Axle shaft end play.

army_inc · Post by **army_inc** » Sat Dec 15, 2012 8:14 am

Ok. I'm a little confused onthe Axle shaft end play. In the Manual it states that you attached a dial indicator so that it contacts the end of the shaft (I'm assuming you attach it to the backing plate, no biggie). THen it states that you push and pull the axle shaft in and out. If it is .001 to .006 then it is within limits. I don't need a dial indicator to KNOW that mine is out of limits. It moves about 1/4 of an inch (roughly). The manual states to add more bearing shims. My question is this. Even if I add more bearing shims, how would it affect the end play? These shims don't come in contact with the shaft. The just push the backing plate, and everything attached to it, further out (or in if you take away shims). So when I would push it in, it would still be out of limits. Am I doing something wrong or misinterpretting? Something just doesn't seem right about it that's all and I need a little help.

skyjeep50 · Post by **skyjeep50** » Sat Dec 15, 2012 11:06 am

You don't state which vehicle you have but refer to Fig. 11-4 Page 229 in the M38 parts manual for a rear axle assembly diagram (in Downloads section). You can see that the shims regulate the free play distance between the axle roller bearing and the cone. The cone is pressed into the end of the axle shaft and held in place by the retainer plate. More shims moves the retainer plate outwards, fewer shims and the retainer is pushed farther into the end of the axle housing and into closer contact with the roller bearing when the backing plate and other parts are bolted in place. The shims have a larger inside circumferance than the cone, so they fit around it, while the retainer plate does not. Shims are usually put on both left and right sides of the vehicle to center the axle but since the axle has some side to side clearance, its not critical that the shims match exactly on each side, free play is more important. Once you take everything apart you will understand how it goes. If you have 1/4 inch freeplay, you may have a well worn bearing that needs to be replaced.

army_inc · Post by **army_inc** » Sat Dec 15, 2012 11:20 am

Well I see that the shims have a larger diameter and fit around the cup and cone. The retainer plate has a smaller diameter. I installed brand new bearings and cups so I don't think that is the issue. Let me explain what I did and maybe my installation was wrong.

I pressed the bearing onto the shaft. I inserted the seal inside the axle housing. Then I place the axle shaft (with bearing and cup) into the Axle housing. Bearing fit in just fine, but cup would not. I had to install the retaining plate and press the cup in evenly. I then took the plate off and installed the shims (this to me seems to be the place where I may have messed up). I can see that if I had just installed the shims first, and then pressed it in evenly, I could've prevented the pulling out measurement to .001 to .006. At that point though, I would have to install everlything to make sure the wheel wouldn't just back "in" because I am pretty sure I can still install the backing plate and be able to push the axle shaft in more than .006. Does this makes sense?

I am working on an M38A1 btw.

army_inc · Post by **army_inc** » Sat Dec 15, 2012 12:01 pm

I feel like an idiot. I figured it out. I just didn't use that thing between my ears.....

oilleaker1 · Post by **oilleaker1** » Sat Dec 15, 2012 4:21 pm

Dave I think I'm missing that part also------

John

army_inc · Post by **army_inc** » Sat Dec 15, 2012 4:57 pm

oilleaker1 wrote:Dave I think I'm missing that part also------ John

It's funny how many people end up missing these over time. I'm sure working on jeeps can make people lose them as well

Bretto · Post by **Bretto** » Sat Dec 15, 2012 6:09 pm

So you going to leave us hangin? Inquiring minds want to know.

army_inc · Post by **army_inc** » Sat Dec 15, 2012 6:47 pm

Well, I initially installed WAAAAY to many shims. So when I pushed and pulled on the axle shaft, it had plenty of room to move around. I didn't see the cup get pushed in or out, but could see the bearing move. The cup wouldn't push in with the bearing, but was out past the bearing itself but being retained by the retaining plate (like it is supposed to be). I basically took off a crap ton of shims and got it to the point where it was .001 - .006 (I haven't taken the measurement yet as it basically doesn't move at the moment).

I plan on torqueing everything down on tuesday after taking my measurement. I just wanted to get it to the point where I could put on the hubs and wheels so I could roll it around in my garage to get it out of my way.

So in the end, I installed way to many shims which gave it the play. After taking them off, it solved the problem. I basically installed the shims the way I took them off. Unfortunately, just because I installed them the way I took them off, doesn't make the installation by someone else right. I see this all the time while working on helicopters and felt like an idiot once I realized what the real problem was and why it wasn't working. Hope that answers the questions for inquiring minds

skyjeep50 · Post by **skyjeep50** » Sat Dec 15, 2012 10:17 pm

It's hard to get the shaft to move using just your hand. And I feel that if the cup is moving in and out of the axle housing that easily, it may be too worn. I just used a plastic dead blow mallet and gently tapped on the opposite end of the shaft to move it out on the side I was measuring. Then tapped it back in. Worked for me.

army_inc · Post by **army_inc** » Sun Dec 16, 2012 8:00 am

skyjeep50 wrote:It's hard to get the shaft to move using just your hand. And I feel that if the cup is moving in and out of the axle housing that easily, it may be too worn. I just used a plastic dead blow mallet and gently tapped on the opposite end of the shaft to move it out on the side I was measuring. Then tapped it back in. Worked for me.

hardware/bearings are new so I knew it wasn't worn. At that point I figured it was just installation or user error so I came on here asking questions... unfortunately I just didn't think before asking

As for the dead blow...
I'll give that a shot when I measure it this coming week. Thanks for the tip!