Early M-300, 8 Lug Budd, Removing Drums/Hubs

[DanD2Soon]

Sent: 10/18/2006

Hubs
    Remove Drums/Hubs

Project Photo Link =   Early M-300 Chassis Rehab (pre-Feb. '71) - 8 Lug Budd: https://www.flickr.com/photos/31522832@N08/albums/72157629423852717

The hardest part of this job is getting up the courage to start it.  The deeper into the project you get, the easier it seems to be.  The first thing you have to do is to get the drums/hubs off...  I broke all 32 lugs loose with the coach's full weight sitting on the ground in park, parking brake on, wheels chocked on dead level pavement.  The lug studs on the driver's side SHOULD have LEFT HAND THREADS and will have an "L" stamped deeply in the end of them - some of the lug nuts may even have an "L" stamped on them - This means OPPOSITE from NORMAL, in other words,  Righty=Loosey/Lefty=Tighty.  Only the Lugs are left hand threaded and only on the left or Drivers' side - ALL the other threads involved (Bearing dust caps, spindle nuts, axle retainer nuts, and axle bearing nuts.) are normal right hand threads!

Then I jacked the frame up all the way around, one wheel at a time, Jackstands under the frame, a little at a time until there was just daylight beneath the wheels with the full weight of the coach on the jackstands.  Now, 8 lug nuts were completely removed from each hub and the wheels & tires removed and set aside.  On ours the tires all cleared the body easily with the suspension hanging down normally from the jacked up frame.  The RV looked really strange setting  high & dry  on the jackstands without wheels & tires. 

NOTE: If your circumstances or equipment dictate it, you can do this one wheel at a time or one end at a time.  BUT don't take any chances of the RV moving/shifting/falling on you!  Take every precaution - Block it, chock it, support it with jackstands and do it on the level.  BE SAFE!

Front Drums/Hubs - (Do these 1st & the rears will seem much easier.)
The Early M-300 Chassis (Built before February of 1971, And having a max GVW of 10,000 lbs.,  And Up to & Including the 159 inch wheelbase.) has threaded front wheel bearing dust caps - Do Not try to "pry" them off.  If you don't have a wrench or the special socket that will fit the octagon nut shaped top of the dust cap,  use a hammer to tap a large screwdriver or a chisel placed against a corner of the octagon shape to drive the cap in a counterclockwise direction to unscrew it.  My hub had been spray painted so many times that it had a paint "seal" around it and I used a utility knife to score the paint between the hub and the dust cap and a small screwdriver to chip some more of the old paint out of the joint.  After that, it unscrewed easily - Both sides have normal / right hand threads.

Once the dust cap is off, the spindle nut cluster is visible..  As this whole cluster is smothered in wheel bearing grease, you may have to clean some of it away to be able to see the tabs and the inner nut.  An outside hexnut and an inside hexnut with a locking washer in between them - this cluster is all that holds your Drum/Hub on its' spindle.  To remove the hub, you must loosen these nuts.  On ours, the locking washer is keyed to a slot in the spindle itself and has several tabs around it - one of the tabs was bent over a flat of the outside nut while another of the tabs was bent over a flat on the inside nut  The same hammer & screwdriver or chisel combination can be used to straighten the outer tab and free the outside nut.  Once that nut was off, the locking washer slid right off the spindle without having to straighten the inner tab.  The inner nut unscrewed with just finger pressure and I later straightened the other tab with a hammer on the anvil flat of my vice.  Though it's not likely,  the hub CAN fall off the spindle as soon as the inner nut is removed, so remove this nut carefully and be prepared to support the weight of the drum/hub so it doesn't drop in your lap, fall on your toes, or damage the bearings.  Keeping slight pressure on the hub as you remove the nut should keep it in place on the bearing races until you can get a solid grasp on it and ease it straight out and off the spindle. 

Rear Drums/Hubs
The rear axles tubes on these chassis perform exactly the same function as the spindles do in front - the bearings of the rear drums/hubs ride on the outside of the axle tubes (think of them as rear spindles) and are held on by an axle bearing nut cluster inside the rear hub hidden beneath the axle end cap flange very much like the way the spindle nut cluster in front is hidden beneath the bearing dust cap.  The ends of the axle tube are threaded to accept the axle bearing nuts which hold the "free floating" rear drum/hub on the axle tube just as the fronts are held on the spindle.  Now comes what I think is the mechanically cool part of this setup - the way the power is transmitted to the wheels - the axles themselves bear no weight.  They are supported only at their ends - at the outside end of the hub by 8 axle bolts through the axle end cap flange - on the inside only by the splined end of the axle riding in the rear end assembly.  The power is transmitted from the splined rear end through the axle shaft rotating free for its entire length in the hollow of the axle tube (rear spindle) and fed back onto the "free floating" wheel through the 8 bolts of its' end cap flange.  For those of you who already understand the mechanics of this process, it must seem like I'm stating something perfectly obvious, but to we mechanical novices it seems a really ingenious, somewhat fascinating & sort of inside-out technique.  For us,  knowing how this works helps us understand why the axle has to be removed so we can get to the bearing retainer nuts hidden beneath its' flange,  which nuts must be removed in order to get the drum/hub off,  which drum/hub must be removed to get to the rear brake parts.   Wow!  Now here's how...

1.  Loosen all 8 axle flange nuts - don't remove them - just back them off far enough that 2-3 threads are still on the studs.  This is to protect the threads as you perform the next step.  There are cone washers beneath these nuts.  Ignore them for now.  Step 2 is designed to loosen them and break the seal between the hub and the axle flange - both good things.  However - Lube from the rear end is going to drip when this seal is broken. (not as much as a cup, maybe only an ounce or two) So you may want to use a catch pan or put a rag under it.
2.  Sharply Rap the center "crown" of the axle flange with a small sledge hammer (I used a little 2 pounder) - be carefull (try not to hit the nuts) but don't be gentle - SMACK IT!   It may take more than one hit, but you'll know immediately when you've got it right - that axle flange will separate from the hub and literally POP out against the loosened flange nuts. 
3.  Remove the flange nuts and loose cone washers and carefully remove the axle and set it aside.  axle coming out  Good time to stuff a rag or wadded up grocery bag into the open end of the axle tube.
4.  At last! you can see the  rear bearing retainer nuts  and they are removed just as the front spindle nuts were.  Bend the washer tab back that locks the outside nut.  Unscrew the nut and remove the tabbed lock washer.  Now unscrew the inner nut being careful as above to support the weight of the drum/hub so it doesn't drop.

A Common Glitch - Front or Rear
If the drum/hub seems to be "stuck" on the spindle/axle or begins to come off but then "hangs up,"  chances are you need to "back off" the brake shoe adjustment.  Replace the inside spindle/axle nut and run it down finger tight to secure the hub from falling while you do this.  I was lucky only having to back off the adjusters a few clicks on each wheel to get the drum "lip" past the brakeshoes.

Take a look at this before you proceed -  How Brake Adjusters Work http://auto.howstuffworks.com/auto-parts/brakes/brake-types/drum-brake2.htm - It has a great close up shot of the star wheel & Adjuster pawl and an animated drawing that you can "Play" to see how a correctly working automatic adjuster works.  Now look at this picture - your M-300 looks like this https://www.flickr.com/photos/31522832@N08/6917849703/in/album-72157629423852717/

The brake adjuster is accessed through a slot in the bottom rear of the brake backing plate - there are 2 slots in each backing plate and they may or may not have rubber slot plugs in them that need to be pried out, but only one of the slots is lined up with the adjuster "Star Wheel."  On mine, it is the slot toward the rear of the coach on all four backing plates.  Use a light or flashlight to peek into the slot and find the "teeth" on the star wheel.  Then insert a brake spoon (cheap & handy) or straight blade screwdriver into the slot so that it engages the teeth high on the side of the star wheel and gently move the handle up forcing the teeth down - you should hear two or three "clicks" with each stroke of the brake spoon.  Then pull the tool away from the teeth, reposition, and repeat for several strokes.    Don't force the tool or the star wheel.  If its really hard, the automatic adjuster pawl may be fighting you.  That pawl is what should be making the "clicking" sound as you move the star wheel with the adjusting tool.  It's o.k. A little tricky, but o.k. 

Now you know what it looks like inside, you'll have a feel for the trick it takes to loosen the adjuster.  One description I read of this procedure suggested that having three hands would be real handy.  Use a very thin screwdriver poked through the same access hole as the brake tool, to put just enough pressure on the Pawl to get it just clear of the far side of the star wheel while you use the tool to stroke the near side of the star wheel.  Routing the little screwdriver over the adjuster body and against the back side of the pawl works best for me, but use whatever works for you.  If the adjuster still frustrates you or seems stiff, give it a good spray of penetrating oil or brake parts cleaner and take a breather - get away from it for a while.  Then go back and try it again - You'll get it done!

[ClydesdaleKevin]

Sent: 10/31/2006

Great pictures and description!  Not too much different from the 5 lug Budd wheels, but some subtle differences, like the rear axle bearing nut.  The animated diagram on how the rear self adjusters works is cool!

Kev

[Cooneytoones]

Sent: 10/31/2006

DD2.......Great dicription and photos....

Like he said the hardest thing to do is to get up the courage and strength to start...The hardest part is the jacking and stabilizing of the rig and if the wheels have been on for a long while, breaking loose the lug nuts.....but that's what PB Blaster is for....don't be afraid to use a whole bunch and let it sit sometimes it has to sit overnight....

And like DAN says......Think Safe and Do Safe....

Again, Great Work Dan....
Timmy

[D20T_73]

I was reading the part about the left handed threads so I had to tell you this short little story! About 13 years ago me and my dad were taking off the front left wheel for some reason, I cant even remember why now. haha.  So after about 15 min of trying to get the lugs off my dad had an idea...and yes we were trying the old fashion Righty tighty on a left hand thread...which doesn't work very well In our defense the wheels had been painted numerous times and the "L" was illegibal. lol

[denisondc]

  Nobody mentioned having an aching back during this work!  And having done the work once, its much easier to do it again a few years later, just to check/clean on your brakes/wheel cylinders/self-adjusters.

    I believe Chrysler's other vehicle products all used left hand threads on the drivers side wheels - all through the 60's at least.   From working on a 1937 Plymouth I know they were doing it then.