Re: Successful Three Across thread - 1988 Subaru Wagon (GL-10)
This is my husband's 1988 Subaru GL-10 wagon. The widest part of the seat is 50 inches. However, the molding where the seat belt comes out cuts in to the seat, leaving us with only 41.5 inches at the seat bight. Fortunately, the seat is flat - there are no contours.
I have done multiples that work.
My favorite: Frontier 90, RF Britax Roundabout 50, RF Radian (The Roundabout's widest parts fit PERFECTLY in the Frontier's most narrow parts, and then overlaps the Radian on the other side)
Frontier 90, FF Britax Roundabout 50, FF Radian (The Roundabout has to nest over the Radian)
Frontier 90, FF Radian, FF Britax Roundabout 50
Harmony Defender, FF Britax Roundabout 50, and FF Radian.
Frontier 90, RF Radian (With Angle Adjuster), RF Radian
Harmony Defender, RF Radian (with Angle Adjuster), RF Britax Roundabout 50 (Again, the Roundabout has to nest over the Radian.)
FF Radian, Harmony Defender, FF Britax Roundabout 50 (The Defender in the middle ONLY works when the other 2 are FF)
FF Radian, Harmony Defender, Baby Trend infant seat (I imagine a FF Britax Roundabout 50 would work in place of a Radian, but for some reason I didn't try)
RF Radian (with Angle Adjuster), Harmony Defender, Baby Trend infant seat (I don't believe a RF Britax Roundabout 50 would have fit in place of the Radian)
The most tricky are the rear-facing combos.
In case it matters, I have Sunshine Kids Radians, not Dionos.
Obviously all are using seat belt, as there was no lower anchors in 88. I had to twist the belt stalk 3 times on all of my seats in every scenario. The webbing is very tall. These belts are Active Locking Retractors (ALR), meaning as soon as you pull the belt out, it is locked. You will need someone to hold the belt while you thread it through the belt path, or something to grab it and hold it. In our case, we used a bread clip. It worked wonderfully. I can't install car seats without it in this car anymore.
I am a tech, but I don't believe that makes my installs any better than someone who has read their manual and knows how to get a seat belt tight. I have not had it double checked by anyone else, but I did check that they were all independently tight.
The tether needs to be retro-fitted if you are going to use either the Harmony or the Frontier, as both REQUIRE the tether to be used. It is hiding in the headliner in the very back of the car. You may need this to get it done:
http://www.seccs.org/tech/1996 Legacy/Tech Service Bulletin/17-04-9934511.pdf
If I can do 3-across with 41.5 inches to work with, I bet anyone can get a wider back seat to work (contours in the seat definitely make or break it though).