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Hydra-Boost Brakes a Success!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BorregoK5, Oct 2, 2001.

  1. BorregoK5

    BorregoK5 1/2 ton status

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    I fitted the K5 today with a hydra boost unit that I happened across in the junkyard. I grabbed it off a 1975 K30 truck, which had a heavy duty braking option from the factory, not a diesel though. The booster had the same mount pattern as my 78 K5 for the firewall but the center two bolt holes had studs in them, which the nuts tightened in from the pedal side of the firewall. I tapped them out with a few light swings from a hammer and then the firewall side of the mount was identical to my vacuum booster. I didn’t keep the master cylinder from the hydra booster but rather opted to use the one I already had. The center pin of the hydra booster was about 2” too long to work with my master cylinder so a little creative work on the grinder making sure to keep the end smooth and rounded with a polish and I was all set, it bolted right up. No mods were needed for the brake pedal attachment either which was a major bonus. I did however need to buy some hoses to plumb it into the system from Napa but it was only about 50 bucks. I’ll post the part numbers later (wife’s out having fun in the K5 right now, wouldn’t let her drive it until it could stop… FAST!). The power steering pump has a line to the hydra booster, then from the hydra booster to the steering box and both the steering box and the hydra boost have return lines that T together back to the power steering pump, simple as that. Thanks to ‘The General’ here on the board for putting up with my questions and such as it all paid off in the end, and you were right, its much much better! I highly recommend the hydra boost system, never has my K5 stopped so smooth and fast with so little effort.

    In addition, I finally got a 14bFF today as well from the same truck as the hydra booster... I'm sure they will work well together once I get it installed! [​IMG]

    What, Me Worry?
    <a target="_blank" href=http://www.echobit.com:81/k5/> The 'BEFORE' pictures</a>
     
  2. right on!!! so it's significatley better than stock? when i upgraded to 3/4 ton i noticed a big improvement in braking. when you get time, give a price breakdown. i would like to see if it's worth doing.

    <font color=blue>"What does mine say?"
    "SWEET! What does mine say?"
    "DUDE!" </font color=blue>
     
  3. TheGeneral

    TheGeneral 1/2 ton status

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    Congratulations, and thanks for given thanks. Glad to hear success. Did you do rear discs? If so, did you put on new proportioning valve, and or remove residual pressure valve? Just interested in getting others' set ups hows, whys, and did it work?

    If you ain't hurt, you ain't playin' hard enough.

    The General
     
  4. BorregoK5

    BorregoK5 1/2 ton status

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    I haven't put the 14bFF on yet, I want to take it apart, inspect it and rebuild it first. As I was telling The General, its a 300% improvement in braking, smoothness and all with my pinky toe on the pedal. I bought the booster from a junk yard for 15 bucks, but , when gathering the hoses at Napa, they show a replacement hydra booster for the 75 k30 w/350 for 98 bucks. The hydra booster to power steering pump high pressure hose (Napa p/n 7-1646) was $31.14 and the hydra booster to steering box was $16.99 (Pep Boys part number 0-3099-25853). You'll need to buy about 5 bucks worth of 3/8 hose and a 'T' connector for the return and thats it... oh, except a few hose clamps here and there. I plan to plumb mine with nice Earls stuff once the prototyping is done.

    What, Me Worry?
    <a target="_blank" href=http://www.echobit.com:81/k5/> The 'BEFORE' pictures</a>
     
  5. BorregoK5

    BorregoK5 1/2 ton status

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    The disk kit is my next big investment. That dang 14bolt weighs enough as it is, anything I can do to lighten it up is very welcome. In fact . its so heavy, that if we have any big earthquakes out here, my garage will be the only thing standing as the foundation probably can't move from under that dead weight!!!

    What, Me Worry?
    <a target="_blank" href=http://www.echobit.com:81/k5/> The 'BEFORE' pictures</a>
     
  6. HispanicPanic

    HispanicPanic 1/2 ton status

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    MAN i wish i could say i have the same luck with my brakes ive changed everything and i still cant get it to stop worth a crap

    <font color=purple>I put the Panic in Hispanic</font color=purple>[​IMG]
    <a target="_blank" href=http://4x4.alloffroad.com>4x4.alloffroad.com</a>
     
  7. Thumper

    Thumper 1/2 ton status

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    Hey General,
    You mentioned doing a disc swap and removing a "residual pressure valve". I gotta ask, where is that bad boy?? I have asked numerous brake 'specialists', and none of them can tell me anything about it besides there "probably" is one. I have gotten the whole lowdown on how it works and why its there, and why it would cause my rear discs to drag and groan, but no-one seems to know where it is. Can you shed some light and help me out?? Thanks.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     
  8. BorregoK5

    BorregoK5 1/2 ton status

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    HispanicPanic, I had the same problem, replaced everything in the whole dang system and still had a stiff pedal when going straight from the gas to the brake or when pumping the brake. Thats what started me down this path. If your running a stock cam or rv/towing cam, you could get away with a vacuum booster, but if your after horsepower it comes at the loss of vacuum with a cam.

    Thumper, my proportioning valve is mounted under the back side of the front coss member, below and in front of the harmonic dampner on my '78.

    What, Me Worry?
    <a target="_blank" href=http://www.echobit.com:81/k5/> The 'BEFORE' pictures</a>
     
  9. Thumper

    Thumper 1/2 ton status

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    So, the residual pressure valve is inside the proportioning/ combo valve???

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     
  10. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Is residual valve the correct name. Usually residual valves are used on brake systems where the master cylinder is lower than the calipers and/or wheel cylinders. There is a valve in the distribution block which is why it is normally called a proportioning valve, but limits (or "proportions") brake bias rather than residual pressures. To my knowledge (which isn't everything) most production brake systems with firewall mounted master cylinders, do not use "residual valves" (just the proportioning valve for disc/drum combos). This is what I have been able to piece together over the years, I could be wrong, so if I am please correct me.

    As for removing the valve in the distribution block, it can be done to dissable the front to rear bias. There was a link on here a few weeks ago about the ??? Impala SS's ??? that explained how to do it. It is used for converting old disc/drum setups to disc/disc

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot>http://coloradok5.com/gallery/Leadfoot</a>
     
  11. BorregoK5

    BorregoK5 1/2 ton status

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    Thumper, Leadfoot is correct. I assumed you meant the proportioning valve. Any residual pressure is handled by the proportioning valve on Chevy's from what I can remember. I believe some Ford's and Toyota's used small residual pressure valves at the master cylender fitted into the brake line itself (they pop in at the flange). It was used to keep a bit of pressure in the lines so the seals in the drum pistons would stay lubricated. I've never seen that type on a Chevy, I believe the proportioning valve is used to keep that pressure there and its only needed for drum brakes or an instance when you want to customize your braking. Some of the drag cars I've built had adjustable proportioning vavles in place of the stock vavle so we could dial in just how much of the rear brakes we wanted to use after a drum to disk conversion, it would prevent the back tires from locking up on hard braking where a proportioning valve was not used. Since most of the trucks here are rock crawlers, I can see how having equal pressure to all four tires may help, but the light back end on the street may alow the rears to lock up early when not using one.

    What, Me Worry?
    <a target="_blank" href=http://www.echobit.com:81/k5/> The 'BEFORE' pictures</a>
     
  12. Thumper

    Thumper 1/2 ton status

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    Cool, thanks for the info. I have completely bypassed the rear system of the prop valve, and they still drag a bit. Guess thats the nature of them. I am going to pick up an adjustable prop valve on my next trip to the US in Jan or Feb. They are way too expensive here.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     

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