Needed to twist seat belt stem on lap belt...

Hello, all. What a wonderful forum!

We had a certified CST help us to install our Britax Marathon rear-facing in the center position of our 1994 Subaru Legacy sedan. But wow, it was really a bear to get in there.

That center belt (a lap belt) is on a fairly long piece coming out of the seat (I'll call that piece, leading up to the female buckle, the "stem"). When tightening the seat, the buckle ended up on top of the seat body edge where the belt path enters the seat--a big no-no.

She had to twist the stem FIVE times to get it short enough that this was not a problem. She remembered that in her training class, they told her up to 5 was ok.

However, after multiple times taking the seat in and out of the car over the past year, I am having a tough time now getting it back in tightly enough.
1.) Could the twisted belt stem be stretching?
2.) Should I be concerned about strength of the belt now, and is 5 twists really ok?
3.) Someday when we go forward-facing, if the stem no longer needs to be twisted to install properly forward-facing, it the belt now weaker for if we untwist it?

I'm having a lot of trouble finding actual data on this issue.

Thanks so much.
Suzanne

Here's the entry from www.carseat.org under "technical", that should have the answer you are looking for...

In short, it looks like you can give it one more twist to shorten it down again as needed, and no, you aren't reducing the strength enough to be harmful to a child in a restraint

Twisted vehicle belt

There are three concerns about twisting vehicle belts under various usage conditions that are reflected in vehicle owner's manual warnings. First, belts that are directly restraining people work best if they spread the impact force over a wide area, and, if they are twisted, this area narrows. Second, a lap-shoulder belt that is twisted when threaded through a CR belt path may be difficult to tighten adequately, but, if tightened first and then twisted once at the latchplate, a locking clip may not be needed. Finally, twisting or tying a knot in belt webbing does reduce its strength, but recent tests have shown this reduction to be small and not enough to risk child safety. In general, warnings against twisting belts do not apply to the practice of twisting to make a secure CR installation possible.

Vehicle belt webbing is extremely strong and can withstand pull tests of over 6000 lb. This is 3 to 4 times the strength needed to restrain a 60-lb child in a severe crash. Laboratory tests conducted by IMMI Child Restraints in 1998-99 found that the average strength of vehicle belt webbing, pulled until failure, gradually reduced depending on the number of full twists: 1=6%, 2=11%, 3=20%, 6=40%. Some of the webbing had been soaked in apple juice or cola, which resulted in slightly more degradation than untreated webbing. When other samples were twisted and later untwisted, the webbing returned to its normal strength. These data indicate that up to three full twists in belt webbing will not reduce its strength enough to risk failure when restraining a child.

There are two situations that call for twisting vehicle belt webbing. First, with a lap-only belt, the locking latchplate may rest on the CR at a angle, so that it does not stay locked. By turning the latchplate over once (a half twist) and inserting it into the buckle, the locking bar will be held in place. If the tongue will not go into the buckle "backwards," turning the latchplate over again (a full twist) may provide enough friction to keep it from slipping. The second situation is for lap-shoulder belts, when the buckle is mounted on a short length of webbing, but this webbing may be a little too long to place the buckle where it can be tightened. Twisting the buckle end once or twice (full twists) may shorten it enough to solve the problem. This technique will not work if the webbing is very long or if the buckle is attached to a stiff cable. If the webbing is supported by a plastic sleeve, the parent may carefully slice down the sleeve and remove it.

thank you

It still worries me a little, as the paragraph notes that "These data indicate that up to three full twists in belt webbing will not reduce its strength enough to risk failure when restraining a child. " But the child is still only 25 lbs (the information cited was for 60lbs), the seat is probably another 15 lbs, and no acidic juices have spilled on the belt (so far).

It helps a lot to know that when we go forward-facing, the untwisted belt will be original strength.

Thanks!