CSRP Manual Front Disc Conversion Issue - Vintage Mustang Forums
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post #1 of 56 (permalink) Old 10-24-2018, 11:24 PM Thread Starter
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CSRP Manual Front Disc Conversion Issue

Installed the manual front disc conversion kit on my 68 FB. After some leaking lines and non sealing bleeding nipples, I got all four corners bled and seeled up. The master cylinder was bench bled with the supplied lines that returned fluid into the resevoir. Brake pedal seemed solid.

I finally took it out of the garage tonight. Barely any brakes until the pedal gets down to the floor. Its even worse when I reverse the car.

What are my options? Should I re-bleed the MC again? Of course, that will then require to bleed the entire system again due to removing the main feed lines.

Any help is greatly appreciated.

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post #2 of 56 (permalink) Old 10-25-2018, 07:16 AM
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Is the pushrod the correct length? Sounds like itís too short.

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post #3 of 56 (permalink) Old 10-25-2018, 08:25 AM Thread Starter
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hmmm, I adjusted it the same length as the stock one. I will have to take a look. The instructions on pedal adjustment are a bit vague. Looks like there should be about 1/2" of play between the pedal and top stop. I'm pretty much there.

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post #4 of 56 (permalink) Old 10-25-2018, 10:50 AM
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hmmm, I adjusted it the same length as the stock one. I will have to take a look. The instructions on pedal adjustment are a bit vague. Looks like there should be about 1/2" of play between the pedal and top stop. I'm pretty much there.
the thing you should be looking at, is how far the pedal moves before the brake rod starts to move the master cylinder piston ? There doesn't need to be much movement, just enough so the master cylinder piston returns completely without any contact with the brake rod


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post #5 of 56 (permalink) Old 10-25-2018, 11:32 AM Thread Starter
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I'll take a look at that tonight. I called Dennis over at CSRP and he gave me a couple of good ideas on possible culprits.

1. Check and make sure the rear brake pads are set properly. I need to make sure they are contacting the drum.

2. Pressure test the master cylinder by plugging the two outlets and pushing down on the brake pedal. If it's solid, the issue is somewhere in the brake lines.
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post #6 of 56 (permalink) Old 10-25-2018, 12:53 PM
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You mentioned the brake pedal is solid, but it goes all the way to the floor while driving?



1966 Convertible (Plant: San Jose, CA)
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post #7 of 56 (permalink) Old 10-25-2018, 01:52 PM Thread Starter
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You mentioned the brake pedal is solid, but it goes all the way to the floor while driving?
yeah, I realize now that's not that doesn't sound right. I'm going to check everything again tonight. It was 11:30 last night when I finally got it out for a road test.

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post #8 of 56 (permalink) Old 10-25-2018, 02:20 PM
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yeah, I realize now that's not that doesn't sound right. I'm going to check everything again tonight. It was 11:30 last night when I finally got it out for a road test.

Ok, keep us posted. I would in addition to what was already mentioned also recheck for leaks. If one of the systems (front or rear) is leaking, the pedal also goes down before the "other" system has enough pressure to start braking.



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post #9 of 56 (permalink) Old 10-25-2018, 02:45 PM Thread Starter
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Silly question, but if I pull the two leads from the master cylinder to test it, once I reattach, I will need to bleed the entire system again?

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post #10 of 56 (permalink) Old 10-25-2018, 03:59 PM
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Silly question, but if I pull the two leads from the master cylinder to test it, once I reattach, I will need to bleed the entire system again?

Yes. Any time you crack into the braking system you introduce air must re-bleed. Now if you are cracking the rear brakes, you only really need to bleed the back as the front should be fine. If you break the master cylinder lines you are introducing air that will compress and give you soft brakes all around.
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post #11 of 56 (permalink) Old 10-25-2018, 09:39 PM Thread Starter
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Worked on it tonight. When I got home I found the answer to my squishy pedal all over the floor. Line to the drivers side Caliper was leaking. Changed the coper crush washer and presto. No leak.

I bled the line again and, adjusted rear brakes to increase the drag slightly. Checked the pedal play... half inch fro, the stopper to when it engages the piston

Took it for a spin. Better than before but still only about 50% brakes. I assume if you put the pedal down all the way you should be able to lock up the tires? I can’t. Just come to a stop rather slowly. Am I just used to power brakes?

I ran out of time tonight, so I will Need to test the MC another night. I’m a bit pressed against the weather as I need to get the car to the body shop for a quote to strip and paint before the snow flies.

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post #12 of 56 (permalink) Old 10-25-2018, 10:24 PM
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"...... Just come to a stop rather slowly. Am I just used to power brakes?

I ran out of time tonight, so I will Need to test the MC another night. Iím a bit pressed against the weather as I need to get the car to the body shop for a quote to strip and paint before the snow flies.
No, it's not a question not having power brakes. The Kelsey- Hayes 4 piston manual brakes will safely haul a vintage Mustang down from 100+ mph speeds over and over and over again, no problem. And if my scrawny daughters @ 16 years old could safely stop with those manual brakes without excessive effort, then anyone can

Since you have a time deadline approaching, maybe just have the car towed to the body shop. That beats a hurry-up job.


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post #13 of 56 (permalink) Old 10-25-2018, 10:35 PM
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Ok, is this a disc/drum setup?

If so, do you have a proportioning valve and a 10 lb. residual valve plumbed into the rear line? Some folks even add a 2 lb to the front, but, I didn't and it all seems to work fine. The "prop" valve will aid in taking up some of the "slack"(?) in rear shoe's distance before contacting the drum. This will reduce some of that pedal drop(?), but, only a little.

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post #14 of 56 (permalink) Old 10-26-2018, 12:08 AM
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Good to hear you are getting closer. I was also fighting with leaks when I did the drum to disk conversion. And yes, you can lock the tires without power brakes. Is the front of your car going down when you brake? If not, you have too much pressure on the rear brakes -> proportioning valve as @kenash wrote.

Listen to @zray ! Time pressure and brakes are not a good combination. Better safe than sorry.
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Last edited by Mustang4SF; 10-26-2018 at 12:11 AM.
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post #15 of 56 (permalink) Old 10-26-2018, 08:19 AM Thread Starter
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thanks all. @kenash, it's a disc / drum setup. I do not have a residual valve plumbed. There was no mention of it in the manual, nor did my car have one when I started. Is that required with this setup?

@Mustang4SF - yes, I spent a little time last night adjusting the proportion valve. The front does drop first when braking.

I will need to isolate the M/C this weekend to ensure it's not that. If the pedal is solid with the M/C disconnected and plugged, then my issue is in the lines and I'm hoping I just didn't get the air all out.
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