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!/2 ton Master Cylinder vs 1-ton Master Cylinder

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Brian 89KBlazer, Jan 29, 2001.

  1. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Is the 1-ton a direct bolt-in swap for the 1/2 ton or is there a big difference. I'm swapping to D60/14-bolt and since the master cyl is shot in my '89 Blazer, I figured I'd just buy the one ton master cyl. if it's a direct bolt-in.

    Thanks
    Brian
    89KBlazer
     
  2. JoeAngelicchio

    JoeAngelicchio 1/2 ton status

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    Hey Brian,
    If I get a chance today and get stuff off the hood of my crewcab I'll take a look. I'm thinking the booster may be different and I know there will hoses to deal with. Actually if I find my GM truck parts books, I'll be able to tell with the diagrams and part numbers. I'll have to wait till I get my son down for a nap.

    <font color=green>Joe Angelicchio
    86 Jimmy 4+3, 35-&gt;39.5 tires,4spd
    </font color=green>
    [​IMG]
     
  3. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Thanks Joe

    I'll await your post. Anyone else??

    Brian
    89KBlazer
     
  4. Burt4x4

    Burt4x4 3/4 ton status

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    From what I understand the big difference is in the Booster!
    So If it was me I would swap out the Booster and Master!
    I wouldn't think a 1 ton Master on a 1/2 ton Booster would do much for your braking, if they fit together!!????

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <A target="_blank" HREF=http://www.burt4x4.coloradok5.com>http://www.burt4x4.coloradok5.com</A>
     
  5. grumpy

    grumpy 1/2 ton status

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    Brian,
    I did the Dana60/14bolt swap on my Suburban and you do need the whole set up swapped to get good braking. The 1 ton sysem is called Hydroboost and it uses hydraulic pressure from the power steering pump. You will need the hydroboost boooster, master cylnder, 3 hoses, correct pump and there is a bracket that goes inside the firewall to help hold up all the extra weight. If I remember correctly I put in the HB master cylinder rod also.
    David
    David
     
  6. grumpy

    grumpy 1/2 ton status

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    Brian,
    I did the Dana60/14bolt swap on my Suburban and you do need the whole set up swapped to get good braking. The 1 ton system is called Hydroboost and it uses hydraulic pressure from the power steering pump. You will need the hydroboost boooster, master cylnder, 3 hoses, correct pump and there is a bracket that goes inside the firewall to help hold up all the extra weight. If I remember correctly I put in the HB master cylinder rod also.
    David
    David
     
  7. JoeAngelicchio

    JoeAngelicchio 1/2 ton status

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    OK Brian I'm back.
    Looking at the parts book (covers 85-91) the 1 ton uses a totally different booster that's connected to a power brake booster pump (belt driven) with the hoses I mentioned before. There's also a height sensing proportioning valve for the rear. If I had a scanner I'd scan this.

    <font color=green>Joe Angelicchio
    86 Jimmy 4+3, 35-&gt;39.5 tires,4spd
    </font color=green>
    [​IMG]
     
  8. Burt4x4

    Burt4x4 3/4 ton status

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    If you don't whant to deal with all thoes hydrolic lines you may want to look into using a 3/4ton Dual Diaphram setup.
    My fatherinlaw did a master/booster swap on his 72 stepside and replaced it with the 3/4ton version and it's all vacume drivin! He loves his new braking power. THis is what I will do when $$ permits!

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <A target="_blank" HREF=http://www.burt4x4.coloradok5.com>http://www.burt4x4.coloradok5.com</A>
     
  9. JoeAngelicchio

    JoeAngelicchio 1/2 ton status

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    Screwed up on the last post. Diagram was showing two pumps. They screwed up and had a pic of a 1/2-3/4 ton pump on the same page. The pump is different from yours as it works both the hydroboost and the steering gear. Found a better diagram showing the routing of the hoses and pressure lines. Burt4x4 has a good point with the Dual-diaphram setup. I'm going to look that up next.

    <font color=green>Joe Angelicchio
    86 Jimmy 4+3, 35-&gt;39.5 tires,4spd
    </font color=green>
    [​IMG]
     
  10. ken

    ken 1/2 ton status

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    You paniking for nothing. I did one ton axle swaps on both my 1977 3/4 ton Sub, and my 1990 1/2 ton Sub. Did not change the MC or booster. Brakes work fine. The '77 even has TSM rear discs, and will lock up the 39.5" Swampers if you want. all this with the stock 3/4 ton booster and MC. The '90 Sub has the 13" rear drum brakes...its been 7 years and 200,000 miles since the swap and no troubles...well except for the stupid 700R4 auto trans, but that's another story!!

    ken
     
  11. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Thanks everyone

    So Ken, you figure I'd be just as well off replacing just the master cyl with a new stock one & skip the work of finding & swapping all those other components??

    Thanks
    Brian
    89KBlazer

    Bye the way, I'll be going to the TSM rear discs when I swap too.
     
  12. JoeAngelicchio

    JoeAngelicchio 1/2 ton status

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    Ken idea sounds like the most logical route. Probably what Steve did also. Would save the extra expense of buying all the extra pieces that you put towards the TSM's. Probably what I would do also.

    <font color=green>Joe Angelicchio
    86 Jimmy 4+3, 35-&gt;39.5 tires,4spd
    </font color=green>
    [​IMG]
     
  13. ken

    ken 1/2 ton status

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    Swap the axles in and be sure you bleed the sh*t outta them to be sure you got ALL the air out...then assess you braking performance. At best, I would install a 3/4 MC, but I imagine that the part number may be the same as for the 1/2 ton. I wouldn't go to the trouble of swapping in a Hydro/Boost...I've got one that was factory installed in my '88 one ton crewcab 4x4, and while the brakes are great, they are by no means THAT much better than a good regular booster/MC setup.

    ken
     
  14. Emmettology 101

    Emmettology 101 3/4 ton status

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    Ken,
    I swapped out the Hydroboost(originally diesel equip. Jimmy) for a normal mater cyl and Booster.

    What would you recomend for me? Everything for the Hydroboost except for the booster and master cyl, but I do have the power steering box and power steerring pump with the Hydoboost nozzles on them....

    Should I go 3/4 ton or back to Hydro?

    Thanks..

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>
     
  15. Shawn

    Shawn 1/2 ton status Premium Member Author

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    I'm going to a 3/4 ton diaphram unit eventually. From what one of the mags said (yes, they actually answered a question I sent and printed it), the 1/2 master rod is smaller requiring more throw of the pedal. The 3/4 ton has a larger rod and doesn't have to be pressed as far. Another reason I'm going to a 3/4 ton is to get rid of that wussy plastic master. Evertime I work on the motor, I come close to breaking that plastic container off. If I even take the lid off, it feels like it will break. The older 1/2 tons have the good cast iron masters.

    Shawn
    87 K5
    few mods[​IMG]
    <A target="_blank" HREF=http://www.off-road.com/chevy>http://www.off-road.com/chevy</A>
     
  16. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    There are MANY variations of masters to choose from. Ex, diesel k5's had hydroboost and a 30 mm. fr. and rear cyl. setup, reg k5 and 1/2T was different sizes front and rear.
    I'd do as ken suggests, put it together and see how it works, if you have too much pedal travel, go to a cylinder with a larger bore, if it's too stiff use one with a smaller bore.
    Be aware you may need a proportioning valve in the rear line to turn down the rear brakes. K5's are short enough that the front does the vast majority of the braking on the street, so you could turn the rears down to avoid locking them up. Make sure to turn them up on the trail to give yourself better backup braking going down hills.
    Hope this helps
    oh yeah, I just looked in a Napa book for the specs on the bore sizes on the masters. interchangability is another story, as is booster power, but at least you can get specs on the bores.

    Making the world better, one truck at a time.
    [​IMG]
    SW-ORD
     
  17. BurbinOR

    BurbinOR 3/4 ton status

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    So if you change over to the 3/4 ton booster and master cylinder, do you have to replace the drive rod.........? And how, is it a simple job? and where do ya get them?

    <font color=orange>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.coloradok5.com>http://www.blazzinor.coloradok5.com</A>
     
  18. smp

    smp 1/2 ton status

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    I have a complete HD 1 ton brake setup pulled sitting in my garage i was going to use it but i want to go to full hydrolic steering and all that would be to much plumbing so i think i am selling it and if you guys need any measurements for mounting or what ever let me know here are some pics of it.
    http://WWW.SMP.COLORADOK5.COM
     

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