Rear axle movement / alignment

[FLYWHEEL]

Hi all.
I have been reading a lot of threads lately about rear axle lateral movement and alignment, most of these threads seem to be quite old and have no definitive answer to the mentioned subject. Some saying there should be some lateral movement of the axles and that it is OK as long as it all aligns it's self when driven straight after a tight turn and others saying no movement .I understand that the spring pack bushing must be correctly adjusted and the dog bones must be in serviceable condition, but could there still be some play in the spring pockets /axles and if so how much is acceptable? Thank you in advance for any info, I am just trying to understand how it all works and learn from members on here who are a lot more knowledgeable than me
Thanks again, Mark

 

[cattlerepairman]

The trunnion bearing is one to check (and grease, while you are at it) - lateral play or lateral shift can originate there. My experience on my truck that has serviceable dog bones and good trunnion bearings is that in a tight turn there is about 1 - 11/2 inches lateral difference between the first and second rear axle and it corrects itself within a few metres of driving straight. I arrive at that conclusion by doing a turn on asphalt, as tightly as possible, and stopping in the turn to check lateral displacement.

 

[Floridianson]

But is that not the movement in the front and rear spring holder that is open and allows the spring to shift a bit.

 

[cattlerepairman]

But is that not the movement in the front and rear spring holder that is open and allows the spring to shift a bit.

Yes, I think that is correct. What I tried to say is that without any other axle or suspension parts being faulty, there is about one to one and a half inches of lateral movement.

 

[FLYWHEEL]

Yes, I think that is correct. What I tried to say is that without any other axle or suspension parts being faulty, there is about one to one and a half inches of lateral movement.

Thanks for your replys, so is this lateral movement is down to the flexibility of the dog bone joints being made of rubber. If so does this mean the more worn the lower dog bone ends the more lateral movent will be seen in the axles.

 

[FLYWHEEL]

Sorry for all the questions but I am new to suspension systems and I am trying to get my head around it all,
and the more I understand the safer I can make my truck by being able to spot problems early.

 

[Tracer]

I have wondered how much lateral movement was acceptable and I have about 1-11/2. My question is when my rear axles are in alignment and I leave my driveway and make a tight right hand turn, I hear a clunk, and when I get out I have about 1-11/2 of lateral movement. What concerns me is the noise, is this common, or does this send up a red flag for you guys? Just checked and greased the trunnion bearings and the dog bones all look good. Also wear on the rear tires looks even.

 

[dmetalmiki]

TM-9-2320-211-35 gives a complete axle schematic repair dissmantle and reassemble. No where in any army technical manual or accompaning litriture I ever studied states anything other than the axles are held rigidily in position. Lateral and for and aft. (other than flexing).

 

[Floridianson]

Yea Tracer some of my 5 tons make the clunk when the axle shifts that 3/4 of an inch in the spring holder. Some have said to lube that area but I just put in 2 gear and go.

 

[Scrounger]

There better be some lateral movement or something will break.
Unlike commercial trucks, the tandem axles on these trucks are always being driven. To clarify a little. On say a typical OTR tractor these is a power divider in the intermediate axle that only allows the rear axle to have power. When one gets into a slippery condition, i.e. snow, mud, one locks the divider and both axles will start pulling. Once one is back on good pavement the divider is unlocked. If not the rear axles will start to bind. It has to do with the different turning radiuses of the two axles.
The military solution was to design some slop in the suspension so things won’t bind up. There is still a little binding, one can see it when one makes a turn on pavement and can see the tire marks left behind.
The amount of lateral movement is determined by how much room the spring ends have to slide back and forth in their respective spring perches. The perches as well as the spring packs should never be lubricated. And it is natural for there to be some noise from the springs sliding and banging around in the perches.

 

[Tracer]

Floridianson & Scrounger thanks for the help with my question. I had my truck down for a couple weeks for rear brakes and seals so I had time to look for something wrong with the rear suspension . I have new forward dog bones, and the rears are in good condition and I couldn't detect anything wrong with the trunnion bearings. I'm leaving in the morning for the Military Vehicle Collectors show in Lodi, CA at Tower Park, so it's nice to know that the noise is nothing unusual.

 

[gringeltaube]

There better be some lateral movement or something will break. .................................................................
The military solution was to design some slop in the suspension so things won’t bind up. There is still a little binding, one can see it when one makes a turn on pavement and can see the tire marks left behind....

So you think that the axles shifting sideways would reduce the wind-up and binding say during a 90º-turn, from both diffs. being connected with a driveshaft...?

The amount of lateral movement is determined by how much room the spring ends have to slide back and forth in their respective spring perches...

From factory - on level ground - there is very little room for any side-to-side movement, or even back and forth...
See my post, here...



G.

 

[Scrounger]

[FONT=&quot]It is not just the shifting sideways but the whole slop that allows things to move around. If everything in the suspension was ridged, say fixed springs ends and non-rubber ends on the dog bones the only thing left to handle the binding would be the sliding of the tires on the pavement.
Using the OTR truck example, driving with the power divider locked on dry pavement causes excessive wear on the tires, differentials and U-joints.[/FONT]

[FONT=&quot]It doesn’t take much to release the tension in the system, just a hop of a tire, a little shift there. [/FONT]

 

[FLYWHEEL]

TM-9-2320-211-35 gives a complete axle schematic repair dissmantle and reassemble. No where in any army technical manual or accompaning litriture I ever studied states anything other than the axles are held rigidily in position. Lateral and for and aft. (other than flexing).

HI dmetalmiki, Is the axle set up the same on the 5 ton trucks as the 2.5 ton trucks, as this is a 5 ton TM, if so it looks like some more informative reading.
many thanks, mark

 

[Recovry4x4]

My initial thought was to send someone out to their truck with a forklift and lift one rear tire assy off the ground and view the springs in the pocket. This helps to illustrate where the extra space in the spring pocket on the perch is and why but as usual, G has already shared the info with the static pics and drawing in the linked post. I'm not sure that there is anywhere on a deuce that G hasn't illustrated and shared with us.

 

[Floridianson]

G did you have your rear apart? I took a pic of 5 five tons and some of the Deuce and there is more like 1/2 inch space on mine. Wonder when these went from paper to field some how some have space and some are tighter. Could it be on assembly the two springs were not parallel when they tighten them down. Here are some of the pics and I tried to go right rear rear left rear right front left front.

 

[Floridianson]

Here is one of the Deuces. Maybe wrong but this little play is what I thought I felt sometimes kick. All most all my Deuces had some play ad not as tight as G's were.

 

[Floridianson]

One more 5 ton.

 

[Floridianson]

One more 5 ton.

Kenny your right about G's and great illustrations just wonder if from paper to the field somehow thing give a bit?

 

[rustystud]

There better be some lateral movement or something will break.
Unlike commercial trucks, the tandem axles on these trucks are always being driven. To clarify a little. On say a typical OTR tractor these is a power divider in the intermediate axle that only allows the rear axle to have power. When one gets into a slippery condition, i.e. snow, mud, one locks the divider and both axles will start pulling. Once one is back on good pavement the divider is unlocked. If not the rear axles will start to bind. It has to do with the different turning radiuses of the two axles.
The military solution was to design some slop in the suspension so things won’t bind up. There is still a little binding, one can see it when one makes a turn on pavement and can see the tire marks left behind.
The amount of lateral movement is determined by how much room the spring ends have to slide back and forth in their respective spring perches. The perches as well as the spring packs should never be lubricated. And it is natural for there to be some noise from the springs sliding and banging around in the perches.

Your description of a power divider is close but not totally. Actually the power divider acts like a differential between the two axles and when locked sends power "equally" to the two differentials. Since our differentials always act like it has a locked power divider there is sometimes "binding" taking place especially on turns (which explains the tire wear we experience) . That is one reason the "dogbones" have rubber joints instead of solid bushings. The other reason is to allow such wild articulation our deuces are capable of.