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Dual Brake Master

Discussion in '40- & 55-Series Tech' started by Eternal, Feb 14, 2004.

  1. Eternal

    Eternal

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    THe 70 40 is in the process of an unknown amount of repair but the brakes are near the top of the list. I was told that keeping a manual master I might experience problems with the pedal ratio and setting the rear to give "good" stopping properties even with a propertioning valve. The Dual master with a balance bar seems like a good option and relatively simple to build. Anyone have experience using or have come in contact with this system? Thanks.

    Eternal
     
  2. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    Spaceghost has a dual master set on his rig

    But I have to ask Why you would want to add a bit of complexity to a system that works very well???
     
  3. plan66

    plan66

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    I replaced the stock single cylinder with one from a 70's ford p/u. Its a dual circuit cyl with residual pressure valves for the drums and is a 1" bore. I did not fit any sort of proportioning valve and have not had problems.
    If you do plan on staying with drum brakes and no booster, I'd recommend you find a smaller cylinder with a 7/8" bore.
    The 1" locks up the tires if I stand on it, but otherwise pedal effort is VERY high. It is difficult to keep the truck from rolling backward on steep hills and the brakes get much heavier as the brakes fade coming down mountain passes.

    hth
    Martin
     
  4. woody

    woody unhelpful spotter Staff Member Admin

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    SG runs dual wilwoods...nice setup, but not cheap.

    What brakes at the axles? Matching the system is as important as anything.
     
  5. Eternal

    Eternal

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    I'm doing the Toyota mini truck disc for front and the chev disc for the rear. I'm gonna change all the lines and my master was new a couple years ago but was thinking that I might as well change it all if I'm gonna go that far. Do you know what the ratios should be for the bore of dual system or where I can get info like that?

    Eternal
     
  6. TonkaC

    TonkaC

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    I've got the mini front disks and the chevy monte calipers in the back. I used a '95 toyota land cruiser master cylinder in it and it works great. I don't have a proportioning valve but haven't noticed any need for one. I might notice more when I'm taking it off road more, but for now it has worked great and it's one of the best things I've done to it.

    Chris
     
  7. Eternal

    Eternal

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    but are you using a booster, I don't want to use a booster cause of space in the 70 40. That's why dual masters seems like a good choice.
     
  8. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    [quote author=Eternal link=board=1;threadid=11497;start=msg105633#msg105633 date=1076946786]
    but are you using a booster, I don't want to use a booster cause of space in the 70 40. That's why dual masters seems like a good choice.
    [/quote]
    Most people that I know that have either the six or a V* conversion do not have a problem with space..

    Pic?
     
  9. Eternal

    Eternal

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    Adding a booster means moving the clutch master over 2-3 inches and cutting out the stiffening rib on the fire wall or mounting the booster out really far and I don't want to do that. I like as much space as possible for adding all the stupid little things I build every now and again and it would mean rebuilding my snorkel which is not out of the question but I don't really want to do that. As well, setting 4 wheel discs with the proper tension can be difficult even with a proportioning valve installed. I heard that duals is the way to go with virtually limitless settings for pressure using a balance bar system. I checked out wilwood.com and talked to them a bit and they say it's awesome but they are the sales people who want me to buy. I think I will go for it and do a pictoral of the process and maybe I can get it into the tech section. :D
     
  10. TonkaC

    TonkaC

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    I didn't have to move my clutch but did have to cut the vertical brace. I've liked the benefit more than the trouble of cutting off the support.

    Just a thought, chris
     
  11. Eternal

    Eternal

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    TonkaC- Have you had any problems on steep inclines with enough pressure to keep you from rolling. I like to lock em up tight if need be... I heard that I may have problem with that. But since you have done it your opinion is quite valuable to me.
     
  12. TonkaC

    TonkaC

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    I haven't noticed not having enough pressure. I know I can lock up all four tires if I wasn't scared of putting it on its nose ;) I've had enough pressure with everything I've put it through. The only problem I've ran into was a brake hose hole because I ran it too close to a shock mount. Of course it happened when I was pulling my buds j**p on a 100 mile trip. I'm just glad it was an X crossing and not a T crossing and low traffic. Do know that my e-brake will stop all that weight, which is nice to know.