Converting Trailer Drum to Disc Brakes- Tutorial

Null&Void

How NOT to Fish
Oct 31, 2003
2,797
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This is a pretty easy, but time consuming process. Most of the time you will spend on this project is removing the old and rusted out gear and prepping the surfaces for the new disc brakes. The total time I spent on this project was about 6.5 hours, spending nearly 4 of those hours cutting the old brakes off of the trailer. This process can be shortened if you have a blow torch or plasma cutter instead of doing it the old fashioned way (My way below).

Necessary weapons:

Sawzall
Disc grinder with metal cutting discs (or other cutting device)
Extension cord
Large diameter wrench
Pliers
5lb sledge hammer
Heavy chisel
Prybar
Work gloves
Nitrile or Latex proctology gloves
Grease gun w/ marine grease
Bearing grease packer
Jackstands
3 ton jack
Assorted small wrenches
clear tubing 12inch- for bleeding brakes
DOT 3 brake fluid
1 pal to help pump the brakes and drive car
18 pack Coors Light or other

Step 1 is to make sure you have the trailer tires chalked. Nothing more humiliating than being run over by a parked boat (except maybe getting stuck in a hatch in 90 degree heat: see SaltyDawg for instructions).

Next is to crack a beer and then loosen the tire lug nuts. Jack the trailer up and place jack stands under the lifted side of the trailer, then remove the tire and set it aside. Lower the jack to “share” the trailer weight with the jack stands.



Grab the 5lb mallet and a short block of wood. Take the wood piece and place the wide end on the side of the bearing buddy. Use the mallet to gently tap the wood piece and “wiggle” the bearing buddy free from the hub assembly. Crush empty beer can with mallet (very entertaining!)

After removing the bearing buddy, use pliers to straighten the cotter pin and remove it. Next use a large crescent wrench to back the castle nut off of the hub and set aside. Verify that your beer is still full and the remaining soldiers have adequate ice. Wipe brow (or shiny, balding dome) as needed.

Here is where the fun begins (If anyone knows a short cut to do this, please chime in). Removing the old hub is normally done with brute strength, a pry bar, sawzall and grinder combination. I have yet to be lucky enough for the brake adjuster to function well enough to back off the brake tension, so I begin the process by pulling the hub out as far as I can and inserting a pry bar between the back plate and the drum.

After gaining enough clearance to see into the brakes, I use a sawzall to remove the top end brake shoe mount to relieve the brake pressure. I cut the brake shoe mounting bolt off and then pry the brake hub off of the axel.

Next, I use a grinder with a metal cutting head to remove the 4 back plate mounting bolts. Wear eye protection and some good ear muffs. You can also use a blow torch or plasma cutter to get the bolts off faster.



Cut off the old horizontal running brake line tubing, but make sure you have a catch bucket for leaking brake fluid once you cut the line. Verify that your new beer is still full and the remaining soldiers are safe



Once all of the old gear has been torn off, clean and prep the axel mounting surfaces for the disc brake mounting plate. Remove as much dirt and rust as possible and then pick up the installation instructions included with your new disc brakes.

Repeat this process for the brakes on the other side of the trailer.

After removing the old hubs, next I remove all of the old brake line cable and mounting fixtures all the way up to the actuator. Examine and clean out the brake fluid reservoir and remove all debris and old brake fluid. Verify that your newest beer is still full and the remaining soldiers are in a cool place. Place new order as required.

Next I started by installing the disc brake back plate, making sure that the mounting plate was mounted to allow the bleed values to point up, make sure to look for the “outside” stamp to mount the plate properly. Follow the manufacturers recommended torque settings for the back plate bolts.

I then prepare the new disc and bearings for installation by packing the bearings with marine grade lube using a grease gun and grease packer.

After inserting the greased bearing, I installed the bearing cover and gently tapped it into place using the mallet and small wood block. I then used the grease gun to fill grease completely over the bearings, while not contaminating the grease cover with excess grease. I stick the end of the grease gun into the space and fill to remove as much air as possible.

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Install a “spindo seal” kit spindle cover and gasket onto the spindle, and then install the disc/hub assembly over it. With the disc now on the spindle, I insert the grease gun tip into the hub space and fill in as much grease as I can. Once that space is filled with grease, I insert the outer bearing (already packed with grease), then the thrust washer, and then the castle nut.

Using a large crescent wrench, I slowly tighten the castle nut, while turning the disc. Once I feel resistance, I then back off the castle nut and ensure free motion of the disc. I insert the cotter pin thru the opening of the spindle and the castle nut and bend it over the spindle to secure it.

Tap the bearing buddy back on the hub and fill bearing buddy with grease using the grease gun. Make sure not to overfill the hub with grease as it will be forced out of the hub causing nasty grease spray when driving!

Slide the brake pad assembly into place over the disc and tighten the two mounting bolts to the manufacturers recommended torque setting. (Oops…forgot to take pics of this with the wheel off!)

Repeat process for the other brake assembly. You should be now finished with all liquid refreshments and seeking a sober and experienced trailer driver for upcoming “live” testing.

Remove all of the old brake lines all the way up to the actuator. Install new “flex line” tubing into both sets of the new brakes. Run the “short side” flex tube directly to the brake line junction connection and connect the stainless steel tubing to the far side flex line.

Install the flex tubing that will link the long brake line to the junction box and connect the pieces. If needed, coil up your extra slack stainless brake line by curling it around a large diameter pipe. Be careful not to kink the tubing!

Connect the new reverse disc brake sensor to the actuator and turn “hand tight” with appropriate wrench. Cut the old trailer harness off and install the new trailer wire pigtail that includes the “reverse” sensor to allow backing of the trailer. Make sure your connections are water tight as this is a critical connection that often gets douched with salt water.

Run the long stainless steel brake line from the brake line junction up to another flex line tube and connect it to the actuator sensor. The entire brake line system should now be assembled and ready to fill with brake fluid. Note the curly Q's I created to compensate for the additional SS tubing below.

Open the brake fluid reservoir and fill with the manufacturer recommended brake fluid (usually DOT 3) and leave the reservoir cap off. Next, grab your spare hitch receiver and insert it into the trailer hitch.

Go to the brake set that is furthest from the brake line junction and attach the 12 inch tubing to the top brake bleed valve.

Once the hose is attached, open the bleed valve with a small wrench and have your assistant plunge the hitch receiver to begin the flow of brake fluid through the brake line. Continue to fill the brake fluid reservoir with additional fluid as you are going through the brake fluid bleeding process.

Continue to compress the brake actuator with the hitch receiver until brake fluid begins to flow out of the bleeder hose and into your catch bucket. Continue this process until the flow of brake fluid is free of air bubbles and then close the bleed valve with "slow" plunging of the actuator to ensure good line pressure.

Move to the other brake set and repeat this same process until the flow of brake fluid is bubble free. As a final check, I repeat this process one additional time on each side until the brake actuator feels solid (not spongy) to the person pumping the actuator.

Put the trailer tires on and begin testing the brakes by hooking your tow vehicle to it as you normally would. Begin by testing the brake and trailer lights, and then move on to low speed testing. I start by moving the trailer a few feet forward and then quickly depressing the brakes/actuator before attempting to back the trailer into its original position.

the trailer passes the reverse and low speed tests, begin by taking the trailer for a neighborhood test ride to ensure all components are working correctly.

After ensuring all is functioning properly, also make sure that you check the trailer on the next few subsequent trips. Check for hubs that may need tightening after your initial few uses.

I think that covers it.
 
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Surg

Expert Marine Electronics
Feb 2, 2004
916
165
43
44
So Cal
www.ExpertMarineElectronics.com
Name
Sergio
Boat
25' Monterey
Been there done that. That’s a lot of work, and can be a pain in the ass. Thanks for posting it for everyone.
The reverse solenoid pictured is great for all the flat land states, but in CA there is another one preferred that blocks the pressure and then also bleeds any residual pressure from the calipers back into the reservoir.

REVERSING SOLENOID VALVES
This is very helpful if you are facing down hill, and need to back up since the weight of the trailer will be enough to pressurize the system before you pop it in reverse. I know this first hand…
 

Mark66

Member
Jul 22, 2004
2,333
4
38
NCSD
Name
Mark
Boat
27' Cat
Thats awesome Vince. I also appreciated your impeller changing tutorial. I'm guessing your post will help people take the plunge and do it themselves. :beerbang: - True BD contribution. Thanks
 

gecsr1

28' Aquasport "Reel Adventure II"
Jul 15, 2005
12,177
2,692
113
Poway Ca
Name
Gary
Boat
28' Aquasport "Reel Adventure II" / PlainJaneRods
Great Job....
 

Null&Void

How NOT to Fish
Oct 31, 2003
2,797
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Thanks for the props doods!

Anyone can contact me if you need some advice. This stuff is easy enough for anyone to save $700 in labor!
:imdumb:
 

Spongerider

The Fish Monger
Sep 2, 2007
184
3
18
Huntington Beach
Name
Dean O.
Boat
39', Fountain, The Michael.
Thanks for the 'How to'. I'm planning on going this route next year but I was wondering if any of you experienced warpage of the rotor?

Thanks!
 

jayyyy

Member
Oct 7, 2008
931
152
43
NorCal
Name
jay
Boat
'04 Sea Pro 220 WA / 225 Honda
Did you replace the drum brake acuator with a disc brake unit or put a larger oriffice plug in? or is it okay to run it with the drum accuator?
 

Gringo Sushi

PB Skipper
Jul 22, 2009
167
0
16
Fullerton, CA
Name
Todd
Boat
28' Farallon Whaleback / 24' Skipjack Open
I recently did this conversion and wish I would have done it years ago. Don't know how I ever stopped before.

I was going to order the parts to ship from pacific trailer but decided to drive out and pick them up instead. Sure am glad I did. They took me out into the shop to pick out the parts, gave me a bunch of good installation tips, and even pre-lubed my hubs/bearing on their pneumatic greaser saving me the hastle of packing the bearings by hand. I give them an A+ on the deal.

Great instructions with photos. Definately a DIY-able project. And yeah, a twelver is about right unless you happen to have "helpers".
 

BigfishGreg

Newbie
Oct 7, 2007
347
0
0
Orange County, CA.
Name
Greg
Boat
none
Great write up and pics! It is much easier to snap the backing plate bolts off with a good impact or even a breaker bar with an 6 point impact socket than grinding or torching the heads off.
 
I

icemanbryan

Has anyone used etrailer to purchase the conversion?

Thanks Bryan
 

DaveR

Newbie
Feb 22, 2006
3,186
8
0
Irvine
Name
David
Boat
28' Skipjack
Has anyone used etrailer to purchase the conversion?

Thanks Bryan
Call Pacific Trailer in Chino. Richard lives in the OC and if you're willing to meet him, there's no SH. They are VERY competitive to the best internet pricing.

Do you do all four wheels, just two rear or two front?
Do the conversion on whichever axles have the drum brakes. Some tandem or triaxle trailers have brakes on just one axle, others on multiple axles (based on trailer rating).
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firefishq

Newbie
May 17, 2013
196
8
18
So Cal
Name
A
Boat
none
i did my trailer years ago and was long over do. What a difference in braking power. I changed the actuator and all the brake lines as well. I got the the actuator and lines from pacific trailer and the brake kits from shadow trailers in cypress. I replaced the brakes on both axles.
 

ltran0614

Member
May 8, 2013
336
183
43
Orange
Name
L Train
Boat
27' Farallon Whaleback & 27' Radon LRB
Going to be taking on this project for my tri-axle Pacific Trailer soon.

EXCELLENT WRITE-UP w/ pics!! Thanks!!
 

Stringer

Idiot Savant
Jul 7, 2005
1,137
73
48
Bakersfield
Name
Stringer
Boat
25 Skipjack FB
I've been thinking about doing the conversion. I was wondering if anyone has done this conversion, and also changed out the actuator to an electric over hydraulic actuator, since my tow vehicle has the electric brake controller installed from the factory. I'm curious as to the pro's and con's. Thanks