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  #301  
Old 06-03-2013, 01:51 PM
KULTULZ
 
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Originally Posted by jopizz View Post

You can change the master cylinder to a dual for drum brakes but the under dash booster will never work for disc brakes. It's woefully inadequate.

John
What is the difference(s) in line pressure regarding the BENDIX as compared to the KH?
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  #302  
Old 06-03-2013, 05:00 PM
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Kultulz raises a great question, one that has been on my mind for a long time. For the answer, I called Booster Dewey because he has loads of experience and he knows his stuff.

He and I grew up together and have many parallel lines in our lives. He's also a great guy who loves his work and is eager to answer any booster questions (503-238-8882 in Portland, OR).

The question is, is there a site that shows real outputs for any size booster? The answer is emphatically, no, because there are too many variables, even in the same car.

Booster output depends on foot pedal pressure, vacuum pressure, and the size & design of the booster. We don't always apply the same foot pressure, but we compensate for all the other variables by only using enough pressure to stop in the correct distance. That happens by 'second nature' as your brain adds up all your senses.

Dewey tells me that there were over fifty different designs for the same size boosters from different manufacturers. They all had different characteristics and the only way to measure comparisons is in a very controlled test. Your car doesn't operate in a lab.

So, sometimes your engine produces more vacuum than at other times; it fluctuates but the check valve will pass any vacuum that is higher than presently in the reservoir. That alters the output for the same foot pressure. Then, the rest of the system plays an important role such as mechanical adjustments, brake fluid condition and the presence of air, temp and humidity, pads or shoes size (it changes), size of M/C bore, speed of the car, how long the brakes are applied, etc., etc.

The closest explanation I found on the net is, "the booster amplifies the foot pressure two-to-four times." (great!) MBM says, "Typically you should expect about 1000 psi to the wheels for a disc brake system. A disc brake system requires this amount of pressure so be careful when using a smaller 7" booster that puts out only 900 psi pressure." They are talking about DUAL DIAPHRAGM boosters. That's why I use dual diaphragm 8" boosters. - Dave
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  #303  
Old 06-03-2013, 05:42 PM
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Another factor is pedal ratio and that ratio is probably different between the Bendix and Kelsey Hayes styles. I remember trying to figure all that out 10 years ago when I converted mine to discs however I have the Bendix under the hood style booster.

Booster Dewey rebuilt and converted my booster so that I could run a modern disc/drum style master cyl. The conversion is simply a change of the face of the booster to a '61-'63 Lincoln style with 2 larger studs from the 4 small stud style that was standard on the Bendix booster.

Something to keep in mind is that if you add a disc or drum master cyl on the firewall in the engine compartment of the Kelsey Hayes under dash system you'll need to drill new holes to adapt the modern 2 bolt style master cyl then try to figure out the right length master cyl push rod to make it work with the old Kelsy Hayes under dash booster.

Good luck,
Eric
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  #304  
Old 06-03-2013, 07:26 PM
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Originally Posted by simplyconnected View Post

The closest explanation I found on the net is, "the booster amplifies the foot pressure two-to-four times." (great!) MBM says, "Typically you should expect about 1000 psi to the wheels for a disc brake system. A disc brake system requires this amount of pressure so be careful when using a smaller 7" booster that puts out only 900 psi pressure." They are talking about DUAL DIAPHRAGM boosters. That's why I use dual diaphragm 8" boosters. - Dave
My contention is that the KH Booster will give greater application pressure as opposed to manual Disc/Drum. It may or may not deliver as much force as a BENDIX setup of the period (line pressure being determined with gauges). The MC design is the more important factor.

The principle of operation is the same, the only difference being a remote vacuum chamber.
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  #305  
Old 06-03-2013, 08:37 PM
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However you get 1,000psi to the wheel cylinders, whether it's from one company or another, as long as it's there when you need it IS the bottom line.

My worry for disk brake retrofits is that your system may be underpowered. The original Squarebird brake system was grossly underpowered from the factory. There is NO reason why your classic car should have inferior brakes compared to modern cars because we have the technology and parts.

We rarely use full foot pressure. Simply because the booster stops the car doesn't mean it's going to deliver enough for a panic stop. Boosters put out only so much assistance, then the rest is up to your foot. Most 16 yr-old girls don't have enough strength, but they shouldn't need it. After all, these are POWER BRAKES. Better to be over-assisted than underpowered. - Dave
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  #306  
Old 06-04-2013, 06:07 AM
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Quote:
Originally Posted by KULTULZ View Post
What is the difference(s) in line pressure regarding the BENDIX as compared to the KH?

this is a great question... I saw some manual M/C disc conversion kit . I suppose they work although the driver needs to make enough foot pressure to stop the car, this is why I asked about a conversion with a working K/H booster in its place. It should be something better than nothing . But John says it does not work because the disc brake need considerably higher pressure than drums
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  #307  
Old 06-04-2013, 07:41 AM
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Originally Posted by sunnybob View Post

this is a great question... I saw some manual M/C disc conversion kit . I suppose they work although the driver needs to make enough foot pressure to stop the car, this is why I asked about a conversion with a working K/H booster in its place. It should be something better than nothing .

But John says it does not work because the disc brake need considerably higher pressure than drums
Actual line pressure has much to do with the MC selection and brake pedal leverage as well as booster style and diaphragm size. GOOGLE and study different types of MC.

We do not know if FORD went away from the KH design to the BENDIX design either by function and/or cost. One would actually have to do an in-depth conversion to know what will and won't work.

To me, even if it gave minimal increased performance (car originally built with the KH System over a manual disc/drum conversion, it would be worth it just for aesthetics, but then again, I am anal. I like the idea of not seeing a booster (especially a dual diaph./GM MC) under the hood of a well detailed engine.
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  #308  
Old 06-04-2013, 11:58 AM
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Other question:

Is there a list of extra parts (like hoses, bearings ecc) I would need if I will buy scarebird adapter?

I saw there is a well done part list for Hotrods kits but I can't find what rotors and caliper are used in their kits.

Thanks. Sorry for all my questions.. I'm going to understand which upgrade kit will fit better my Tbird and my wallet (shipping overseas is very expensive )
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  #309  
Old 06-28-2013, 09:55 AM
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Default Granada spindle problem

Yet another reason to re-consider using the Granada spindle conversion.

The drivers side on my conversion has always scraped in a right hand turn. Looked when I first completed the conversion but didn't really see anything. Sounded like the rotor was scraping against something - not real bad but just annoying. I always figured it was the bottom back angled edge of the A-arm pushing the backing plate into the rotor. That was sort of right.

Since I replaced the engine and have the car back on the road I decided there would be enough wear by now to see what the noise was.

Apparently the geometry is such that in a right turn when the car is leaning and you are braking (compressing the front suspension) the spindle moves enough for the outside edge of the A-arm to push the backing plate into the rotor (or it may just be the difference in geometry). There is about 1 1/2 distance between the lower edge of the A-arm and the rotor in the static or resting state of the suspension so initial clearance is not a problem. All bushings, tie rods, ball joints, sway bar links etc are new. May be doing the same thing on the passenger side but I haven't noticed it - might be because it's on the far side of the car and I just don't hear it.

Removed the lower ball joint (has less than 5k miles on it) and it still seems tight but I plan on replacing it just to see if that makes a difference.

You can see the oval rub mark in this pic where the A-arm is pushing the backing plate into the rotor.



Here is an old pic showing how the geometry is changed.
Basically the Granada spindle sits higher on the lower ball joint.

Red vertical line is an imaginary line through center of the upper and lower ball joints, Horizontal red line is an imaginary line through the center of the axle and yellow horizontal line is a 90 deg imaginary line through the center of the spindle where it connects to the bottom ball joint showing the difference in axle angle and height.



(the '77 Tbird spindles have a geometry closer to the Tbird but I tried those and they have way too much positive camber (blue line) to adjust out - the car won't align)

Just some fyi,
Eric
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  #310  
Old 06-28-2013, 11:30 AM
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Default Disk Brake Conversion Discussion

Thanks for this post, Eric. This information is good to know for people who are considering going the Granada route....
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