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Master cylinder renewal

Started by johngmm7, July 23, 2017, 05:19:02 PM

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johngmm7

I have bench bled and installed a new Delco master cylinder on my 65 deville.  I cannot get the brake lines to screw in to the ports after spending quite a time trying. I'm starting to wonder if the threads are different?  Has anyone experienced the same problem.

TJ Hopland

What jumps out at me is the word 'new'.    Many of these new parts for old cars are pretty poor copies of originals.   Having the wrong threads would not be a shock. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

johngmm7

I bought it from RockAuto where I have purchased quite a few parts over the years with no problem.  This has a Delco box with all instructions etc..  I have no reason to doubt it's authenticity but if you know something, would you let me know please.

76eldo

Try taking it all the way loose and try starting the threads from the lines.  You need to start the fittings at the exact angle and the threads are very fine.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

savemy67

Hello John,

I second what Brian suggested.  The axis of the line/fitting has to be near-perfectly aligned with the axis of the port in the master cylinder.  You should be able to gently bend the lines a small amount to get the line/fitting aligned with the port.  You should also have a little axial play so that you can maneuver the line/fitting back and forth.

I have bought many parts from Rock Auto, but occasionally, I have received an incorrect part.  Rock Auto replaced the incorrect part without any fuss.  Do you know if the master cylinder you are replacing is the original, or was it a replacement?  Good luck.

Respectfully submitted,
Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

D.Yaros

Brian's advice is spot on.  When I had to re-install a brake booster/MC set up on one of my rides I thought I would never get the brake line to start on the MC port.  As stated, "the angle has to be just right."
Dave Yaros
CLC #25195
55 Coupe de Ville
92 Allante
62 Olds  

You will find me on the web @:
http://GDYNets.atwebpages.com  -Dave's Den
http://graylady.atwebpages.com -'55 CDV site
http://www.freewebs.com/jeandaveyaros  -Saved 62 (Oldsmobile) Web Site
The home of Car Collector Chronicles.  A  monthly GDYNets newsletter focusing on classic car collecting.
http://www.scribd.com/D_Yaros/

Lexi

While not a MC line connection, for what its worth I ran into a similar problem hooking up the line to my automatic choke. Would not go back together and that was with original equipment! Very frustrating. I thought the threads must have stripped during removal, it was that bad. I finally removed the carburetor mounting nuts to help align things better, by tipping the carb. Bingo! Got it re-assembled immediately. Consistent with remarks by Brian, Chris and Dave, "the angle has to be just right." I was shocked at how critical it was. Almost no axial play was permitted to get a fit. The rigidity of a steel line can also work against you. If this is also the same problem, you have to ensure that both mating surfaces interface 'dead on' for the threads to grab, else those near by will learn some new cuss words. Clay/Lexi

johngmm7

Many thanks to all of you on this.  I discovered the cylinder I had purchased and fitted wasn't a moraine hence my difficulty.  I have now ordered a Dorman MORAINE cylinder which should arrive in a couple of days - fingers and eyes crossed it's going to work.  :-[

johngmm7

Having ascertained that the Dorman Moraine cylinder is correct (the threads on the ports work easily with those on the brake lines), I have been bench bleeding over two days for about 2 and a half hours and apparently, there is still air in the front chamber. The rear brake side was cleared in about 10 minutes.  I get quite a spout of fluid each time I pump the piston with the piston pushing in about an eighth to quarter of an inch.  I am inclined to just fit the thing as is but would very much appreciate some comments please before I go with my ideas.  Just how long can it take or ????

CadillacRob

Shouldn't take but a few minutes to bench bleed.  I say put it on and bleed your lines and wheel cylinders and run it
1950 series 61 sedan
1956 coupe de ville

Glen

I think a spout of fluid is OK as long as there is no air coming out with it.   
Glen Houlton CLC #727 
CLCMRC benefactor #104

TJ Hopland

Is this one that 'self' bleeds with the caps?  Or the old way with the loop of hoses?     The rear does work first so you need more stroke to get the front one.   On the one that I just did for my 73 the front cleaned up before the rear did.   This one came with the hose kit for bleeding but had a twist I had not seen before.    It came with 2 sets of the little wedge in hose adapters.   At a glance they appeared identical except for the color.   I just picked a set and went to work.   Odd thing was I kept getting the spouts instead of flow through the hoses.   That was when I noticed that one set wasn't drilled.  One set is just solid plugs.   I had never seen that before. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason