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#1 |
Registered User
![]() Join Date: Sep 2017
Location: Sunny CA
Posts: 59
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I have a 1969 C20 with 4 wheel manual drum brakes. It does not stop on a dime, to put it mildly...
Question is, can I purchase a booster and bolt it up with a bracket, and keep the drum brakes? I need some help braking for sure, but don't feel like pumping out over $1k for disc brakes... Is there anything else i would need to consider to do an upgrade, considering 4 wheel drum brakes, 3/4 ton, no power options prior to this upgrade? TYIA! ![]() |
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#2 |
Registered User
![]() Join Date: Apr 2017
Location: Boise, ID
Posts: 856
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Re: C20 3/4 ton brake upgrade question
You can buy the front end off a 73-87 and some later years and it bolts right in and they have disc brakes already. That's my plan when I get around to it...
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1968 GMC C2500 Long Bed Fleetside |
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#3 |
Registered User
Join Date: Jan 2016
Location: Barber City, CA
Posts: 4,778
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Re: C20 3/4 ton brake upgrade question
have you inspected all four wheel ends to make sure they're all adjusted properly and making good shoe contact?
flushed and bleed the entire system? brake fluid is hygroscopic so needs to be replaced periodically.. not every year but more often than every 50 years.. does the master cylinder hold or does it slowly creep down? I see a lot of folks converting and upgrading systems that would probably be sufficient if properly maintained.. my '65 C20 in all its farm years of road salt and manure will still lockup all four wheels.. as far as increasing your pedal effort, I'm sure there are kits for vac and hydro if you're truck has p/s.. good luck!
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I started out with nothing - and I still have most of it |
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#4 |
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Location: Boise, ID
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Re: C20 3/4 ton brake upgrade question
And yes, they have the 8 lug hubs as well.
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1968 GMC C2500 Long Bed Fleetside |
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#5 |
Registered User
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Location: Sunny CA
Posts: 59
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Re: C20 3/4 ton brake upgrade question
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#6 | |
Registered User
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Location: Sunny CA
Posts: 59
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Re: C20 3/4 ton brake upgrade question
Quote:
OK i think you set me on the better path... It would be nice to upgrade the system but you are right, i should inspect and maintain the system as it sits... The answers are, No I haven't checked all four shoes/drums, and it likely needs new shoes and drums to be resurfaced, but it was adjusted in the last few years.... Yes it was bled completely in the last two years or so, and has held the fluid... but it would definitely be the starting point to replace the shoes and drums. The truck does not have P/S, would that be a requirement for the vacuum needed for the booster? I was thinking there would be a place on the manifold that i could get vacuum from? |
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#7 | |
Registered User
![]() Join Date: Apr 2017
Location: Boise, ID
Posts: 856
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Re: C20 3/4 ton brake upgrade question
Quote:
![]() Either way, I think it's a cost effective solution. I want to do disc brakes soon on my 68 3/4 ton and that's the route I'll go. I just haven't taken my research any further than that to answer your questions about a booster or master. I have to take care of my steering gear first, but that's after I get this new motor in! Too many projects....
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1968 GMC C2500 Long Bed Fleetside |
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#8 | |
Registered User
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Location: Sunny CA
Posts: 59
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Re: C20 3/4 ton brake upgrade question
Quote:
There is a ton of options for 1/2 ton with P/S, barely anything out there for 3/4 ton manual drum... |
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#9 | |
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Location: Boise, ID
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Re: C20 3/4 ton brake upgrade question
Quote:
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1968 GMC C2500 Long Bed Fleetside |
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#10 | ||
Registered User
Join Date: Jan 2016
Location: Barber City, CA
Posts: 4,778
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Re: C20 3/4 ton brake upgrade question
Quote:
Quote:
there are kits for vacuum booster installs that should work in your '69 C20 with all drums.. as long as the engine isn't cammed out of wack, stock engine vacuum should operate a stock booster nicely.. p/s not a factor there.. hydroboost actuators are the preferred choice for heavier trucks but they do require a power steering pump to operate.. I'm not sure about this, but you may even be able to install a p/s pump on the engine to run a hydroboost brake actuator only without a p/s box but I'm not sure about the plumbing.. I think you might be pleasantly surprised with a good solid all-around brake inspection/replace as necessary.. good luck!
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I started out with nothing - and I still have most of it |
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#11 | |
Registered User
![]() Join Date: Sep 2017
Location: Sunny CA
Posts: 59
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Re: C20 3/4 ton brake upgrade question
Quote:
No problem, I saw the hydraulic kit and noted that it requires a PS pump... I was thinking it would be an option to add the pump for just the vaccum, but the hydraulic kit is over $800 by itself... I am going to start with the shoes, cleaning and resurfacing the drums, and adjust and bleed and see if that helps. If that isn't helping, i will look into the booster option since yes, the truck is a stock 350 with no cam changes. |
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#12 | |
Registered User
![]() Join Date: Apr 2017
Location: Boise, ID
Posts: 856
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Re: C20 3/4 ton brake upgrade question
Quote:
Definitely go over everything and if it looks suspicious, just replace it because this is your braking system we're talking about. And anything you replace on one side, replace it on the other side. That way everything is the same and you don't have a mix of old and new parts. I didn't do both wheel cylinders (one of those late-night and beer influenced decisions) and the next time I took the truck out I had to put in a new wheel cylinder in on the other side.
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1968 GMC C2500 Long Bed Fleetside |
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#13 |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: C20 3/4 ton brake upgrade question
Even if you install the coolest front disks ever, you still need a properly functioning rear drum system. So, as KB pointed out, you'll be surprised just how well a properly tuned 4 wheel drum system will work. If you're "pumping" the brakes as you stated, then you have a problem that swapping to disks or adding a booster won't help. The system needs to be gone through and checked out.
Here's my recommendation: 1) Replace rear wheel cylinders and shoes and rubber lines and get the drums turned if you can - and adjust (in other words, do a full rear brake job). 2) INSPECT the fronts and see how they look - if the lines and wheel cylinders aren't leaking, then adjust as best you can and go do a test drive. If there's an improvement and ONLY the pedal effort seems high at this point (not pumping, I mean leg strength is required, but the brakes bring it to a stop controllably and in an acceptable distance), then: a) replace front wheel cylinders, shoes, get new shoes and rubber lines, and get the front drums turned and b) get a vacuum powered brake booster (i.e. stock setup). You can get a stock setup from one of the many trucks being parted on the parts board, or you can buy a custom/tight to the firewall booster bracket from member Captainfab and install it and a new booster - AND buy a factory stock power 4-drum master cylinder for your year truck. You will need to pay attention to the depth of the hole in the back of piston that the brake pushrod inserts into - power or non-power have a shallow and the other has a deep - it will make sense when you look, but you have to make sure you have the rod that comes out of the front of the booster that properly engages the back of the master cylinder. If you stay with 4 wheel drums, you can reuse all your existing hard lines, but a flush would be worthwhile. IF, on the other hand - you're NOT happy with the braking performance at all after you've tuned it up and before you have even messed with a booster (you have to asses this based on stopping performance, not how much leg effort it took to do it) - then you may want to go ahead and do a front disk swap. Or, if you already know you just want to go with disks, skip step 2 above and go for it. Your rear brakes will already be good to go from step 1 above. You can either: a) swap a 71-87 front crossmember (and remember to buy parts for the year crossmember you installed when the time comes) as it will have factory disk brakes, or b) buy an 8 lug disk brake conversion kit at POL or one of the many vendors. Regardless of how you get there, if you do a front disk install - convert it to power at that time (if you go the donor/parted truck route, try to get as many parts of the front brake system as you can when you buy, then just replace the consumables, like booster, rubber anything, lines, etc as needed) - you will need a power DISK brake master cylinder. And technically, you should convert your front lines to 3/16" if you want to mirror what the factory did. All this stuff is available pre-bent from places like inline tube, etc. I would not mess with hydroboost personally - vac boost was sufficient for the factory for decades, and still is (unless you have a big cam, as mentioned above) - and with the money you save, you can spring for power steering ![]() All up to you how you'd like to go. If you plan to keep this truck for a long time, I'd tune it up, then search for a donor crossmember from spindle to spindle or save up for a kit. It is safer to have disks, but only a little. If you don't tailgate, drums are fine. If you do, you'll probably eventually get in a wreck anyway, so, well, there you go. Nowadays, it doesn't really matter how well you can stop - because almost ANY new vehicle can stop better and has anti-skid, so the old 2 second rule doesn't really apply if the guy in front of you can stop like he hit a puddle of super glue, you'll still rear end him in a C20 with drums or disks up front. Don't forget to always bench bleed a master cylinder before install/before bleeding the rest of the system. Also, invest in a shop manual - make SURE to buy a 3/4 ton master cylinder for disk or drum, depending on what you go with - they can be different from 1/2 ton master cylinders and, in some cases, the front reservoir is hooked to the rear brakes system, in some cases, the front brake system. You will want to mimic the factory system you are installing if swapping. Last edited by jocko; 05-11-2018 at 08:21 PM. |
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#14 |
Registered User
Join Date: Mar 2018
Location: Texas
Posts: 51
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Re: C20 3/4 ton brake upgrade question
You will need the lower control arms and spindles from the donor truck.
http://www.azproperformance.com/Alum...71-87-C10.html I used these for the tie rods. You can also use the center link from the donor and skip the sleeve. |
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#15 |
Scrapper 1
Join Date: Jan 2007
Location: Riverside Calif
Posts: 1,649
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Re: C20 3/4 ton brake upgrade question
You know CCP makes front spindles that instead of you changing the whole front end just change the spindles and add backing or dust plates to the spindles and Put in a portion device add calibers and new brake hoses An me Yes add the booster.Never could get a straight answer's from any one on why not just change the spindles i did it to my 1968 longhorn.Put new ball joints in and i was done.
NO More Molesting 1973--87 trucks |
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#16 | |
Registered User
![]() Join Date: Sep 2017
Location: Sunny CA
Posts: 59
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Re: C20 3/4 ton brake upgrade question
Quote:
SO much good info here, thank you Jocko! ![]() |
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#17 |
Registered User
Join Date: Aug 2004
Location: Sacramento Ca
Posts: 126
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Re: C20 3/4 ton brake upgrade question
Dial in the manual brakes and they work, but after one hard emergency stop they need time to cool. I found on my 68 they replaced the master cylinder with one for power brakes. Once I installed the 1" piston vs the 1 1/8" they were like night and day. No more standing on the pedal.
FYI hit a big puddle and you have no brakes, well until they dry off. So I learned to ride the brakes a bit as needed. x2 on flushing the brake fluid. It should be replaced every two years to prevent rust at the slave cylinders |
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brake, drum, power, power brake swap, upgrade |
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