When to lock front hubs

[DokWatson]

That's all fine. I'm very confident in my knowledge of the inner workings of axles. That and I'm not stupid enough to shift out of 4wd going up hill, especially in winter conditions. Good luck in the future.

 

[stumps]

Yeah, its harder turning another few hundred pounds of metal along with the tire isn't it?

Not really. It is a trivial amount of mass compared to the 200 lbs of tire, wheel and brake drum. The reason it feels hard to turn is the gears, and bearings, are pumping very thick oil.

Think about it, if it was just the mass, once you got it spinning, it should stay spinning (like a bicycle wheel)... but it won't, it will stop almost the instant you stop pushing it.... unlike the tire/wheel with the hubs unlocked... That is because of the friction caused by the gears chomping on, and spitting out, thick gear oil.

-Chuck

 

[stumps]

That's all fine. I'm very confident in my knowledge of the inner workings of axles. That and I'm not stupid enough to shift out of 4wd going up hill, especially in winter conditions. Good luck in the future.

So, how did you learn not to be stupid in that way? Was it innate knowledge you came with straight from the womb, or did someone (or something) teach you not to shift out of 4WD when going up hill in winter weather conditions?

I learned not to shift out of 4WD (on anything even slightly slippery) when my hubs are locked, and my truck is cold, by making the mistake and spinning my truck into a guard rail.

I naively thought others might benefit from my words explaining the problem, and how to avoid it, without actually having to live through the mistake, as I did.

My bad...

-Chuck

 

[2deuce]

I appreciate your advice stumps, I wasn't aware that that can happen. I hope I'm not in that kind of cold. Living in western OR we rarely see snow in the valley. I have turned my hubs in pulling a load over my GVW on long down grades, thinking it might create some more rolling resistance. I also turn the hubs in, in some offroad situations before I pull into 4wd if I'm in and out of traction to avoid the binding when you don't need 4wd.

 

[KsM715]

Locking in the hubs will not create enough noticeable drag to help when pulling a load down hill.

 

[2deuce]

I agree but it would have an effect if I had to pull it into 4hi. At least the option was there if I needed it.

 

[stumps]

Locked vs. unlocked is not a terrifically large amount of drag in the scheme of things, but leaving my hubs locked (in 2WD), does drag my PU truck's average gas mileage down from about 15MPG to about 10MPG. That would tend to indicate an increase in drag of 33%. Most of the time it might not matter, but on one slippery day, it made me lose control, when I otherwise wouldn't have.

-Chuck

 

[Iamnewatthis]

Agreed, and no offense taken.
I think we all have a valid point.
I should be dong more reading for sure.
I should also do allot of stuff more.
But life just wont have it. lol.
Work, kids, dogs, kids in sports, old house falling down around us, etc., etc.,
just not enough money or time to do anything 100% well these days.
I have glossed over the TM's when i had 20 minutes, and i do have the civilian manual as well. I have done allot more work on this thing than i have told anyone.
Just some stuff comes up and I dont have time to sit and read/hunt for it.

Like yesterday, the truck just turned itself off as i was pulling into a parking lot.
I thought it was out of gas so i put in the 4 gallon can i keep in the back. As I was
I noticed i could see that it was almost full. For whatever reason, after cranking for awhile, it started again, i drove to the gas station, it was nearly full, only took 2 gallons. I could see the gas in the filler neck. I drove home, changed the fuel filter. No problems since. We'll see.
The gas gauge is way off, reads almost on empty with a full tank.
Dont know if the gauge has anything to do with anything at all.
I will go thru the trouble shooting manual tonight about 11pm.
Hopefully that will help me figure out why it shut off.

Okay, engine shutting off on me problem not solved.

I have used the search, i have looked at the civilian manual and the -20 is still down.
Here are my questions;

Does anyone have a picture of the return valve on top of the injection pump, and can you tell me how to get it off? I am going to clean it. The picture in the civi manual looks different and i dont want to go and make something worse.

Also, as i mentioned above the engine cut out on me the other day,
I changed the fuel filter and everything seemed okay for a day or two, then it cut out on me again driving the kid to school. It had been warming up for about 15 minutes before we left and had no trouble starting.
We went about 5 miles when it cut out.
After a few seconds it started again, went another 1/2 mile, cut out again, a few more trys cranking and started again, then cut out after about a city block for good.
Would not start back up no matter how long i cranked it so i towed it home. Did not want to drain batts. completely or burn up starter.

Here's what i did,
bleed the fuel filter again at top left, cranked it, fuel came out.
pulled one of the return lines on the block, front left one, slightly bubbly fuel came out, put it back on.
So i have fuel in the filter, and fuel in the return lines by the glow plugs/injection lines.
After basically doing nothing it started again.
Idled for awhile, drove it back across the street from where i was working on it.
Still afraid to drive it anywhere till i know i solved the problem.
I read on a search that someone had a similar problem and cleaned the glass ball/float ball in the return valve but my brain is not firing today and like i said the picture in the civie manual looks way diferent than what im looking at on top of the injection pump.
I would like to clean the return valve.
Any advise would help greatly, thank you.
P.S. I know this is probally a dumb question but does the gas gauge have anything to do with the truck shutting itself off? Like to protect something? Mine is reading almost on E with a full tank of Fuel. Noticed both times when it shut down it was reading empty for awhile when it happened.
Also I have been using power service diesel clean, could i just be getting some clogs?

 

[Barrman]

The IP return check valve is on top of the pump. It is a brass fitting with a black hose attached to it. A red squeeze clamp holds the hose on. Just use pliers to pull off the clamp, remove hose, use a 9/16" socket to pull off the fitting. Then look inside the fitting and see if you can see through it. If it is full of black stuff, your pump is dying.

 

[OL AG '89]

This thread somehow just took a SEVER left hand turn From "when to lock hubs" to IP discussion.... WTheck?????

 

[Iamnewatthis]

This thread somehow just took a SEVER left hand turn From "when to lock hubs" to IP discussion.... WTheck?????

I know, i was the original poster of the hub question, then i had another.
Figured while i had everyones attention kinda thing.
I made a new post and have since worked it out.

 

[m16ty]

The hop you feel when on hard surfaces in a turn (4X4, hubs locked) has nothing to do with the differential. It is the velocity change in the steering knuckle u-joints. These trucks to not have constant velocity u-joints. When in a turn, the velocity of the axle shaft changes throughout the 360deg of rotation. The sharper the turn, the more velocity change.

 

[SmokeyDod]

Hubs locked when in 4wd DON"T have nothing to do with the wheel hop.
That's profound!!

 

[m16ty]

Hubs locked when in 4wd DON"T have nothing to do with the wheel hop.
That's profound!!

Do you even know what I'm talking about? If not you've never driven a 4X4 locked in on pavement.

If it doesn't have anything to do with it then why doesn't it do it in 2X4? If it doesn't have anything to do with it (like you said) it should also hop it 2X4.

If I am wrong I'd love to hear your explaination on what causes it.

 

[SmokeyDod]

I was wrong. My sentence should have ended with a ? mark & not a period. I know while turning that the outer most wheel is turning faster than the inside wheel. This difference is transferred to the "differential" which when locked causes both wheels to try to turn at same speed. I was, in a round about way saying that this hop is caused by the "diff". when it all comes down to it.

 

[m16ty]

I was wrong. My sentence should have ended with a ? mark & not a period. I know while turning that the outer most wheel is turning faster than the inside wheel. This difference is transferred to the "differential" which when locked causes both wheels to try to turn at same speed. I was, in a round about way saying that this hop is caused by the "diff". when it all comes down to it.

Well the velocity change is transfered through the diff but that's not what causes it. Think about front wheel drive vehicles. They don't have the "hop" because they use CV joints.

The u-joint velocity change also applies to driveshafts. That is why you try and keep your inputs and outputs as parallel as possible. That way each u-joint will cancel out the velocity change from the other one. This is also why it's very important to "time" a driveshaft when you install it.

 

[KsM715]

I know while turning that the outer most wheel is turning faster than the inside wheel. This difference is transferred to the "differential" which when locked causes both wheels to try to turn at same speed. I was, in a round about way saying that this hop is caused by the "diff". when it all comes down to it.

While that would be true if these trucks came with lockers in the front, but they dont. Locking in the hubs has nothing to do with locking the diff. gears.