So on some projects it seems the shopping/research/ordering is the most difficult part...Trying to figure ot which swivels are the best, what problems could occur, what people gave good reviews to and bad and why... this was one of those projects where i went down the figurative rabbit hole way to far!
All swivels are going to raise your seats at least an inch, which i didn't love the idea of- but theres simply no getting around unless you want to cut/lower your factory seat box, which also causes trouble because the drivers side at least is stuffed full of fuses and wires, which is going to open an even bigger headache for you.
As it turns out, the front seats in the sprinter are so high to begin with, and the floor in the rear falls away as it is...so your unlikely to have your feet touch down in the back even without the extra inch (we will eventually build a footrest/additional storage for at least the shorter of us if not both)... so it becomes a bit of a moot point. Basically, its a tie.
Apparently, several makers of swivel seats actually wont swivel without having to open the door first. Not exactly convenient, but even for people who stealth camp as much as we do- you aren't likely to swivel the seats when hiding out so probably not the end of the world to pop the door open for a second when entering your chosen campground, park, beach or wilderness area. Still, we went the other way.
I wanted the heaviest, most solid most tested and approved swivel i could find and i wanted to rotate without opening our doors. We ended up going with Eurocampers swivels and so far are glad we did. These bases are HEFTY. Like, solid steel. Like you'll wish you had team lifted with a buddy. They are also in german and have mercedes emblems on the sticker (the same as all stickers hiding out inside the depths of the sprinter itself), so i'm fairly certain these are the same swivels install from the factory (which we would have done if we ended up having to order...but didn't have a chance since we jumped on our sprinter because it was available and on the lot immediately.)
The process should be pretty simple- take out the old seats, put in the swivels and reinstall. You will need specialty tools for this, so either be ready or plan a trip to the hardware store (luckily our community shop had a set waiting on us even though Ive never seen that set before or after the day we did this project (thank you sprinter gods).
We opted to leave the seatbelts attached and instead of pulling the seat all the way out simply push it to the side. Our drivers swivel went on smoothly enough. Holes lined up like a glove and we simply bolted it down and moved along (after gawking for a while at the nest of fuses and wires under the seat, which i'm certain I'll need access to in a future phase). If you have a late model sprinter you'll also need a way to lower the emergency/hand brake...but it came with our kit from eurocamper, so it was just another step (attaching the new brake mounting plate) in the install.
The passenger seat (sadly) wasn't quite as willing. I had read online that a few people had swivels delivered that needed redrilling of the holes because they were misaligned...add ours to the list. It was only out a fraction of an inch. Infuriatingly so. We tried everything to get the bolts to start threading, but the hole was off just...just enough that we couldn't get the threading to catch. Deep sigh. At least we were already at the shop.
This didn't sound like that big of a deal when i read those stories...but because the seat base is such a thick grade of steel you cant simply pull our your handdrill and widen the hole. In our case, it appeared we could get away with only re-drilling one hole, but the act of setting up this giant movable object on the drill press was a feat to behold. Trying to figure out how to safely clamp this monster down took the majority of our time. Then we simply widened the hole in the right direction and got back to work.
With both installed, we swiveled them around facing the back and hung out for a while in the new, larger, more comfortable camper space. Love it.
Before this we had talked about building in a bench of seats in the back, but now I think we'll go with the swivels alone. If were stealth camping and cant move the seats, chances are we'll either be out exploring, or we'll be in the bed so no real loss there.