Quicksilver to the Rescue (Post # 131)

Armed with the "Need to Know",  Dave's MIG welding
setup, and a confident, but misplaced sense of "How Hard
 Can It Be?", I finally screwed up the courage to start 
welding.  Let's hope I don't also screw up the exhaust 
system! 

Better late than never . . . . I spent a few days last week teaching myself how to MIG weld, something I should have done years ago but didn't have a sufficiently compelling "need to know" until now. Replacing The Alfatross' exhaust system provided the need and, as luck would have it, Dave Carrell just happened to have a complete MIG welding set he no longer needed. It's amazing what you can learn on U-Tube these days . . . .

The system Jeff Robison and I put on The Alfatross last year was good enough for the car to do well in the 2016 Arizona Concours d'Elegance and Santa Fe Concorso, but I knew it wasn't an exact reproduction of the original. And it sounded a little too loud--OK maybe more than a little--even to my admittedly "insensitive" ears.   

After removing the part of the exhaust system that still
survived, I sketched it and added a few gross measure-
ments.  Note the crossover pipe between the two long
straight sections.  

When I got The Alfatross in 1969 it was already 14 years old and had spent at least half that time in Michigan and Illinois subjected to harsh winters and salted roads. In those days no one expected an exhaust system to last that long, so I wasn't too surprised to discover that The Alfatross' was intact but heavily rusted from the headers to the rear axle . . . where it ended abruptly!  Beyond that the system was entirely missing except for a hanger strap dangling forlornly from the frame.  I concluded that the remaining elements of the system were original and made a simple sketch with measurements. But what about the missing parts? What did they look like?   

I was surprised how complicated the remaining system was with twin pipes running the whole way through at least two sets of mufflers.  The large cavity in the bodywork next to the trunk was obviously for another muffler or resonator, but I couldn't tell if the pipes were supposed to pass over or under the rear axle on the way there.  It took several years to figure that out.

This period photo of one of The Alfatross' siblings shows
that the twin tail pipes are not just straight pipes, but
angle down from inside the body before angling up. 

The official parts catalog is the ultimate
source for establishing what is original!
Note the crossover between the two 
long pipes.

The breakthrough came when I found this illustration in the 1955 Alfa Romeo Model 1900 parts catalog that David Smith sent me.  Not only does it show the complete system including the headers (The Alfatross' original headers were in excellent condition), but also the absolutely essential heat shield located between the first muffler and the driver's seat!  As I was to discover later after I got the car running, that muffler gets really hot!

I also found a page from an in-period catalog offering replacement exhaust system parts.  Back in the day I could have bought a full system including the headers for only 63,500 lira. I have no idea what that  translates to in modern dollar$, but it doesn't sound like a bargain . . . .

As a result of all this I knew what an original exhaust system should look like, but did not want to try to make one from scratch and for years couldn't find a decent reproduction . . . until several months ago when David Smith made me aware that Quicksilver Exhaust Systems, based in England, now makes a very authentic stainless steel system for Alfa 1900C Super Sprint spec cars.  I was delighted to discover that the US distributor for those systems is The Creative Workshop in Dania Beach, FL, an outfit that has already been very generous and supportive of The Alfatross' restoration. I e-mailed proprietor Jason Wenig, ordered the full system, and it arrived about three weeks later. Compare that to the order I placed with AFRA last year. It cost almost the same but took 9 months to manufacture and in the end there wasn't a single piece I could use!

The Quicksilver exhaust system came in 17 pieces running from the headers to the tailpipes and including the clamps and hanger tabs .  The head pipes, straight pipes, and tail pipes had to be shortened considerably to fit the short wheelbase of the Zagato-bodied Alfatross.

So now I am deep into the process of lining all the parts up, supporting them under the car, marking them, cutting off excess length, making sure they fit, positioning the hangers, attaching the header flanges, and tack-welding it all together. It should be finished by next week, but will still need to be coated. It turns out that there are a lot of other things that should be done while the exhaust system is off, including adding additional insulation to the heat shield, removing and testing the brake master cylinder, adding a filter to the fuel line, and installing the new, shorter coil springs on the rear axle. 

The Piston Head Army

Yes, there is still a lot of work ahead.  Problem is, I got distracted by all the things you can do with a MIG welder.  Now I'm looking for excuses to play with it . . . . 

More Brake Mysteries (Post # 130)

Following up the last post about The Alfatross' drum brakes, which was already longer than it should have been, there are still some observations I need to make and a lingering, pestering question I need to pose.  

Drum brakes vs. disc brakes

An historian of automotive history might ask why manufacturers and even racers kept making and using drum brakes long after disc brakes had been invented and proven in battle.  As a person who owns cars with both types of brakes I can say with certainty that discs do a much better job of stopping, and as a mechanic who works on both types I can't understand why drum brakes were ever used on cars in the first place.  After all, the first appearance of disc brakes on a production motor vehicle was in 1902!

The Alfatross' finned aluminum brake drums.  Note the
air scoop attached to the backing plate at left.

The front drums, which are enormous, do most of the
braking and completely fill the space inside the wheel
rims.

The Alfatross was built the same year that modern hydraulic disc brakes began to appear on production European cars such as the Citroen DS, but it took another decade before 4-wheel disc brakes appeared on production cars in the US.  That said, the brakes on The Alfatross exemplify a high degree of refinement of drum brake technology.  All four drums are made of cast and machined aluminum with steel liners, reducing unsprung weight. All drums are finned to increase surface area and improve cooling. The fins on the rear drums are cast parallel to the direction of wheel travel while the front drums are cut diagonally to the direction. Under speed, scoops on the backing plates of the front brakes force air across the fins to further maximize cooling and reduce brake fade. 

Front brake shoes from the Alfa factory
repair manual. Note the two wheel cylinders,
 location of the liners on their shoes, and how
 the liners are attached to their shoes by
rivets.

Inside the drums, the shoes are aluminum, again  to reduce unsprung weight. The front brakes are equipped with two wheel cylinders per wheel to better handle the stronger forces, while only one cylinder is sufficient for the rears. 

One concession to modernity necessary during The Alfatross' restoration was the replacement of its original brake liners with asbestos-free liners chemically bonded to their shoes instead of being riveted as were the originals. 

Right rear brake shoes from the factory
repair manual.  Note the the liners are offset
 on their shoes. 

One of Dan Allen's shoes fitted with the thicker 1/4in
(6.4mm) lining (above) and the thinner 3/16in (4.8mm)
lining more in keeping with the originals.

Rear Brake Liner Mystery

As reported previously, The Alfatross has been plagued by a mysterious problem that rendered the rear brakes ineffectual.  One of the suggested causes was brake shoe linings that were too thin or drums that were too worn. Measuring the inside diameter of the drums revealed they are well within specification, so that eliminated them from suspicion. 

To test the "linings too thin" theory Dan Allen had four of his spare shoes re-lined with thicker material and sent to me. I thought "Now this will surely be the cure!". Much to my dismay, the extra 1/16in of lining prevented the drums from fitting over the shoes! Now we know the thinner linings are not the problem. Not that it matters any more, because at this point I am hopeful that the rear brake problem was solved during the process described in the previous post (# 127)--but I won't know for sure until I put the whole system back together and test it. 

When I unpacked the newly re-shod brake shoes Dan 
Allen sent I noticed that two of them had linings across 
the entire surface of the shoes (upper example) and two 
had linings that only partially covered the shoes. 
Was that intentional or a mistake?

The lingering mystery that no one has been able to solve so far: While fiddling with the shoes Dan sent I noticed that two of the four linings are not applied evenly across the faces of their shoes, but asymmetrically offset a considerable distance more toward one end of the shoe. You can see it clearly in the images above and below. The other two are symmetrical, as one would expect. At first I thought this was some kind of oversight or mistake.  Did the brake shoe re-liner guys run out of material? But then I noticed a similar arrangement in the image of the rear brake shoes in the factory repair manual. The image of the front brake liners shows they are evenly and symmetrically distributed across the face of their shoes but both rear liners are offset.  There must be a reason for this but so far no one has come up with a definitive explanation. 

Definitive explanations, scientific hypotheses, and wildass guesses are herewith invited . . . .

A pair of the new linings seen from one 
end . . .

. . . and seen from the other.  what's
going on?