Why does it not feel like it's secure?

[atx]

Installing my Britax boulevard in my mom's borrowed 1998 Mercedes S320 and I don't find any LATCH in the back, only lap belts. So following the instructions for rear facing for a lap belt, I did my very best to install it, pushing down on it as hard as I could to get the seat belt to tighten and not using the lock offs.

It's ok but has a little wiggle room but I'm not sure if it's less than or equal to an inch. I'm so used to the LATCH install that it feels loose and I can't say for certain that it's less than an inch. I don't know how to get it tighter. I practically sat in the seat trying to get it as tight as possible. Are there other tricks for lap belt RF install?

Also, I can't find the D Ring connector to tether it for added stability. I guess I'll go hunting to see if I can order one.

[queenmama]

I've never used a latch install (our cars don't have them), I just put all of my weight down on the seat while pulling the belt. Sometimes it's easier to accomplish this with a partner for a RF install. Our Roundabouts never wiggled a bit! I love Britax for this reason!

[jjordan]

I would guess that it is fine. Most people pull too hard on the seat when they're testing for movement. Remember you want to use your non-dominant hand, and only pull as hard as a firm handshake. The length of your thumb between the knuckle and the tip is about 1", so you can use that to help determine if you have too much movement. Take note of where one particular point on the seat is at the "outsides" of the movement, and compare that distance to your thumb.

One thing that can happen with lap-only belts is that they might not lock properly if the latchplate is too close to where the seatbelt bends to go through the car seat. If that happens, then the belt does not lock properly, which could be the reason for the movement. If you think this is the case, two possible fixes: (1) bring the latchplate down out of the belt path by twisting the "female" end of the seatbelt up to 3 full (360*) twists, or (2) flip the "male" end of the seatbelt over 180*.

[legaleagle]

Is this a lap only belt or a lap and shoulder belt?

[Joolsplus2]

Is this a lap only belt or a lap and shoulder belt?

Yeah, that's my question...since you didn't use the lockoffs (why not? They are great for getting a tight install, once you figure them out--ask me how long that took ME to do! lol), then a shoulderbelt would need to be manually locked, like, pull it all the way out so it can retract slowly and stay tight.
Mercedes are a pain, I remember hating them back in the days when I did a lot of installs, I definitely needed some sort of rolled towel or pool noodle in the seat bight to get Britaxes in right.

[atx]

It's a lap belt only and the instructions said not to use the lock offs if lap belt only.

[mom2binsd]

Hmm, are you installing in the center position, if so, try using the outboard positions (which should have a lap/shoulder belt and then you can use the lock offs) often the outboard spot is flatter and you get a better install.

[Joolsplus2]

Ah ok, lapbelt (sorry, you would not *believe* how often I read people say 'lap belt' and don't really mean it, I should know someone on HERE would use the proper terminology! :love-retry:). Anyway, you still can use a lockoff to see if it helps (in this case, it would not be performing the function of a pre crash positioner, like it does with a lap/shoulderbelt, it would be performing the function of clamping the seat to the belt, so the seat can't slide relative to the belt in a crash), and I think even a rolled handtowel in the seat bight might be just enough to keep the front of the base from wobbling (if memory serves, and of course that's with the old style seats, so it might NOT do the trick, but it's worth a shot).