Driving in front high
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From: Vegas
Driving in front high
If part of the reason vehicle manufacturers have largely gone to front wheel drive is that it is more efficient to pull a vehicle than to push it, would a truck with a twin sticked transfer case see better mileage in front high? Kind a goofy question that came to me late at night 
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From: Chatsworth, CA
Most front wheel drive cars have there engine traversed meaning the engine is put in sideways. Your engine is placed in straight with a tranny and transfercase. If you are running a twin stick you would be putting to much pressure and torque just on that front axle. I think its fine for short periods of time put to permanently run it like that your gonna start breaking stuff. Your gonna be giving that front axle to much stress from steering and having all your power going to that front axle which usually is the weaker of the two axles.
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From: USA
Many years ago my friend had a Blazer with an NP205 and lost his rear shaft on the highway. He took it off and drove about 300 miles on the front axle. At the end of his trip, the NP205 broke down and he towed the truck the rest of the way. He ended up rebuilding the t-case and having a new rear shaft built. Not sure if throwing the rear shaft is what ate the t-case or if it was just the long trip on the front axle that did it, or maybe a combination of the two, but after that he didn't drive on the front axle anymore.
As far as the gas mileage issue, I doubt you will see any change in mileage from running on the front axle. The front wheel drive cars probably get better mileage because they have less parts (no driving rear axle or driveshaft) and the trans/axle is an integral case made of aluminum. The CV shafts are tiny in comparision to our rear alxe shafts. All this equates to less weight and less rotating mass for the engine to overcome. On our big V8's the weight and rotating mass isn't much of an issue, but on a tiny 4 cyl it is.
As far as the gas mileage issue, I doubt you will see any change in mileage from running on the front axle. The front wheel drive cars probably get better mileage because they have less parts (no driving rear axle or driveshaft) and the trans/axle is an integral case made of aluminum. The CV shafts are tiny in comparision to our rear alxe shafts. All this equates to less weight and less rotating mass for the engine to overcome. On our big V8's the weight and rotating mass isn't much of an issue, but on a tiny 4 cyl it is.
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From: Vegas
I kinda figured there were reasons people dont do it. I have driven on a front shaft for short distances in an emergency. While were on the front axle, if my front diff is an open type, why is it bad to drive with the hubs locked. Is there typicaly a small difference in the ratio(front to rear)?
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From: USA
Like Ford Perf said, with part time 4wd you can drive with the hubs locked wthout hurting anything IF you leave the transfer case in 2wd when on pavement or other hard surface. Wait untill you are on a slippery surface to engage 4wd.
You are right, differences between front and rear driveshaft speeds causes binding in the drivetrain. As long as the surface is soft/slippery and your tires can slip, the binding is alleviated.
Full-time 4wd transfer cases have a center differential that allows the front and rear driveshafts to safely spin at different speeds so you can be in 4wd on the pavement. There are positions on the shift lever that lock the center differential and front and rear driveshafts together for use off road.
You are right, differences between front and rear driveshaft speeds causes binding in the drivetrain. As long as the surface is soft/slippery and your tires can slip, the binding is alleviated.
Full-time 4wd transfer cases have a center differential that allows the front and rear driveshafts to safely spin at different speeds so you can be in 4wd on the pavement. There are positions on the shift lever that lock the center differential and front and rear driveshafts together for use off road.
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From: Vegas
I drove a 5 ton 6x6 truck in the Army. Over in Iraq the transfer went out and when the mechanics replaced it they reversed two air lines that have to do with engaging the spragg unit. I kept getting stuck in the sand in places I should've been able to get through. A week later after driving about 80 miles on a paved road we had stopped and I was walking around the truck and I noticed the new front tires were completely bald. I looked under the truck and smoke was coming out of the diff breather. I just dropped the front shaft till it could be fixed(didn't know about the air lines at this point). Similar effect in our part time trucks I suppose.
Last edited by Dreampiper; Jun 4, 2004 at 07:52 AM.
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Postmaster
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From: USA
Hmmm... an air shift transfer case, interesting, sounds like the air lines controlled the differential lock. That must have been a fun truck to drive. Glad you were able to drop the shaft and get on your way, and certainly glad you made it back to the US too!
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Junior User
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From: Vegas
You manually shifted from high to low. It was a 5 speed manual tranny. When you shifted into reverse you would hear a short burst of air releasing as it went into gear. I'm not sure why the air popped in R unless it was disabling the spragg. The truck was a late 1960's vintage 23000 lb 6x6 dump truck. Tough and powerful. I got most of my mechanical knowledge from trying to keep that thing running. At various points during the war I had to drive w/out: a clutch, a starter, power steering, brakes, front drive. The beauty of those old trucks was you could fix'em in the field with duct tape and bailing wire..... hmm, wonder why I'm so fond of my old ford??
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From: Ont. Can.
Hold up on the throttle :
SoCal : The NP205 will stand up just fine on pavement and hard surface roads
as long as the speed is kept under 45mph . as the owners manual details in most part time 4X4's that were equiped with this set up . With the rear drive shaft removed as I've had occasion to have to do myself when I trashed one (bent)
mudding , the strain an the transfer case becomes minimal as well but 45mph
top end is the key .
as long as the speed is kept under 45mph . as the owners manual details in most part time 4X4's that were equiped with this set up . With the rear drive shaft removed as I've had occasion to have to do myself when I trashed one (bent)
mudding , the strain an the transfer case becomes minimal as well but 45mph
top end is the key .
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From: USA
Yes, good to know, and I know the NP205 is a stout t-case, but I would nonetheless avoid using 4wd on the pavement.
Dreampiper, seems like Unlce Sam could at least give you guys a truck that can get from A to B without stranding people in hostile territitory... Fortunately you are resourceful and got it fixed.
Dreampiper, seems like Unlce Sam could at least give you guys a truck that can get from A to B without stranding people in hostile territitory... Fortunately you are resourceful and got it fixed.
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From: Ont. Can.
An army on foot :
Yes Dreampiper; Maybe Uncle Sam could plate some F 350's and set them up for you boys so you make it back to base without tools . Also good to see you made it home in one piece to your family and loved ones , from a Ford guy north of the 49th who did not agree with our Gov's position , as a good many of us did not .
Gives a guy a new appreciation for life and our freedome though dosen't it .
Today is the day we remember our boys that bought our freedom at Normandy at Juno Beach and there are 1500 Can. over there for the services to revisit the
2000 that we lost there and a good majority of them are the remaining Vets
who's average age is now 80 , Not a lot of Politicians seeking the limelight .
It's a Rum toast and a good cigar for me today in there honor when I have my sit on the deck to appreciate the beauty of The Georgain Bay in Ont. that our boys fought to protect on this side of the line . Kudos :
Gives a guy a new appreciation for life and our freedome though dosen't it .
Today is the day we remember our boys that bought our freedom at Normandy at Juno Beach and there are 1500 Can. over there for the services to revisit the
2000 that we lost there and a good majority of them are the remaining Vets
who's average age is now 80 , Not a lot of Politicians seeking the limelight .
It's a Rum toast and a good cigar for me today in there honor when I have my sit on the deck to appreciate the beauty of The Georgain Bay in Ont. that our boys fought to protect on this side of the line . Kudos :
Last edited by Jerry Gougeon; Jun 6, 2004 at 06:58 AM.
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From: Vegas
Amen brother.
"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf" -- George Orwell (probably)
If you are reading this - thank a teacher.
If you're reading it in English - thank a vet.
"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf" -- George Orwell (probably)
If you are reading this - thank a teacher.
If you're reading it in English - thank a vet.