Add addl. seatbelts?

texasmb

New member
Hi, my husband and I have a 2005 MB Cruiser/Sprinter/Diesel. It only has 3 seatbelts. We would like to add 1 or 2 additional seatbelts. Can this be done? Thanks for any info on that subject.
texasmb.
 

sikwan

06 Tin Can
There are online places that sell seat belt parts, but where are you thinking of adding more seat belts to?
 

texasmb

New member
I was hoping on the sofa. My husband just tells me there is NOTHING to connect these belts to. Is that correct??
 

220629

Well-known member
Re: adding seat belts?

Let me say first this is totally my opinion. I'm certain others can enlighten you as to the legal implications of modifications.

If the vehicle were carrying passengers for hire, my response would be that they wouldn't be good enough unless they were factory/dealer installed.

For a private use vehicle I would say that they can be added, but there are standards as to installation design, fastener type, backer washer size, etc. that may be difficult to conform to. As a practical matter if you review the standards, install to that design and your seatbelt installation withstands an accident without failure (heaven forbid that test ever happens) you will be fine. Whether you feel comfortable with that is your decision. Hope this helps.
 

sikwan

06 Tin Can
I was hoping on the sofa. My husband just tells me there is NOTHING to connect these belts to. Is that correct??
He may be correct.

If it's an aftermarket sofa, and it sounds like it is, there may not be any provisions for seatbelts. Another thing is you can probably get away with lap belts (if you can mount them through to the floor correctly), but the shoulder belts need to be mounted correctly. The pivot point of the shoulder belt needs to be above the shoulder, but not so far that it's mounted on the roof.

Not easy to just slap a few belts and call it a day.
 

autostaretx

Erratic Member
Well, as it happens i recently -did- this.

I added a sideways-facing Flexsteel sofabed (purchased from Camper's World) and then added lap belts. The sofa/bed was as rear in the van as possible, on the driver's side.
(in a 118" passenger van, with the original seats removed).

There were lots of factors:
(a) here in Washington State, you are not -required- to have seatbelts in the rear area, if they were not put there for the seats you're using by the original vehicle manufacturer.
(b) in Australia (and most other places) they may require seatbelts on all forward/rearward facing seats, but they do -not- require belts on sideways-facing seats, both for "lack of data" and the possibilites of severe trauma from the lateral forces.
(c) some juristictions don't allow seating if there are not seatbelts there.

When you buy "add in" seat belts, they come with big washers and stronger, fine-thread bolts for the attachments.
And recommendations for the angle which the belt should rise from the floor, usually about 70 degrees.
In our case (with the movable bed frame) that required cutting holes through the foam mattress to hit the angle.
You can run a plate under the Sprinter floor to spread the anticipated forces across a wider area.
In my case, the places we wanted to mount the belt anchors were "inconvenient" in terms of how they hit the understructure. So i created bridging structures in the van which let me bolt through the floor fore and aft of the underframe. With those, I was even able to use the existing seat receiver attachment bolts (after buying longer, harder versions) for one end of each "bridge". The bridges were short-side steel channel, which just allowed the head of the belt attachment bolt to clear the floor.
Eventually i'll add a second (and perhaps third) set of belts back there. At least the second set will be "simple" drill through the floor just beside where the wheel well's inner wall ends.
I did not do a shoulder harness, since the "stong point" would've put the anchor behind the passenger.

I'm not -thrilled- with the current installation, it was done quickly for a "must have third seat" visitor, and had to be fully removable for our cargo usage.
That trip has passed, the belts were not "tested" by any accident.

If your sofa is in a permanent spot, you can add lots of above-the-floor bracing (such as my "bridge") to help with the "where can we bolt them?" issues

have fun
--dick
 
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BaywoodBill

pre-Yuppiedom
Is that a stock sofa in the MB Cruiser? You have the bathroom in the rear, right?

If it's a sofa mounted along the side then autostartex's mention of "severe trauma from lateral forces" is a concern.
 

KL2BE

Member
I was hoping on the sofa. My husband just tells me there is NOTHING to connect these belts to. Is that correct??
I bought a seat-belt (lap) at Schucks for $20 :thumbup:. Installed it for the rear sofa using the same anchor bolts as for the existing center lap-belt :smirk:. Took all of 10 minutes :rad:; now I can seat 4 abreast in the rear of our LTV Free Spirit :cheers:.
Just completed a 500 mile trip with two Moms (82 & 88) and two grandchildren (2 & 4) :clapping: . It worked fine (lap-belts are actually better for anchoring the child-seats).
My next project is to figure out how to disable the passenger-side air bag so our granddaughter can use the front seat with her car-seat :thinking:.
 

sikwan

06 Tin Can
My next project is to figure out how to disable the passenger-side air bag so our granddaughter can use the front seat with her car-seat :thinking:.
Connect a 2 ohm resistor in place of the airbag or connect up a switch that reroutes the signal to either the resistor or airbag. Be careful on the switching. It must be switched when the key is off otherwise it will store a code and it will have to be reset at the dealer.

I removed mine entirely and replaced it with a cd changer.
IMGP0007.JPG
After everything is buttoned down, you can't tell it's there.

Sorry for the hijack.
 

KL2BE

Member
Connect a 2 ohm resistor in place of the airbag or connect up a switch that reroutes the signal to either the resistor or airbag. Be careful on the switching. It must be switched when the key is off otherwise it will store a code and it will have to be reset at the dealer.

I removed mine entirely and replaced it with a cd changer.
View attachment 9177
Thank you very much for the info :bow: !
It may be a while before I get to the project, but I've now printed a copy of your note; will be back in-touch if I run into problems finding the right wires :thinking:.
 

zigzagguzzi

05 Interstate, N. Fl.
My 05 Airstream Interstate has factory seatbelts on the foldout bedsofa thing which sits front to back. There is also a belt on the front facing dinette seat. These are all attached to the floor. Seatbelts for 5 but only sleeps 2. zz
 

Allan McInnis

Seasoned Member
can the air bag be switched off? I have a laptop computer posed to be launch by a air bag discharge. I would like the option to switch it off. Where and what do I tap into to place a switch/
 

sikwan

06 Tin Can
can the air bag be switched off? I have a laptop computer posed to be launch by a air bag discharge. I would like the option to switch it off. Where and what do I tap into to place a switch/
Easiest way is to just pull the airbag fuse underneath the steering column. I don't know if that will store a code, but it is the fuse to the airbag control module.

You can't just switch it off. You need to do some wire rerouting to resistor. That is how most airbag switches are made. It just reroutes the line to a resistor.

The wire is here at #5...
airbag.JPG
To remove the connector, press the connector into the airbag and it should just pop off.
 

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