When things are investigated, knowledge is extended. When knowledge is extended, the will becomes sincere. When the will is sincere, the mind is correct. When the mind is correct, the self is cultivated. -- Confucius
Politically correct ideals are garbage: true wisdom comes from decades of deep thought and neutral observation. Only a so-called sociopath could ascertain wisdom from this crazy world in a neutral way. Cool thoughts- uncorrupted by modern politics, social norms, or societal ideals- are required for wisdom. Questioning everything, and going against the grain on all universally accepted norms is the path to true intelligence. The Gods notice this.

3/27/09

How To Fix Dually Brakes

I have just finished the process of repairing my rear brakes on a C-30 Chevy truck. It has dually wheels and I have never worked on something like this before, so I sought out advice online before starting. There are many articles, mostly on mechanics' forums and blogs. I thought I had obtained some pretty good advice, but was ill-prepared in the end.

Therefore I am going to add a few helpful hints to the net, to facilitate other first timers. Though it sounds obvious, remember there is a reason jack stands are always recommended- jacks can tip over! Especially bottle jacks, so use a trolley jack with large jack stands while chocking the other wheels...

"Remove axle" means you need to get a 3 foot long pipe to put over a 1/2" breaker bar in order to break the hub bolts loose. Then after removing them, 'simply' pull out the inner floating axle.

After taking off both wheels on one side, and pulling out the axle, "remove brake drum". Now the fun begins. (I hope by now you have placed a large jack stand under the outer axle...and even these can tip over so make sure they are on level solid ground!!!) In order to remove the brake drum, you will first pull on it with all your strength. Then you will beat it with a 5 pound hammer- a sledgehammer is too big because of the fear of cracking it: these drums cost 165.00 apiece! Next, the inevitable curse-fest and hurling of insults toward GM engineers. Now, search for extra large drum pullers. Even tool stores don't have them, but a few can be found online that are big enough...for a few c-notes. So forget that. Searching online for tips is next. Wiki-How is good. There you will learn that there is a nut to remove in there. How were you supposed to know if it is not even visible? Regardless, go ahead and go through lots of trouble to dig out your biggest sockets in preparation for this massive spindle nut. Next, clean off the old gear oil and look at the nut. It ain't a spindle nut at all. It is a castle nut. So just pop off the c-clip over it, then pull out the key with a pair of needle nose, and it turns right off with a screwdriver.

Now, the freaking drum will pull off..Interesting, indeed. In my case, the shoes were worn down to nothing and were bare metal. The emergency brake bar had fallen out and bent in half somehow. The shoe retainer springs were bent. The cylinder seals were cracked and popped off, leaking fluid. Brake dust was piled over an inch high on top of stuff.

So, next, you need to clean everything off with carburetor spray and paper towels.(Brake cleaner spray is really just marked up carb spray.) You will end up needing about six cans of spray and four rolls of towels. Spray out the two bearings as well in the drum. Do not set the drum in the yard, or grass and rocks will get into the bearings which will have to be picked out with needle nosed pliers. Trust me on that. The only way to repack them without removing them is to get a grease gun and shoot it directly into the bearing, several times to expel the old grease and make sure it is full. If your other 3 grease guns are stored in a trailer 90 miles away, you will need to buy a new one to do this. Use the grease labeled for 'industrial and mining operations'. With cheap brands, you have to overdo things a little to ensure it will work right.

Set the drum aside- being careful not to cramp your back lifting the 80 pound motha. Now, "remove old brake shoes". This means grabbing the springs with vice grips and unhooking them all, then, about a half hour later, the shoes will be off. Lay out the springs how they came off, so you will know later how to put them back on. Then you will kick them sooner or later, and it will become a guessing game. Such is brakes. (update on 1/26/10: since most people incl. myself do not take a before picture of their brakes, I have done it for you. taken after all was completed and where it should be. see below). It is wise to place all parts inside a ziploc bag, to avoid losing any. If you lose even one, you will have to buy a new spring kit.

The brilliant GM engineers designed a backing plate a full 1/2 inch from the leaf springs behind it, so it has to come off to remove the cylinder. There are four bolts that hold it on. Next is the brake line. Undo it with a lot of PB spray and a 3/8 line wrench. It will still strip, but by using the spray and a line wrench you will feel good knowing it is not your fault...Ditto for the bolts holding on the wheel cylinder. I stripped the head on one, and had to chisel the head off of another. New cylinders do not come with bolts for some stupidass reason, so the quest now begins to find new ones.

Parts stores sell them, but at least one chain does not like to help you find them. Suggesting going to a hardware store is a lazy way out for the incompetent counter attendant. But I won't be spiteful and say the name of this store, which rhymes with o'smileys...Anyway, other parts stores will find the exact replacement bolts for you, so try that first before checking every hardware store in town like I did.

If your screw adjusters have their teeth worn down to nothing, make sure you specify when you order new ones that they are left and right: counter attendants- especially at o'smileys- will not think of that and order two right ones. Then you will have to go back later after they have ordered a left one. Don't take any lip from them either, and let them say they are the same part. They move in opposite directions and the right one has left-hand threads. This is true regardless of the manager's claims. Place a glob of bearing grease inside the head and onto the threads of the new adjusters before installing. Some use lithium grease (the white stuff) but it dries out.

Once the cylinder is bolted back onto the plate, and the line is attached, you will have to reattach the plate to the outer axle and put the new shoes and springs on. It is easiest to attach line to cylinder, cylinder to plate, and plate to hub- in that order. Then, attach line to its junction block. Trust me on this. After all is well, the drum must be replaced before you can bleed them. We all know how to bleed brakes I suppose, but on these trucks there is a catch: accessing the bleeder valve. There is 1/2" of clearance between the backing plate and the leaf springs. Your fingers can get caught in there (and it hurts). A 3/8 ratchet or breaker bar will not fit. A 1/4" ratchet is no good because you can't reach in to switch the direction lever on it. A 1/4" flex bar is required, with a small 1/4" pipe to go over the handle for length. This is the only way to move the bleeder back and forth. When finished (after dozens of bleeds), good luck getting your tools out of there. Or, just leave them and start with new ones on the other side. (Someday they will vibrate off and someone will find them on the road. It may make a teenage boy's day, or a young girl might use them to punish her barbies with...) Another way is to just open the valve and let the fluid run out awhile, keeping the master cylinder refilled. This extrudes most air from the line, but is not as good as actual forced bleeding by pressing the brake pedal. The one-man bleeder kits you can buy are notorious for falling apart, but you can make your own easily. It is sturdier and cheaper to use an plastic jar like from peanut butter and make two holes in the lid. Fill the jar about 1/3 with clean fluid. Run a clear vinyl hose (hardware stores sell them for a few cents per foot) into the fluid and then over the opened bleeder valve. Press brake pedal until no bubbles are seen going through tube. The trick is getting the exact size of tubing to go over your valves.

After bleeding, the tires can be put back on. Remember to re-insert the axle too, and seal the bolts/cap to it. You must tighten the hub bolts with the tire off the ground, or it will not line up right and at least one will strip out. Then you will need to buy a replacement bolt with washers, which will prevent the rims from passing over it. Just guessing on this (maybe).

If you decide to change the differential fluid too, here is one more tip: all of the web pages say to use a funnel. They do not mention that gear oil is nearly as thick as honey, and requires a special type funnel (one with hose, on/off twisty valve, and tube). Cut the factory tube off the top of the differential and attach funnel hose with a small hose clamp. Jam funnel into position against vehicle floor then open valve to drain it. It will take about an hour per quart to drain from the funnel into the differential fill tube. At 3.5 quarts capacity, this is an all day task.

After all this, you will be glad you are done, despite the idiots at the parts stores and the special difficulties with these kinds of trucks. But there is one more thing.

Now, repeat on other side........
 


 

some final, random tips:
top blue spring does not hook onto top pin, but onto adjuster arm wire. make sure the e-brake crossbar has its square spring on the right way- these do not come in kits and have to be bought at dealers or junkyards. taller, black shoe retainer spring goes to front shoe/short blue one to rear. clean inner drum surface thoroughly with wire brush and spray. be careful to put thicker shoe to rear and smaller one to front.this is a very good time to repack bearings with new grease- there are two in each drum. see addendum below on this.



UPDATE!

Note original date of this post. Now, on 1/26/10, I am updating this as the job is finally, truly done. All of this time I have been refixing /waiting on weather to warm up/redoing/etc. They kept locking up. They would work fine for a ways, grab, lock up. Either side at random and independently.

Posting questions about this on Yahoo Answers was an exercise in futility. Several mechanics with many years experience offered tips of all sorts. They meant well, but no one was correct. I took it apart again.

The new shoes, with barely 200 miles on them, were worn halfway down and cracking. I got new ones from a different parts store. Not 130. Wagners, but not generics either. While replacing them, I bent a spring and had to get a new spring kit. That was when I learned that the other new spring kit from the other store  (o'smiley's again) was crap. The shoe retainer springs were all four the same- that's funny- the ones I had now had different ones for the front and back shoes. What else could be wrong, tension maybe, who knows? So with the new shoes (American) and the new springs (American) it all went together fairly easily.

I have taken pics and added them along with a few tips for anyone needing help. 

My brakes work fine now and no longer lock up.

Buy domestic.

Addendum:
Do not use cheapy grease!!! Generic or cheapo bearing grease will break down in less than a year and turn into a watery goop that will get on everyhting inside the drum, and can even ruin the brake shoe linings. Pics below are of the mess made inside a G30 van drum that had bearing repacked with super tech red grease.







--these tips work on all Chevy one-ton drums and brake systems, such as C30 trucks, G30 vans, 3500s, and others--


(c) james platt, both article and pictures. ask for repost permission.

No comments:

Post a Comment

constructive comments appreciated. name calling and links deleted.