Brake System Upgrade
 

This will be an ongoing thread detailing the complete overhaul of the brake system in my '67 Estate. Currently my brakes are horrible and since it's my daily driver I should have done this back when I bought it March. Oh well, there's no time like the present. Here's what I have planned:

Dual circuit master cylinder
New stainless hardline throughout
Braided stainless lines up front
Adjustable bias valve
Front calipers rebuilt
Disc brake rearend from an 1800
Brake light switch converted from hydraulic to pedal-mount type
Build a custom LED conversion for the rear brake lights


I have yet to order any of the major stuff since I'm still narrowing it down to a few options/brands. The 1800 rear might be difficult to find but I'm hopeful somebody we be able to ship me one if I can't get one within driving distance. This will be a pretty big project but I'm excited nonetheless.

Step one was fixing all the play in my brake and clutch lever arms. I'm not sure why but so many car manufacturers don't seem to comprehend the concept of load bearing area. I've seen elongated pivot holes on every car I've ever worked on. Why is this? Is it merely for cost savings in materials or is it to keep you coming back for replacement parts? Even worse I see a lot of things pivoting on the threaded part of a bolt, which is just plain stupid. Here are two pics to show the elongated pivot holes I'm talking about. You can see that the clevis pins have both been machined down by the massive force concentrated by the knife edges:

http://img69.imageshack.us/img69/298...wornlevers.jpg

http://img263.imageshack.us/img263/8...wornclevis.jpg




I always use bolts with a shoulder that's long enough to completely support the pivoting pieces. Sometimes I have to use extra washers to make this possible but so be it. Ideally I like to also increase the load bearing area as much as is practical. For my pedal arms I hand filed then drilled out the pivot holes to 3/8"(9.5mm) and then welded in a short section of stainless steel tube with an ID of 5/16"(7.9mm). This increases the load bearing area to the full width of the pedal arm instead of just at the thin edges of the arm tube itself. Here's a pic of the SS tube being tacked in:

http://img214.imageshack.us/img214/1963/dsc02231.jpg




The clevises for the brake and clutch master cylinder rods also got the treatment. I hand filed the oblong holes round again then drilled them out to 15/32"(11.9mm). I then machined some 5/8"(15.9mm) steel rod to have a 15/32"(11.9mm) lip to fit the clevises as well as a 5/16"(7.9mm) bore for the pivot bolt. Each side is about 3/8"(9.5mm) deep so the load bearing area is about 3/4"(19.05mm) per clevis now instead of 1/4"(6.4mm) each.

http://img195.imageshack.us/img195/9128/dsc02244ag.jpg




Here's the group shot of the finished modified parts:

http://img682.imageshack.us/img682/8837/dsc02254l.jpg




And here's everything re-installed on my car. You can see that I had to significantly turn down the head of the SS pivot bolt on the brake arm for firewall clearance:

http://img36.imageshack.us/img36/2172/dsc02259e.jpg




There is very little play in the clutch and brake arms now, but some play remains due to the worn out rod couplers on the master cylinders. Once they are both replaced the whole system should be nice and tight, even decades from now hopefully. It's the little things like this that make a vehicle much more pleasant to daily drive IMO, but can take an entire day to do right.

Peace,
Derek.

Derek

This is fantastic, well done man! I can really appreciate this. Very impressed!

Phil Singer on The Brick Board built the La Carrera Pan America Apple Farmer Racing 122 and swopped in an 1800 rear end. You should get hold of him if you need any info to make life and R&D simpler.

Dylan

Good job! I like to see a car done right.
About the stainless braided hoses though, can you now buy DOT approved ones? They use to be illegal on road cars a few years ago, but I haven't kept up. Something to do with not being able to inspect the hose rubber itself come MOT time.

Thanks for the nice comments guys. :cool:

Dylan,

Thanks for the heads up on the 1800 rear end car. I'll get in contact and see where it leads me.


asneddon,

DOT-approved braided SS brake lines are indeed available for the 122, at least I know that IPD sells them. I'm still debating if I want to deal with replacing them often though. I might just stick with OEM lines for their longer life. Here's a wiki on brake lines with a good amount of info.

Proper job!

Were you not etmpted to put bearing races in instead. ;-)

You'd have a fright if you saw the brake pedal linkage on a RHD P1800 ...

jimbo1593,

I considered that, but I wanted to keep things simple this early on since I'll be fabricating an entirely new pedal assembly. When that time comes though I do want to have bushings on everything that pivots. I'll machine them from either oil-impregnated sintered bronze or Delrin plastic.


Trommel,

Sounds bad, care to post a pic? :)


I found an excellent 9 page tech article explaining all the things to consider when doing custom braking system design. After reading it I'm convinced that a fully manual dual master cylinder/balance bar setup is the way to go for my wagon. I've been wanting to try this kind of setup for years and now is the perfect chance to do so. I'll probably use this pedal assembly from Wilwood Engineering to make it easier. To line up properly I'd have to fabricate longer, 14" pedal arms for it though.

Good link.

This is the best picture of a RHD car I could find:

http://pds.exblog.jp/pds/1/200703/10...48_1425794.jpg

Wow, yeah with 6 pivots points that could get real bad over time. :)


So according to my dated Haynes repair manual the stock front calipers in my '67 single circuit Amazon are 3 piston type with 2x 1.5" and 1x 2.125 pistons each. Also the '70 to '73 1800 disc brake rear end I'll be using has 2 piston calipers with 2x 1.422" pistons each. I won't know if these numbers are accurate until my caliper rebuild kits arrive, but I emailed Wilwood Engineering and with the above caliper piston specifications they recommended a 7/8" bore for the front master cylinder and 1" for the rear when using a 6.25:1 or 6:1 pedal ratio. This should hopefully allow enough bias adjustment using just the balance bar that I won't need a separate adjustable bias valve. Also the stock clutch and brake pedal arm spacing is about 4.75"(120.7mm) and the Wilwood triple master cylinder pedal assembly is around 3.93"(99.8mm) spacing so it should fit nicely between the steering column.

How will you mount the Wilwood pedal assembly? Will the master cylinders end up in the engine bay or in the car? I'm curious as i need to do the same thing as i have converted my Wagon to P1800ES disc rear end and big Brembo calipers on the front.