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06-04-2023, 11:12 AM | #1 |
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Anybody running manual disc brakes? Pics
Hi there in order to do some troubleshooting on my 1971 GMC 1/2 ton CORRECTION (71 cab on a 69 chassis) that came with factory drum brakes at all four corners that I have since converted to disc in the front I need to install a non power disk brake master cylinder and I would love to see some pics of how that mounts. My drum/drum setup was power so it had the big vacuum booster can on it
please and thank you Last edited by Gregski; 06-04-2023 at 02:07 PM. |
06-04-2023, 11:25 AM | #2 |
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Re: Anybody running manual disc brakes? Pics
1971 with drum brakes in front, I didn't know there was such a thing.
I have a 1969 C10, I put on it 1971 donor front disc brakes and spindles with new 1971-72 ball joints and steel brake tubing, and 1971 donor rear drum brakes and new 5-lug conversion rear axle shafts. I did manual brakes. The master cylinder bolts directly to the firewall. http://www.67-72chevytrucks.com/vboard//showthread.php?p=9167631#post9167631 Last edited by dmjlambert; 06-04-2023 at 11:30 AM. |
06-04-2023, 12:00 PM | #3 |
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Re: Anybody running manual disc brakes? Pics
1971 was the first year of disc brakes in all the trucks. There were many trucks with manual disc brakes from the factory.
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06-04-2023, 12:06 PM | #4 |
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Re: Anybody running manual disc brakes? Pics
Yes that is what I thought, and I didn't know front drum brakes were an option for 1971. Gregski may have had the only one. Or it may be a GMC thing.
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06-04-2023, 01:04 PM | #5 | |
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Re: Anybody running manual disc brakes? Pics
Quote:
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06-04-2023, 01:10 PM | #6 | |
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Re: Anybody running manual disc brakes? Pics
Quote:
"Drum to Disc" conversions 67-70 pics and videos Last edited by Gregski; 06-04-2023 at 02:07 PM. |
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06-04-2023, 02:43 PM | #7 |
At the body shop.
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Re: Anybody running manual disc brakes? Pics
I do on my squarebody. Master from a '84 with manual brakes.
Aluminum master plastic reservoir
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06-04-2023, 03:04 PM | #8 |
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Re: Anybody running manual disc brakes? Pics
yes, you can bolt directly to the firewall per djmlambert's great pic (pro looking conversion!). Also note he's got 3/16" lines on the disk circuit and 1/4" lines on the drum circuit, just like the factory 71+ disk/drum set-up. A stock 71-72 combo valve would be perfect, or you can run an aftermarket adjustable prop valve - but you are correct in that the original distribution block from a 69 is not the correct valve for your soon-to-be-modified brake system. It appears you have the correct mc in your 1st post; assuming you purchased a manual brake mc (for disk/drum), it should have the deep hole in the rear piston (as opposed to the little shallow hole that accepts the short intermediate push-rod associated with a booster. Recommend check that your mc has a deep hole piston in the bore where it accepts the brake pedal pushrod. If it doesn't, i.e. just has a shallow little depression where the push-rod goes, then you may have a power brake mc (for disk/drum).
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06-04-2023, 03:18 PM | #9 |
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Re: Anybody running manual disc brakes? Pics
I sold my 71 gmc 1500 a few years ago. It came with non power discs up front. Master was mounted to the firewall just like in the photo above. It took me a few attempts to locate the proper NON POWER master, finally got it at Napa by going into the old paper parts books. Guy on counter was useless.
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06-04-2023, 03:55 PM | #10 | |
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Re: Anybody running manual disc brakes? Pics
Quote:
I will check like you suggested |
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06-04-2023, 03:56 PM | #11 | |
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Re: Anybody running manual disc brakes? Pics
Quote:
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06-04-2023, 03:58 PM | #12 |
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Re: Anybody running manual disc brakes? Pics
my 72 was manual disc/drum but I converted to power.
Here is a pic as it was with stock manual MC |
06-04-2023, 04:03 PM | #13 |
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Re: Anybody running manual disc brakes? Pics
Gregski, LMC used to carry manual vs power 71-72 master cylinders - here's a part # ref for you - https://67-72chevytrucks.com/vboard/...81&postcount=7
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06-04-2023, 04:31 PM | #14 |
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Re: Anybody running manual disc brakes? Pics
Love your L6 with power steering !
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06-04-2023, 04:47 PM | #15 |
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Re: Anybody running manual disc brakes? Pics
If its mine your talking about, yeah it is factory PS. I pulled the huge stock steering wheel and put in a smaller one as at 6'2" My leg was sideways to hit the brakes. Easy turning with the power with smaller wheel
Now power disc/drum brakes to.... |
06-04-2023, 07:34 PM | #16 | |
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Re: Anybody running manual disc brakes? Pics
Quote:
Some Specs BrakeBest Select Brake Master Cylinder - New - NMC11339 Warranty: Limited Lifetime Warranty Unit of Measure: Each UPC: # 848074025655 New Or Remanufactured: New Dust Boot Included: No Number Of Ports: 2 Bore Size (in): 1.130 Inch Reservoir Included: Yes Bore Size (mm): 28.58mm Reservoir Type: Integral Number Of Pistons: 1 Sensor Included: No Number Of Mounting Holes: 2 Gasket Or Seal Included: No Bleeder Kit Included: Yes Pedal Rod Included: No Brake Booster Included: No Port 1 Thread Size (Forward) (in): 1/2-20 Inch Port 1 Thread Type (Forward): Inverted Flare Port 2 Thread Size (in): 9/16-18 Inch Port 2 Thread Type: Inverted Flare Master Cylinder Body Material: Cast Iron Last edited by Gregski; 06-04-2023 at 09:07 PM. |
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06-04-2023, 07:38 PM | #17 |
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Re: Anybody running manual disc brakes? Pics
I don't know for sure about the master cylinders for manual disc brakes in our trucks, but I do know that in Pontiacs that the manual disc master cylinders were a one year only option and they had a different bore diameter than the power brake master cylinders did.
Last time searched for one I had to have the counterman look the number up in a BOOK! There was no listing in the computer for a manual master cylinder. I would bet the bore diameters are different for our trucks also.
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
06-04-2023, 07:45 PM | #18 | |
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Re: Anybody running manual disc brakes? Pics
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06-04-2023, 07:56 PM | #19 | |
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Re: Anybody running manual disc brakes? Pics
Quote:
This is the same thread where 54blackhornet discussed his research at NAPA going into paper parts books to figure out the correct master cylinder. http://67-72chevytrucks.com/vboard/s...30#post8909230 |
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06-04-2023, 07:58 PM | #20 |
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Re: Anybody running manual disc brakes? Pics
I used this master on my Studebaker to go from manual drum to manual disc .
https://www.speedwaymotors.com/GM-Co...ore,51673.html Some pictures I used an inline portioning valve for the rear .
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Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. Last edited by 72c20customcamper; 06-04-2023 at 08:44 PM. |
06-04-2023, 08:18 PM | #21 |
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Re: Anybody running manual disc brakes? Pics
yep, 2nd the motion that you have a deep hole non-power brake mc - good news!
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06-04-2023, 08:57 PM | #22 |
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Re: Anybody running manual disc brakes? Pics
and a few hours and a bucket of sweat later she's on
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06-04-2023, 08:59 PM | #23 |
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Re: Anybody running manual disc brakes? Pics
hey bro, hey bro, what kinda carburetor are you running is that one of them organic Holley Carter Rochester Quadrajet Edelbrocks?
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06-04-2023, 09:18 PM | #24 |
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Re: Anybody running manual disc brakes? Pics
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06-05-2023, 08:57 AM | #25 |
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Re: Anybody running manual disc brakes? Pics
I think they're called Quadrazaps.
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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