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Discussion Starter · #1 ·
I just finished installing a Wilwood front disc brake conversion on my 68. WIL-140-15272-R . I bled both fronts but I have a soft pedal and almost no brakes. If I pump the brakes a few times it works like it should. It holds pressure and has no bleed down when firm. It product say compatible with stock proportioning valve and M/C.
Any thoughts?

Thanks
 

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I installed a dynalite kit as well recently.

sounds like air in the lines somewhere. did you bench bleed your master?

if these are power brakes it could also be a vacuum issue with your booster, but that is usually a hard pedal feel with weak braking.

if you switched from front drum to front disc, then you should also have plumbed in a proportioning valve for a disc/drum set up.
 

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As @ylwgto said, you need the correct proportioning valve for the front disk to work properly. The one for the original front drum brakes will not give you the correct brake bias. Another thing you can check and this is going to sound odd, but try adjusting the rear drums. The self adjusters don't always work the best and if they are way out of adjustment more brake pedal travel could be needed just to get the shoes to hit the drums. This will affect how well your car stops.
 

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Discussion Starter · #5 ·
Thanks, I am hoping it’s air in the system. Going to bleed every thing again this weekend and go from there. Figure once I get a decent pedal I can see how the brake bias is.
 

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Discussion Starter · #6 ·
I bled all 4 brakes again and if anything it just got worse. I guess I need a new proportioning valve and might as well get a new M/C. Any recomendations? I have manual brakes and don't have enough vacuum to run power.

Thanks
 

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I went with a later model MC and proportioning valve on mine. I forget if it was Right Stuff or In-line tube but I went with the one sold with the factory style disc brake swap kits. My car was a manual brake car from new and I didn't add a booster when I upgraded to be sure vacuum would never be a concern. With the cam I'm running now I doubt there would be enough to power a booster. Be sure to get the correct MC. The bore size is different for manual brake vs power brake applications.

I will say that the pedal felt different to me when I switched from the front drum to disk. I'm not sure if the brakes actually stop better, but they are way more predictable and linear than the drums were. Basically, the car feels way safer than it used to.
 

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Discussion Starter · #8 ·
So I ordered a M/C for a 1970 Olds 442. Apparently they are one of the few that came with manual front disc rear drum brakes. I’ll let you know how it works out.
 

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So I ordered a M/C for a 1970 Olds 442. Apparently they are one of the few that came with manual front disc rear drum brakes. I’ll let you know how it works out.
Probably true. Disk brakes were standard on the W31 but power brakes were not available. Olds used a cam that was too radical to support power brakes from the factory on those cars. I had a buddy who had a W31 post car back in the 90s. There were only a little over 100 of them built and even less that were 4 speed cars like his was.

Did you get the correct proportioning valve too?
 

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Discussion Starter · #11 ·
I did not get the Proportioning valve yet. Honestly not sure what one will work best. Was thinking of getting this. Wilwood Disc Brakes 260-8419 - Wilwood Brake Proportioning Valves
 

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1971 GTO resto mod. Modified 428 HO, 4 sp (built by midwest muncie) Dana 60, 3.55 rear
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If after the install of the MC and proportioning valve, if you still have soft brakes, It's critical on Wilwood brake systems to get the brake cylinder housing exactly even and square to the wheel disc. If it's not, that can cause "soft" feeling brakes and no stopping power.
 

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Discussion Starter · #14 ·
Installed the M/C and I can get the rears brake to lock up but getting nothing in front. Figured I would need the proportioning valve but wanted to see if the M/C worked first.
With the proportion valve can I leave the distribution block and just plumb in the valve? or will I need to run new lines from each wheel in front? Was looking at install instructions and some said if you have one line going to a tee for the fronts just plug the right front outlet on the valve
 

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The original distribution block had one line going to it from the master (if it was a single pot), and three lines coming out of it (one to each front wheel and one to the rear end).

If you added a dual pot master and a prop valve, you need to run new lines from the prop valve to the fronts and one line to the rear end. The prop valve sends more power to the front and less to the rear.
 

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...The original distribution block had one line going to it from the master...
The important words that ylwgto used was "distribution block". Drum brake cars used a combination of different shoe widths and sometimes different sized wheel cylinders to obtain the proper braking balance front to rear and the block was nothing more than a glorified "T" in operation. When you toss the front drum brakes and install disks you definitely need a true proportioning valve to limit rear wheel braking. While disk brakes are far superior, the application pressure is higher for the front disks which has the rear drums locking up on heavy braking.

Neither a distribution block or proportioning valve really has anything to do with a soft pedal, and that just comes down to air in the system.
 

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Installed the M/C and I can get the rears brake to lock up but getting nothing in front. Figured I would need the proportioning valve but wanted to see if the M/C worked first.
With the proportion valve can I leave the distribution block and just plumb in the valve? or will I need to run new lines from each wheel in front? Was looking at install instructions and some said if you have one line going to a tee for the fronts just plug the right front outlet on the valve
I'm thinking you need both lines plugged into the distribution valve to get this to work correctly. Others may know different but my thought is plugging one of the ports on the DV will cause an odd pressure distribution and your brakes will still not be right. To simplify, you could removed the distribution block and splice in line to the new valve, or install new front brake lines. Reuse the rear if it will route correctly.

 

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Discussion Starter · #18 ·
The original distribution block had one line going to it from the master (if it was a single pot), and three lines coming out of it (one to each front wheel and one to the rear end).

If you added a dual pot master and a prop valve, you need to run new lines from the prop valve to the fronts and one line to the rear end. The prop valve sends more power to the front and less to the rear.
YLWGTO,
My current set up is a dual M/C with both lines going to a block (distribution valve?) attached to the frame. the front split off to each wheel and the a single line runs to the back and then splits to each drum. (https://www.opgi.com/brake-systems/...ution-block-brake-1970-72-a-body-ch26981.html) Just wondering if I can install the P valve with this still in place. Or if I need to do as Jared suggested and run all new lines. Sorry for sounding so confused. LOL
 

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No worries, it can be confusing! Was my first time doing a complete brake system last year.

it is my understanding that distribution blocks do not alter line pressure, as Jared and lust say. They simply reroute fluid. You have switched from a drum/drum system to a disc/drum system. The front discs require different line pressure to operate without simultaneously locking out the rear drums (less pressure). The prop valve makes that adjustment (they even make adjustable ones so so can fine tune your braking bias).

your original dual MC has 2 lines out. One for the rear and one for the front (separate systems in case one fails, the other still allows you to stop. The existing distribution block is just sending the fluid to the front 2 wheels (separate lines) or to the rear (single line split at axle)…it is not changing pressure.

I believe you need to eliminate the existing block and plumb in the correct prop valve in its place. Maybe you can use existing lines down by the block (not sure), but most mount it off one of the MC bolts with a bracket. I don’t think location matters for braking, but you would want it secured t something and away from header heat.

lmk if pics would help, can post pics of my line routing!
 
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