Hi Gary,
On brake parts, we are in the RV world or trailer parts world and not automotive. If you are use to working on older auto drum brakes, you have been pre-trained for these. But, do not be expecting to see automotive duty beefyness on trailer brakes. And with that, if yours are in need of new shoes, most times you can buy the entire brake plate with shoes, magents, springs the magnet arm, adjuster all in a unit cheaper then you can buy just the shoes alone.
Since yours is a 2004, Sunline used Dexter Axle on the 7,000# class trailers. Which is good as Dexter is one the higher end quality trailer parts manufacturers.
There should be an axle manual in Sunline manual binder if yours came with it. If not, here is one on-line.
https://www.dexteraxle.com/docs/def...omplete_service_manual.pdf?sfvrsn=cfe1e328_42
Most times, the brakes can be cleaned up and reused. Then, clean out the old grease in the wheel bearings, check the bearings for corrosion/wear, replace as needed, repack with good wheel bearing grease and put a new grease seals in. Check the brake wiring too for wire damage.
Here is a show and tell on doing clean up and repack on a Sunline 2004 T2499. Yours should look just like these. I never made it to posting this hear on Sunline club. Its on another camping forum.
Annual Brake Inspection and Axle Re - Lube (Pic's)
Dexter declares when the lining approaches 1/16" it's time to replace. They are not as thick as automotive linings to start with. There may also have (most likely will have) small heat cracks in the linings that makes you think they need replacing. Dexter declares these are acceptable. And I can attest to, they are there and they do not create an issue unless the lining itself starts to become unbonded. Then it's time to replace.
If you need to replace, here is one of the places I get many of my Dexter parts and have had good results.
Yours are 10" x 2 1/4" wide drum brakes. Manual adjust. They have lefts and rights.
https://www.easternmarine.com/electric-brake-assy-right-hand-k23-027-00
https://www.easternmarine.com/electric-brake-assy-left-hand-k23-026-00
About the only brake parts that are declared as spares are, the shoes and the magnets. If you need much more than that, you have buy the entire brake plate.
Bearings,drums and seals.
Eastern Marine has them too if needed.
https://www.easternmarine.com/trailer-brakes-electric
I do shop Etrailer
https://www.etrailer.com/Trailer-Parts and Amazon on line as well and compare prices on all 3 of them. Sometimes the orders get split up if the cost difference is great enough.
Freight is charged at Eastern Marine, E trailer is free over $100, Amazon if you have Prime is free so take freight into account. Amazingly Eastern Marine with freight still trumps the other two sometimes. Just look for Genuine Dexter, there are lots of clones out there. And the parts are not interchangeable short of replacing the entire brake plate.
Bearings and seals, you can get these at your local NAPA or other auto parts stores. They are standard sizes.
Dexter does make (or have made for them) grease seals. They offer 2 different types and they are interchangeable with other manufacturers. The heads up is what type to get.
They make a single lip seal. It's more of a dirt seal. It may even be what is on your camper now, if they are original. I recommend "not" using the single lip seal.
The other type they make is a double lip seal. It has the outer dust seal and an inner seal with a garter spring around it. They also make an EZ lube feature on some axles which you can pump grease into a zerk fitting and grease both bearings. You can see if yours has this feature by the zerk fitting. If is not there, then you do not have the feature. They use the double lip seal on the EZ lube, but still recommend the standard hand pack lube. If yours by chance has the zerk, I can explain the why it's not a good idea to grease the bearings that way if wanted.
Here is the Dexter double lip for the 10 x 2 1/4" brake.
https://www.easternmarine.com/dexter-172-id-grease-seal-010-019-00
The cost difference between the 2 styles is not much and why they even bother with the single lip seal, I cannot imagine with the double being so much better. I guess it is mass production savings maybe.
You can find the double lip seal and the bearings at the local auto parts store. Just look for the garter spring, that is a tell tail on the seals.
While you're in their doing the brakes, check the suspension assuming it has leaf springs. Odds are high the standard nylon spring pin bushings are worn through and possibly there are spring pins which can spin which wears out the bushing, shackle links and hanger holes even faster. The spring pins have serrations on the bolt body by the head that press into the hangers & shackles for anti spin. When the bushing starts going, the pins wobble and strips out the serrations making the problem wear even faster. With enough wear, the shackle plates can and have broke free leaving you somewhat stranded on the side of the road.
The top center pivot bushing on the equalizer seems to want to wear out the fastest. Then the other pivot points follow. The stock nylon bushings are only good for about 8,000 to 10,000 miles. After that, the spring pins are grinding into the leaf springs. Most times you have to pull out the spring pins to see the bushing wear. Unless yours has lots of shackle plate wear or pins that spin, then you know the bushings are shot.
If you want more on the suspension, ask away. We have lots of pics and posts on them.
Hope this helps
John