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hydro boost brakes

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by fad2blk99, Oct 23, 2003.

  1. fad2blk99

    fad2blk99 1/2 ton status

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    I got a hydro-boost set up off an '88 or '87 C2500 diesel (our body style). I got all the lines, the pump, and the master cylinder.
    My question is do I need the power steering pump or can I use mine. Mine is in better condition and is a serpentine set up were the diesel's is v-belt. Same thing for the master cylinder, it is also pretty rough looking, and I'd like to keep my old one if I can....
    Thanks,
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    You'll probably want to keep the hydro-boost pump reservoir since it is a bit larger and has an extra return, but it's not necessary, you can "T" in the return lines and it should be fine. The pumps can be swapped in the reservoirs if you like, and the pulleys will interchange as well. One thing to consider (depending on who you talk too) is that the HB pump relief valve has a larger orifice size to allow more volume to flow. I have been told on very good authority that they are no different, and I have also been told on almost as good authority that they *definitely* are larger orifice in the HB. I have never checked and do not know for sure. Maybe some are and some aren’t??? <shrug>
     
  3. camiswelding

    camiswelding 1/2 ton status

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    hydroboost pump runs at a higher pressure 1300 psi as opposed to 750 or so for a non hydro pump
    source- JML's brake paper/chevrolet
    I tried a regular pump and it didnt run the brakes.. put the hydro one on and poof they worked,,,
    imagine that
    remote reservoir is nice too
    I have this setup on all three of my trucks
    I have a complete hydro set available if anyone wants one...bead blasted and painted
    cam
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    [ QUOTE ]
    hydroboost pump runs at a higher pressure 1300 psi as opposed to 750 or so for a non hydro pump
    source

    [/ QUOTE ]
    Hmmm, that's not what I've observed at all. I've run my hydro boost system with hydro assist on both standard non HB (came on my TBI 350 from a Burb with Vac assist) pump and also on the stock HB pump with no noticeable difference in pressure. Also, pressure has nothing to do with the pump in this case. The relief valve is the pressure regulator. And when pressure is bumped more than a little (by increasing spring rate in the valve), the pump housings tend to blow/crack. I am no expert, but based on my anecdotal evidence, what I’ve read, and what knowledgeable people (like Matt at West Texas Offroad – Red Neck Ram) have told be, this simply does not fit at all. I might be convinced that there could be small differences in pressure relief valves for each, but not that there would be that much difference… For one thing, it would require a completely different steering sector to work with nearly double the pressure and mixing components for systems designed for such radically different pressures would HAVE to be clearly noticeable. I *have* mixed parts from both systems in various configurations and I can tell you there was no observable difference for me.
     
  5. fad2blk99

    fad2blk99 1/2 ton status

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    Thanks guys for the info....
    I'll see if I can swap pullys and brackets to run the HB pump, but if it looks to be too much trouble I'll try staying with the old pump and see what happens.
    How about the master cylinder? Should I stay with the HB master cylinder (again, it's off a 3/4 ton 2wd truck)?
    I also am running rear disc, so is extra fluid volume, like from a 1 ton mc, a must?
     
  6. camiswelding

    camiswelding 1/2 ton status

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    I went back and did a little research because I want to know and not because I want to tell anyone they might be wrong...
    anyway I would heartily suggest reading JimL's brake paper on hydroboost... its what i used and it made good common sense to me.. as to what parts work and dont.. well here on K5 we all use parts that arent always intended or specd for what we use them for because we push the envelope and arent afraid to try something just because the manufacturer said we cant...
    that being said .. read the article ..it will help
    http://rpierce.freeyellow.com/BrakePaper.htm
    cam
    heres an article quote if you dont want to go there:
    "You will also want to check to see if your power steering pump is the same, in three respects, as the pump used on a Sub with H-B - it will save you money if you can avoid automatically buying a new one. First, you will need to make sure that your pump puts out the 1200 psi required by all H-B's, rather than the 800 psi that is found on some vehicles with power steering only. You can confirm this if the part numbers for the front (pumping portion, including the pressure relief valve that determines output pressure) of your present pump (not including the reservoir can on the back), are the same in either the Chevy catalog, or in a re-built pump catalog, as the part numbers for the pump and relief valve used on a vehicle that came stock with H-B. If necessary, you could change the pressure relief valve (the big nut fitting on the rear face of the can) to a 1200 psi one. Or, you could buy a rebuilt pump meant for a H-B'ed vehicle (one that puts out 1200 psi) for about $54. The second way in which the pump will have to be the same is that it will need to have an extra return nipple. Some stock pumps already have that extra nipple, blocked off but ready to be used. Or, you could braze an extra nipple on your can - but see caution about adequate reservoir volume, next. Third, while the can on the back of the H-B compatible pump will have an obvious difference - the extra nipple for the low pressure return line from the H-B unit, it could also have a less obvious, but still important, difference. Since the H-B system has more fluid in it, the can may be larger, to leave room for the expansion of the extra fluid due to heat. You don't want fluid expanding out of the can and onto the headers - that could cause a fire! A complete new genuine GM pump, made to work with H-B so it has 1200 psi, and including the can with extra nipple, is $220 at Brasleton. Part number 26065182. (In my case, I was able to re-use the front of my pump, but had to buy a different, larger, pump can from chevy"
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Cool, thanks for the info! I want to be proven wrong when I am wrong. Self delusion is not something I aspire too. /forums/images/graemlins/thumb.gif

    I'll do some more investigation. Maybe my sources were wrong, and my observations based on chance/luck? If so, that's rare since luck (at least of the good variety) is not something I'm known for. I'm really interested in what comes from this...
     
  8. fad2blk99

    fad2blk99 1/2 ton status

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    Thanks for the info. I've followed many links posted for that paper and none of them took me to the one you gave me--which seems to include all the important info... Thanks again!
     
  9. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Like anything you find on the net (including this post) you need to take it with the proverbial "grain of salt". Sometimes, people are mistaken or misunderstood, or even opinion/guess stated as fact (or not clearly labeled as opinion at least). That brake article looks rather impressive and well done, but I'm still not sure how much to believe...

    Anyway, I talked to my friend the walking parts encyclopedia (who also has access to paper and electronic versions) who verifies that there is only 1 part number listed for all pumps regardless of vehicle equipment. That does not mean the relief valve could not be different (at least I don’t think he checked that) but the pumps have only 1 number in the after market. It would surprise me if the after market consolidated pumps ranging from 800 to 1200 psi into one part number.

    Don’t get me wrong, I’m not saying this is definitive in any way, it’s just more information…
     
  10. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Ahhhh, just noticed something...
    [ QUOTE ]
    rather than the 800 psi that is found on some vehicles with power steering only

    [/ QUOTE ]
    I wonder if that is refering to automotive/passenger car pumps? My friend did say there were some differences in those used in some cars. I wonder if all trucks have the high pressure pump/valves? Just a thought...
     
  11. camiswelding

    camiswelding 1/2 ton status

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    its all about learning.... what works and what doesnt...
    and that my friends is why its worth being a member here..
    let the other guy spend the money make the mistakes and learn from their errors before we (I)spend the bucks//
    thanks everyone for the info and updates
    ck5 rocks
    cam
     

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