M35A2 Front axle and brake service.

[ATPTac]

Well I was initially going to wait until I got the rear axles done and do one big write up, but its looking like its going to be a while before I'm going to be able to get to the rears. So I'm going to go ahead and do my write up for the fronts and do the rears later. I know this has been done on here before, but I figured a fresh thread with a different perspective couldn't hurt.

All in all it wasn't a bad job, a little time consuming (had a few mishaps which I'll get to later), and extremely messy. I'm going to do this write up as if it were intended for someone who has never turned a wrench before as best I can, so for the "veterans" on here this going to seem a little excessively dumbed down. Now on to the write up:

First things first, the front wheels have to be removed. Obviously you need to jack up the front axle before doing so (and don't forget to break the lugs loose before hand). For those that don't know, the drivers side of the truck are left hand thread (left tight, right loose) assuming nobody previously replaced them with right hand thread. The end of the studs should be stamped with either a "R" or "L" indicating which thread direction they are. The general rule of thumb is if you're starting a breaker bar at the 12 o'clock position on the lug nut you always turn to the rear of the truck to loosen. To jack up the truck you can pick up a 6+ ton bottle jack or use an applicable floor jack and then ALWAYS put jack stands under the axle and lower onto them before proceeding (I got 12 ton jack stands from Harbor Freight).

Now back onto getting the lug nuts loose. There are several different ways to get lugs loose: torque multipliers, 3/4" and up impact guns, breaker bars, etc... I ended up buying a combo 1 1/2" and Budd socket from snap on to use and just put it on a 3/4" breaker bar and went to Lowe's and bought a 6' pipe to put on the breaker bar to bust the nuts loose. It took a little bit of muscle, but they cracked loose relatively easy. There are tons of threads on the subject, and everyone has their own way of doing it. I needed the socket regardless, and the pipe only cost me $18, plus the 3/4" breaker bar.

Now that the wheel is off, the drum assembly is exposed and the fun begins!


The next step is the remove the 8 bolts that hold the hub on. Frankly, I didn't think this through and did it after the wheel was off. So I put my ratchet on and hit it a couple times to loosen the bolts, vs. if you do it with the tire on the ground you won't need to hurt your hand or ding up your ratchet with a hammer. Not really a huge deal, but it would be easier to do before removing the tire.

Once you get the hub off you'll be able to see the 3" 8 point nuts and lock washer between them. Use a 3" 8 point socket to remove the outer nut:


After you get the outer nut off, use a chisel and tap the ears on the lock washer back flush so you can easily remove it. It just slides off, you might need to lightly pry on it a little bit. Once off you'll just have the inner nut and bearing left:


Once again use the 3" socket to remove the inner nut. Then its just the outer wheel bearing left holding the drum on:


If you give the drum a little wiggle and tug, it should pop the bearing loose. Remove the bearing and set it aside for packing later:


Once the bearing is removed you can remove the drum. The drums are deceptively heavy, so either get someone to help you with it or make sure you have some decent upper body strength and a good grip on the drum so you can gently pull it off and set it aside. Once that's removed you now have access to the brake shoes and wheel cylinder:


As you can see the wheel cylinder (top middle) has a cover over it. This is where I started to brain fart and forgot to take some pictures. But if you look on the back of the brake assembly there are 2 bolts that old the wheel cylinder in, as well as the brake hose. Take the hose loose, and the 2 bolts that hold the wheel cylinder in. The shield is held in between the cylinder and the backing plate and will come loose once the 2 bolts are removed. Then you can take the wheel cylinder and shield out (this can also be done after removing the backing plate minus the hose, which is actually easier to do it that way):


Next you need to remove the 12 nuts that hold the backing plate on. As you can see in the following picture a pretty good chunk of mine pulled the studs out with the nuts (don't lose the small lock washers behind the nuts). There is a ring that's under the nuts that comes off first then the spindle, then the backing plate. After that comes off you can pull your axle assembly out: (sorry for the lack of pictures in these steps, it was rather greasy and I couldn't get my phone out without ruining it)

 

[ATPTac]

After getting to this point you can remove the steering knuckle. Once again I unfortunately don't have pictures of this step. Its mostly straight forward. There are 4 bolts on the top of the knuckle and 4 on the bottom. Remove those bolts and the 2 plates (they have the grease fittings on them, and the kingpin bushings) and the knuckle should fall free and be sitting on the kingpins (you can see them on the top and bottom of the axle house in the picture below). This is also when you would remove the boot shield. Now, I was unable to remove my tie rod without beating the crap out of it with a hammer, and I really didn't want to mushroom out the threads. So I as able to remove the knuckle with it still attached, it was a little cumbersome but it can be done. The top of the knuckle has a channel for the kingpin to slide through and the bottom doesn't. So you need to raise the knuckle up and slide the top off and then it will lower off the bottom kingpin. As a side note, the drivers side of the truck is set up differently with the pitman arm being attached to the top kingpin.

Next step I did was to clean all the old grease out of the axle housing. It was darker than I would prefer, plus it looks like it might have gotten water in it at some point. It had small crystal looking formations in it like you would see when dirt gets moisture in it and freezes, so I decided to clean it all out:

Yes it was messy, and yes it was time consuming. I scooped out most of it by hand and then used some brake clean to hose down the rest of it.

Next its onto removing the axle seal retainer. Its the flat disc mounted all the way in the back of the housing:


I had a pretty large Snap-On slide hammer that I used to remove it, and I will say it took a LOT of hammering away to get that thing to budge. I've seen some guys on here say they did it with the smaller Harbor Freight slide hammers, I guess it worked for them but I don't even want to know how much effort it took. Either way, expect to be hammering away for a while until it starts to budge. It will come out eventually, just keep at it. Once out, make sure you put a catch pan underneath it to catch any gear oil that may come out. Some guys use the opportunity to drain the axle and refill it with fresh gear oil when done, I didn't have any gear oil so I didn't do it this go round. I plan to service all 3 axles when I do the rears. Once you get the seal/retainer out you'll have this:


Here is the removed seal retainer. I took pictures of the front side and the back side (where the actual seal sits), you can see how badly the slide hammer beat up the seal while removing it:


Now this is where the 3" 8 point socket came in handy for a second use. I set the seal retainer in the socket and used a different socket (I don't remember which size, just one that fits decently onto the seal) and tapped the old seal out:


Now you can see the retainer, old seal, and new seal:


I used some RTV and put a decent amount around the new seal before installing it back into the retainer to make sure I don't have any seepage. I used 2 nylon blocks that my father in law had lying around and just sandwiched the retainer and seal between them and gently tapped the upper block with a hammer until the seal was seated. Once installed back in the retainer I put a little bit more RTV around it and packed it into the groove. I just wanted to make sure I don't have any leaks:


I then took the retainer and put some RTV around it as well before setting it into the axle housing. Before doing this step make sure you clean any and all grease/gear oil out of the housing so the RTV can actually bond. I once again used the 3" socket and a hammer to tap the retainer back into place:


Any time during this process is a good time to replace your axle boots. Mine had zipper boots on it, so I just unzipped them and removed them. I got new silicone zipperless boots and new clamps to put on. Once again, this is a pretty straight forward step. You just put the boot over one of the kingpins, and slide it rearwards, then gently stretch it over the other kingpin. There are groves in the axle housing where the inner part of the boot/clamp are supposed to ride. Once you get the steering knuckle back on, getting the outer part of the boot on the knuckle and getting the clamp on is quite a pain, I highly recommend getting someone to help you hold the boot onto the knuckle and tighten down the clamp.

 

[ATPTac]

As you can now see the new boot installed onto the axle housing with the inner clamp already tightened:


Now from there you can reinstall the steering knuckle. It is a little bit of a pain to get the kingpin bushings and plates lined up while holding the steering knuckle centered. It can be done by yourself, but is easier with some help. I ended up putting a very thin layer of RTV on the plates before installing, MAKE SURE you don't cover the grease passages though. Once you get those back on, put the outer part of the boot on the knuckle with the clamp (this is the part that is much easier with help). Also, before putting all of your bolts in and torquing them, put your boot shield back on :


Next I packed the crap out of the axle housing with new grease, and then packed the U-joint on the axle with new grease as well. Then I reinstalled the axle:


Being that I was pretty heavy into grease at this point this is where the camera unfortunately got put away. The next thing I did was replace the grease seal on the spindle behind the inner wheel bearing. I just used a flat head screw driver and pried the old seal off after removing the wheel bearing, we got a small section of 3" PVC pipe with a coupler and used that to tap on the new seal. Now before you put everything back together you need to repack the wheel bearings. You can accomplish this by either getting a bearing packer (do a Google search), or do it by hand, which is what I did. You basically take the bearing in one hand, and a very large glob of grease in the other and then just smash the wider part of the bearing taper down onto the grease repeatedly in the same spot until you see clean grease coming out of the smaller tapered side. Repeat that all the way around the wheel bearing until the entire thing has fresh grease in it.

 

[ATPTac]

Once your wheel bearings are packed and you've thoroughly cleaned and lubricated everything its time to go back together. Everything obviously goes back together the reverse of how it came apart. Make sure you pack everything with a generous amount of grease, and don't forget to use a grease gun and grease the kingpin bushings (the 2 grease fittings on the plates that hold the steering knuckle on).

Once you get to the point where you're putting the outer bearing back on you're going to need to set your bearing pre-load with the inner nut. But before doing this, you should go ahead and adjust your shoes. Take your 3" 8 point socket and snug down the inner nut a little bit so it draws everything together. Then take the inspection cover off of the drum (its the little piece of metal held on by one nut). Use a feeler gauge to check the top and bottom of each shoe. If I remember correctly the top is supposed to have .020" and the bottom is supposed to be .010". There are bolts on the top of the backing plate that you turn to adjust the cam on the shoe to move it in or out. The bottom has a nut locking a stud that adjusts the bottom of the shoes, you just loosen the nut and can turn the stud. Now this can be time consuming, but basically insert your feeler gauge and adjust until you get some light drag on the feeler gauge. When you adjust the top it can also adjust the bottom as well, so you'll end up going back and forth for a while until you get it correct. I actually split the difference between them and adjusted the top and bottom to .015", if you're not comfortable with that then follow the TM.

Then put the wheel and tire back on and get the lugs nice and snug so you can set your bearing pre-load. Now according to the TM you are supposed to spin the tire and tighten the nut until it binds the tire and it doesn't spin freely, then back off 1/8 of a turn IIRC. I used this as a guideline but otherwise used my judgement when setting the pre-load. Basically you want to have very little to no play when you grab the tire on the top and bottom and push/pull in opposite directions. I have experience with setting bearing pre-load so I knew what I was looking for. If you're unsure always side with caution and follow the TM. If you over tighten the bearings you can/will burn up your bearings and seals due to excessive friction when driving, and we all know that friction leads to heat.

After you get the pre-load set, put the lock washer on (I purchased new ones). Then you put the outer nut onto the lock washer and torque it to 150 ft/lbs. After you've torqued the outer nut, bend the tabs on the washer over the outer nut. From here just put a little bit of RTV on your hub, and reinstall. It probably wouldn't hurt to put some grease in your hub before installing as well. From there you can lower the tire back onto the ground and torque your lug nuts down.

You're almost done from here. Now all you need to do is bleed your brakes thoroughly. I built a pressure bleeder which I will say is WELL worth the money (there is a stickied thread on here for building one). Just fill up the bleeder with a few quarts of brake fluid, attach it to your master cylinder and pressurize it. Once its pressurized you can go to the airpack and crack the bleeder, let it flow until you see nice clean purple brake fluid coming out. Close that up, and then move to the passenger side rear most wheel cylinder and crack the bleeder loose. Let it bleed for a good while until you see the clean purple fluid. Then go to the driver side rear most bleeder and let it bleed until you see clean fluid (should be less time if you let the passenger side bleed long enough), then the passenger rear forward axle, and etc...

I'm pretty sure I covered everything, if not somebody let me know and I'll add it in. The next post I'm going to go into some of the issues I ran into while doing the job. And things you might need to prepare for as well.

 

[ATPTac]

When I got the drivers side drum off I discovered that the rear shoe had an uncomfortable amount of friction material missing, as well as the friction material starting to separate from the backing:


I have no idea what caused this to happen, and I also didn't find the chunks of material in the drum. Which leads me to believe that somebody had the drum off after it happened and didn't replace the shoe . This is why I am a very firm believer in going through your brake system after purchasing a truck, even if the seller claims the took very good care of it. The passenger side shoes were still good, had some wear and a couple nicks in the friction material but I was comfortable with them so I let them be. I clearly replaced the driver side shoes.

Another thing to note was that both of the front wheel cylinders were leaking. The cylinder on the passenger side of the truck hadn't leaked through the boot yet, but the boot was full when I pulled it back to check. The drivers side was just starting to leak externally. So I clearly replaced both of those. When I got the old cylinders to my work, I thoroughly cleaned them (I love having a 55 gallon drum of brake cleaner at my disposal )and pulled them apart to make sure they were good to rebuild for later use. Luckily they had no pitting and very little surface rust on the outer part of the housing.

Also when I was putting the passenger side hub back on, I was running the bolts down with my electric 3/8" impact gun just to where it hit bottom and POP this happened:


Luckily I was able to get a small punch in the hole and tap on a ridge on the broken off bolt to where it finally started backing itself back out. I absolutely despise drilling out broken bolts unless I have no other options, so thankfully it came out. I sent my father in law up to Lowe's to pick up a new bolt and some corresponding lock washers (I had a couple of those broken in 2 pieces after removing bolts).

My recommendation for anybody doing this job is to absolutely have all the parts you're going to need for the job obviously, and be prepared to make runs to the parts store for any other miscellaneous nuts, bolts, and washers you might need. Luckily I was overly paranoid about finding bad parts once I got into the job, so I ordered pretty much anything that could possibly have gone bad before hand:

Enough brake shoes for the entire truck
6 wheel cylinders
6 wheel bearing lock nuts
All applicable seals
Axle boots and clamps
A couple tubes of RTV (It goes a lot further than you think it does if you've never used it)
A LOT of axle grease (I ended up using probably 6lbs +/- between both front)
Lots of brake parts cleaner (I probably used 6-7 cans)
DOT5 brake fluid (I went a little over board and got 8 quarts, but at least I have it now)
And I'm sure some stuff I'm forgetting now...

One thing I didn't say during the write up on the process was that I thoroughly cleaned all the parts I removed of dirt, grease, grime, etc... This is where most of the brake clean I used went. If you spray something with a little bit of brake clean and then scrub it with a steel or brass brush it will do wonders. Just spray, scrub, and repeat until its clean.

I will say that the 3" 8 point socket was money well spent. For one I was able to properly remove the bearing nuts without damaging them, and I also used it for several other purposes as seen above. You can't beat the right tool for the job, even though there are other ways of doing things.

Apparently I "reserved" more posts below than I needed to... I might add more to this later so I'll leave them blank. Once again, if anybody has anything they would like to add that I might have left out, or has a better or different way of doing this, please post away.

 

[ATPTac]

....

 

[ATPTac]

.....

 

[Sephirothq]

Looks good

 

[wilfreeman]

You were just in time with this thread! I will be doing mine in the next few weeks, so I've been reading ALOT! Seems pretty straight forward, just like my Jeep - just ALOT bigger parts and the boot instead of felt seals. Thanks for the write-up!

 

[Lieutenant Dan]

So there is a inner seal in the housing and a outer seal in the knuckle for the axle shaft?

 

[Flyingvan911]

The inner seal keeps the differential lube from getting into the steering knuckles. The knuckle boot keeps junk from the outside from getting into the steering knuckle.

 

[Lieutenant Dan]

He said there is a seal behind the inner bearing he pry out with a screw driver but I think he meant outer bearing.

 

[Rusty nuts]

FYI, if you use a rod or dowel to drive out the Inner seal retainer from the opposite side instead of a puller, drape a heavy cloth or towel over the end of the knuckle.....If not you possibly might have it pop out and roll across your driveway and down into a canyon never to be found......

 

[Rusty nuts]

So there is a inner seal in the housing and a outer seal in the knuckle for the axle shaft?

The inner seal is in a retainer where the axle tube ends and the knuckle starts. The outer seal is the one on the spindle to seal the wheel bearings.

 

[welldigger]

He said there is a seal behind the inner bearing he pry out with a screw driver but I think he meant outer bearing.

All 6 hubs have an inner and outer seal. The steer axle has 2 additional seals in the axle tube behind the steering knuckles. These keep gear oil inside the axle tube.

 

[ATPTac]

Ok, I edited the original posts and it (hopefully) has everything in it.

The seal I was referring to that I pried off was the grease seal that goes behind the inner bearing.

 

[ATPTac]

FYI, if you use a rod or dowel to drive out the Inner seal retainer from the opposite side instead of a puller, drape a heavy cloth or towel over the end of the knuckle.....If not you possibly might have it pop out and roll across your driveway and down into a canyon never to be found......

I was going to go that route, but I already had the slide hammer and the driveway we were working in was pretty narrow so I could only take one side apart at a time before having to move the truck.

 

[Lieutenant Dan]

I'm hoping to go over my truck good once it gets warmer out, so this thread will be great once I'm ready.

 

[ATPTac]

I'm hoping to go over my truck good once it gets warmer out, so this thread will be great once I'm ready.

Yeah, I think I'm going to wait until it warms up before I do much else to our truck. We had a fluke warm spell after Christmas and I was off that entire week. A lot of the stuff that I was unable to get pictures of will be pretty obvious once you start taking things apart. The next time I do work and a write up I'm going to get a dedicated "cameraman" so I don't miss stuff if my hands are full/messy.

 

[Lieutenant Dan]

I have a huge warehouse to work in that's heated, all depends if my boss/owner is ok with me working there on weekends. I'm a supervisor in welding and fab so I have some pull lol. I'm picking the truck up in a few weeks. I'm hoping to bob it the weekend after I get it.