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BRINGING IT ALL TOGETHER.... A's, G's & E's


5 posters

    Brakes on my 1970 A100 (question)

    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

    Brakes on my 1970 A100 (question) Empty Brakes on my 1970 A100 (question)

    Post by Hamilton Tue Jul 06, 2010 7:00 pm

    hey all!

    I picked up this van yesterday and it's been some time since I was around an older vehicle. But the brakes seem incredibly hard to depress and stop the van easily. I inspected it tonight and noticed the discs up front:

    Brakes on my 1970 A100 (question) Frontpassdisk

    and it's got drums in the back.

    Brakes on my 1970 A100 (question) Backbrakes

    could it be that the master cylinder is too small for these brakes? that may be a dumb question.

    Brakes on my 1970 A100 (question) Mastercylindar

    I am just snooping around, I have not taken the wheels off to inspect the drums just yet, but the discs are smooth, no grooves.

    is this a bleeding issue? a adjustment issue? I'm not sure...

    thanks in advance for the advice!

    hami
    RodStRace
    RodStRace


    Number of posts : 3046
    Location : Chino Valley
    Registration date : 2010-01-21

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    Post by RodStRace Tue Jul 06, 2010 9:24 pm

    Disc brakes are not self-energizing, and the function of the design requires more M/C pressure. This is commonly addressed by changing the pedal ratio or adding vacuum assist. All modern cars have front discs and even little lightweight cars like a Kia or Honda have a booster.
    Since this was a drum to disc swap, you can assume that the pedal ratio is the same old drum/drum, and there is no added vacuum booster.

    To get a softer pedal will require adding a booster ( I have no knowledge of anyone offering a kit) or changing the pedal ratio ( this is also something that is not available as a ready-made part with all design done).
    To be able to design and fabricate something that will require less pedal effort is going to require a through understanding of brakes, fluid dynamics, lever ratios and high quality welding skills. Brakes must be safe!
    Most owners are willing to sacrifice higher pedal effort for better stopping.
    The area around the front of the master cylinder is a busy place, requiring any booster installation to deal with moving all the other parts in the area.



    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

    Brakes on my 1970 A100 (question) Empty Re: Brakes on my 1970 A100 (question)

    Post by Hamilton Wed Jul 07, 2010 3:29 am

    good info RodSR, that makes total sense....

    you state: "Most owners are willing to sacrifice higher pedal effort for better stopping"

    do you mean, that having the discs up front does indeed make the leg effort more, but the braking better?

    .....thanks for the advice....looks like I need to build up the old leg muscle!



    Last edited by Hamilton on Wed Jul 07, 2010 3:32 am; edited 1 time in total (Reason for editing : added quote)
    RodStRace
    RodStRace


    Number of posts : 3046
    Location : Chino Valley
    Registration date : 2010-01-21

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    Post by RodStRace Wed Jul 07, 2010 7:23 am

    Discs will stop better, but require more pressure from the master cylinder to do so.
    With no other changes (like your van), the increased pressure needed is all supplied by you!
    Basic info
    http://auto.howstuffworks.com/auto-parts/brakes/brake-types/disc-brake.htm
    overview and history
    http://en.wikipedia.org/wiki/Disc_brake
    Good article on upgrading a brake system and typical 'rules'
    http://www.hotrodheaven.com/tech/brakes/

    more hardcore info
    http://www.mitchellsoftware.com/prod05.htm
    stuff to make your eyes cross
    http://www.engineeringinspiration.co.uk/brakecalcs.html
    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

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    Post by Hamilton Wed Jul 07, 2010 7:40 am

    awesome! thanks RSR, looks like I have some reading to do! thanks for the advice...
    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

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    Post by Hamilton Wed Jul 07, 2010 7:43 am

    and one more question RSR, on one of the pages of your links it states:

    "Some cars with four-wheel disc brakes have a separate drum brake integrated into the hub of the rear wheels. This drum brake is only for the emergency brake system, and it is actuated only by the cable; it has no hydraulics."

    is this the case with my brake set up? is that little MC not controlling the rear drums? I noticed the parking brake doesn't work at all on this van.

    RodStRace
    RodStRace


    Number of posts : 3046
    Location : Chino Valley
    Registration date : 2010-01-21

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    Post by RodStRace Wed Jul 07, 2010 7:52 am

    No. You have drum brakes in the back.
    The ebrake system on yours is all factory and pretty simple.
    As required by law, all e-brake systems are mechanical, not hydraulic.
    Most common causes for it not working is stuck cables or linkage or the rear brakes are not adjusted properly or all the parts are not installed right.

    You can get a factory manual that will cover it on amazon or ebay, or download a copy here since one of the members has very graciously scanned his copy.
    https://vintage-vans.forumotion.com/a-van-general-discussion-f3/service-manual-download-t13582.htm
    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

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    Post by Hamilton Wed Jul 07, 2010 7:55 am

    ten four! I have a maual I found on Amazon on the way...thanks!!
    donivan65
    donivan65
    Governor
    Governor


    Number of posts : 12227
    Location : San Diego, California
    Registration date : 2008-05-12

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    Post by donivan65 Wed Jul 07, 2010 10:31 am

    Well,,,,,,,you got to learn the rules on owning an Early Van,,,,,like if you drive something with power brakes, a van's brakes feel like they are not working right,,,,,,,power brakes STOP you,,,,,,,,manual brakes, SLOW you down then STOP you,,,,,and if you got disks up front, its worse because disk brakes want a power booster to stop efficiently. But at least the van stop straight with front disks. If you have some doubts about how those rear brakes are doing,,,,,,try stopping the van just by pulling on the parking brake,,,,,,,see what those rear wheels do,,,,,,,
    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

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    Post by Hamilton Wed Jul 07, 2010 10:37 am

    ok Donivan, I will try that....you're right, it's just going to take some adjusting to!

    thank you!
    67a 100 pickup
    67a 100 pickup


    Number of posts : 1319
    Location : ann arbor, mi
    Registration date : 2009-01-29

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    Post by 67a 100 pickup Wed Jul 07, 2010 1:22 pm

    Check the rubber brake lines, sometimes they colapse on the inside and restrict flow making the pedal hard.
    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

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    Post by Hamilton Wed Jul 07, 2010 1:27 pm

    cool, will do 67a 100....
    kiwimopar
    kiwimopar


    Number of posts : 749
    Location : New Zealand
    Registration date : 2010-01-23

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    Post by kiwimopar Wed Jul 07, 2010 2:37 pm

    Sounds like you need a remote booster for the front discs. I am trying to get a buddy of mine to source one for me.
    Hamilton
    Hamilton


    Number of posts : 95
    Location : Texas
    Registration date : 2010-07-06

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    Post by Hamilton Wed Jul 07, 2010 3:49 pm

    sweet! keep us posted Kiwimopar...

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