What are safe speeds to engage the front axel?

[Flyingvan911]

This winter I would engage mine at low speed with the clutch pedal pressed. If you concider the need to be gentle you'll be fine. I tried to engage it at a stop since that is the time of least stress. Less wear and tear is always better.

 

[stumps]

I'm leaving for lunch now, but somebody please post a screenshot of the -10 Operator's Manual where it deals with engaging the front axle, so we can get the official word instead of a bunch of folks's interpretations of the TM. (Even though most of them are mostly correct.)

Ok,

Here are all places where the words "Front Wheel Drive" appear in the TM9-2320-361-10.

-Chuck

 

[stumps]

I think what he was saying is that he assumed the operator would know not to try to engage the transfer if one set of wheels was spinning while the other was not. If the operator does not know that and still tries to do engage the front axle they get what they get. In other words......you can't fix stupid.

Hi Dan,

My point is that unless someone told you, or you tried it, how would you know what would happen when you shifted into FWD with the wheels slipping and spinning?

A person that was raised driving manual transmissions, will be naturally very leery of shifting transmissions/transfer cases/whatever without clutching... and... A person that was raised driving automatic transmissions will think nothing of it.

Older heavy duty trucks, and PU trucks generally will have bad things happen if you shift into AWD with the wheels slipping and spinning. Newer trucks and little Subaru's, KIA's, ... with automatic transmissions have computers/fluid differentials, etc in the way, and no harm will come from shifting into AWD under any condition... if it is harmful, these vehicles just won't do it.

The OP was very right to ask. Common sense in this case depends on what is common to you.

-Chuck

 

[73m819]

Well, that does NOT say anything about in motion or not. Hope the following helps the OP

I have been running equipment with JAW CLUTCHES since the late 50s
I do know that engaging a JAW CLUTCH is not meant for a lot of rpm, BAD things WILL happen from just the shock of the engagement which includes everything from broken shafts to busted jaw clutch, don't believe me, ask ANY OLD time cable rig operator, this is before hydraulics, all the cranes had at least 1/2 of the clutches were jaw, I can go down the list of equipment with jaw clutches, some JWs had spring loaded buffers but still must be used at LOW SPEED engagement

You guys do what you want, OTHER then SAME WHEEL speed for ALL wheels for dropping in front drive, SOMETHING will have to give, if not at the time, the next, ect but IT WILL HAPPEN, just look at the design, tell me how it can't, we are talking about a JAW CLUTCH, not a sprag, not a fluid lockup, not a disc lockup, not a cam lockup or any other type of lockup. none of the last lockups are used with the air shift deuce.

At the price of parts and the time it takes to do a R/R and the chance of being DEAD IN THE WATER in the middle of NO WHERE, don't you think just a BIT of THOUGHT and a few seconds SLOWER might be worth it

 

[dittle]

Hi Dan,

My point is that unless someone told you, or you tried it, how would you know what would happen when you shifted into FWD with the wheels slipping and spinning?

A person that was raised driving manual transmissions, will be naturally very leery of shifting transmissions/transfer cases/whatever without clutching... and... A person that was raised driving automatic transmissions will think nothing of it.

Older heavy duty trucks, and PU trucks generally will have bad things happen if you shift into AWD with the wheels slipping and spinning. Newer trucks and little Subaru's, KIA's, ... with automatic transmissions have computers/fluid differentials, etc in the way, and no harm will come from shifting into AWD under any condition... if it is harmful, these vehicles just won't do it.

The OP was very right to ask. Common sense in this case depends on what is common to you.

-Chuck

I agree with everything you said Chuck

 

[Recovry4x4]

I'm not quite sure what you are trying to say with that sentence, but common sense doesn't really apply here.

-Chuck

We will just have to agree to disagree here. My humble opinion is that common sense, although rare, has a place most everywhere with life and driveline dynamics. Example, common sense would tell you not to dump the clutch on a loaded dump truck but I guess for those without common sense, this would need to be explained. My previous statement was along those lines. Life will be long and expensive without applying common sense.

 

[Capt.Marion]

Now I'm curious... does anyone know where in the TMs (if anywhere) it deals with proper usage of the front axle? Two of us have struck out...

 

[91W350]

I just went through my operator's manual, it only shows the air switch and indicator light. It will show you how to use the water controls on a water truck, the boring tools, the dump on a dump truck, but it will not say a thing about the engagement of the front axle. I tried to cheat and check a A3 manual as well, nothing there either. Glen

 

[stumps]

I just went through my operator's manual, it only shows the air switch and indicator light. It will show you how to use the water controls on a water truck, the boring tools, the dump on a dump truck, but it will not say a thing about the engagement of the front axle. I tried to cheat and check a A3 manual as well, nothing there either. Glen

Read the three pages I posted above. Basically, they say that for deep mud, engage before you start out, and for fording they say start out in low first, and then engage.

-Chuck

 

[Josh]

I've shifted mine a few dozen times this winter at speeds over 45mph. Mostly on roads that where going from clear to snow covered. Always used the clutch and always got the normal thud of it engaging(same noise as when doing it from a stop). I have found, Alot of times it wont disengage at speed, and it seemed to have to come to a stop for it to disengage. Doing a burn out(relitivly speaking), and trying to lock the front end is asking for broken parts.

Ive done a it a few times @ 55mph while about to engage a hill covered in snow with no ill effects to notice to date. Just changed the transfer case fluid and there was virtually no metal shavings in it.

 

[stumps]

We will just have to agree to disagree here. My humble opinion is that common sense, although rare, has a place most everywhere with life and driveline dynamics. Example, common sense would tell you not to dump the clutch on a loaded dump truck but I guess for those without common sense, this would need to be explained. My previous statement was along those lines. Life will be long and expensive without applying common sense.

Common sense is great, but machines don't always work the way one's intuition, or common sense, says they ought to.

Intuition, and I argue common sense, would tell you that switching to AWD when your wheels are slipping and spinning is exactly what you should do. If you follow that intuition in a Subaru, Toyota, or Honda, you just did the right thing.... In a deuce you did the absolute dog clutch crunching wrong thing.

So much for intuition and common sense.

-Chuck

 

[stumps]

I've shifted mine a few dozen times this winter at speeds over 45mph. Mostly on roads that where going from clear to snow covered. Always used the clutch and always got the normal thud of it engaging(same noise as when doing it from a stop). I have found, Alot of times it wont disengage at speed, and it seemed to have to come to a stop for it to disengage. Doing a burn out(relitivly speaking), and trying to lock the front end is asking for broken parts.

Ive done a it a few times @ 55mph while about to engage a hill covered in snow with no ill effects to notice to date. Just changed the transfer case fluid and there was virtually no metal shavings in it.

The transfer case doesn't care at all what speed you are going when you shift into AWD, only what the difference between the front axle rotation, and the rear axle rotation speed is. Relative to each other, the two halves of the dog clutch, should be at, or near, zero speed difference when they are being engaged.

-Chuck

 

[91W350]

I found those pages, and the instructions for fording. The closest thing to instructions on how to shift is low gear, low side of transfer case and in motion. I was hoping for instructions for encountering snow or mud, it says to engage the front axle before starting into motion for mud. Snow and ice recommend 2nd gear and low t-case, but it does not say anything about the front axle, just that driving wheels should have chains. I think the common sense reflected throughout this thread should prevail.

 

[Josh]

The transfer case doesn't care at all what speed you are going when you shift into AWD, only what the difference between the front axle rotation, and the rear axle rotation speed is. Relative to each other, the two halves of the dog clutch, should be at, or near, zero speed difference when they are being engaged.

-Chuck

That was a direct responce to the OPs question if its possable to shift the Tcase at speed. Im aware how dog clutch's work, And when to and not to shift into 4wd.

 

[stumps]

That was a direct responce to the OPs question if its possable to shift the Tcase at speed. Im aware how dog clutch's work, And when to and not to shift into 4wd.

I'm sorry, I didn't intend to offend. The way I read what you wrote led me to think you thought it was exceptional that you got away with shifting into AWD at 55.

-Chuck

 

[Josh]

I'm sorry, I didn't intend to offend. The way I read what you wrote led me to think you thought it was exceptional that you got away with shifting into AWD at 55.

-Chuck

Np. Just giving the OP a real world answer to his question, No offense taken.

 

[stud_man50]

Sorry for bringing up an old thread but I couldn't find much about this subject. A coworker and I bought an M35A3 several months ago, finally got it titled and were able to do a little off-road exploring and we tried to engage the front axle in neutral while stopped and the light lit up but we know the front axle didn't engage due to the fact that the front tires did not spin while in deep sand we almost got stuck in. when we dis-engaged the front axle, the switch made a rushing air sound. we did not hear any clunking or anything from underneath the vehicle. Are there any common problems with this system?

 

[General Mcgregor]

Sorry for bringing up an old thread but I couldn't find much about this subject. A coworker and I bought an M35A3 several months ago, finally got it titled and were able to do a little off-road exploring and we tried to engage the front axle in neutral while stopped and the light lit up but we know the front axle didn't engage due to the fact that the front tires did not spin while in deep sand we almost got stuck in. when we dis-engaged the front axle, the switch made a rushing air sound. we did not hear any clunking or anything from underneath the vehicle. Are there any common problems with this system?

Does it have lockout hubs?

 

[stud_man50]

i'm not exactly positive, i'm pretty sure its stock. what should I look for? just a "dial" on the outside of the tire on the axle?

 

[General Mcgregor]

i'm not exactly positive, i'm pretty sure its stock. what should I look for? just a "dial" on the outside of the tire on the axle?

Does it have CTIS? If it does I don't think it would have locking hubs, I'm not an A3 guy so I'm sure the others will chime in. Does the drive shaft spin at all?