1968 Brakes are really slowing down my progress on the HCS

[admin]

I finally had a chance to spend most of the day working on my 68 HCS, but unfortunately I didn't get very far. I spent the whole time on brakes and at the end of the day I can only get my driver's front bleeder to bleed. The rest I can't get any fluid out of.

On my passenger front (factory discs) I started at the MC trying to figure out where the blockage is. I was able to narrow it down to the caliper itself. The bleeder is completely removed and I still can't get a drop of fluid out of it.

So my question is should I attempt to rebuild (ie. new seal kit) or just replace the caliper? My car is unrestored so I like the idea of keeping as many original parts as possible. Guess I can pull the piston out and see if it or the cylinder are too badly pitted.

My second question is about the rear brakes. Again, even with the bleeders totally removed I'm not getting any fluid. But my brake warning light is on, so I'm wonderimg if the plunger in the brake distribution block got shifted off center and is now blocking all fluid from getting to the rear. Is that how the distribution block works?

I suppose I can loosen the rear lines at the distribution block and see if fluid comes out there. I just ran out of time today.

Thanks in advance for any thoughs.

 

[Ruppstang]

Let start with the front. Have you changed the hoses? If not change them. If that does not help. I would get different calipers but keep your originals.

In the back I would disconnect the brake lines at the wheel cylinders and see if you get fluid. If so I would replace the wheel cylinders. I would also replace the rear flex line.

The piston can move in the distribution block and that does not effect the flow of the fluid. You can sometimes recenter it by opening a bleeder and applying hard pedal pressure while watching the light. If it does not go out open a bleeder on the other end of the car. If all else fails take the distribution block out and rebuild it. I would not mess with the light till all of the brakes work.
Marty

 

[admin]

Thanks Marty.

I have not changed the hoses yet, but have all 3 on order (2 front, 1 rear). On the passenger front, when the hose it disconnected at the caliper I do get fluid out of the hose.

The piston can move in the distribution block and that does not effect the flow of the fluid.

I thought once the piston moved over in the block it stopped the flow. Maybe I'm reading this diagram wrong? When the piston is shifted toward the rear brakes (left hand diagram) does it not block the fluid? Or does the piston simply act as a mechanism to trigger the warning light?

 

[Ruppstang]

Thanks Marty.

I have not changed the hoses yet, but have all 3 on order (2 front, 1 rear). On the passenger front, when the hose it disconnected at the caliper I do get fluid out of the hose.


I thought once the piston moved over in the block it stopped the flow. Maybe I'm reading this diagram wrong? When the piston is shifted toward the rear brakes (left hand diagram) does it not block the fluid? Or does the piston simply act as a mechanism to trigger the warning light?

The piston is simply a switch to turn on the light that says you have had a front or back brake frailer it does not block the flow.
If you get fluid in the back the proportion valve is ok.

 

[calspcl]

+1 with what Marty said. Replace/rebuild master cylinder, calipers and wheel cylinders and new hoses. The proportioning valve should be OK once you run new fluid through it, then you can recenter it as Marty stated.

 

[admin]

Weekend #2 working on the HCS brakes and I made a lot more progress.

The right front caliper was not getting any fluid from the bleeder screw. I checked both the hard line and hose and both allowed fluid to flow. It was the caliper that appeared to be the culprit. So I replaced calipers and hoses on both sides and now get fluid at both front bleeders!

Then I moved to the rear. I disconnected the rubber hose at the steel line coming from the MC and got fluid there, so my problem is probably the rubber hose. I have a new one, but ran out of time to install it. From the rubber hose to each rear wheel, the steel lines are clear. I blew them out with compressed air to confirm. I have new wheel cylinders, shoes and hardware ready to go in. Hopefully next weekend.

 

[Ruppstang]

It appears you have it covered. Those old hose are often swollen and blocked internally.
You may need to center the piston in the block. But till then you will have brakes! Another tip is to keep pumping fluid through the system till it is all clear.
Marty

 

[admin]

Weekend #3. I got the rear brakes rebuilt. New wheel cylinders, hardware, shoes and rubber line. I had to fight a couple of steel break lines that didn't want to thread in, but took a break and when I came back they went in without much more trouble, and more importantly no cross threading!

Oh, when I pulled off one of the drums a couple of parts fell out. Good thing I didn't try driving it before rebuilding the brakes! :smile:



I had finished the front brakes last weekend, but noticed today that one was leaking when the hose connects to the caliper. I had used the new copper crush washers on both sides of the hose block connection and I confirmed that the hose was installed correctly and the caliper surface flush. I pulled the hose a couple of times and reassembled, but still had a slow leak (drip every 5 minutes or so)

Finally I re-used my original copper crush washers. No leaks since. Go figure. Maybe the new washers aren't as soft as the old ones?

Oh, and I now have fluid to all 4 bleeders! :grin: I'll bleed the brakes tomorrow.

 

[robert campbell]

Jon,
Your carb is rebuilt and I hope to wet test Sunday or Monday!! Now that you have brakes, you can have go fast!!

Rob

 

[admin]

Excellent! Thanks again Rob!

 

[robert campbell]

Jon,
Your carb is done and it passed its wet test. Attached is a short video of it running. Runs absolutely awesome! We need to talk about engine timing and a few other things when it arrives for your installation.

I will include the parts receipts in the box. The rebuild kit, a float, and a fuel filter cost $48.26. We will ship it USPS. So around 60 or so bucks will pay the bill, which is my gift to you for all you have done for our hobby! You can send me a personal check.

Rob

https://youtu.be/t6Gtm2ZbkTk

 

[admin]

Excellent Rob! Thanks so much. Cool video. My carb sounds much better on that test Mustang than it does on mine.

 

[robert campbell]

Jon,
Carb is on its way!!

Rob

 

[admin]

I got to do more work on the HCS this last weekend... and drive it around a bit more. Here's an update:

I installed my carb after Rob graciously rebuilt it for me. (thanks again Rob!) It ran great! I think I need to play with the choke a bit. It runs well when warmed up, but seems to want the throttle plate closed off more when cold to get a good high, smooth idle. If I adjust the choke to close off the throttle plate when cold then it doesn't open up enough once warmed up.

I also finished up the brakes and bled them. New master cylinder. New calipers and pads up front. New wheel cylinders, hardware and shoes in the rear. I blew out all the hard brake lines with compressed air and replaced all the rubber lines. Speed bleeders all around.

On the disc calipers I really had a hard time getting a good seal at the banjo bolt where the rubber line connects to the caliper. I started with new copper crush washers and it still leaked. So I tried reusing the old washers, which I thought had fixed the problem, but that just slowed the leak to 1-2 drops overnight. Still not good.

So I ordered some stat-o-seal crush washers with a rubber seal molded in. That seems to have done the trick. No leaks after several days.

I also replaced a few odd and ends, like new shocks, reattached my rear view mirror, replaced the shifter bushings in my C4, new battery tray to replace my rusted out one.

She still looks terrible from the outside, but I feel much better about driving her now than I did a few weeks ago.

Oh, the the photo is of my helper. :grin:

 

[Ruppstang]

Great news Jon. It is reassuring knowing it will stop when needed and is not going to leave you beside the road somewhere.

Loved the picture of your son. Reminds me of my sons, working with them on their cars was the best investment of time I could have ever made.
Marty

 

[robert campbell]

Jon,
You live in such hot weather, so the choke can be set very very light. Ensure that the tube that goes to the exhaust manifold is clear and plugged into the exhaust. Just worked on one yesterday that the tube ran down near the hole in the manifold, but was not attached.

Give me a call at (360) 377-5164 and we can step you through the choke adjustment. I set it up in 50 degree temperature, and set it very light, but maybe not light enough for the desert SW.

Rob