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Expert
  
Location: Cottage Grove, OR | A number of years ago, I had the brake fluid lines for the rear brakes on my coach moved from the top wheel cylinder to the bottom wheel cylinder. That made air removal much more efficient. Recently, another coach owner was having much difficulty in getting the air out of his rear brakes. After another owner suggested that he redo his brake lines to be like mine, the bleeding challenge was resolved and the air was quickly and completely removed. He now has good, solid brakes like I do. It is also necessary to have properly adjusted brake shoes as well.
If you have an interest in making the same change to your coach, you can see how my lines are secured and routed in the photo album on this website. Properly securing the line is absolutely necessary to avoid getting the line in contact with the axel as that would destroy the brake line and cause total loss of your ability to brake the coach.
Here is the link to the album: http://fmcowners.com/mbbs22/photos/photo-thumbnails.asp?albumid=151
If you want to personally view or inspect the line arrangement on my coach, you can do so at the February Rally in Southern California as detailed here: http://www.fmcowners.com/mbbs22/forums/thread-view.asp?tid=770&post... |
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Elite Veteran
Location: Oceanside, CA | I still need to get this done, I can tell when bleeding the rear I've still got a little air trapped in there, rear brakes are working but I know they could be better...going to be a little tougher on mine as I've now got the rear air bag mount structure to contend with. |
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Elite Veteran
Location: Medford, OR | Is there a part number for those lines Stephen?
Dan
#850 |
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Elite Veteran
Location: Oceanside, CA | Looks like you converted to -3 AN fittings for the new hoses, I did similar for the hydroboost install in the front of my rig. I had planned on changing all 4 of the flex hoses over to that as they are inexpensive and easy to get just about anywhere.
Summit Racing has a great selection of differing lengths.
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Expert
Location: Cottage Grove, OR | dkarnath - 2016-11-11 7:05 PM Is there a part number for those lines Stephen? Dan #850
No part number as you just need to measure the length of line needed with the new routing and then go to a local brake shop and, if a premade one of the correct length is not available, have them make one up with the length that you need. You will need to ensure that your fittings at both ends are compatible with what you have/will have at the end of the line and at the wheel cylinder. Mine were actually done by RVS rather than myself. I would have to look again to see how the clamps are attached. I think a nut was welded to the backing plate and then a short bolt used to screw into the nut to hold the clamp. |
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Expert
Location: Cottage Grove, OR | LCAC_Man - 2016-11-12 5:26 AM Summit Racing has a great selection of differing lengths.
This is a good option for sourcing the line after you have measured what you need.
Dan, perhaps I can stop by your place on my next trip south which will be at the end of this month and you can measure my lines and take a closer look at how they are attached. The result can then be posted. |
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Elite Veteran
Location: Oceanside, CA | Stephen,
can you put a wrench on one of the hose fittings and tell us what size it is? I'm curious if they used -3 or -4 hose..it looks like -4 in the pictures..
-3 will be 1/2"
-4 will be 9/16"
Edited by LCAC_Man 2016-11-17 2:26 PM
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Expert
Location: Cottage Grove, OR | LCAC_Man - 2016-11-17 12:20 PM Stephen, can you put a wrench on one of the hose fittings and tell us what size it is? I'm curious if they used -3 or -4 hose..it looks like -4 in the pictures.. -3 will be 1/2" -4 will be 9/16"
My floor jack is still in CA so will get better pictures of both ends at the end of the month when I am there. Without the floor jack, I "can't get there from here"!
The backing plate end has a 9/16" fitting. The frame end has a fitting smaller than 1/2" but I didn't bring a smaller wrench with me when I went under. My guess is that it is 7/16". It attaches to a fitting that has the steel hard line attached to one side and the flex line to the other side. That fitting is securely attached to the chassis bracket by a large nut on the chassis side.
Hopefully the above info helps, |
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Elite Veteran
Location: Oceanside, CA | I purchased my hoses this week from Crown Industrial (they are really close to me so I can just drive there) and will be updating the installation/modification (to all four) on this photo album:
http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=137&p...
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Extreme Veteran
Location: Scottsdale, Aridzona |
CAUTION !
The wheel cylinder (WC28851) used on the FMC is tapped for 7/16-20 thread . . . but it is NOT bottom finished to accept an inverted flare male fitting. The two outside holes in the FMC wheel cylinder are bottom finished to a taper that matches the brake bleed screw fitting. Both holes are bottom finished the same so a bleed screw can be used in either hole. The"pointed" male taper of the bleed screw seals against the "pointed" female bottom of the hole machined into the wheel cylinder. That matching "point" fit is what seals the bleed screw to the wheel cylinder.
All the hoses on my #120 have wheel cylinder hose end fittings have the thin COPPER WASHER to seal the fitting against the flat MACHINED surface of either hole of the wheel cylinder. After much searching, and discussion with several brake fitting and hose manufacturers (Parker-Hannefin, BrakeQuip, Fragola, Earl's) . . . there are no fittings made (for hose end or as a loose fitting) that have the male taper to fit into the wheel cylinder to seal like the bleed screw. You have to use a thin copper washer with the wheel cylinder fitting, whether it is made onto the end of the hose, or a single loose fitting that accepts a -3 or -4 AN type hose end fitting, to seal the brake supply line AT THE WHEEL CYLINDER. That fitting should be made with the cylinder side flat to use against the thin copper washer and the flat machined surface of the wheel cylinder.
The transfer tube between the two wheel cylinders uses the "inside" hole of the WC28851 wheel cylinder and is tapped 3/8-24 with the same "pointed" bottom of the hole machining as the two outside holes. It to requires a thin copper flat washer between the machined wheel cylinder surface and the fitting that accepts the B-nuts made onto the metal transfer TUBE.
The WC28851 wheel cylinders I got from NAPA came with a bleed screw, and plastic plugs in the other two holes that captured the two thin copper washers that were also supplied.
The inverted flare 7/16-20 fittings are made short enough that the fitting tightens the thin copper washer between itself and the flat machined surface of the wheel cylinder . . . before the inverted flare "end" hits the bottom of the hole in the wheel cylinder . . . providing the 2000 psi or so SEAL of the brake fluid going into the wheel cylinder . . . and also keeping any AIR (bad, bad, bad) OUT.
See pictures of Wheel Cylinder and Fittings in Albums. I'll add a few more in a week or so.
THIN COPPER WASHER AT THE FITTING AT THE WHEEL CYLINDER . . . Don't leave the driveway without them !
Brake ON ! Lou #120 |
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Elite Veteran
Location: Oceanside, CA | Great info Lou, I've got a pretty good selection of small copper crush washers but I'll be sure I have enough of the right size before I start. |
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Elite Veteran
Location: Oceanside, CA | Installation went pretty well with the exception of the passenger rear hose, the original was seized to the tube connection and I had to cut it off , install a new b-nut and double flare it(which is a PITA), I had plenty of 7/16" x 1/32" crush washers on hand so I didn't have to make any parts runs to complete, everything fit really well, I'll have by "brake bleeding assistant" back tomorrow so hopefully I'll be leak free.
Install pics here:
http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=137&p...
Edited by LCAC_Man 2016-12-10 7:34 PM
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Elite Veteran
Location: Oceanside, CA | No leaks...but I'm having a heck of a time getting it bled; which I suppose I shouldn't be too surprised about as I've opened and drained all four wheel positions while installing these new hoses. I purchased a pressure bleeder from Summit https://www.summitracing.com/parts/mvp-0108 that should arrive later this week that should make life a little easier. As a silver lining; at least I'll be getting a good fluid flush.. |
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Elite Veteran
Location: Medford, OR | That is the same brake bleeder I have Len, it worked great on the FMC. I tapped it in at the MC. Makes it a one man job. I have full brake pedal even with the rear hoses in the factory "upper" position.. |
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Elite Veteran
Location: Oceanside, CA | Dan,
That's good news, I knew I was in for a fight with my master cylinder well below some of my hardlines and the fact that I've had the system completely drained...I only had an "ok" bleed on it before when I did my test drives but had decent braking, now after having drained all 8 wheel cylinders with this hose change out I made it much worse.. |
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Elite Veteran
Location: Oceanside, CA | Can't say enough good things about the Motive Power Bleeder (linked in my earlier post) I pushed nearly 3 quarts of fluid though the system to finally get good clean airfree flow. I still needed to adjust my brakes a bit to get the pedal height right but I knew that was going to be something that needed attention; got a couple real good test drives with it today.
My 37mm/1.45" bore master cylinder is really just barely large enough for the brakes. I've already started parts gathering to move to a 2" bore master cylinder(ACDelco 18M870 from a Chev C4500 Kodiak) that will be more than enough and make the adjustment less critical, it is a 4bolt attachment rather than the 2 bolt I currently have so I'll have to install an extended output rod on the Hydroboost and make an adapter plate. Here's what I'll be installing (I only paid a 1/3rd of that price) http://www.ebay.com/itm/Brake-Master-Cylinder-ACDELCO-PRO-DURASTOP-...
Edited by LCAC_Man 2016-12-14 3:43 PM
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Veteran
Location: Bethune, SC | I have a question. How did you get the pressurized fluid into the master cylinder? I bought the Motive with a large plate to replace the master cylinder lid when bleeding. It was way too large to fit in the compartment on top of the master cylinder. My next thought is to modify a stock lid with two inputs with the hoses from these inputs going through a tee into one hose that attaches to the Motive pressure device.
Do you think that will work?
Henry |
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Elite Veteran
Location: Oceanside, CA | Henry,
My system is completely custom, my master cylinder is from a 2006 Chev Duramax pickup with the 3 tab threaded cap, here's a couple pic's of what I have:
http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=127&p...
http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=127&p...
Dan mentioned he has the same bleeder, he may be able to share with you how best to use it, if it were me, I'd get a second metal master cylinder cap and gasket then cut the center/compensating cups out of the gasket (just leaving the perimeter to seal) then drill it and put in a nipple fitting to match the hose to the bleeder, no reason that wouldn't work. |
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Elite Veteran
Location: Medford, OR | Henry,
I took the MC completely out of the equation during the bleeding process with this pressure bleeder. It worked great on both #184 and #850.
1)BEFORE you do any of this, make sure you have already properly bench bleed, the MC, or bleed it with it mounted isolated by itself using a couple threaded plugs or however "you" prefer to bleed a MC.
2)You just need to adapt a piece of 1/4" rubber fuel line to the end of the bleeder, the slide the 1/4" hose over the end of the brake line coming OUT of the MC after you slide the brake line nut out of the way of course, clamp the hose down with a small hose clamp, do one system at a time obviously (front then rear). I installed a plug into the out port of the MC also while I have the brake line disconnected for piece of mind.
3)Pump up your bleeder to around 20 psi and start the bleeding process at the hydrovac, then on to the wheel cylinders.
4)When your done with the front brakes, just depressurize the bleeder, pull the hose off the end of the steel brake line, and thread it back into the MC. The small amount of exposed time you have with the brake line threading it back on the MC isn't going to cause a major air intrusion in the brake system.
5)I did a long write up (basically embarrassing if you ask me) of all my cussing of the brake system and having "buddies" dying at the steering wheel pumping the brakes. The small MC (in my case) doesn't have enough volume to bleed an FMC system from scratch. Unless you like removing the MC cover and topping off fluid every couple pumps while bleeding the wheel cylinders.....My issue with #850 was a "new" faulty MC, it would suck air "in" on the back stroke....anyway, I tried the "plate" first that you put over top of the MC, TOTAL WASTE OF TIME AND MONEY AND ITS MESSY. I'll give you the fancy one I bought if you want it? I'll never use it again on anything. EVER. I hope I drew a picture of my process...
Edited by dkarnath 2016-12-15 9:47 AM
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Veteran
Location: Bethune, SC | Thanks for the replies. Both methods sound easily doable. I plan to buy a plug for the master cylinder port, and try the direct brake line hook up. If I can find the proper brass fittings, I will also set up an old master cylinder lid.
Will report back,
Henry |
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Regular
Location: Greensboro, NC | I like the idea of of changing the rear brake lines I never thought about that just always thought it was the way it would always be pump the brakes 2 or 3 times to stop. #934 is in dire need of brake adjustment I will be measuring my lines and getting new ones made thanks to all that have made post as to doing this I am learning a lot. Just one more thing to make sure I understand correctly I need to run my brake shoes all the way out to the drum them back them off 7 clicks before I bleed them is my understanding correct? Thanks again to all for the wealth of knowledge that you are supplying.
Chip Rives
#471,#721, #934 |
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Elite Veteran
Location: Oceanside, CA | I've never subscribed to a certain number of clicks to back off. I run them out to make solid/even contact(as best as I can tell) then back them off just enough not to restrict free rotation (tire has to be jacked up). It is a bit of a guessing game (unless you remove the drum and look) if the two adjusters are equally set. |
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Regular
Location: Greensboro, NC | Okay thank you Len I guess I was/am reading to much into trying to understand the proper way to adjust the brakes the correct way I think I should get the brake hoses made first then get the brakes adjusted. Thanks again for you help, hope to get to the West Coast sometime and meet all of you Fine people and expand my learning on these fine coaches.
Chip Rives
#471, #721, #934 |
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Rear brake bleeding improvement
