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#26 | |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: Help Diagnose Brake Issue
Quote:
Livrat's input on the linked thread is very helpful - but does not apply to the OP's question about which chamber the front or rear lines go to. All MCs that I am aware of, 1/2 or 3/4 ton, have the front brake lines connected to the rear chamber of the MC and the rear brakes connected to the front chamber of the MC. Livrat's comments are all related to booster interchangeability and the differences between 1/2 ton and 3/4 ton booster mounting, etc. I didn't see any info on line placement to specific reservoirs. Did I miss it? But the dead giveaway, as firstowner pointed out, is the size of the reservoir - larger res for the disk half of the truck, and the larger res is always in the rear of the ones I have seen. I'm a little more used to older systems, so I'm interested to hear a definitive answer on this. |
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#27 | |||
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,628
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Re: Help Diagnose Brake Issue
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Livrat may not say how the lines are to be connected, but his 1st pic, post #6, shows how they are connected..... rear of the MC to front of the prop. valve, then to front brakes. It is hard to see b/c it's partially hidden behind the other line, which goes from the front of the MC to the rear of the prop. valve, then to the rear brakes. The larger MC reservoir -- which would be the rear one in the OP's K20 -- does serve the front discs. In this case, it is front-to-rear.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#28 |
Senior Member
![]() Join Date: May 2010
Location: Wisconsin & Arizona
Posts: 4,844
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Re: Help Diagnose Brake Issue
Boy, I sure hope we haven't scared a new forum member away!!
BY THE WAY, WELCOME ABOARD MFCopenhagen! ![]() I also still feel the master in the picture he posted is incorrect for discs as it's exactly like the one that has been on my 69 since new. Can anyone verify that? |
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#29 |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: Help Diagnose Brake Issue
Thanks for clarifying Mike, that helps. So, the main reason this thread grabbed my interest is because of the 3/4 ton comment (what I have). OP's is a 3/4 ton also - so I strolled out to the garage and double checked to make sure I'm not losing my mind - and yes, I think we all agree(?) - my mc front res line goes to the rear of the prop valve and the rear mc res line goes to the front of the prop valve - i.e. matches post 6 (of the linked thread) pic #1, which is labeled as 3/4 ton, correctly.
So, I agree with your last statement of your post - and did before, I think ![]() Thanks for pointing out that chipflyer was just referring to the pic, I was reading the whole thread word-for-word wondering how he pulled that info out of the linked thread - but you just cleared it up for me, thanks. Also, I think what was confusing me a bit was that on a 67 1/2 ton drum/drum mc (no prop) the rear res is for front brakes and vice versa (which is contrary to the 1/2 ton info in the linked thread). But the linked thread was focusing on disk/drum, so apparently different rule of thumb for a drum/drum setup. The 67 manual dual res mc was built such that the piston itself did some proportioning by uncovering the circuit for the front brakes (in the rear reservoir) first when you press the pedal. |
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#30 | |
Registered User
Join Date: May 2004
Location: Topeka, Ks
Posts: 2,293
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Re: Help Diagnose Brake Issue
Quote:
I think I muddied the water by saying that the lines could be attached to the prop valve either way depending on if it were a 1/2 or 3/4 ton, which is correct but in this case it should be front of res to rear of prop which I think is what we all agree on and I was trying to show with a pic in post 6 of the other thread. Jeff Posted via Mobile Device
__________________
I'm not a pessimist, I'm just optimistic that bad things are going to happen. 1971 Cheyenne Super K10 - tilt, cruise, air, am/fm, tow hooks, factory buckets! 1986 Jeep J10 pickup, - 5.3L Vortec with 4L60e and NP241. Last edited by chipflyer; 01-26-2013 at 10:53 AM. |
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#31 |
Registered User
Join Date: May 2004
Location: Topeka, Ks
Posts: 2,293
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Re: Help Diagnose Brake Issue
This photo from the 1971 service manual may also help untangle this mess.
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__________________
I'm not a pessimist, I'm just optimistic that bad things are going to happen. 1971 Cheyenne Super K10 - tilt, cruise, air, am/fm, tow hooks, factory buckets! 1986 Jeep J10 pickup, - 5.3L Vortec with 4L60e and NP241. |
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#32 |
Member #1049
Join Date: Jun 2000
Location: Troy Montana
Posts: 3,940
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Re: Help Diagnose Brake Issue
I'll chime in here and see if I can help out...
MFCopenhagen, from looking at the picture of your current setup I do know that will not work correctly with a disc brake system, it appears you have the original 69 drum brake master cylinder and a booster that I am not familiar with. There has been some discussion about what is the correct plumbing of the lines from the MC to the proportioning valve. On 3/4 ton disc brake setups the front line from the MC goes to the rear of the proportioning valve. (1/2 tons are opposite) The Picture post #14 above is the correct MC,booster and plumbing. Also discussed is the shapes of the different 3/4 ton MC's, this would be difficult as I have seen several different styles which I do believe could be aftermarket replacements, most I have see from the factory have the "bulge" in the rear. Post #7 bottom picture. http://67-72chevytrucks.com/vboard/s...d.php?t=214559 The one Identifying factor for me on the differences between 1/2 ton and 3/4 ton MC's is the depth of the rod going into the piston in the MC. See pic #8 below http://67-72chevytrucks.com/vboard/s...d.php?t=214559 IMO the easiest thing to do would be obtain a complete 71/72 3/4 ton MC,booster,brackets, and proportioning valve with the correct MC to prop valve lines, And all the 71/72 K series (4X4) front brake lines from proportioning valve to front brake hoses, (these can come from a K10 or K20). One thing to keep in mind that 71 had a different sized fitting on the passenger side line to brake hose than 72. Hope this explanation helps out and was not too confusing. Oh... and by the way.. WELCOME to the Board!! Last edited by Livrat; 01-26-2013 at 01:11 PM. Reason: spelling |
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#33 | |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: Help Diagnose Brake Issue
Quote:
![]() Thanks much chip and livrat |
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#34 |
Registered User
Join Date: May 2004
Location: Topeka, Ks
Posts: 2,293
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Re: Help Diagnose Brake Issue
Yes, you are correct Jocko. This photo should also be included in this thread as it kind of helps tie it all together.
Also MFcopenhagen, I was up at teeitups earlier and he does have a good used booster, bracket, master cylinder and prop valve assembly for sale at a good price that would be an easy swap and get you put back together correctly. Jeff
__________________
I'm not a pessimist, I'm just optimistic that bad things are going to happen. 1971 Cheyenne Super K10 - tilt, cruise, air, am/fm, tow hooks, factory buckets! 1986 Jeep J10 pickup, - 5.3L Vortec with 4L60e and NP241. |
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#35 |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: Help Diagnose Brake Issue
all makes sense now, life is in balance again! Thanks chipflyer, yep, that is the last piece of the puzzle. Thanks very much for the great answers. MFcopenhagen, thanks for posting your question - was very helpful to me too.
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