How to install trailer coupler on Camplite 14DBS. Do I need foam insulation?

[RV Squirrel]

Late last year I noticed that the trailer coupler on my CL 14DBS began to get cracks around the bolt holes.  I recently purchased a new coupler from etrailer.  I had to get a "weld on" coupler because the "bolt on" models had the holes in the wrong place (horizontal, not vertical).  I intend to drill holes in the "weld on" coupler to match the existing holes in the aluminum frame.

When I removed the old coupler, I noticed that there was something like foam insulation tape on the coupler.  Does anyone know why it is there?  At first I thought that it was there to provide a "snug fit" (which admittedly sounds a little strange).  Now I am wondering if it was there to provide a barrier between dissimilar metals (iron coupler and aluminum frame). 

I went to the Lowes to look for robust foam rubber tape, and the best that I could find was sponge window seal, which looks like it would compress a lot and may not be a good dielectric. 

I have some old 3M tape that seems less compressible, but definitely not rubber.  I'm not sure of the part number, but it looks like this.

Any ideas?  Do I need something to provide a barrier between dissimilar metals (which are going to be held together with bolts anyway) or to provide a "snug fit"?

I've attached pictures of the old coupler (hairline crack on top of coupler, and black foam tape on bottom of coupler).

[Merlin]

Scary cracks! Good thing you noticed. I also assume the strips are there to reduce galvanic action between steel and aluminum. Etrailer will know what to use there, so give them a call or email.

Member @charliem added side bolts to his hitch to reduce the stress causing the kind of cracks you have. I'll see if I can find his photos of that. As long as you're drilling, you may want to add those too.

[RV Squirrel]

As Merlin suggested, I called Etrailer.  I asked if they thought that the strips were there to reduce galvanic action between the steel and aluminum.  They quickly said "yes", but then pointed out that the hitch that I had ordered was zinc-plated, so it should not have any problem.  I was confused, because it looked like the old hitch coupler was zinc-plated as well.  When I asked them why Camplite would put foamy insulation strips on a zinc-plated coupler, they didn't have an answer.

They did not think that it would hurt anything if I were to add the foamy strips, though.  When I described the two types that I had, they seemed to lean more toward the more compressible foam ones but did not have a strong opinion about it.  So I'm back to deciding which tape to use, if any.  I probably will use something though.  Any thoughts here would be appreciated.

I thought about buying the "bolt on" coupler, but thought that Camplite probably had a good reason for putting the holes where they are.  Given that there are already holes in the aluminum frame, I'm leery about adding new ones.  This past coupler lasted nearly 10 years... if the new one lasts as long before it bends then I'll be a happy camper.  I'd rather the coupler bend then my aluminum frame. 

I'd appreciate seeing the pictures if you have them though.  I found the following from charliem, but it seems to be before he made repairs: https://aluminumcamperforum.com/index.php?topic=1338.msg9756#msg9756.

I have stabilizer bars on my trailer. When they were originally installed, I heard someone at the dealership express concerns that the stabilizers might cause the frame to bend.  Could it have caused the coupler to crack instead?

[RV Squirrel]

A good amount of discussion has been occurring with CharlieM at Coupler Replacement Side Bolts

Now that I finally have the hitch coupler installed it seemed appropriate to wrap things up here.  I think that the hitch coupler may have cracked since the bolts were put in at an angle (see first picture).  Since the holes went entirely through the frame, I didn't have much choice other than to put them back in at the same angles. (Yes, Charlie... this may be a good reason to put in those extra side bolts!)

CharlieM said that he got his foamy tape at an auto parts store.  I went to one and found "nitrile camper tape".  It was a little wider and thicker, but seemed to be made of the same material (see second picture). 

I've attached a picture of the final install as well (third picture).

[Merlin]

Nice job! Good follow-up. I bet Charlie will talk you into side bolts.