Axle switch / Bleeding the brakes

[Joe 26M Time Warp]

Not sure exactly when I'm going to do this, but it's going to happen soon.
I'm swapping the axles between my two boats, the 2003 fire damaged one has the heavy duty 5000 lb axle, the 2004 trailer has the 4200 lb'er which I'll sell along with the old boat & trailer.
I done lot's of brake jobs on cars where I didn't break the fluid system open, so I didn't have to worry about bleeding the brakes. On this project however I'll have no choice. Does anyone have any helpfull hints to bleeding the air out of the lines, or even better, minimizing the amount of air that gets in? Obviously on a car you can just push the brake pedal while opening the bleeder screw, with a trailer hitch activator I'm thinking pipe clamps or ?
Any thoughts?

Heres some raw data if anyone is curious;

Tires
2003 hull #32 - ST 225/75D15
2004 hull #358 - ST 205/75D15
Max load
2003 hull #32 - 2540
2004 hull #358 - 2150
Approx height of tire (measured vertically under load) 27" both
Wheel diameter 16.375" both
Number of lugs
2003 hull #32 - 6
2004 hull #358 - 5
Axle hub (grease cap diameter)
2003 hull #32 - 2.675"
2004 hull #358- 2.3125"
Spring separation (width at perches)
66" both
Spring length (from bolt centers)
2003 hull #32 - 24.5"
2004 hull #358 - 26.5"
A little side note for those checking these numbers; When I added the extended spring shackles to allow clearance from fender to tires, I noticed the longer shackles were now angled more - from the spring in a forward direction toward the perch. It looks like this should work out very nicely switching to the 2004 perch setup because it gives me 2 extra inches, and will result in a more straight (vertical) shackle. Tire/fender clearance will be someone elses problem with the 2003 boat & trailer, our keeper might gain another 1/4" or so in clearance and overall height.

[Chip Hindes]

There's not a heck of a lot you can do to avoid getting air into the system, but bleeding isn't that tough and it's not a bad idea to flush all the nasty old fluid out periodically anyway.

I used one of those ratchet tie down straps on the actuator. Hook the ends to the winch bracket, and run a loop around the front of the ball coupling. ratchet it up tight (you can watch it compress against the spring), walk back, open the bleed screw, close the bleed screw, walk back to the actuator, release the ratchet, add fluid if necessary, repeat until done. I use a small glass jar wired to the frame rail and a piece of clear tubing on the bleed screw to catch the fluid. It will damage the paint or your driveway or kill the grass if you just let it squirt out.

While I had it apart to install the solenoid valve, I rebuilt my master cylinder when I added the second axle. From empty, it took about five trips back and forth to bleed the first one, three trips each for the others. Maybe 20 minutes total. If you have a helper on the ratchet (or on the bleed screw, depending on the helper ) it might take five minutes.

[Dimitri-2000X-Tampa]

I don't know why you are going to all that trouble to go back and forth, open and close the screw, etc. A simple solution is to take that glass jar and put it on an upside down bucket or something else that will raise it above the level of the screw. (do the shorter brake line side first..I think that is the starboard side on mine) Use a clear piece of tubing to connect the screw nipple to the jar (1/4 inch I believe). I just use a beefy screw driver to push the actuator in...making sure you don't drain the master cylinder. Bubbles will travel up the hose and into the jar. Once you've pumped a bunch and there are no bubbles in the tubing near the nipple, just close the screw, remove the tube, and you are done....then go do the longer side. I don't see why you have to have pressure on the actuator when you close the screw if you are using the tube method...the important thing is to have no air bubbles in the line (putting on my flame retardant suit now).

I time it so that the whole bottle of new brake fluid goes into the system. You aren't supposed to use it after its been opened and sat around for a while (collects moisture or something I believe). I have flushed it a couple times now because when I got my boat last june, the master cylinder was empty and a bit rusted (blown slave cylinder). I replaced the original brakes last year with some heavier duty (galvanized) drum brakes which work well...guess I'll see how long they hold up. Funny thing was that the guy who sold them to me did not recommend brake flushers...said that the chlorine in the water reacts with heated salt and makes it worse if its not flushed the moment its taken out of salt water (not sure if I believe that one or not). He said the best thing to do was pull the drums off every 6-12 months and spray anti-corrosive stuff in there...guess I'm about due to do that and see what they look like.

[norbert]

hmmm, joe, why don't you simply keep th old trailer? the hull shape is the same, so your new boat fits on the old trailer as well.

[Tom Root]

Yea Joe, maybe I just dont get it, you can go to the closest launch site, drop a trailer off, go get the other one, launch the boats and swap 'em, it sure sounds easier to me anyway? Is it because you have to travel too far....or? Is the perch situation that much of an advantage?

[Don T]

Hello:
Back to bleeding brakes. Without opening and closing the bleeder or in my case, having a check valve in that tube, the fluid just goes back and forth. You will not get it to move fast enough or in enough volume to purge the lines. You will purge the wheel cylinder / caliper though. Check valve or pressure bleeding is the prefered way. You can accomplish a great purge if you pump fresh fluid under pressure into the master cylinder. It will push everything out the bleeders with no need of check valves etc. and will keep the master cylinder full too. Single handed bleeding.

[Chip Hindes]

Funny thing was that the guy who sold them to me did not recommend brake flushers...said that the chlorine in the water reacts with heated salt and makes it worse if its not flushed the moment its taken out of salt water

Once again proving that you don't have to know squat in order to be a sales man. If he was also a mechanic, take your stuff somewhere else to get it fixed. That is without a doubt one of the most ridiculous pieces of pseudo-science I've ever heard.

Corrosion preventive won't help; you can't use it on the inside surface of the drums, and the failure mode is that the shoes weld themselves to the drums. If you don't flush them within days, if not hours, they'll likely freeze up solid as a rock.

When launching at Homestead for the Bimini cruise last year, it was raining and based on sage advice I did not get out of the tow vehicle, so did not realize I had dipped my truck rear brakes in the salt water. After the launch I flushed the trailer brakes though the homemade flushers. Returning to Homestead after ten days the trailer brakes were fine, but the truck emergency brakes were frozen. Low range 4WD and about 3500 RPM and they literally broke loose with a bang. I pulled the wheels in the parking lot and managed to remove enough of the pieces to get home. The shoes, backing plates, springs, pawls; every piece looked like it had been though a crusher. $420 later they're good as new, because they are new.

[Joe 26M Time Warp]

To Tom & Norbert, I'm hoping the slightly beefy'er 5000 lbs axle setup will keep our trailer within reasonably safe load limits into the future. I know Chip and many others have made adjustments such as adding a second axle because the factory trailer is so marginally sized. I was one of the lucky few that ended up with the oversized axle on hull #32, and that's not something a little old fire is going to take away from me.
To all;
On closer inspection tonight, wearing my snowmobilesuit in whats left of our 4" snowfall on Tuesday, I found the basic layout of the brake system(s).
Both the 2003 and 2004 have the same flex hose connection to an axle fitting that is closer to the starboard side of the axle.
The flexhose fitting (on the 2003) measures 5/8 flare wrench, it's about 1 foot from the spring on the starboard. The squared off hydraulic fitting is bolted onto the axle, and the rest of the brake system to each disc brake caliper is also connected to the axle. I figure I'll disconnect it and install what I think are either 1/8" or 1/4" pipe plugs.
It makes me wonder if I couldn't apply the brakes using Chip's strap method before I open the flex connection. I was thinking if I locked the brakes on and then found a way to clamp or hold the discs on, I could then know when I relieved the clamped discs I have extra fluid coming back from the axle line.
If I break the line only at the flexline, which is pointed down towards the axle fitting, I might be able to bleed any air out right there from the actuator side by leaving the connection loose. Any thoughts?

I'll have two flex hose connections to disconnect and then eight bolts, I have a two floor jacks and four safety stands, but I have to move both boats before I start. Boat nose down, I figure they should roll straight out the back. I should be able to just roll the axles from one boat to the other on a floorjack and then reconnect everything.
Then I'll add fluid while relieving the strap on the actuator. If I can do that, I'll know the only air now in the system should be able to come out at the flexhose fitting and I'll bleed it out there with the actuator before I bleed it by loosening the discs.

[Chip Hindes]

It might work but I wouldn't count on it.

Disc brakes have no springs, the only thing that pulls them away from the rotors is a small amount of elasticity in the piston seals. Even if you clamped the pads tight, the seals would still pull the pistons back slightly, so you'd be wasting your time.

You must disconnect the lines at the bubble flare fittings (the ones that spin freely on the lines) and it is pretty much impossibile to seal one of these when it's disconnected.

Adding fluid while releasing the actuator will not prevent the master cylinder piston from sucking some fluid back into the reservoir; if any of the fittings or bleeder valves is loose when you do this, it will suck air at the loose fitting.

Bleed them all. It's not that tough. BTW, Don's pressure bleeding system is certainly best if you can get your hands on one. I'm cheap; I like to make do with what I have.

[DeMaster]

Do not forget safety goggles. Brake fluid in the eyes is not funny.

[Joe 26M Time Warp]

Rethinking this, I'd have to remove the wheels, four of them, so maybe my best bet is just do it and bleed them.
Finding the proper sized plugs for the flexline fittings is first. Again they look like regular old 1/8 or 1/4 inch NPT.

[Frank C]

hmmm, joe, why don't you simply keep th old trailer? the hull shape is the same, so your new boat fits on the old trailer as well.

Joe,
I'm just as curious as Norbert, and I didn't see that you answered his question, so I'll ask it again ...

Instead of swapping the axles, why wouldn't you simply keep the older 2003 trailer for your new boat, and sell the damaged boat on the newer trailer??

[Joe 26M Time Warp]

Hey Frank. There's actually another reason besides keeping the 5000 lbs. capacity axle, the 2004 has the 5 wire actuator. That's the setup with the fifth wire going to the back up lights and a lock out solenoid for backing up. The 2003 required a bolt stuck in there every time I wanted to back up, but of course I could buy a back up - lock out solenoid and then install that.
Also a factor is the availability of liquid water at a boat launch.
Near as I can tell both actuators are welded to the trailer frames and even that could rather easily be dealt with, but I think I'm getting the most out of the two trailers, with the least amount of time and effort by swapping the axles.
Hey I just swapped motor and transmissions on my truck, this project I expect to be a bunch easier than that.