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dheming · Nov 13th, 2009, 22:46

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:

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:

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.

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

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:

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.

Nov 13th, 2009, 22:46	#1
dheming Member Last Online: Jun 29th, 2022 04:38 Join Date: Mar 2009 Location: Corvallis, Oregon USA	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: 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: 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. Here's the group shot of the finished modified parts: 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: 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.