| Repeat of a note about brake bleed screws [message #370230] |
Fri, 29 July 2022 19:18  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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We discussed this some years back on this forum, but I feel it merits re-stating.
If you plan to own the coach long enough to ever bleed the brakes again, you yourself two big favors:
1 - Pull the bleed screws out and clean the threads, then put a turn and an half of teflon tape on them.
2 - Buy and use the rubber caps.
This really helps if you like anyplace that has water around at all. Brake fluid is highly hydroscopic. It can use that moisture to corrode the threads. With the teflon on there, it can't get into the threads. The cap just keeps any extra water from getting in there.
I started doing this several decades back after having to replace wheel parts on funny furrin cars because bleed screws could not be moved without breaking. I started by using teflon pipe thread sealant, and while it was better than nothing, it had to be replaced with every bleed. Then Chuck Boyd said he used teflon tape. I changed and still do.
This also helps if you vacuum bleed. I vacuum bleed because funny furrin cars can't take a clamp plate on the plastic reservoir.
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: Repeat of a note about brake bleed screws [message #370239 is a reply to message #370230] |
Sun, 31 July 2022 20:31  |
dsmithy
Messages: 210
Registered: July 2012
Location: Lincoln Nebraska
Karma: 0
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Thanks Matt,
Do you care to weigh in on changing/flushing brake fluid? I put 4 wheel disks from Applied on in 2016. I still have great braking but haven't touched them since then. I also put the SS clad flex hoses on at that time, but the long runs are still OEM tube. Comments?
Doug
Douglas & Virginia Smith,
dsmithy18 at gmail,
Lincoln Nebraska,
’73 “Sequoia” since ‘95: "Wanabizo";
Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other
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| Re: Repeat of a note about brake bleed screws [message #370250 is a reply to message #370239] |
Tue, 02 August 2022 10:08 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Doug,
If you ever stood in front of your coach in the rain.... (Standing in the rain is not always stupid.)
But if you had, you would have seen the windshield directing the run-off to the master cylinder. If that rubber diaphragm in the master cylinder cover has any sort of porosity, water will get into the brake fluid there.
I am hugely in favor of flushing the brake system. What I also do is periodically check the reservoir fluid with a conductivity device. The devices are not expensive and are actually less expensive than the half gallon of brake fluid it takes to flush the system of a TZE.
There are also other places that water molecules can get into the brake system. Unlike drum brakes where the parts live in the shelter of a drum, the piston of a disc caliper are right in the flow of water that the pads are peeling off the disc. While the piston seals don't wipe in normal operation, they do slide as a matter of course over time. This is not as much of an issue as a wheel cylinder that has a bad boot. The cup seals of drum brake wheel cylinders almost invite moisture intrusion. The boots age out just like all the other rubber part of a 50yo coach.
Oh, if you still have the OE steel brake lines, inspect the areas where it is clamped. That is where I had corrosion issues. Metal brakes lines of the period were terne plate, and while that is corrosion resistant, it isn't all that thick and not as good as real galvanizing.
Matt
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: Repeat of a note about brake bleed screws [message #370251 is a reply to message #370239] |
Tue, 02 August 2022 10:12 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Doug,
If you ever stood in front of your coach in the rain.... (Standing in the rain is not always stupid.)
But if you had, you would have seen the windshield directing the run-off to the master cylinder. If that rubber diaphragm in the master cylinder cover has any sort of porosity, water will get into the brake fluid there.
I am hugely in favor of flushing the brake system. What I also do is periodically check the reservoir fluid with a conductivity device. The devices are not expensive and are actually less expensive than the half gallon of brake fluid it takes to flush the system of a TZE.
There are also other places that water molecules can get into the brake system. Unlike drum brakes where the parts live in the shelter of a drum, the piston of a disc caliper are right in the flow of water that the pads are peeling off the disc. While the piston seals don't wipe in normal operation, they do slide as a matter of course over time. This is not as much of an issue as a wheel cylinder that has a bad boot. The cup seals of drum brake wheel cylinders almost invite moisture intrusion. The boots age out just like all the other rubber part of a 50yo coach.
When it comes to the steel brake lines, they were terne plated as OE, but that is not as good as other things like real galvanized or stainless. Inspect that in the places it is clamped as the clamps will hold moisture that can help corrode those lines.
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: Repeat of a note about brake bleed screws [message #370252 is a reply to message #370230] |
Tue, 02 August 2022 12:43 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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Doug,
Our coach came from the dryer southern states so the brake lines were in pretty good condition. So every year I put the coach up on ramps and spray down portions of the frame with Used ATF. In addition while I'm under there, I will also spray the brake line clamped contact points with the ATF. Seems to have kept things from rusting for the last 20yrs of my ownership.
As for the MC, Matt is right about the rain water heading straight for that MC. So, this is what I did to help that situation. Involves using an aluminum meatloaf pan, held in place with a zip-tie or Velcro strap. Seems to work for me.
http://www.gmcmhphotos.com/photos/g6527-master-cylinder-cover.html
Also, ON TOPIC, I bleed the brake lines with fresh fluid about every 3 or so years. Much cheaper and easier than not doing it and having to replace calipers, Master Cylinders or wheel cylinders when they rust from the inside.
JWID
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
[Updated on: Tue, 02 August 2022 12:49] Report message to a moderator |
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| Re: Repeat of a note about brake bleed screws [message #370254 is a reply to message #370252] |
Wed, 03 August 2022 09:02 |
dsmithy
Messages: 210
Registered: July 2012
Location: Lincoln Nebraska
Karma: 0
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Senior Member |
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Many thanks to you both. I hope others are watching.
Douglas & Virginia Smith,
dsmithy18 at gmail,
Lincoln Nebraska,
’73 “Sequoia” since ‘95: "Wanabizo";
Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other
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| Re: Repeat of a note about brake bleed screws [message #370283 is a reply to message #370230] |
Thu, 04 August 2022 17:27 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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I cut a piece of 1/16" lexan and secured it to stainless screws installed in the inner flange of the door over the MC. I made two keyhole slots in the lexan which allows it to move upward and off the screw heads. On the bottom, three holes are drilled in the lexan and 1/8" bungee cord secures the bottom to aluminum hooks screwed to the top of the front grill with stainless machine screws. This sheds all the water that sluices down the front of the coach and into the door area and keeps the MC dry, along with my Jeep blend door actuator. I'd post a picture, but that takes more time than I have right now.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Repeat of a note about brake bleed screws [message #370381 is a reply to message #370230] |
Wed, 17 August 2022 14:33 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I took a gallon water bottle and cut it to fit over the master cylinder - trick I learned from Chuck Boyd.
--johnny
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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