Has anyone done this on an aluminum trailer? Wondering what changes need to be made specifically concerning the coupler.

I did one a few years back, if I remember right I gutted the surge coupler and placed some grade 8 bolts to stop it from moving. I may have drilled new holes. Then I mounted a brake rite assembly on the trailer and connected the hydraulic lines and ran some new wires. It was not too hard. I like the control of electric brakes alot better. You can also buy a new coupler and get rid of the whole surge brake coupler. IMO it would look alot cleaner. I had a steel trailer with the coupler welded and painted. Carlisle makes another electric/hydraulic actuator that is smaller. I have had both and like the carlisle one better. Just make sure you order the one you need, they have different pressures for disk versus drum brakes.

Do they still have the lag time?

The only coupler I can find rated high enough (10,000+) are the cast A-Frame type. If anyone knows of another product or where to look for a better solution please chime in.

Have you tried your trailer manufacturer?

I was thinking about switching oner to electric also the surge are a pain....especially when your trailer is getting older. How much better are they?

Not to mention better braking whne backing down a ramp.

You will love the electric over hydraulic. You can adjust the delay out completely if you like. They are also much safer when stopping. I run mine where the trailer actually pulls slightly harder than the truck brakes, this keeps you straight with the trailer and your stopping distance doesn't change except than you may run stop lights with out the boat.
The conversion is very easy, I have done several. I also like the calisle unit. If you can mount it close to the front of your trailer, you may be able to use the flex line going into the surge and just go straight into the new unit, If not you can buy a union and a short hose at any parts house. Be-sure to fill the new unit first and run it to make sure you get all the air out of it before you connect it to the lines. As far as the coupler we have always just had it welded up solid, only takes few mines and cost very little.
I have pulled boats all over the country with this and love it. I think it should be standard on any large trailer. Good luck.

Thanx for the ideas. Welding the coupler together would definately work. How well do these units work when reversing?

I was looking for a coupler to clean-up my installation and thought that I found one rated high enough and specifically told the people that I ordered it from that I did not want a BullDog type coupler(split over the ball with a sleeve that slides and holds the halves). They special ordered the part (20,000# rating) and shipped it to me and it was the exact coupling I did not want. Said it was special order and would not allow me to return it. Anybody need a 20k# BullDog coupler? I still want a coupler that will attach to my Al trailer to replace the disabled surge unit.