CPP Disc Conversion - Good and Bad

[metalprelude]

Finally finished the Classic Performance front disc conversion on my 61. It looks amazing. I hit some speed bumps around a stripped brake line and disentegrated ball joint bushings but, overall it was pretty easy with some googling.

Energy Suspension makes some really affordable bushing replacements and I went ahead and replaced the outer tie rod ends with new Moog pieces. Additionally, I learned how to use a flaring tool and took the opportunity to pressure-wash the A arms and suspension.

Here's my remaining issues and I'd love some guidance-

1. My factory steelie rims are too small for the new brake setup. Anyone know the wheel specs required for the CPP Conversion?
2. I can't get the brake pressure to build. I've verified there are no leaks but, even with a Mityvac, I can't get the hydraulic pressure to build. Any ideas?

I attached a before and after shot.

[Chevy Fleetside]

70's 4x4 wheels will work.

[LostMy65]

For the pressure issue, try adjusting the rod that's attached to the brake pedal in so it engages sooner.
For your current Steelies not fitting could be because you are using original steelies that don't work with discs. You need 6-lug steelies from a newer truck that had discs.
There's threads on both these topics.

[1966burb]

I used 15 x 6 OEM wheels from a 72 K5 4x4 Blazer and they worked great. j

[MikeN]

I can't see the bleeder screw on your caliper in the photo. The bleeder screw has to be at the top of the caliper. L & R calipers are therefore different.

[slepysal]

Two things come to mind First one did you bench bleed the master cylinder?
Second are you running a power booster ? If so you may need to drill a new attachment hole on your brake pedal arm about 1/2 lower from the old one.

[nail pounder]

Was it bench bled properly was my thought also. Are you running a prop valve? I know they can trip and give you grief. On the wheel issue, I'm not sure how much clearance you need, but, mine were so close on my 58 that they rub UNTIL you tighten them down all the way. Then they have maybe an ⅛" clearance, maybe. You can use a grinder on the calipers if it's just an RCH, or run spacers? OR use it as an excuse to go get a new set of wheels and tires...

[theastronaut]

A bolt on 1" wheel spacer will let you run your stock wheels. I had a set of 1.5" spacers on my '66 which pushed the stock skinny wheels out to match the wheel fitment of the 8" rear wheels.

[slepysal]

Any updates?

[metalprelude]

I determined that I had my brake lines reversed. I flipped them over and was able to bleed the calipers. The pressure is still not as firm as I'd like but, it's better.

In regard to the rims, I've decided to buy the Cragar rims shown below as they'll fit my Coker white walls at 15x7 and at $60, I can't beat it.

https://www.summitracing.com/parts/crr-69576037

Anyone have experience with these?

[metalprelude]

Originally Posted by MikeN

I can't see the bleeder screw on your caliper in the photo. The bleeder screw has to be at the top of the caliper. L & R calipers are therefore different.

You were correct. I had the calipers swapped. I fixed it when I fixed the backwards brake lines.

[metalprelude]

This also helped:

[MikeN]

Glad you got it fixed.

[KALAHEO]

Wheel Vintiques has steel wheels that will fit and look close to OEM

[PMDc]

I bought a set of rims just like this but are US Wheel brand. I am in the process of making buttons to pop my original hub caps on.

I was too cheap to pony up for the Wheel Vintiques at $200+ each for the same size wheel.

[metalprelude]

I finally bought Cragar 69 black steelies and they luckily fit my 15" Coker white walls. But, I'm having an issue with my passenger side caliper. I got the driver side bled but, even completely removing the bleeder from the passenger side doesn't produce fluid. What now?

Also, I'm still running a single reservoir non-power MC. So, my brake line hits like three t-connectors. Should I add a proportioning valve since I now have a disc/drum setup?

Now, to clean-up the white walls.

[PMDc]

Originally Posted by metalprelude

I finally bought Cragar 69 black steelies and they luckily fit my 15" Coker white walls. But, I'm having an issue with my passenger side caliper. I got the driver side bled but, even completely removing the bleeder from the passenger side doesn't produce fluid. What now?

Also, I'm still running a single reservoir non-power MC. So, my brake line hits like three t-connectors. Should I add a proportioning valve since I now have a disc/drum setup?

Now, to clean-up the white walls.

The wheels and tires will look great!

If you are using the original style master cylinder, this will need to be replaced with a dual reservoir unit and a Disc/Drum proportioning valve for the system to work safely and correctly.

That being said, the passenger side "T"-fitting feeding the rear will go away and a line from the Prop valve to the rear is needed instead.

As for the lack of fluid, the fluid travels to the path of least resistance first so there most likely is a blockage somewhere.

Hope this helps.

[Robert Haas]

you will not be happy at all with the MC set up you are trying to use. Disc Brakes require completely different volumes and pressures then the standard drums.

you can source a dual line MC at any wrecking yard and there are several members here that have gone that route.

A proportioning valve may be left out once you go to a dual line MC as most of them are already set up for drum rear/disc front.

[chevy_mike]

Agree with what has been said. You MUST use a disc/drum master. The original single pot drum brake master will not work correctly and you will never get the proper brake pressure.

[theastronaut]

I used a stock manual single circuit master cylinder on my '66 with CPP's disc conversion and stock rear drums. It worked great, the pedal throw and and pedal effort were both very good without the overly boosted feeling that you might get with power brakes. The original M/C has a 1" bore , same as the disc/drum M/C's.

http://www.speedwaymotors.com/Univer...tyle,4316.html

[Robert Haas]

A lesson in life I have learned;

Just because you can, does not mean you should.

Simple reasoning here. On our trucks with a standard single circuit MC if for some reason we lose a wheel cylinder, chances are good that the loss will be a small failure and we will still have enough pressure on the other three wheels to get our trucks stopped. However losing anything major like a brake line, or a caliper/piston failure or even having a brake pad get displaced and you can go to zero pressure on all 4 wheels instantly. There is a darn good reason to upgrade to a dual circuit MC and separate our systems.

[theastronaut]

I agree that a single circuit isn't the safest option if there's ever a failure of any of the hydralics. I had a car with a single m/c that developed a small leak in a hose while driving home one night, and I had almost zero brakes, so I know that it's not the best idea.

Function wise the stock single m/c works great. The front to rear brake balance was good (fronts locked up just before the rears) and the pedal effort, travel, and pedal feedback was great. I haven't driven any car/truck with a power brake setup that had as good of pedal feel/feedback that a manual brake system has.

A manual 1" bore dual circuit m/c would be my choice over a power 1" bore m/c. If you just have to have power brakes, a larger 1.25" bore m/c or a smaller booster, or both will help gain back some brake pedal feel and avoid the over boosted/mushy pedal that a lot of power brake systems have.

[metalprelude]

So, regardless if I go power brakes or not, a dual reservoir MC is the safest approach but, I have to install a separate MC for the clutch?

Also, if I go to a salvage yard, what are my best options for donors?

[PMDc]

Originally Posted by metalprelude

So, regardless if I go power brakes or not, a dual reservoir MC is the safest approach but, I have to install a separate MC for the clutch?

Also, if I go to a salvage yard, what are my best options for donors?

CPP offers a unit for both the clutch and dual master cylinder for 60-60 trucks. Part number MT6062BB2 I think. It's pricey at $450 but requires the least amount of work in my opinion. Otherwise you are changing the linkage to fit any other unit due to the 60-62 clutch linkage being on the passenger side of the steering wheel.

[Brad54]

If you blow a rear wheel cylinder, you will have nonfront brakes at all. And the wheel with the blown cylinder will be slick with Dot 3, and will not grab at all... so when you pull back on the emergency brake handle, you'll be trying to stop your truck with one drum.
I know from experience with a '54 Buick that can't be done.