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| That round thing has to come out, but it doesn't want to. I guess that it got a little to settled after 28 years! |
My original plan for the Mark VII was simple, dismantle the hydraulic components of the brake system, inspect everything, I would then rebuild the wheel cylinders, replace the flex hoses, clean up the drums and linings and see what happens.
Rebuilding wheel cylinders is actually very cheap and easy. The piston cup and outer seal are usually the only parts that are replaced. The bore can be honed lightly, very lightly, with a power drill driven hone to remove pitting and provide a smooth surface for the new piston seal to work on. One pass only please! Most wheel cylinders are made of cast iron, the pistons either aluminium or steel. The bore usually becomes pitted by the moisture that is absorbed into the brake fluid. That moisture doesn't get hot enough to evaporate. Actually dispersed into the fluid, unless the car is regularly used. A good reason to drive your car and change the brake fluid every couple of years. Off road vehicles that routinely submerge their brakes during water crossings should be changed every year. Back in the old days it was much worse. A can of fluid that was left uncapped on the workbench overnight could absorb enough moisture to be rendered worthless. The rubber piston and end seals cost only about five bucks or less for popular models. So there's no excuse not to replace them.
Complete new wheel cylinders are easily available and cheap for popular models like my old Mustang, so most guys don't bother with rebuilding, they just chuck 'em. Not in this case. Rebuilt wheel cylinders for my Mark will run 600 pound,s with a possibly refundable core charge of 400 pounds. It could conceivably cost me one thousand pounds for a working set of cylinders! How much is that in dollars?
One common restoration process done by a machine shop, is to bore out a worn cylinder and install a stainless steel sleeve, thereby restoring the cylinder to original specs. But you still have to get the damn piston out first! This could run anywhere from 125 to 250 dollars a pop.
If you run a new piston seal in a slightly pitted/somewhat worn bore you will probably find that the seal will wear out faster and start to leak much sooner than normal. There's a gamble there. If it doesn't leak immediately, it may last for thousands of miles. It might give you some time to locate or afford those rare expensive cylinders. Piston seals are cheap, but better be sure your emergency brake is up to snuff! And keep an eye out for wet backing plates.
I also investigated some alternatives. Coopercraft is a company that I've seen advertised in Jaguar World magazine, as a Jaguar brake specialist. I contacted them and found that they offer a complete disc brake upgrade package for 1250 pounds. I guess this is around 15 or 16 hundred bucks, which sounds like a really good deal. So I'm keeping that in mind. It wouldn't make a lot of sense to spend a grand on rebuilt cylinders by themselves. Keeping in mind that I might need linings, hoses, or drums also.
But getting back to the task at hand.
The first job was going to be handled one wheel position at a time. I started with the right front wheel. Removing and cleaning was the easy part. When the repair kits arrived from I tackled the task of dismantling the wheel cylinders, two per side in this case.
Usually the problem is to keep the pistons from popping out on their own while you handle them. Not in this case. Last registration was in '91, and I'll bet not many miles crossed the odometer after that.
First I tried to squeeze the piston back using my bench vise. It wouldn't even budge. Then I tried my 6 ton press, it moved about a 1/4 in. with a loud worrisome abrupt POP! I still couldn't turn the piston end with a wrench. I let the end soak some more with Liquid Wrench (L/W). I had removed the bleeder screw and transfer line and filled the inside of the cylinder with L/W. No luck.
I thought that I could introduce the solvent through the brake fluid or the bleed fitting of the wheel cylinder. The problem is that the solvent cannot get past the piston seal to reach the corroded piston/bore.
I thought I could shock the corrosion bond with heat, not too much, just enough to induce a temp shock with rapid recooling. I considered using a propane torch, or a heat gun, but I'm always worried about burning down my house! Then it occurred to me that I could just heat it up on the barbeque grille in the back yard. So I placed the cylinders on the extra burner and heated them up a bit. I didn't think that they would get too hot, but I stopped when spit sprayed on them would sizzle and totally evaporate. I then dropped them in a bucket of water. I repeated this a couple times. Did it work? Well not right away.
I went back to the L/W soak and hit the web.
I had already tried the vise method.
One of the tried and true methods is to blow some compressed air through the cylinder. My compressor limited me to only 130 lbs. That didn't seem enough. One of the pistons started to turn a bit I worked it back and forth, added more L/W. Then applied the air pressure. The piston slowly emerged!
After I cleaned it off I found that That piston was a pretty solid large chunk of steel. I also could see that there was not a step at the end of the bore so that theoretically the piston should be able to be pushed back at least an inch and a half more. I set it up in my press and let it sit under pressure. I went about other things when I suddenly heard a loud snap and the cylinder shot out sideways against the cardboard that I had placed around the press, just in case. I initially thought that the thing had slipped out under pressure because of an alignment issue. Not so. I found that one of the cast iron base blocks on the press, had snapped in half! And the darn piston was still stuck!
Another approach was to fasten a grease fitting to either the bleeder or hose port and send in grease under pressure. This sounded like a great idea, a grease gun can generate up to 1,000 psi. ( I won't mention that the piston only budged a 1/4 in. under my six ton press!) An added benefit is that instead of breaking the piston loose and having it fly across the room. it just kind of pops and oozes out. The problem was finding a fitting that would fit. The brake hose and bleeder ports were both 1/8 inch. I initially didn't find any grease fittings that size at Winchester Auto . I concluded that it was an unusual size. I found an appropriate sized bolt at OSH and figured that I would have to drill and tap that. That sounded like a lot of work so I put this idea aside for awhile.
Was there a more effective penetrating oil? I hit the web and found some interesting info.
I saw something called C RC freezing shock spray. When sprayed at a frozen joint it would cool it to near freezing. That would "shock" and break the corrosion bond. It seemed that this could be a pretty dangerous item. Bad for your skin and particularly for your eyes, but it sounded like it would work. I had watched a demo on U Tube.
I had also seen a comparison of the efficacy of several popular penetrating oils. As you might expect WD 40 was the least effective. Liquid Wrench was considerably better and something called "kroil" was even better. The best of all was a home brew, 50/50 blend of ATF and Acetone, or lacquer thinner.
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| Fail! |
I went off to several local auto stores to look for the CRC product. I couldn't find it at the local Kragens. Or the Kroil. I went to my best store, Winchester Auto. I found the Kroil, when I asked him about the CRC he said they no longer carried that now they had kroil, Twenty bucks a can, who would care as long as it worked. I went to another local Kragens ( they are all around here!) but couldn't find the CRC product either. I wandered over to the "lube" section to look at the grease fittings that I figured that I would have to tap that bolt for. Wow! I found a large selection of varying sizes, 1/8 th. in. all the way to 1/4 in. with some metric sizes thrown in for good measure.
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| Fail! |
I had found a found a double threaded stud in my stash, one side was fine thread the other coarse. It was a stud for my old Sportster's front crankcase assembly. The coarse side screwed into the aluminum case and the fine side held the nut that secured the case half. At OSH I found that the fine thread was 1/8 in. that would fit a brass fitting. I found a 1/8 steel nipple that can be combined with a 1/8th. coupler. The nipple should thread into the cylinder and the coupler will allow a 1/8 th. in. grease fitting to be attached. Hopefully this will work.
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| Double fail! To be fair it might have worked in other circumstances. |
The offending cylinder had been soaking in kroil overnight.
Things don't look too good. While it seemed like a good idea, the pipe fittings didn't fit the wheel cylinder. Drilling and tapping a couple of bolts just might be my only alternative. Things are coming to a grinding halt in this area. Right now all I can see are some expensive options. I will have to apply some project car triage.
I'm going to redirect my efforts to the carbs and see if the motor will run. I already know that it will spin freely with the starter. If it does run without any noises of impending doom I'll at least know that it's worth proceeding with the braking system rebuild. I'll try to get the emergency brake system to work so I can use it to move the car around. If the motor fails to run or smokes or sounds really bad than this car will have to go straight to the back burner.
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| Here's the piston that yielded to air pressure and twisting. You can see how much surface area there is to develop a corrosion hold. The piston and bore aren't really rusted together more like they are stuck with glue. |
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| This piston is still stuck.That shiny bolt fits perfectly in the fitting thread. Now all I have to do is drill through the bolt then tap the top to take a screw in grease fitting, a piece of cake. Right? Still, there doesn't seem to be any alternative. Keep tuned to see what transpires. |
Looking at my fleet, the XJ6 needs the least work, It does needs the front suspension rebuilt and I will have to deal with the CEL but the rest of the car is in good shape. Registration is due in November and so is the smog check. I have enough time to fix this without being in a panic.
The XJS needs a bunch of things also, but I'll have to see how it runs as I drive it to work this week. It will be a shake down test, that will tell me a lot. I bought a new battery this morning. I had been running it with a used battery I bought last year. It had been holding up pretty good but there will be a heavy load with the cooling fan running after shut off. I still need to get that driver's window to work. Funny thing is that it did work for a while, as soon as I put the door panel on, it quit. I pulled the door panel today and was checking out the wiring. There is power at the switch and at the motor. The motor makes a funny clicking sound so I guess I'll have to pull it out to test it. I patched up the top in a few places but it could use a couple more. The top isn't that expensive, at least for the actual fabric and headliner. Labor may be another thing. The XJS needs the front end gone through also. If the car runs pretty good I'll park it in the sideyard for a while and turn my efforts to the XJ6.
I need to direct my time, effort and money into the car that will give me the best return. I'm not giving up on any of them but I've got to invest my efforts wisely, or I'll end up with three unusable cars.
Yesterday I took my XJ6 out of the sidyard and the XjS took it's place. Again. It had been out of the yard for over a month. As I related a couple of posts ago, the XJS was running very well and cool in the hundred degree weather we've been having. Since I actually got to drive the XJS like a real car ( for the first time since I bought it two years ago) I don't feel bad about putting it away for a bit. Is it a practical car? Well, it's practical enough, though city fuel mileage is not too impressive. My commute is only twenty two miles round trip, so that isn't a real factor. Nowadays, I don't usually carry more than one passenger, my Wife, who was a great sport riding in that very hot car, for one little trip. The trunk is fairly large and when I picked her up from a Girl's day at an antique mall she had of course bought a few things. It all fit in the trunk, which surprised me. I can't say that I love the car, like I do my XJ6, but I do like it. If it needed less work I might like it a bit more!
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