Home » Public Forums » GMCnet » update on master cylinder replace
| update on master cylinder replace [message #197719] |
Thu, 07 February 2013 16:48  |
bronevaya
Messages: 63
Registered: May 2011
Location: birmingham al
Karma: 0
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Member |
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I finally got around to replacing the MC today (in the wind and cold and rain) and some observations. I mentioned before that at one point the coach did not want to stop. the pedal traveled to the floor and I had to throw it in park (to my displeasure). It was only going about 5 mph but I still hate doing that.
so taking the old one off I saw that there was a leak in the seal at the piston. I cleaned and installed the new one. As I was moving about I kicked the old MC over and the top came off. A sea of rusty brake fluid and really black fluid (looked like oil) spilled onto the street.
I bought a hand held vacuum bleeder from HF and soon enough Ill have the pleasure of doing all six brakes!!
1977 Palm beach
Bham AL
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| Re: [GMCnet] update on master cylinder replace [message #197727 is a reply to message #197719] |
Thu, 07 February 2013 18:17  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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m
Michael, I hate to tell you something that should be obvious, but, black,
rusty crap runs downhill. You absolutely need to flush the entire brake
system. Please for the safety of yourself and others in the vicinity of
your Gmc, make sure all rusty brake fluid is out of the system before
driving it. A 12,500 # vehicle with no brakes will make your butt pucker
for sure.
Jim Hupy
Salem, Or.
78 Gmc Royale 403
On Feb 7, 2013 2:48 PM, "michael" <bronevaya@gmail.com> wrote:
>
>
> I finally got around to replacing the MC today (in the wind and cold and
> rain) and some observations. I mentioned before that at one point the coach
> did not want to stop. the pedal traveled to the floor and I had to throw it
> in park (to my displeasure). It was only going about 5 mph but I still hate
> doing that.
>
> so taking the old one off I saw that there was a leak in the seal at the
> piston. I cleaned and installed the new one. As I was moving about I kicked
> the old MC over and the top came off. A sea of rusty brake fluid and really
> black fluid (looked like oil) spilled onto the street.
>
> I bought a hand held vacuum bleeder from HF and soon enough Ill have the
> pleasure of doing all six brakes!!
> --
> 1977 Palm beach
> Bham AL
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: update on master cylinder replace [message #197740 is a reply to message #197739] |
Thu, 07 February 2013 19:38 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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| bronevaya wrote on Thu, 07 February 2013 18:31 |
can I use the vacuum pump to pump out the old fluid from each caliper/drum?
|
Actually, it's more of a "sucking it out" process, but yes - that's how I did it.
I did have a small inline reservoir between the vacuum pump and the bleed tube though, for two reasons. First, it keeps the brake fluid out of the vacuum pump innards. Second, when it's full, it's my signal to go top off the master cylinder reservoir again (since it doesn't hold much more than the inline reservoir, which is essentially the one from an el-cheapo hand-pump system).
FWIW, I've had two of the Harbor Freight hand-vacuum pumps, and both of them broke in short order (before completing a single vehicle in both cases). I normally have pretty good luck with their stuff, but not in this case.
Also, when I used the vacuum pump, it worked TOO well, and would pull air into the bleed hose (apparently around the threads of the nipple?) so I really couldn't tell when I had all the air out. But since I was more interested in flushing all the old brake fluid out, it wasn't a problem... I just went until the fluid went from dark(er) to light(er). It wasn't really bad, but brake fluid is cheap, and brake cylinders and lines aren't.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: update on master cylinder replace [message #197742 is a reply to message #197740] |
Thu, 07 February 2013 19:44 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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Useful tip, use ATE brake fluid. It comes in two colors. Alternate colors on brake fluid changes. Easy to see the new vs the old.
Unfortunatly, P.O. Put DOT 5 in my brakes, and without changing everything in the system, I'm stuck with it.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: update on master cylinder replace [message #197746 is a reply to message #197740] |
Thu, 07 February 2013 20:10 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Thats how I do it also. You can wrap teflon tape around the bleeder screw threads only to reduce the air leakage. Also when doing the rears I block the frame and remove the wheels, dump the air and jack each wheel up till the bleed screw is higher than the lines. It is easier with 3 people 2 on the wheels, one pumping and holding the catch can while one holds the box wrench and air line on the bleeder screw, and one on the mc fluid. Advanced has a sale on dot 3 brake fluid right now, 2 for 1. I usually start at the closest (lf) to the mc and work to the farthest(rrr)till I have clean fluid. While you are there its a good time to check the rear adjustment and make sure the adjusters are working. Prying up on an adjuster tightens the brake. It should click and turn fairly easy. To loosen put a skinny screwdriver in the hole and push the adjuster arm away from the gear and you should be able to back it up. I usually tighten the brake tight then loosen till I get a free wheel with slight drag.
| habbyguy wrote on Thu, 07 February 2013 20:38 |
| bronevaya wrote on Thu, 07 February 2013 18:31 |
can I use the vacuum pump to pump out the old fluid from each caliper/drum?
|
Actually, it's more of a "sucking it out" process, but yes - that's how I did it.
I did have a small inline reservoir between the vacuum pump and the bleed tube though, for two reasons. First, it keeps the brake fluid out of the vacuum pump innards. Second, when it's full, it's my signal to go top off the master cylinder reservoir again (since it doesn't hold much more than the inline reservoir, which is essentially the one from an el-cheapo hand-pump system).
FWIW, I've had two of the Harbor Freight hand-vacuum pumps, and both of them broke in short order (before completing a single vehicle in both cases). I normally have pretty good luck with their stuff, but not in this case.
Also, when I used the vacuum pump, it worked TOO well, and would pull air into the bleed hose (apparently around the threads of the nipple?) so I really couldn't tell when I had all the air out. But since I was more interested in flushing all the old brake fluid out, it wasn't a problem... I just went until the fluid went from dark(er) to light(er). It wasn't really bad, but brake fluid is cheap, and brake cylinders and lines aren't.
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] update on master cylinder replace [message #197761 is a reply to message #197746] |
Thu, 07 February 2013 23:55 |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
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Senior Member |
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Rob
Do you expect me to think of two things at once? Installing a master
cylinder AND determining how many beer are in the fridge?
You are totally correct and Chucks commentary should be followed.
Mike In NM
On Thu, Feb 7, 2013 at 10:10 PM, Charles Boyd <covered-wagon@comcast.net>wrote:
>
>
> Thats how I do it also. You can wrap teflon tape around the bleeder screw
> threads only to reduce the air leakage. Also when doing the rears I block
> the frame and remove the wheels, dump the air and jack each wheel up till
> the bleed screw is higher than the lines. It is easier with 3 people 2 on
> the wheels, one pumping and holding the catch can while one holds the box
> wrench and air line on the bleeder screw, and one on the mc fluid.
> Advanced has a sale on dot 3 brake fluid right now, 2 for 1. I usually
> start at the closest (lf) to the mc and work to the farthest(rrr)till I
> have clean fluid. While you are there its a good time to check the rear
> adjustment and make sure the adjusters are working. Prying up on an
> adjuster tightens the brake. It should click and turn fairly easy. To
> loosen put a skinny screwdriver in the hole and push the adjuster arm away
> from the gear and you should be able to back it up. I usually tighten the
> brake tight then loosen till I get a free w
> heel with slight drag.
>
>
>
> habbyguy wrote on Thu, 07 February 2013 20:38
> > bronevaya wrote on Thu, 07 February 2013 18:31
> > > can I use the vacuum pump to pump out the old fluid from each
> caliper/drum?
> >
> > Actually, it's more of a "sucking it out" process, but yes - that's how
> I did it.
> >
> > I did have a small inline reservoir between the vacuum pump and the
> bleed tube though, for two reasons. First, it keeps the brake fluid out of
> the vacuum pump innards. Second, when it's full, it's my signal to go top
> off the master cylinder reservoir again (since it doesn't hold much more
> than the inline reservoir, which is essentially the one from an el-cheapo
> hand-pump system).
> >
> > FWIW, I've had two of the Harbor Freight hand-vacuum pumps, and both of
> them broke in short order (before completing a single vehicle in both
> cases). I normally have pretty good luck with their stuff, but not in this
> case.
> >
> > Also, when I used the vacuum pump, it worked TOO well, and would pull
> air into the bleed hose (apparently around the threads of the nipple?) so I
> really couldn't tell when I had all the air out. But since I was more
> interested in flushing all the old brake fluid out, it wasn't a problem...
> I just went until the fluid went from dark(er) to light(er). It wasn't
> really bad, but brake fluid is cheap, and brake cylinders and lines aren't.
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
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| Re: [GMCnet] update on master cylinder replace [message #197771 is a reply to message #197739] |
Fri, 08 February 2013 07:11 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Shoert answer - no. The bleed nipple is at the top so air will come out of it. What I did was fill the system, then open the bleed valve and compress the caliper to the max, close the valve and refill it with the pedal (watch the master cylinder level doing this) three or four times. This will get most of it. If it's really cruddy, the only way to clean it is remove the caliper and pull it apart. Clean and check the bore - hone if necessary - replace the rubber parts, and put it back together and fill/bleed the system. If the bore is pitted more than can be honed, replace the assembly. Hupy is right, stopping one of these with non-functional brakes isn't a lot of fun. Ask me how I know this...
--johnny
'76 23' transmode norris
'76 palm beach
From: michael <bronevaya@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Thursday, February 7, 2013 8:31 PM
Subject: Re: [GMCnet] update on master cylinder replace
can I use the vacuum pump to pump out the old fluid from each caliper/drum?
--
1977 Palm beach
Bham AL
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] update on master cylinder replace [message #197791 is a reply to message #197771] |
Fri, 08 February 2013 08:53 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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| Johnny Bridges wrote on Fri, 08 February 2013 06:11 |
Shoert answer - no. The bleed nipple is at the top so air will come out of it.
|
I had to read the above (and the question below) a couple times to understand Johnny's comment. I think he's assuming that you want to "drain" the caliper, while most of us are talking about "flushing" the caliper with new fluid.
No doubt it is possible to remove, drain and clean our calipers - and no doubt this would result in a marginally cleaner result... but it sure seems like a LOT of work compared to doing a traditional brake fluid flush (using the new fluid to push out the old fluid). Having a little of the old fluid left in the system isn't going to make any real difference unless there was some sort of contamination that has you worried.
In the same way, it would be "better" to disassemble your motor every time you do an oil change... but it's kinda hard to justify the effort, IMHO.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: update on master cylinder replace [message #197793 is a reply to message #197739] |
Fri, 08 February 2013 09:06 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| bronevaya wrote on Thu, 07 February 2013 20:31 |
can I use the vacuum pump to pump out the old fluid from each caliper/drum?
|
The short answer is YES.
I have been doing that for years. But before you start, you want to make up a catch jar to:
A - Keep the brake fluid out of your pump, and
B - Let you see the color of fluid coming out of the system.
Use clear tubing to connect to the bleed screw so you can see the color and the bubbles.
For reference, the coaches brakes need just under 1 quart of brake fluid for a fill, but if you are flushing, you better have two handy.
Years ago I started greasing bleeder screws and plugging them so water count not get in. If done, this will cause fewer wheel cylinder changes because the bleed screw broke off.
As Chuck noted, you need to either grease or teflon tape the bleed screws so they don't leak air in or you will never see solid fluid. Making sure that there are caps on them will also serve you well in the future. The caps only last about 5~6 years (it seems) before they crack or get hard.
Also somethings to store in your memory....
If you clear (suck it dry) the system before you start replacing the aged out rubber brake lines, you will have a much nicer time and no spilled brake fluid to clean of the floor or you.
If you are going to be working on brake lines, look up ViceGrip tools 4LW and 7LW. These are specials made to grab the flats of a hex. Use them before you blow the corners off the steel brake lines. (There is a bigger number too, but I use it very rarely.)
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: update on master cylinder replace [message #197808 is a reply to message #197793] |
Fri, 08 February 2013 10:37 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Matt: I like the dry tip, thanks. Instead of rounding off the line fittings I have had good luck using a small pipe wrench.
| Matt Colie wrote on Fri, 08 February 2013 10:06 |
| bronevaya wrote on Thu, 07 February 2013 20:31 |
can I use the vacuum pump to pump out the old fluid from each caliper/drum?
|
The short answer is YES.
I have been doing that for years. But before you start, you want to make up a catch jar to:
A - Keep the brake fluid out of your pump, and
B - Let you see the color of fluid coming out of the system.
Use clear tubing to connect to the bleed screw so you can see the color and the bubbles.
For reference, the coaches brakes need just under 1 quart of brake fluid for a fill, but if you are flushing, you better have two handy.
Years ago I started greasing bleeder screws and plugging them so water count not get in. If done, this will cause fewer wheel cylinder changes because the bleed screw broke off.
As Chuck noted, you need to either grease or teflon tape the bleed screws so they don't leak air in or you will never see solid fluid. Making sure that there are caps on them will also serve you well in the future. The caps only last about 5~6 years (it seems) before they crack or get hard.
Also somethings to store in your memory....
If you clear (suck it dry) the system before you start replacing the aged out rubber brake lines, you will have a much nicer time and no spilled brake fluid to clean of the floor or you.
If you are going to be working on brake lines, look up ViceGrip tools 4LW and 7LW. These are specials made to grab the flats of a hex. Use them before you blow the corners off the steel brake lines. (There is a bigger number too, but I use it very rarely.)
Matt
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] update on master cylinder replace [message #197820 is a reply to message #197793] |
Fri, 08 February 2013 12:03 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Matt,
Thanks for recommending the Vice Grips. I just ordered the 4LW -- don't
expect to need anything bigger. The last time I had to break loose a flare
nut, I had to put Vice Grips on the flare wrench to keep it from spreading.
This tool should work better.
Ken H.
On Fri, Feb 8, 2013 at 10:06 AM, Matt Colie wrote:
>
> ...
If you are going to be working on brake lines, look up ViceGrip tools 4LW
> and 7LW. These are specials made to grab the flats of a hex. Use them
> before you blow the corners off the steel brake lines. (There is a bigger
> number too, but I use it very rarely.)
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: update on master cylinder replace [message #197857 is a reply to message #197719] |
Fri, 08 February 2013 17:34 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Will a flare nut wrench work? Is this on old lines being tossed? I prefer to leave the vise grips and pipe wrenches for plumbing jobs.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] update on master cylinder replace [message #197881 is a reply to message #197857] |
Fri, 08 February 2013 20:00 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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John,
Many times when working with old, rusted, already-rounded, flare nut
wrenches, even my high quality flare nut wrenches are not up to the job of
loosening them. Usually, if there's room, I can clamp down with Vice Grips
on the wrench and turn the nut -- IF THERE"S ROOM. I'm expecting these
special purpose Vice Grips to ease the ROOM problem. I certainly don't
intend to use them except as a last resort, but I don't want to have to
wait for USPS when that arises. :-)
Ken H.
On Fri, Feb 8, 2013 at 6:34 PM, John R. Lebetski wrote:
>
>
> Will a flare nut wrench work? Is this on old lines being tossed? I
> prefer to leave the vise grips and pipe wrenches for plumbing jobs.
> --
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] update on master cylinder replace [message #197942 is a reply to message #197940] |
Sat, 09 February 2013 10:53 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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At the risk of appearing to be self serving, I am going to throw a few
words into the burning vocabulary. On long wheelbase vehicles, particularly
ones with more than one rear axle, that are serviced with tandem or siamese
brake fluid supply lines, it is VERY difficult to get rid of trapped air in
the back brakes. By far the worst way to bleed them is to gravity bleed
them, followed quite closely by pumping the brake pedal and releasing the
bleeders, and third by using a "mity vac" type vacuum pump bleeder on the
bleeder screws. By far the most efficient method of bleeding the system, is
a power bleeder. I am not saying that it can NOT be accomplished by any
other method, just that it is a one person 30 minute job with a power
bleeder. And no destroyed marriages or friendships either. (Grin)
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, Feb 9, 2013 at 8:30 AM, Matt Colie <matt7323tze@gmail.com> wrote:
>
>
> JohnL455 wrote on Fri, 08 February 2013 18:34
> > Will a flare nut wrench work? Is this on old lines being tossed? I
> prefer to leave the vise grips and pipe wrenches for plumbing jobs.
>
> John,
>
> The XLW ViceGrips are designed to grab a hex on the flats only. Actually
> three flats. They actually do less damage to a fastener than a loose line
> wrench and they take up less room than a line wrench being held closed by a
> pair of Vice Grips (Known as Plan VG in many circles).
>
> Want to know how I know?
>
> Have you replaced any of the rubber brake lines yet?
> Have fun with the rear....
>
> Matt
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will
> find
> SE Michigan - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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