others have mentioned this happening but most people, including myself, did not believe it. Today I had my manual front hubs locked from being off road a few days ago. I have drove it like this without trouble many times with the t-case in 2wd. Today in the Wal-mart parking lot I made a tight, full lock, right turn. I felt the truck 'wheel hop' and felt it bind up. This must be the limited slip diff trying to lock up. I unlocked my hubs and tried the same move again, smooth as silk.
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2001 F-250 Powerstroke, auto, super cab, short bed, 4x4. Bright red with silver on the bottom, lighted visor, chrome step bumpers and fender trim.
1988 F-150 302 V8 five speed, full bed, 2x4. Over 207,000 miles and runs like it just rolled off the assembly line.
If you have the hubs locked there's no difference from being in 4WD as far as the axles are concerned. It will still bind just the same. The only difference is that the transfer case isn't putting power to the front end.
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Yes that's normal. There's no differential in the front axle so the wheels are driving at the same speed and if you're getting good traction, you will definately feel it when the wheels are turned. You definately don't want to run it in 4 wheel drive on dry pavement.
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there absolutely is a differential in the front axle. anyway, yes the binding is normal. limited slips & lockers make it even more noticable.
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Early 99 (couldn't wait to get my butt in the seat of the new SD) Crew Cab 4X4, 6 speed, AIC, 5" lift, 38X14.50 Nitto Mud Grapplers (awesome mud tire, noisy though), Bushwhacker cutout flares, 4" straight exhaust w/6" tip, open element filter, cowl induction hood, custom grill, stereo upgrade, and most importantly - new style cup holder. 'Pane. H2O soon to come. Kill Record: 1 Honda Accord
Sold the SCMT and replaced it with a DP Tuner, and aint looking back!
A stock front axle has an OPEN differential. The "wheel hop" you are feeling is caused by the u-joints. The u-joints have a limited angle of operation. The front wheels can turn greater than this angle of operation. Be careful when in four-wheel drive and making turns. These engines have enough torque to snap those axle shafts and u-joints like dry twigs.
I don't like the Dodge front end for this reason. Their front shafts spin all the time. And it is for this reason that the front u-joints don't last very long. Tight turn = broken u-joint. No dodges for me!
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2001 4x4 F-250 58,000+ Miles, 7.3L, Crew Cab, 6-Spd Handshaker. Bought used 09/09. Fold over gooseneck ball. SCMT-1705 on Tow Safe. Gauges: Boost, & Pyrometer. 4" Turbo-back Exhaust. So much I want to do to this one....
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The "wheel hop" you are feeling is caused by the u-joints. The u-joints have a limited angle of operation.
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Wrong again.
The wheel hop is because there is no differential between the front and rear wheels. The front wheels travel a longer distance than the rear wheels when turning. If all the tires have traction, something has to give. One or more tires will slip or something will break, like a u-joint. That's why you should not use four wheel drive on good traction surfaces.
Exactly, I was hoping someone would explain that it was the u-joint bind causing the feeling even with the T-case disengaged.
And the lurching/binding when in 4wd on a good surface is because of the obvious fact that the rear axle is traveling in a MUCH tigher arc than the front axle leaving it with much less actual distance covered or less revolutions for the same distance traveled. And with the front and rear axles mechanically linked through the driveshafts with no center differential like you see in AWD cars, the "slack" goes into wheel slip that is very noticable on these heavy trucks with relatively narrow tires because the static friction is so high that they woln't just break loose a little and be smooth with it, but the force builds up and then a tire breaks loose and you get a jerk, then the cycle is repeated again and again as long as you continue to turn sharp and the surface is uniform and has good traction.
The front diff is definately open. I don't even know if anyone offers a L/S unit for a Dana 50.
Either way, it's pretty stressfull on the drivetrain, so I would avoid it when possible. Or at least pull through it as slowly as you can so you don't shock load one of those front u-joints and pop it.
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The "wheel hop" you are feeling is caused by the u-joints. The u-joints have a limited angle of operation.
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Wrong again.
The wheel hop is because there is no differential between the front and rear wheels. The front wheels travel a longer distance than the rear wheels when turning. If all the tires have traction, something has to give. One or more tires will slip or something will break, like a u-joint. That's why you should not use four wheel drive on good traction surfaces.
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I need to clarify...What I was referring to was during 2wd operation with the front hubs still locked in. My bad. Now that I've completely muddied the water...let me try again...
With the transfer case in 2wd..."wheel hop" in the front is caused by the u-joints being turned past their normal operation angle.
With the transfer case in 4wd...on a dry surface you will get "wheel hop" because the front and rear wheels are trying to roll at the same speed but the rear wheels have less ground to cover because they are "cheating".
With the transfer case in 4wd...on a wet/slippery surface you will get "wheel hop" or a jerky front end when you turn too tight.
In all of these cases be careful because you can cause serious damage to your vehicle.
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2001 4x4 F-250 58,000+ Miles, 7.3L, Crew Cab, 6-Spd Handshaker. Bought used 09/09. Fold over gooseneck ball. SCMT-1705 on Tow Safe. Gauges: Boost, & Pyrometer. 4" Turbo-back Exhaust. So much I want to do to this one....
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A stock front axle has an OPEN differential. The "wheel hop" you are feeling is caused by the u-joints. The u-joints have a limited angle of operation. The front wheels can turn greater than this angle of operation. Be careful when in four-wheel drive and making turns. These engines have enough torque to snap those axle shafts and u-joints like dry twigs.
I don't like the Dodge front end for this reason. Their front shafts spin all the time. And it is for this reason that the front u-joints don't last very long. Tight turn = broken u-joint. No dodges for me!
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what kind of limited edition axles are ya'll running that the outer shaft u-joints bind & cause bucking? want to test that theory? unlock the hubs, turn the truck full lock either direction, put the transfer case in neutral. now crawl under the truck and spin the driveshaft. if you're theory is correct the axle will bind up. but my friends, you will find that it will rotate quite easily, no binding. like casey_1 said, the bucking is caused by the tires traveling at two different speeds in a turn.
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Early 99 (couldn't wait to get my butt in the seat of the new SD) Crew Cab 4X4, 6 speed, AIC, 5" lift, 38X14.50 Nitto Mud Grapplers (awesome mud tire, noisy though), Bushwhacker cutout flares, 4" straight exhaust w/6" tip, open element filter, cowl induction hood, custom grill, stereo upgrade, and most importantly - new style cup holder. 'Pane. H2O soon to come. Kill Record: 1 Honda Accord
Sold the SCMT and replaced it with a DP Tuner, and aint looking back!
next time there's an icy parking lot, go do a 4wd donut and crank the wheel hard over, and feel the u-joints bind and then release,
and it's the u joints binding in 4wd too, cause with an open diff in the front and back there is nothing preventing the wheel speed from evening out.
the old axle's use to have these bolts and jam nuts to prevent over turning the knuckles, but now the stop is cast and non adjustable. so to allow for a tighter turning radius in 4wd, they allow the knuckles to turn past the working angle for the u-joint.
somebody jump in here, the working angle for a single u-joint is somewhere around 25 degrees, i think
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