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Miscellaneous things, some more significant than others.....
Parts which we include with sleeved cylinders as needed We charge $10 to install a bleeder repair kit, but all the other items are included at no charge with those cylinders which need them. Pictured are 1/8" pipe plugs, various grease fittings, brass tube seats, reservoir gaskets, inch and metric bleeder screws, copper gaskets, lockwasher, and piston retaining clips.
The 1967 Master cylinder is a good upgrade for older Econolines This is the one-year-only master cylinder used in the 1967 Ford Econoline vans and pickups. It is very close to a bolt-in upgrade to dual circuit for 1960-1966 models. They were originally fitted with residual valves under the tube seats in the rear and side outlet ports. These valves are needed for drum brakes to prevent the wheel cylinders from pumping air past the cups on the return stroke when the brake pedal is released. If you are using this cylinder as part of a conversion to front disk brakes, you should connect the disk brakes to the side outlet and remove the residual valve from under the side tube seat. Bendix manufactured this cylinder with the unequal reservoir sizes appropriate for disk brakes anticipating that a disk brake option would be offered in subsequent years, but Ford fooled them and went to the second generation Econoline in 1968. We were told a few years ago by a customer who is a retired Bendix engineer that they had invested a great amount of money in tooling and inventory for this cylinder, and were very upset when Ford told them that no more would be required. Our customer's department was responsible for disassembling and scrapping thousands of these cylinders in 1968. Sure wish we could have bought a few... If you send us one of these for a complete rebuild, tell us how you are using it and we will set it up properly for your application. If you're sending one for sleeving only and include the residual valves and seats from your rebuild kit, we'll be happy to install them as needed. Note that cylinders made early in the model year have a stop bolt in the bottom of the bore next to the side outlet. The stop bolt was deleted in later production. The castings still have the raised area, but it is not drilled and tapped for the bolt.
Here's a picture of a 1967 Econoline cylinder all dressed up in VHT Bright Blue paint.
We often see little cosmetic or mechanical glitches that make us shake our heads, but we rarely see something that has us running for the camera so we can document it. This one really caught our attention. We immediately called our customer to confirm our understanding that the work was done by one of the leading names in brake cylinder restoration, and quite frankly we were disappointed to learn we were correct. We've always preferred to compete on the basis of customer service and have never criticized the quality of their work. We have even referred customers to them in the past for certain jobs we don't handle. We don't believe we'll be comfortable doing that in the future. The cylinder in question is the very rare 1965-1966 Corvette dual-circuit power disk brake unit with the two screw caps.
It was sent with the complaint that it would not bench-bleed. We were surprised to see that it contained an obviously brand-new primary piston, as new pistons for these cylinders have not been available for many years. Current rebuild kits contain only new rubber parts to install on the old pistons. We were even more surprised to see that it was on the verge of falling apart.
This piston assembly is made so that it is the correct length when the shoulder bolt is tightened all the way into the piston. As you can see from the photo, this bolt is about 3/16" from tight. This was done in an attempt to duplicate the overall length of the correct piston assembly, but no effort was made to secure the bolt at this setting. Further, since the hole in the piston has no threads for the first 1/8" or so, there were fewer than two threads engaged. We were able to take it apart with our fingers, whereas we normally have to use proper tools and considerable effort. By the time we got the secondary piston out, we realized that the entire bore of the newly sleeved cylinder was about 0.001" too small and that there was an additional restriction in diameter at the location of the secondary ports. This, combined with the divot in the secondary piston probably caused by tightening the piston retaining screw onto the rib of the piston instead of behind it, was the cause of the bench-bleeding difficulty. We consider it fortunate that the secondary piston was sticking, as otherwise the owner would have been able to install and use the cylinder--until the bolt came out of the primary piston, at which time it would have failed to operate properly. The owner wanted his cylinder back by Next Day shipment in order to make a car show, so we didn't have time to order a proper shoulder bolt. Instead, we fabricated a temporary replacement from a standard Allen-head bolt.
Assembling the piston tightly with this bolt resulted in an assembly with the correct overall length, and allowed us to get the cylinder back to the customer in time for his car show. He reported later that the cylinder bench-bled properly and worked perfectly in the car. We'll get the cylinder back in the shop in the near future to replace the all-thread bolt with a correct shoulder bolt. Converting Master Cylinders to 3/4" with Wilwood Parts We see this type of combination clutch/brake master cylinder
fairly often. The first one was originally used in International trucks, and the
second in early '60s GM trucks.
One is installed in a street rod; the other in a 51 Ford Altered Wheelbase
drag racer.
This owner has installed a Wilwood pull-type hydraulic clutch slave cylinder which requires a clutch master cylinder with a bore of 3/4". Attempting to operate the Wilwood cylinder with a 1" master results in very high pedal effort and poor clutch feel as well as driving the Wilwood cylinder to the stop, which is not good. Reducing the diameter to 3/4" is an easy matter for us. The problem arises in finding parts to put in the new bore. Fortunately, Wilwood offers a 3/4" master cylinder rebuild kit, their number 260-6898, which includes a new piston that is almost the same length as the original 1" piston. Since it is a clutch master, which will be operated through its full travel at every application, and since the Wilwood piston assembly is 1/8" shorter, we must check some dimensions to be sure that the modified cylinder will have enough travel and that the leading edge of the secondary cup (the one closest to the mouth of the bore, to the right in the photo below) does not pass the inlet port, which would allow fluid to run past the seal and out of the cylinder at the bottom of the pedal stroke.
The photo on the left shows that the leading edge of the secondary seal must not get closer than about 3" to the bottom of the bore, which is to the left. We must therefore insure that the piston bottoms out solidly before the seal reaches that point, else fluid will run past the seal and out the open end of the bore.. The photo on the right shows the plugs that the factory installed in the original return spring to limit piston travel. Since the Wilwood return spring is wound straight for most of its length and is a fairly close fit in the bore, we can rely on the spring itself for most of the limitation. We added a brass washer measuring about a tenth of an inch to fine-tune the travel limit. It is, of course, best if the pedal itself has a limiting arrangement to stop the travel before the piston bottoms out, but just in case it doesn't we have the problem handled. The next issues that must be addressed are the pushrod and the overall piston length. As the photo on the left shows, the original piston has a deep pocket to receive the end of a pushrod which is secured to the clutch pedal. The Wilwood piston requires that the pushrod be captured at the cylinder by a washer with a conical recess. The Wilwood retaining washer was too thick, making the effective overall length of the piston too long. We machined a conical recess in a standard USS flat washer turned to the correct OD to make a new one. This allows the primary pressure seal, on the left in the right-hand photo, to return past the compensating port on the return stroke of the piston after pedal release.
The last thing we need to check is the piston travel as installed in the International cylinder with the reduced bore. Wilwood tells us that any of their 3/4" master cylinders, which have strokes of 1-3/8" and 1-7/16", will work with their slave cylinder. Our completed cylinder has a stroke of just over 1-3/8", so it should drive the Wilwood slave cylinder properly.
The GM version is very similar. It has 3 mounting holes rather than four, and has 1-1/8" bores rather than 1". Also, the clutch and brake bores are on opposite sides because the GM pedal assembly has a tube-within-a-tube design that reverses the linkages. (NOTE: If you are going to use this cylinder with a non-reversing pedal assembly, you MUST tell us.) All of the same measurements were made and compared. In this cylinder we were able to use the Wilwood retaining washer and let it into a counterbore in the thick-walled sleeve. The Wilwood return spring is just the right length at coil bind to limit the travel of the piston. This picture shows the cylinder after sleeving of the clutch bore.
This picture shows the counterbore....
...and this picture shows the cylinder after assembly but before the dust boots were fitted.
1963 Z06/1964 J56 Corvette Master Cylinder This is a special cylinder used only on the high-performance Z06 model with production of 199 in 1963, and on the J56 model with production of 24 in 1964. There is a very interesting article on this car at z06vette.com which includes the photo at right.
The next photo is from VetteWeb.com. At right is a photo of one that came into our shop with multiple problems after it was sent to a production rebuilder. See our article on this cylinder here.
Bendix Master Cylinders for 1965-66 Corvette and Mustangs with Manual Disc Brakes We have been asked about the differences between the Bendix 2225032 castings used on the 1965-66 Mustangs and Corvettes with manual disc brakes. Below is a photo of a pair of these cylinders, and they appear at first glance to be identical. However, there are two significant differences in addition to the date codes in the castings. The Corvette version has a 1" bore and mount bolt spacing of 3-3/8". The Mustang version has a 15/16" bore and mount bolt spacing of 3-3/16". Most of the Corvette masters have a single outlet port threaded 7/16"-24 with a brass tube seat for a standard inverted flare 1/4" brake tube nut. Mustang masters have several different outlet port arrangements. Some have two outlet ports threaded 1/8" pipe thread. One port receives a brake light switch and the other receives a brass manifold which accepts 3/8"-24 inverted flare tube nuts. A typical Ford manifold is shown below, but is not correct for the Mustang application. Others have two outlet ports threaded 3/8"-24 with brass tube seats. We have also seen the Ford cylinder (photo below) with a casting number of 618967. Our guess is that this may be an early version.
Benditalia and Bonaldi Dual Master Cylinders These cylinders are used in Ferrari, Alfa Romeo, Fiat and other Italian and European cars. We see them in three sizes--7/8", 23mm and 1". Some suppliers refer to the 7/8" cylinder as 22mm and the 1" as 25mm, but those are "soft" conversions. Some suppliers refer to the 23mm cylinder as 29/32" Here we show a Bonaldi 7/8" cylinder, but they are all very similar. Note that the washer at the lower right is not the original washer. This one is a very thin washer from a domestic cylinder. The original washer is about 1/32" thick. We're going to replace it with a custom part, so it doesn't matter. Also, the brass collar next to the small spring at bottom is one we made to replace the missing original part.
We can sleeve all sizes of this cylinder. The original doughnut-shaped seals are available, but the 7/8" size are a very poor fit. They may be a duplicate of a worn-out part, or allowance may not have been made for shrinkage in the molding process. They are only 0.002" or so larger than the bore they fit, which is not enough to seal properly. Cylinders assembled with these seals will bypass under pressure. We have identified lip-type seals from the catalog of our U.S. brake rubber parts supplier that are a good fit. They work very well as a direct replacement in the pumping seal locations, which are to the left of the two pistons in the above photo. The seal at the intermediate position, the one at lower right in the photo above, is held in place by the middle return spring bearing against it with the washer mentioned earlier in between to protect the seal from the spring. See the next photo showing all the parts in line. This works fine with the original seals because they are solid blocks of stiff rubber, but if we allow the spring to bear against the lip-type seal it will be crushed.
The photo below shows the piston assemblies with the new seals fitted. In place of the intermediate washer we have fitted a hat-shape spring seat which bears against the end of the piston and establishes a groove for the lip seal. The new spring seat takes all the pressure from the return spring. We make these spring seats from solid brass bar stock.
The next photo shows the full length of the piston assemblies.
The OE-style replacement seals for the 23mm and 1" versions of these cylinders are a slightly better fit, but some of our customers have had similar troubles with them. We have lip-type seals for all three sizes, and can replace them in the same way we did this cylinder. Customers for whom we have converted cylinders in this manner report that they bleed quickly and work well. |
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