Hi all.
I had almost a whole weekend to myself this time, so I got a bit done, even with the crap weather.
I started off by cleaning out the diff tube. I borrowed some pink degreaser from one of my contractor's service trucks during the week and mixed it up with kero, as per the directions. I lowered the vehicle stand on the driver's side, so it would run back out and squirted the mixture up the pipe. It seemed to be working, but needed a scrub so I took the handle off my broom, as it has a cap on the end with a hole through it to hang it up. Next I got 3 new Curly Girl pot scrubbers and tangled them together and stuck them on the end of the broom handle, tieing them in place with string through the hole. With this I was able to give the tube a really good scrub. I started at the outer end to see how it went, as I was a bit worried about strands getting free and getting into the diff, but it seemed to work well so I did the whole length. Looking up the pipe, there is a sort of restriction before it got to the diff, so I could feel when I was getting close. Every now and then I would give it a blast up the pipe with the pressure washer and another good dose of degreaser and another scrub. Finally, the stuff running out looked clean. I had the bung out of the diff housing and caught the oil/sludge/water that ran out in my big oil drain pan. Even when the tube was clean, there was still nasty stuff in the diff housing.
Next step was to pull all the hub and guts off the passenger side rear wheel so I could clean it out too. The brake drum came off with just a few taps this time, as I had coated the surface around the studs and where the drum fits to the hub with nickel-seize when I had it off last time. The bolts that hold the expander units/slave cylinders to the back plate were only finger tight, but at least they had the locking tabs on the washer/plate bent over, so they couldn't have unscrewed. With all the brake bits off, I was able to remove the back plate and the stub axle. Eww.
Luckily, this gunk hadn't pushed past the seal and mixed with the wheel bearing grease, which was still bright blue, but very runny, almost like a thick oil in places.
When pulling the brake shoes off the expander unit, I noticed that the expander pins weren't going all the way back in, even if I tapped on them. When I got the slave cylinder/expander unit out of the back of the housing, I saw this odd rubber thing between the spring and the aluminium spacer thing. No idea what it is, but the other side doesn't have one.
It's a bit hard to make out in that photo. I left my good camera at work. When I pull that slave unit apart I'll see what it is.
Next job was to clean this side axle tube too. I jacked up the other side and repeated the previous process and cleaned it out. After that, I replaced the Curly Girls with some clean rags and mopped both sides out, until the rags came out dry. I'm not sure what to do about the actual diff housing. I could pull out the filler bung and squirt degreaser in and then try to get the pressure washer close enough to get most of the jet in there. I can't think of a better way to clean it out short of dropping the rear drive shaft and removing the diff guts, and I REALLY don't want to do that out in a sloping paddock. I think for now I will just degrease and blast it through the bung hole and maybe later once it's registered and I have my Heavy Rigid license I can look at doing more at work on the concrete, with people around to help.
Once dry, I made a new gasket and gave it a coat of RTV Silicone Sealant and refitted the back plate, stub axle and the tin dust/dirt deflector using new high tensile bolts and lock nuts. I only did them up enough to pull the stub axle in lightly, then left it a few hours for the sealant to cure. Last thing today I will do them all up to 30 ft-lbs and that should be that.
I had already cleaned out the brake adjuster housing so today I put it all back together and packed it with high-temp moly grease. I refitted it to the back plate and wrapped it all in plastic until I get the rest rebuilt.
During the week I was trying to work out how the "puller" type brake slave system came apart. The book says to undo the locking pin, turn the shaft anti clockwise and the piston and seals will slide out. Well, they left a LOT of steps out. First you remove the brake line from the slave cylinder. This is done by loosening the inverted flare nut. I even have proper imperial flare nut spanners, and the first thing they did was to round off all the edges. Out with the vice grips. They worked. Unfortunately, the flared end has corroded itself to the nut, so when the nut turns, so does the pipe, twisting and collapsing it. Out with the vice grips and the end is now crimped off. Oh well, I figured I would have to replace a lot of the old brake lines, as I could see where brake fluid had leaked at many of the junctions and stripped the paint, exposing it to the weather and corroding things. With the pipe safely crimped closed, I could take the slave cylinder up to the house and pull it apart on the work bench.
With the handbrake rod removed, I slipped the rubber boot off and found an external circlip. With that removed, I cut the safety wire that stops the locking pin from undoing and backed the pin out. I tried rotating the shaft anti clockwise, but it wouldn't come out. After levering the aluminium spacer plate away from the steel slave cylinder, I found another circlip stopping the guts from sliding out. With that removed, another whole lot of nothing happened.
I decided to clean it up a bit so I could see better, so I taped up all the openings and gave it a good blast in my sandblasting cabinet. With it all nice and clean, I could see that it definitely came out through the bottom. I stuck it in the press and it popped out pretty easily.
With that out, I found that the part number for the 2 rubber seals is PBR P621. These look ok, but if it's apart, I may as well put new ones in, if I can get them.
I tapped the pin out that locks the internals together and was able to separate them all. Looking into the slave housing, I found a ring of hardened sludge that had stopped the internals sliding out easily. I removed the bleeder and block-off bolt opposite where I twisted off the brake pipe, and found that these recesses were also full of sludge and gunk. I cleaned them out and gave the main cylinder bore a light clean with 1200 grit wet & dry. With everything clean now, and tools all over the work bench and around the truck, it decided to rain, so that was the end of the fun for the weekend.
I'll try and find 4 of those brake seals during the week. There's a pair for sale on eBay, but if I can get them locally it will save a lot of time.
I already picked up 4m of pre-coated 1/4" brake line and 11 new flare nuts, as that was all they had in stock. I'll try loosening the brake line on the other side during the week, so I can strip the slave cylinder down and see why it is not returning properly. The days are getting longer, so I can do a bit after work most days, when it isn't raining.
It was good to see parts actually going back on for a change.
Greg.
