I got a problem
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New User
Joined: Nov 2003
Posts: 8
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From: Cottonwood Arizona
I got a problem
Hi there,
Just signed on! Been lurking around for a while tho. I got a problem with a project and it has us stumped.
We installed an 84 Chrysler new yorker front end in a 50 f100. used the under frame bracketing recommended on another site and a 78 mustang II booster and master. Put in metering valve and residual valves from Master brakes. Even had the 10lb for the rears tweeked up a bit.
Now we can't get the master to hold pressure. it will pump up and work but on the initial hit it goes almost to the floor. rears work good but the fronts don't.
My question is
1. is the master too small for the calipers?
thanks in advance!
Just signed on! Been lurking around for a while tho. I got a problem with a project and it has us stumped.
We installed an 84 Chrysler new yorker front end in a 50 f100. used the under frame bracketing recommended on another site and a 78 mustang II booster and master. Put in metering valve and residual valves from Master brakes. Even had the 10lb for the rears tweeked up a bit.
Now we can't get the master to hold pressure. it will pump up and work but on the initial hit it goes almost to the floor. rears work good but the fronts don't.
My question is
1. is the master too small for the calipers?
thanks in advance!
Laughing Gas
Joined: Nov 1999
Posts: 954
Likes: 2
From: 15 miles west of Venus
Are the brakes adjusted? I do not think that the m/c is too small. I am running Cordoba calipers and 9" with drums off of as stock '55 m/c. Otherwise you have a bad m/c or air in the lines.
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New User
Joined: Nov 2003
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From: Cottonwood Arizona
i got a problem
Hi Scott,
Thanks for the reply. Yes the brakes are adjusted. we have bled them with the old pedal method and no air is found. this is the second "new" m/c we have tried. even tried a rebuilt one from a different supplier.
we thought it was because the m/c was lower than the calipers. but if you are running cordoba calipers on a stock m/c under the floor.
that's why we were wondering about capacity or piston size in the m/c. we even swapped lines on the m/c to see what happened. rears lock up real good but no fronts at all.
heh! with this new info from you i am really scratching my head!
may try a pressure flush to see if there is a hidden bubble somewhere?????
thanks again
Thanks for the reply. Yes the brakes are adjusted. we have bled them with the old pedal method and no air is found. this is the second "new" m/c we have tried. even tried a rebuilt one from a different supplier.
we thought it was because the m/c was lower than the calipers. but if you are running cordoba calipers on a stock m/c under the floor.
that's why we were wondering about capacity or piston size in the m/c. we even swapped lines on the m/c to see what happened. rears lock up real good but no fronts at all.
heh! with this new info from you i am really scratching my head!
may try a pressure flush to see if there is a hidden bubble somewhere?????
thanks again
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New User
Joined: Nov 2003
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From: Cottonwood Arizona
Scot,
Yes Sir. we checked the depth of the rod and it is ok. one thing we thought of was the pedal pivot ratio. but it too seems to be in spec for disc/drum brakes. it aqcts like it has the volume to operate the calipers but it runs out of stroke when the calipers fill hence no more stroke to build pressure. we got a chry new yorker m/c in late wed. just a quick glance looks like it has a longer stroke than the must II m/c. same res capacity tho.
Yes Sir. we checked the depth of the rod and it is ok. one thing we thought of was the pedal pivot ratio. but it too seems to be in spec for disc/drum brakes. it aqcts like it has the volume to operate the calipers but it runs out of stroke when the calipers fill hence no more stroke to build pressure. we got a chry new yorker m/c in late wed. just a quick glance looks like it has a longer stroke than the must II m/c. same res capacity tho.
Senior User
Joined: Aug 2003
Posts: 103
Likes: 1
From: Poplar-Point Manitoba
Did you check the calipers to see if they are sticking? They may be pulling the piston too far back in the bore when released.
Adjust your rear brakes to full lock on, jack up the front and stand on the brakes.Can you turn the wheels? When released, there should be a little bit of drag left.
Graham
Adjust your rear brakes to full lock on, jack up the front and stand on the brakes.Can you turn the wheels? When released, there should be a little bit of drag left.
Graham
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all alone in the world
Joined: Feb 2002
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From: oklahoma
check the bore on the calipers you have, and find the bore for the mustang11 calipers. i bet you will find that the newyorker calipers are a bigger bore, and probably a longer stroke than the mustang11. that means the mastercyl. is not pushing enough fluid to activate the calipers on the first try. you will probably need a bigger bore master cyl. are you sure the back pressure valve is holding properly?
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Thread Starter
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New User
Joined: Nov 2003
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From: Cottonwood Arizona
Hi,
Thanks again for all the great feedback! Hope y'all had a great turkey day!
Ziggy,
yes each of the 3 m/c's we tried were bench bled.
Graham,
We replaced one questionable caliper. when you pump the brakes up they work fine. spongy but seem to work like they should.
jimbare,
now here is where it gets questionable.
Scot commented commented about this problem and he stated he was running cordoba front disc's and a 9" rear on the stock m/c in a 55 f-100 with no problems. now taking into consideration the size of the old wheel cyl's the stock m/c had to push a lot of fluid to operate the system.
we are running a metering valve and a 2lb residual valve to each front caliper. all new parts.
Thanks again for all the great feedback! Hope y'all had a great turkey day!
Ziggy,
yes each of the 3 m/c's we tried were bench bled.
Graham,
We replaced one questionable caliper. when you pump the brakes up they work fine. spongy but seem to work like they should.
jimbare,
now here is where it gets questionable.
Scot commented commented about this problem and he stated he was running cordoba front disc's and a 9" rear on the stock m/c in a 55 f-100 with no problems. now taking into consideration the size of the old wheel cyl's the stock m/c had to push a lot of fluid to operate the system.
we are running a metering valve and a 2lb residual valve to each front caliper. all new parts.
Last edited by 58panel; Nov 29, 2003 at 05:25 AM.
Thread Starter
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New User
Joined: Nov 2003
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From: Cottonwood Arizona
Scot,
I got a couple of questions for ya? go figger huh!
you are running this brake system with under floor stock m/c?
did you have to install metering and residual valves because the m/c is lower than the calipers?
did you have to tweek or boost the rating on the rear residual valve? " this is what the tech at mpbrakes did for us!" to try to solve the problem
I got a couple of questions for ya? go figger huh!
you are running this brake system with under floor stock m/c?
did you have to install metering and residual valves because the m/c is lower than the calipers?
did you have to tweek or boost the rating on the rear residual valve? " this is what the tech at mpbrakes did for us!" to try to solve the problem
Laughing Gas
Joined: Nov 1999
Posts: 954
Likes: 2
From: 15 miles west of Venus
I did this 14 years ago or so...
I am running the stock m/c with its residual valve removed. That runs into a Midland hydroboost like what was used in that period. The line T's out of the hydroboost. There is a #2 Wilwood check for the front and a #8 for the back.
The MII setup was real new or yet to be when I set this up.
I wonder if one of the checks is defective or backwards. You should be able to crack a bleeder and bleed a bit of fluid from the residual pressure assuming the c/v's are working properly.
I am running the stock m/c with its residual valve removed. That runs into a Midland hydroboost like what was used in that period. The line T's out of the hydroboost. There is a #2 Wilwood check for the front and a #8 for the back.
The MII setup was real new or yet to be when I set this up.
I wonder if one of the checks is defective or backwards. You should be able to crack a bleeder and bleed a bit of fluid from the residual pressure assuming the c/v's are working properly.
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New User
Joined: Nov 2003
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From: Cottonwood Arizona
Scot,
So the master goes into the hydro-boost unit?
i take it that this is the vac booster?/ no fluid involved? the term hydro-boost sounds familiar but can't picture the application!
So the master goes into the hydro-boost unit?
i take it that this is the vac booster?/ no fluid involved? the term hydro-boost sounds familiar but can't picture the application!
Laughing Gas
Joined: Nov 1999
Posts: 954
Likes: 2
From: 15 miles west of Venus
Yes, there is one line that goes from the m/c to the hydroboost. The h/b has a vacuum chamber and a m/c looking thing on it. It has a vacuum line and one brake line leading in and one out. Either way, I do not see how you could get a larger amount of fluid out than what came in.
The more I ponder your situation, the more it sounds like a check valve problem that is allowing the brake cylinders and or calipers to collapse. You might try plugging the line on the rear brakes, then the front, then both and see if you can get pedal. My guess is rear.
The more I ponder your situation, the more it sounds like a check valve problem that is allowing the brake cylinders and or calipers to collapse. You might try plugging the line on the rear brakes, then the front, then both and see if you can get pedal. My guess is rear.
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New User
Joined: Nov 2003
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From: Cottonwood Arizona
Scot
so the hydro-boost unit has a res on it too?
so maybe it is increasing the volume of fluid? just thinking out loud! lol
the residual valves seem to be working as when released the fronts have some drag on them.
one test master brakes said to do was clamp off the front lines and see what ya got!
i did this snd the pedal came right to the top and held just fine! they said this indicates that the problem is in the front brakes
i am gonna try the new yorker m/c this morn. it is about an inch longer than the must II m/c. i don't see how it won't work as it is the correct m/c for the calipers. bolt spread for the booster flange is the same on both.
i'll let ya know what happens
so the hydro-boost unit has a res on it too?
so maybe it is increasing the volume of fluid? just thinking out loud! lol
the residual valves seem to be working as when released the fronts have some drag on them.
one test master brakes said to do was clamp off the front lines and see what ya got!
i did this snd the pedal came right to the top and held just fine! they said this indicates that the problem is in the front brakes
i am gonna try the new yorker m/c this morn. it is about an inch longer than the must II m/c. i don't see how it won't work as it is the correct m/c for the calipers. bolt spread for the booster flange is the same on both.
i'll let ya know what happens
Laughing Gas
Joined: Nov 1999
Posts: 954
Likes: 2
From: 15 miles west of Venus
The Midland hydroboost does not have a reservoir. It is just a hydraulically actuated master cylinder with a vacuum booster attached. I put the best picture I have right now of it in my gallery.
I still find it hard to imagine the MII m/c not having enough volume.
I still find it hard to imagine the MII m/c not having enough volume.