"e" switch in glove box

[Cherokid]

I'm new to this FSJ thing. I have owned two other 4x4's. (81 toy truck and 85 cherokee) How is the diff lock actuated? Vac? Cable? Also I read somewhere that jeep doesn't recommend driving a quadra-trac faster than 65mph. True? Why? Any way around it without changing xfer cases? (Locking hubs?)
Thanks,
Cherokid

[reddog]

Welcome Kid!

The x-fer case is vacuum activated. I am not an Quadra Trac expert BUT it sounds like you do not have a part time kit installed since you have no front hubs or the different sticker on your e-drive switch so you do not want to drive it in e-drive on the pavement. Without a part time kit you do not want hubs as driving it without the front axle engaged can destroy the cones in the xfer case in short order. I have heard the 65 MPH thing before but know that more than a few drive theirs faster than that. I am sure Qtrac owners will give you more info. Again welcome!

Kerry

[ November 06, 2002, 12:59 PM: Message edited by: reddog ]

[bvibert]

Welcome to the group!

I hope that thing about not taking the QT over 65 isn't true :eek: :eek: I often go over that...

The QT is vacum activated, all it does is lock the front and rear drive shafts together to make it true four wheel drive. Otherwise the front and rear dirveshafts are able to spin at different speeds. You do NOT want to drive with it locked up on dry pavement! There are part time conversion kits out there that make the Quadra Trac more like a normal trnasfer case. You'll have 2wd mode and 4wd mode (no more full time 4 wheel drive) I don't have any experience with these kits though.

[fulsizjeep]

Welcome Cherokid! If you have an 85 Cherokee, it must be an XJ. 83 was the last year for Full Sized Cherokee. Or, maybe, you have a rare 83 Cherokee that was not titled until 85? OK, OK, so if you have an 83 Cherokee, it probably has an NP208 transfer case. Let's see a picture of the Chero? Oh - if you have a 83 Cherokee that has a Quadra Trac, it is probably a NP219 - which is not a true QT, they just called it that for marketing purposes. A true QT is a Borg Warner unit used in FSJs from 73 thru 79. And yes, they can take high speeds, as I have run well over 100 in a couple of them. ;)

[John V]

Welcome to the nightmare!!!

65?!?!?! :eek: :eek: :eek: Been at 100+ in my 78 waggy qt, 85+ towing Gwamp's little trailer and 70+ towing my 77 waggy on a dolly. No troubles yet... smile.gif ;)

[ November 06, 2002, 01:36 PM: Message edited by: John V ]

[Peter Matusov]

Cherokid,

no problem doing 85mph for many hours with QT, shouldn't be any at higher speeds as well.

no need to replace the QT, unless you want to built a rock buggy or high-hp mud racer out of your jeep. and if you want to replace it anyway, it's a PITA since you'll be looking into taking the transmission apart to adapt for any other case.

peter

[Stuka]

off topic:

Flint: That is one *HUGE* cat!!

[Crazy_Jeepman]

The 85 Cherokee is not an FSJ, as mentioned. There is no DIFF Lock on any Jeep, unless a Air or Cable controled locker has been installed. Only controls are to lock the Transfer Case, some lever, or Vac. Some front axles are Vac operated to engage the the axle into 4 wheel drive. ;)

[Peter Matusov]

quote: "I'm new to this FSJ thing. I have owned two other 4x4's. (81 toy truck and 85 cherokee)"

he didn't ask the question about an 85 Cherokee, as far as I understand.
the "e-drive" switch in the glovebox is only a QT FSJ's feature, and it controls the center DIFF lock.

peter

[jeepguzzi]

Bottom line, Whoever said that the Quadratrac transfer case is only good to 65 mph has no idea what they are talking about. Desert racers used these cases for years to run Baja and like events. Those guys don't like going UNDER 65!!!

As far as the part time conversion referred to above, I have had one in mine since around 1983 or so. I like the conversion, I can leave the hubs locked in during trips between the times I require 4x4 such as partially snow covered roads or when I'm at the dunes and go to and from the campground. I just use the glovebox knob to shift into and out of 4x4, now. Without the conversion kit, the vehicle is full time 4x4.

[Cherokid]

Thanks for the info/input! I should've been a little clearer in that I am between jeeps right now but getting my ducks in a row. I've seen a couple of FSJ Cherokees and really like the features and style. A big concern was the 65mph question bu that out of the way, a big cherokee is lookin like the way to go. On a side note I let a good running complete unmolested 79 get away from me that a dealer was selling for $995. The line is forming to kick my back side to knock some sense into me.

[jode]

Originally posted by Cherokid:
How is the diff lock actuated? Vac? Cable? Funny story:
Shortly after purchasing my first FSJ, I was talking with another FSJ owner who was trying to tell me that the BWQT system was the best thing since sliced butter and how it "locks up all four wheels so you CANNOT get stuck." What a load of crap! He had jsut been seriously "taken" by whoever sold hiom that FSJ and thought he was running around in the baddest vehicle on the planet...I hated to burst his bubble (...OK, i enjoyed it :D )
Anyway, as was mentioned, the E-drive does NOT lock the diffs, it locks the drivelines. And that is a HUGE difference. In other words, E-drive is what turns your truck into a true fourwheel drive....if E-drive aint on, there is a potential for 3 out of 4 wheels to be slipping....you cant do that in a normal 4X4.
FYI :D

[Peter Matusov]

Jode, there's always a potential for 1,2,3, or all 4 wheels slipping in any 4x4, "normal" or not.

Speaking of "normal," most 4x4s today are full-time.

peter

[jode]

Bolshevik!

Ok, maybe I used the term slipping incorrectly. In a real 4X4, one wheel on each axle gets driven at all times...that's a total of two driven wheels minimum at all times. It may be slipping, but it is getting driven....what I meant was that with the BWQT, if one wheel is slipping, all the power can be "directed" to that slipping wheel and you go nowhere (AKA stuck). In a real 4X4, two wheels always have power, so there has to be two wheels that slip B4 you are stuck.
"Normal" 4X4 is not FT...I dont care what kind of IFS, tin can, foreign, mini suv crap they are producing these days. :D

[crispyboy]

These guys are right when they say the quadratrack system is a full time 4wd. The emergency switch locks the driveshafts together so there is no slippage between them.
My father had a 78 4 door cherokee with quadratrack - he put 178,000 miles on it with nothing but normal maintenance of brakes and fluids. Its extremely important to keep up with the fluid changes on the quadratrack system.

[Peter Matusov]

Jode, you're still wrong. in any 4x4 setup, any number of wheels can be slipping; the slipping wheel gets no power.

Speaking of Bolsheviks, today's 85 years since they've taken over Russia. smile.gif

back to a "normal 4x4" vs IFS, tin can, foreign, mini suv crap - all Land Rovers have full time 4WD, and most of them are just as capable as an FSJ right out of the box. So have Toyota Land Cruisers, and many others. Many soccer-mom-ski-mobiles state-side have full-time 4WD as well (including the Aerostar I owned for four years).

peter

[jeepguzzi]

Originally posted by Peter Matusov:
Jode, you're still wrong. in any 4x4 setup, any number of wheels can be slipping; the slipping wheel gets no power.

peterNot quite, Peter! Without a locker, the slipping wheel is getting all of the power.

[Peter Matusov]

power is product of torque times rate of rotation.
that means that the wheels that don't turn get zero power; however, it doesn't say much about how much power get the wheels that do spin.

which is very small, for the absence of traction limits the torque you can apply to them.

peter

[Al Johnson]

Originally posted by Peter Matusov:
power is product of torque times rate of rotation.
that means that the wheels that don't turn get zero power; however, it doesn't say much about how much power get the wheels that do spin.

which is very small, for the absence of traction limits the torque you can apply to them.

peterBINGO!! We have a winner! An open diff guarantees you get the same torque to both wheels at all times. Can't develop torque in a wheel (axleshaft) with no resistance. Can't develop torque in one wheel, none goes to the other wheel.
A locker or spool guarantees that both wheels will turn at the same speed, no matter the torque distribution. (Ignore auto lockers ability to let one wheel turn faster for a moment.)
The QT case has a limited slip diff in it. Until you hit the E-Drive switch, then it locks front and rear driveshafts together like a spool.

:D

[jeepguzzi]

Originally posted by Peter Matusov:
power is product of torque times rate of rotation.
that means that the wheels that don't turn get zero power; however, it doesn't say much about how much power get the wheels that do spin.

which is very small, for the absence of traction limits the torque you can apply to them.

peterI disagree, somewhat. The absence of traction does not limit the amount of power supplied to the spinning wheel. The spinning wheel is actually proof of the amount of power supplied. The more power supplied, the faster the wheel spins. The total amount of power supplied to a spinning wheel in a stuck vehicle with an open diff., is 100 percent. The power is released by spinning the wheel. You can supply all of the torque in an engine to one spinning wheel.

[jeepguzzi]

Originally posted by Al Johnson:
BINGO!! We have a winner! An open diff guarantees you get the same torque to both wheels at all times. :D [/QB][/QUOTE]

My understanding of an open diff. is that power will follow the path of least resistance. This means if one wheel loses traction, the power will go to that wheel, reducing or eliminating power going to the other wheel. That is why we get stuck, because all power goes to the spinning wheel. If torque were supplied in equal amounts to both wheels at all times, it would be a locked differential, and half of the power supplied would go to the wheel with traction (not spinning) and we would not yet be stuck. Right or Wrong, and why?

[Al Johnson]

Originally posted by jeepguzzi:
</font><blockquote>quote:</font><hr />Originally posted by Al Johnson:
BINGO!! We have a winner! An open diff guarantees you get the same torque to both wheels at all times. :D </font>[/QUOTE]My understanding of an open diff. is that power will follow the path of least resistance. This means if one wheel loses traction, the power will go to that wheel, reducing or eliminating power going to the other wheel. That is why we get stuck, because all power goes to the spinning wheel. If torque were supplied in equal amounts to both wheels at all times, it would be a locked differential, and half of the power supplied would go to the wheel with traction (not spinning) and we would not yet be stuck. Right or Wrong, and why?[/QB][/QUOTE]

Okay, I'll try. But I only have half an hour. :D
Forget about power, think in terms of torque, which is a force trying to twist the axleshaft. If there is no resistance to the twisting motion, there can be very little torque developed. The only torque required is that needed to overcome friction and to increase the wheel speed. The spider gears will spin freely on the wheel with traction, but not put any torque into that shaft.
If this is impossible to visualize, then try an experiment. Put your open diff up in the air, both wheels off the ground. Have a helper. (Engine off, drivetrain in neutral.) Hold both wheels from turning, and have helper turn driveshaft. You will feel both wheels try to turn. Torque to both sides. Now let one wheel go, helper keeps turning driveshaft. The free wheel will turn, you will feel no turning force (torque) on the side you are still holding, and the helper will report that it is now very easy to turn the driveshaft.
Hope this is starting to make more sense. Yes? No?

Al smile.gif

[jeepguzzi]

O.K. Now let me try!!

With both wheels being held, the paths of resistance are equal, so power goes to both. If you let one go, power goes to the freed wheel to make it turn. You will feel no resitance to the wheel still held because all power now goes to the other side, which is opposite of your statement that equal torque goes to both wheels at all times. The reason the driveshaft is hard to turn when both wheels are held is because my helper cannot supply enough force to overcome the resistance!

It is my understanding that the torque is still developed, but is spent as inertia to spin the wheel faster. You don't lose the torque that is supplied to the spinning axleshaft simply because it has no traction. But, because it is an open diff, all available torque IS supplied to the shaft that spins.

I hope that sufficiently muddies things up; my brain hurts!!

[Peter Matusov]

Jeepguzzi,

you're absolutely right. Now, does it help or not? Power will indeed go to the wheel that has the least resistance (a case of all open differentials). The problem is that the power it takes to spin a wheel in the air or on ice is dismal. Visualize the 401 screaming on top of its lungs at 5000rpm, and only making 15 horsepower (and your gas pedal barely depressed).

It is rather pointless to discuss the "stuck" situations in terms of power - whatever spins, spins nearly free, whatever doesn't is stopped.
Much more convenient, as Al Johnson pointed out, is to only mind torque in such situations.
Here are some "true" statements about differentials:

- open differential sends equal torque to both sides (axles or driveshafts in non-"normal" 4x4).
- locked differential (spool) forces both sides to spin at the same rotation rate.
- limited slip differential will progressively bias torque towards the side that spins slower, in attempt to equalize the rate of rotation.

All speculations in terms of power should be done with regards to the above statements.

peter

[jeepguzzi]

My basic point is that the torque generated by the motor turning @5000 rpm is making far more than 15 horsepower. It ,for example makes 250H.P. It doesn't make less and send less to the wheels just because the wheels are slipping. The torque does not evaporate, it goes somewhere,,,,out to the wheel and is used to spin the wheel.

Your first statement about open diffs. needs to be corrected to say " power can be sent to either wheel, and will be biased towards the one that is moving faster."
If it sends equal torque to both sides,,,that is a locker.

[Peter Matusov]

Jeepguzzi,

what power do you think your engine does when it screams at 5000rmp with transmission in Neutral?
250HP? and where goes all the torque?
same thing when a wheel is slipping.

you don't seem to understand the differential idea. "If it sends equal torque to both sides,,,that is a locker." - plain wrong.
your previous correction is also only half-way okay - okay from the observation point of view, but is rather like "we have power crisis when newspapers write about it."

peter

[Crazy_Jeepman]

Open Diff only sends power to the axle with the least amount of traction. Only time power is sent to both axles, is when traction is equal (dry pavement and running it in a straight line). If the open diff sent equal power to both wheels, the Locker Market would Suck!!

[jeepguzzi]

The power is being used to turn the crank,,,it is still there, it is just not being transmitted anywhere.The transmission does nothing to add power. It simply transfers most of the power being made by the engine on down the line, and through gearing, allows it to be converted to forward momentum. An engine will not make less power by running and not being connected to something. It will make 250 hp weather we use it to spin a tire or not.

An open diff will send equal power to both sides, provided there is equal resistance on both sides,(as when driving in a straight line without spinning a tire) , but it will not do it at all time

P.S. Crap, now we gotta go back and forth between two pages!!! :mad: :eek: :D :D

[ November 07, 2002, 06:19 PM: Message edited by: jeepguzzi ]

[Peter Matusov]

Jeepguzzi,

lol, no, if the engine is not connected to anything, it will not make 250 hp. Believe me.

Just to get you thinkin' - does it take the same amount of gas pedal to get the engine spinning at 3k rpm in Neutral or going up 10% grade?

BTW, was that you who towed the J-truck up to California Pass from Poughkeepsie gulch?

peter

[jeepguzzi]

O.K., I think I see where you are going. To get the max torque from an engine, you need to place a demand on that engine. The more demand, the more power supplied, up to the maximum the engine is capable of making. I now realize where I am wrong.

But, the wheel that is not spinning in our stuck vehicle is getting zero torque. Period. If it were getting any torque it would be doing one of three things. 1)It would also spin,2)it would move the vehicle or 3)it would break an axle. The fact that it does none of these means that the open differential has sent all available torque over to the spinning wheel.

[Peter Matusov]

LOL, not there yet, so don't go around putting periods smile.gif

The wheel that is not spinning is getting exactly the same torque as the one that is spinning (with open differential).

Now, what happens when two wheels on the same axle are jammed solid? Does any of them get torque? With the open diff, yes, they both do, and the exactly the same amount. Does it break an axle? sometimes yes, but most often, it doesn't.

peter

p.s. here's two links for you - I couldn't find the one I liked the best, but these will do.
the Randy's Ring and Pinion uses the language that seems convenient for you - so
while I don't like it for being not clear on physics, it's still correct:

http://www.howstuffworks.com/differential1.htm
http://www.ring-pinion.com/standard-carriers.shtml

[Al Johnson]

Originally posted by jeepguzzi:

If it sends equal torque to both sides,,,that is a locker.I'm still disagreeing here. Consider the spooled or Lincoln locked rear end. (Can't say diff any more really, because there is no "differentiation".) Anyway, with the really locked rear end, say you have one wheel in the air and the other on asphalt. You try to drive away, and you do. While you are accelerating, the wheel in the air has only the torque needed to freely turn the wheel against the resistance of the bearings and the air, and to overcome it's inertia. The wheel on the ground, however, has the inertia of the entire vehicle to resist the force trying to turn it. This means that torque can be developed in the axleshaft on that side. And ONLY on that side. The two axleshafts turn at the same speed, but only one has torque in it. Or power, if we have to use that term.

Example: Use a bending beam torque wrench to tighten a nut. You will get no indication of torque in the wrench until the nut bottoms out and starts to resist the force acting on it. Then you get increasing torque shown on the wrench dial as you apply more force. If you continue until the bolt fails, the nut immediately turns fast, as the torque goes back near zero.

Torque is a twisting force. If there is no resistance to the force, no torque is developed in the shaft being turned. Work is the application of a force (such as torque) through a distance. Power is the performance of work over a period of time. It's too far of a link from torque to power, we get lost along the way. That's why I suggested just thinking in terms of torque.

Hope this helps, not trying to be argumentative!

:D

[jeepguzzi]

O.K., thanks. Our non spinning wheel is getting torque, but it is not enough to overcome the resistance.

[Al Johnson]

Originally posted by jeepguzzi:
O.K., thanks. Our non spinning wheel is getting torque, but it is not enough to overcome the resistance.Yup, you got it. The non-spinning wheel is getting the same torque as the one with less traction. It does just as much driving as the less traction one. No more or less. That's what's great about a locker - to put it in the confusing but popular terms, the locker "sends the power" to the wheel with traction.

Thanks for going along for the ride. Now can I get a ride in that great-looking truck in your avatar? Sweeeet.

Al

[Al Johnson]

I just realized that I could make a good argument for the original statement that "the power is sent to the wheel that spins" on the basis that with equal torque to both sides, the wheel that is going faster is getting more power. ( Torque X RPM = power.) BUT really the point here is that it's torque that moves the vehicle. Power just tells you how quick it's going to move. And that's only by applying the power to the road.

I'm going to bed now, my head hurts.

:D

[Joe H.]

Not to muddy the waters any further, but it has been my understanding that torque is *developed*, i.e. torque as a force is only present when there is a resistance to rotation.

It's all academic, anyway--if you have one wheel up in the air w/o some kind of diff locker, that wheel's gonna spin....ummmm, right?

Peter M.--I've read your posts over the years on the FSJ List. Welcome to the board.

[jode]

OK...y'all have had a blast with your physics lesson, but you have thoroughly digressed from the orifginal issue in which I used "common" terms to try to explain a simple concept. Unfortunatly, those "common" terms also have a scientific meaning which, for the purposes of the cnversation are a little too far indepth.

The point is this.
If an FT 4X4 (not E-locked) has one wheel in the air. It could potentially be stuck there.

If a "normal" 4X4 has one wheel in the air, it will still pull with the other three and it wont be stuck.

If a "normal" 4X4 has TWO wheels in the air, it will have the potential to be stuck.

Add lockers and the situation changes....

BTW, the all-wheel drive in a minivan is not the same as QT. The differnce between AWD and a 4X4 is the lowrange. Plus, I bet your minivan doesn't have a locking center diff... tongue.gif

[Al Johnson]

I apologize for my part in the thread hijacking. Like a regular conversation, threads tend to wander, but we are not supposed to contribute to the wandering.

Al

[Bombadier]

hey, just from this thread i think i just learned EVERYTHING i need to know about 4x4, torque, power applied etc etc..... you guys should co-write a book or have a 4x4 radio talk-show or something ;) :D :D :D

BTW- This should be put into the technical archives either in whole or in part. Great stuff when it comes to delving into 4x4 quantum theory smile.gif

[ November 08, 2002, 11:37 PM: Message edited by: Bombadier ]