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Hello!

I finished a 4 wheel disc conversion on my '64 Galaxie recently and just took it for a drive. The car stops very well, but the pedal doesn't feel quite right. When I hit the pedal, I get maybe 1" of travel, then it's like it hits a stop, and no matter how hard I press, the car doesn't stop any quicker. I REALLY laid on them a few times, and I could not get the wheels to lock up, either front or rear.

I checked the brake pedal ratio, and it's 6:1, exactly what it should be for manual brakes (which the car had), but not the 4:1 it should be for power brakes.

I'm also running a 4 wheel disc proportioning valve, but it's non-adjustable.

Could the manual brake pedal setup be causing the blocked pedal feel? I don't know how much travel it takes manual brakes to fully engage vs. power brakes. More? Less?

If I have to change the pedal ratio to 4:1, can I simply redrill the brake pedal shaft and angle the MC push rod down.

If I cannot angle the push rod down, will fabricating an offset work? I will have to drop the fastening point of the MC push rod down 1" to get a 4:1 pedal ratio.

Should I look into an adjustable proportioning valve? The rear discs have wear marks on them that tell me that the pads are hitting the rotors, but it seems as if the front brakes are bearing most of the load.

I bought the MC/front disc kit off of Ebay from Tom's Classics in Isanti, MN. If you search for Galaxie disc on Ebay, they pop right up. The rear brake kit came from The Rod Shop in CO.

Thanks in advance.

Chris
 

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If you are using a small diameter booster you could be running out of boost making the hard feel or the rod from the booster to the MC may need to be adjusted?

SMG...
 

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What size is the M/C bore? I had the same problem when I went to 4 wheel discs.
I had to have the bore sleeved down to smaller than 1". Works great now.
 

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Hello!

I finished a 4 wheel disc conversion on my '64 Galaxie recently and just took it for a drive. The car stops very well, but the pedal doesn't feel quite right.
Think I just responded to you over on the HAMB. Will recap here:

Okay, from looking at the guy's ad on eBay - it's all GM hardware. Can't tell the original caliper application or bore from that pic. The big-car GM calipers have I think two different possible bore sizes. It looks like decent hardware but it's in no way an improvement over using, say, a set of '70-72 Galaxie disc spindles and related hardware.

If you've got what's in the pic it's a very small booster. Something bigger may help.

Measure the caliper piston diameter.

I don't see any rear disc listings from him, what are you using for the rears? Once again, original application and piston size for the caliper is important.

A fixed-ratio proportioning valve may be good or it may be bad. Depends on the original application and how it's set up.

What pads are you using? Did they come with the kit?

Whether a 1" MC is big or small depends on the caliper piston size. GM setups tend to lean toward larger volumes/larger pistons.

More mechanical advantage (pedal ratio) means less pedal effort at the expense of longer pedal travel.

I'm becoming quite fond of hydraboosts, myself, but an early Galaxie power steering pump won't be able to drive one.
 

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X2 on Hyroboost brakes. I got tired of fighting the same problems and went to the hydroboost set up, They work great. The problems I had were low vacuum from big cam and I could never get the right mix by changing master cylinder dia, Always had too hard of a pedal or too much pedal travel. I can make a max stop now with just a light touch of the pedal. The early power steering pump will drive the hydroboost set up but it is noisy, I ended up going to a mid 90s mustang pump with the reservoir attached. Witch was a mod I wanted to make anyway, My 63.5 still had the p/s reservoir attached to the fender.
 
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