True tales of the Super Snipe (Page 3 of 10)

True Tales of the Super Snipe -- Episode 10: Give Me A Brake

Now that I knew the engine ran, I had much more confidence that I could get the car to go.   The question then became, could I get it to stop?   As you recall from Episode 3, the Super Snipe came with no brake calipers at all, and the parts car had drum brakes.

The full story has been covered in the separate thread at http://forums.24hoursoflemons.com/viewt … pid=107578 so I will just hit the high points here.

I set out to search every self-serve junkyard in the area, but accidentally wound up at one that wasn't even on my list: U-Pull-It in Sun Valley (California), which handles only foreign cars.   About two-thirds through the lot, I discovered a 1972(?) Mercedes 250 (not 300, as stated in the other thread) which looked promising.   Indeed, upon removing a caliper I found that it matched up to my cardboard template perfectly!

The price was exceptional: $13.74 each, plus tax, $2.00 entry fee, and "environmental charge", for a grand total of $32.63.   You can't beat that with a stick.   The pads were almost new, too!

The only problem was minor: the mounting holes in the caliper are 0.498", to fit the metric bolts with a 0.4975" shank.   The Super Snipe requires 7/16-20 bolts, which have a 0.434" shank.   I just have to make four small sleeves to fit.   My friend Richard just happened to have a piece of steel tubing with a 0.501" OD and a 0.404" ID -- almost all the work is done for me!   An hour or so with the lathe and an adjustable reamer will take care of the rest.

Of course, German (metric) calipers on an English car would require special hoses, if not a peace treaty.   In addition, the caliper inlets were in the wrong location, and a straight hose fitting would hit the trunnion at full steering lock.   The local NAPA store referred me to Hose Line, just up the street, where the proprietor quickly made some custom hoses with right-angle fittings.   Perfect!

This brings us pretty much up to date on the Super Snipe story.   I'm waiting for Grainger to deliver the adjustable reamer so I can make the sleeves.   If it doesn't arrive soon, I'll just use a boring bar.

I have taken the brake master cylinder and booster off the car to disassemble and inspect.   It is an odd (to me) arrangement.   The brake booster is an entirely separate unit from the master cylinder.   It has, of course, a vacuum hose connection to the intake manifold, and two hydraulic pipe connections: one from the master cylinder and one to the brake lines.   I suspect that the booster has a leaky diaphragm and is probably unrepairable.

If this proves to be the case, I'm guessing that I should replace the master cylinder with one that will do the job without a booster.   Can anyone offer any suggestions on how to select one of the proper size?   The brake system is so old that it is a single line system, not dual as in modern cars.

A Google search reveals a large variety of new master cylinders with various piston diameters.   For this big heavy car, should I be looking for a large diameter or small?   Any advice?

The next episode will be another out-of-order one from mid-summer, when I discovered just how hungry the British Tinworm can be.   In the meantime, I'll be installing the brakes, flushing the radiator & block, re-installing the radiator, and getting the car ready to move under its own power.

Next: British Engineering and a Tinworm Feeding Frenzy

I would just go back to the yard and get the master that came on the Merc and figure how to make it work.

I have several remote brake boosters (Lockheed no less!) that are independent of the master cylinder-- came off  of minis. If you feel you need a booster just plumb one in.

You are planning on updating to a dual circuit master cylinder since you're replacing it anyway right?  I would not be relying on ANY of the stock brake system except maybe the pedal itself on a car like this.

Nice work so far...  Motor does sound GOOD!

Nick

I know absolutely nothing about how to update a car to a dual circuit system.   How would I go about it?

GM and many others also used hydroboost.  This sysem tapped into the power steering system for boost pressure vs. the vaccum system of the motor.  That said a smaller vacuum booster and matching master cylinder (aluminum master cylinder so if doesn't corrode internally) would be easy to adapt.  Though maybe not as easy as no booster at all.

Nick

True Tales of the Super Snipe -- Episode 11: Breakthrough.  Or is that Brakethrough...

Now that I am temporarily prevented from working on the car, perhaps I can get caught up on the Super Snipe status.   Why am I prevented from working on it?   I came close to amputating my index finger with a cut-off disk in the angle grinder.   For all the gory details, see http://forums.24hoursoflemons.com/viewt … p?id=14380

Now, back to the tales...

I'm going to defer the promised episode on British Engineering and a Tinworm Feeding Frenzy, and finish up the brake topic.

It is now late September and early October...

I discovered that Wilwood Brakes had an (almost) exact replacement master cylinder, and were just up the freeway from me.   A quick (OK, an hour each way) lunchtime trip netted me a new master cylinder and a few accessories.   The mounting holes were exactly the same, and I only had to file the main hole a little bit to clear the thicker rubber boot.   Neither the original nor the new pushrod would fit exactly, so I had to cut the threads a bit longer and make a new end for it.   Big deal.

Since the steel brake lines had been open to the atmosphere for 20 years, they were pretty rusty and looked totally untrustworthy.   In one of my "throw money at the problem" moments, I simply took all the old lines to a local hydraulic shop and told them to make a new set shaped just like the old set.   They also made some custom brake hoses to go from the German (metric) calipers to the British line fittings.   Meanwhile, I set about cleaning the remaining parts.

As you may recall, the brake booster looked pretty bad.   It was.   Opening it up revealed lots of rust and water -- not what you should find in a brake booster.   I spent a weekend or two cleaning it out.   One of the memorable statements in the repair manual says, "Remove Plug (#37) by tapping the flange end of the body on a soft surface."

I will pause while owners of British cars recover from their laughing fits.

That "simple" operation actually took several hours, using lots of penetrating oil, whacking with a plastic mallet, swearing, an ultrasonic cleaner, compressed air, more swearing, wiggling an interior part with a tiny probe, and breaking several fingernails attempting to get a grip.   Loads of fun.

In the end, with a fresh coat of paint, the booster looked like new, save for a copper pipe kludge that I had made to replace a non-obtainable rubber fitting.

Then it turned that the booster could not be re-installed because my kludge replacement for the rubber fitting ran right into the battery.   At that point I decided to reassemble the brake system without the booster.   In the end, that turned out to be the right decision, as I am told the booster only provides about a 1.1:1 advantage, while requiring lots of travel.

I then turned my attention to the rear brakes.   They were a mass of rust and corrosion, so I figured that the cylinders were a lost cause.   At that very moment, a set of NOS spares appeared on eBay, and I got them!   While waiting for them to arrive, I started cleaning what I had.

The drums, after lots of wire-brushing, turned out to be in great shape, as were the shoes.   This was wonderful, as replacements are unobtainable, except by applying new linings to the old shoes.

To my great surprise, the wheel cylinders turned out to be OK after being throughly cleaned!  The next day the eBay NOS replacements arrived from England.   Oh well, I now have spares.

Hooking up this new British-German-American brake system actually went well, and I was able to con a friend into helping me fill and bleed the system.   We'll just have to see if they go to war or peacefully coexist.   Now I can proceed to the next stage, seeing if this barge can move under its own power!

Next: British Engineering and a Tinworm Feeding Frenzy

Now you know that if you need front brake calipers, you can always use the ones from the Super Snipe you find in the junkyard!   

British Estate........

Awesome

Episode 12: British Engineering and a Tinworm Feeding Frenzy

This is somewhat out of order, as it actually happened back in July (2011), but the brake story got in the way.

While inspecting the underside of the car, I spotted a potential problem: the transmission support appeared to be bent, as if by a jack.   This seemed odd, as they are usually pretty beefy, but this one looked rather flimsy.   Since I had some time to kill, I decided to pull it out and check it.

Removing the support revealed the sad story: the metal was simply a lacework container packed full of dirt.   Some brilliant British engineer had designed a U-shaped channel with only a tiny drainage hole.   It must not have taken long for it to fill with dirt and water, providing an excellent environment for the hungry tinworms:

In places, the metal was completely gone:

It was no wonder that it had bent when someone used a jack on it.   Of course, bending the support also sheared the rubber transmission mounts, which no auto parts store in the country has.

This turned out to be the one part that the "parts car" was good for.   Not only was the support in perfect condition, but so were the rubber mounts:

A close examination showed that they must have learned something over the years, as the later support had drainage holes that were large enough to be useful.   While this was a part that I could have easily fabricated myself, it was nice to get some use out of the parts car!

Next: Getting tired and ready to move

"New Tires? A Capitol Idea!" they can have that slogan for free.

According to my brief research the DG(Detroit Gear)-250 came in Jaguars, Studebaker, and some Packards, Dodge Trucks, Hudson and Rolls Royce. http://www.charlietranny.com/Automatic%20Drive.htm So its not quite as rare as hens teeth.

Also, revving the motor to high in Park or Neutral will destroy it.