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front brake lines--would this work

Discussion in 'The Garage' started by DERBINATOR, Jul 26, 2002.

  1. DERBINATOR

    DERBINATOR 1/2 ton status

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    Why couldn't you run the front brake lines like the back. Bring one flex line down in the center then hard lines out to the knuckles then flex again to the calipers. Then you would only need one longer flex hose in the middle and the stock ones would be long enuff at the calipers. Would this work or would there be some problems with how the prop valve works with the fronts.
     
  2. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> I think that this is how SW ran the brakes in the ORD Blazer. Not sure if it would cause problems on the street or not.</font color>
     
  3. Swanson52

    Swanson52 1/2 ton status

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    Aren't Dodge fronts like this?
     
  4. HarryH3

    HarryH3 1 ton status Author

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    I've seen rock buggies set up that way, so it is possible. /forums/images/icons/cool.gif I'd have to crawl under and have a look at the brake line routing to see how hard it would be to make it work with a GM proportioning valve. I'm not sure where they make the split to the front calipers offhand.
     
  5. m j

    m j 1/2 ton status

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    you can run the lines anywhere.
    you could run them down your draglink if you so desired
     
  6. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    The prop valve has two lines in and 3 lines out (2 front and 1 rear). He wants to have just 1 front come out of the prop valve and then split by the axle (same as rear), can you just block one front port?? or do you have to use a different prop valve?? Effects on braking?
     
  7. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> Might be better to use a T fitting to run the 2 lines to the front together into one, then use a line to the axle, then T it off again to the wheels. Wouldn't have to mess with a plug and if you might be able to find a fitting for a hose with an ID that flows the same volume as the two seperate lines together. </font color>
     
  8. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I know most of the pre '94 Dodges had the lines set up like that. Plugging one port on the Chevy valve might work but you may find out the hard way if it doesn't. It would probably be better to get a Dodge valve and redo the fittings if needed.
     
  9. TopOff

    TopOff 1/2 ton status

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    If there are indeed two coming out of the proportioning valve for the front, I would wonder if the proportioning valve equalizes pressure to the two front calipers. If this equalizes pressure between the two fronts, then you get straight line braking. If you change that around and one of your calipers are better than the other, then you can get brake pull.

    If this valve doesn't do this, then nevermind... /forums/images/icons/blush.gif
     
  10. DERBINATOR

    DERBINATOR 1/2 ton status

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    I think you could use 2 of the blocks off of a rear. One to splice the 2 lines off the prop valve into one then one to return it to 2 lines. Using the blocks off the rear I believe the line coming into it is larger then the 2 coming out so that would make up for volume or pressure when splicing into one line. I just thought this might be an answer to some of the guys looking for extended brake lines for high lifts.

    p.s. way to many 2's in this replay HA,HA
     
  11. Scorpion

    Scorpion Registered Member

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    The brake line dedicated to the front comming out of the master cynlinder is larger than the one for the rear. The proportioning valve then sends more fluid to the front (in effort to cause more of the braking in the front) and it splits into two lines both of which allow more fluid to the calipers. GM has done it the same way for as long as can be remembered and Dodge has changed it to be like GM. If it had worked better the other way, wouldn't GM have changed? Dodge isn't exactly the model company to base a design after...
     
  12. DERBINATOR

    DERBINATOR 1/2 ton status

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    Good point
     
  13. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I agree with your statement about inherent design of single line splitting vs. two lines right from the prop valve not being as effective, but the part about:
    </font><blockquote><font class="small">In reply to:</font><hr />
    The brake line dedicated to the front comming out of the master cynlinder is larger than the one for the rear. The proportioning valve then sends more fluid to the front (in effort to cause more of the braking in the front)

    [/ QUOTE ]

    I thought (could be wrong, and wouldn't be the first time) that the proportioning valve determined brake bias and not the size of the line. The size of the line was due to the amount of fluid needed to move caliper pistons vs. wheel cylinders, or is that what you meant? It sounded as if you were stating larger line = larger PSI which I'm not sure is true.

    If am correct that is also the reason most do not have to worry about resetting the prop valve after a rear disc conversion as the smaller line "slow" the caliper down forcing most of the braking to be done by the front. Even when people modify the prop valve (see article on monte carlo website) to remove bias from the prop valve when doing a rear disc conversion, the front brakes grab sooner/quicker providing more of the breaking action (bias) except the bias is now controlled by line diameter and fluid flow rather than a mechanical bias.

    Again I could be wrong, but my curious mind likes to know /forums/images/icons/grin.gif
     
  14. Scorpion

    Scorpion Registered Member

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    Nope, you're right, that's what I meant. More fluid is required for the calipers and a larger line doesn't = greater psi unless the PSI is greater, it would actually have less PSI but more volume (conversly, a smaller line at the same PSI comming into it as a larger line would actually have more PSI but less volume).

    The fluid to the rear has less volume and has to travel a greater distance as well. This also has an affect on the PSI when it gets to it's destination. All of this was factored in when a proportioning valve was implemented in the braking system.

    In order to create an equal breaking system at all 4 wheels, someone would have to deal with the fluid dynamics and engineer a system that results in the same pressure at the braking component of all 4 wheels by taking in to account each of the braking devices, the bends in each of the brake lines, the diameter of the brake lines, the pressures going into them, and even the temperature of the actual braking component when applied.
     
  15. m j

    m j 1/2 ton status

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    the line size has nothing to do with PSI or Volume, it is just a line
     
  16. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I like the idea, though I'd like to know more about the tradeoffs.

    It would be less "stuff" to get snagged, ripped off, or damaged.....and THAT'S a good thing.

    Maybe you should create a link to this on the ORD board and ask Dr. Watson to comment?
     
  17. Batmanjr

    Batmanjr 1/2 ton status

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    Just my .02 cents:

    The bends have nothing to do with how they work, this is a liquid based system, therefor length and volume is key! The PSI is just the amount of force at the end... First, the best way to get equal braking preasure at all four is to get a master cylinder off of an all wheel disc brake truck. These have equal chambers for the front and rear pistons in the brake cylinder.... Your original one has a larger resevior for the front than the rear because the fronts take more fluid, not because they apply more preasure.... The amount of preasure is the same into the proportioning valve front and rear do to it all comes from YOUR FOOT! the only difference is the volume! More volume doesn't mean more braking..... The rear cylinders take less volume and therefor require less fluid, but do to laws of physics(not sure the name) in a hydrolic system, the amount of preasure applied in a closed system, wil equal the preasure applied at the end of the same system... This is why you get soft brakes if there is air in your hydrolics.. Therefor, in order to run a single line up front as well as a single line in the rear, to do it right, one must replace master cylinder and run the larger lines to a dual proportioning valve(2 in 2 out)or modify the original to act as a dual(2 in, 2front out to a tee down with a larger tube, 1 rear) Then run your lines front and back and split to the left and right side... The proportioning valve only regulates preasure front and rear and left and right up front... If you were to remove the dual up front, you would have to watch for uneven braking in the front which would cause wheel pull. Then the proportioning valve would only regulate front to rear..... But it's all completely doable! /forums/images/icons/grin.gif
    /forums/images/icons/cool.gif
     
  18. m j

    m j 1/2 ton status

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    I disagree from "Therefor, in order to run a single line up front " on.
    I thought you were on to it in the first half then you went out to lunch.
    plug one port , run single line to front dif. done deal.
    IF the line is too small it will just take longer for the fluid to transfer to the caliper, I would guess.
    no one here has come up with a formula to prove a single 3/16 is too small
     
  19. Batmanjr

    Batmanjr 1/2 ton status

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    If the fluid takes longer to transfer to the caliper, you get insufficant braking, correct? Part of the problem with the disc conversion is that if you leave the old style master cylinder on the truck, you dont get enough fluid to the rear calipers to FILL the larger calipers, therefore the calipers aren't doing as much as they could be doing in the way of braking!!!! This is why you change, if you are running drums in the rear, I would still run a large line from the proprtioning valve cause now you have to fill BOTH front calipers using half as much fluid FLOW! Therefor, I would increase the size of the tube inorder to keep from having insufficiant braking power up front... The rear take about half the amount of fluid as the front with drums... If you change to disks in the rear, and then disconnect the front entirly, then drive it around the block, you will see what half as much fluid feels like in Caliper brakes.... DRIVE SLOW!!!! THerefor, I would change the size of the tube, I believe that is the only thing we do not agree on cause everything else is either the same aor a modified old versio to make the same! OH, about "Plug one side port and run a single line" Does the proportioning have a side to side valve in it? IF so, it will throw off your preasure to the front by plugging the one port, if not, you are trying to force 100% of the fluid through Half the valve.... OR is it just a BIG Tee fitting itself? I haven't ever torn one apart.... I would just use both sides for overall gaurenteed flow..... The worst thing you can have in a brake system is a restriction of flow.... /forums/images/icons/tongue.gif
    /forums/images/icons/cool.gif
     
  20. m j

    m j 1/2 ton status

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    the very first word you typed is the key "IF"
    you have still not come up with anything that states 3/16 is too small.
    it is the industry standard size line and IMO will be plenty big.
    as for time to transfer = insufficient braking, perhaps but go and prove the line is too small first.
    as the line is far from being the smallest restriction in the brake system I think you are barking up the wrong tree

    as there are several kits using stock MC and there are a ton of members on this site that are using stock MC and rear discs and I have yet to here that the huge bore in the truck MC is too small to feed the brakes

    fluid flow would be the same. prove otherwise

    "does the prop valve have side to side" no, just cheaper to drill the prop valve then add a T

    who ever typed that it would equalize side to side was smoking an illegal substance.
    hydraulics 'equalize' automatically, I cannot find the words to describe that as it is the whole enchilada in hydraulics.
     

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