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Posted this in Mods and Customs - throwing out here to see if any one can help me out.

Preface: I spent the better part of Saturday reading through about 19 pages of posts about this subject. Didn't quite find what I was looking for.

Project: Installation of 3 point retractor belts in rear seat of '66 coupe

I see discussion about the safety issues with mounting the retractors on the trunk floor below shoulder height. I kinda sorta understand it. I saw some great posts and pictures on how to accomplish that task. What I"m interested in comparing this to is mounting the retractors somewhere on the rear package tray. I don't have alot of real estate available on it as it has the large 5 holes on mine.

Anyone have any photo's of seat belt retractors installed on their rear tray as opposed to the trunk floor?

Thanks
J
 

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being the rear tray is very thin and flimsy I wouldn't recommend it. I always recommend NOT trying to add 3 point belts in a car that didn't have them. Adding them incorrectly can do more harm than good.
 
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+1 to that. Don't mount them to the tray, they'll rip right out when you need them most. Unless you can seriously over engineer that package tray.
 

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Mine are mounted to the rear trunk floor / frame and pass through the package tray metal, the package tray board and a plastic guide that are just above shoulder level for my occasional rear passengers...and the shoulder harness through that is still safer than just a lap belt any day. Maybe not as strong as a brand new Mustang, but definitely an improvement.
 

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Mine are mounted to the rear trunk floor / frame and pass through the package tray metal, the package tray board and a plastic guide that are just above shoulder level for my occasional rear passengers...and the shoulder harness through that is still safer than just a lap belt any day. Maybe not as strong as a brand new Mustang, but definitely an improvement.
Out of curiousity where is the mounting point in the trunk?
 

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There is WAY more to safety restraints than the strength of the mount. There is a reason that sanctioning bodies have rules about where the mounts can be placed in relation to the person sitting in the seat.
 

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The retractors are bolted on the trunk floor through the edge of the frame rail overlap at the apex of the wheel arc with some steel plate and grade 8 bolts to help prevent shear / tear-through. The other two mounting points use the factory ones on either side of the rear seat occupants. I'm not a mechanical engineer but I did pass a Holiday Inn Express on my way home...
 

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I am not sure why you would be worried about mounting them the floor? The Factory rear lap belts are mounted to an anchor installed on the bottom of the floor and they work just fine(outer mount). The inner mount for the rears is mounted to the vertical section of the floor right by where the dual exhaust hangers are(this is an area that is prone to rust and probably not the best choice, but its where Ford put them). The front inner anchors are mounted to the side of the trans tunnel, with the outers being mounted to the rockers. The point being....mounting to the floor is perfectly acceptable...just use actual seat belt anchors spot welded or perimeter welded to the bottom of the floor pan and you are being just as safe as Ford was with their seat belt mounting locations(for whatever that is worth).

If you want to add a layer of strength(this is what I would do myself), when you place the floor anchor plates, simply install some gussets tying those plates to the rockers as well as the floor pans(or in my case, they would tie into my jacking rails). I do NOT reccomend installing belts to the floor pans without the correct anchors(IE, big washers that sandwich the floor pans like come in a lot of the kits). Proper seat belt anchors always have a bigger surface area to distribute force than washers....they also tend to be rectangular or oval in shape(when I added rear seat belt anchors to my car, I cut some anchors from 1/4" plate steel in a rectangle slightly larger than the stock ones and perimeter welded them to the floor pans).

For the OP: If you arent using the rear seat belts...I suppose you can always use the rear seat belt outer anchor?(though that would make for one long belt needed and probably would not be the cleanest look...at least it wouldn't flap in the wind though.
 

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I would not install the shoulder harness below the height of your shoulder, otherwise there's a downward force on your shoulder in a wreck. That's why you shouldn't use the rear seat belt mounts. The only time I've seen this done is in a racing style seat with shoulder harness slots and a seat that won't collapse from the downward force, even there it's more common to use a shoulder harness bar above the shoulders.

Why not install them on the roof rail, like the optional shoulder harness on a 67 mustang? Mine came with that option and has a stout threaded block that installed there. I don't see why that couldn't be done on an earlier mustang as long is the threads are installed properly.

Sent from my SM-G973U using Tapatalk
 

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I think this is getting off track. I believe the OP asked about REAR seat shoulder harnesses and anchoring them to package tray vs running them through the tray and anchoring in the trunk.
 

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While I am NOT an engineer, I find it helpful to visualize the loads a seat belt mount experiences during sudden deceleration. For example at the moment of impact (assume a frontal crash), your body is still traveling in the same direction and at the same speed the car was the moment before impact. The shoulder belt retractor locks up and restrains you as you move forward in your seat. That forward load of your still moving body on the shoulder belt pulls hard against the upper mount. The forward energy then follows the belt as it turns downward to the lower retractor mount which is typically anchored to the floor, rocker, or bulkhead. The retractor locks up due to the sudden acceleration of you and the load on the retractor then becomes upward, pulling the retractor toward the upper mount as your body quickly decelerates. If the retractor mount is sturdy enough, the restraint system remains intact to its design limits. If the retractor mount is not up to the task of dissipating forces of the sudden deceleration of your body, the upward force on the belt/retractor may overcome the mounting point and fail. Remember that the goal of a restraint system is to dissipate the energy of a fast moving body (yours) while minimizing the likelihood of serious injury or death. Sometimes the forces on your body are so great that even a well engineered restraint system cannot prevent serious injury or death. Simply put, there are few absolutes when it comes to surviving a high impact crash. It's called assumption of risk.

Short of hiring an engineer to design a mounting system with sufficient capacity to handle the anticipated deceleration load, reinforcing the retractor mounts sounds like a minimum upgrade to me. Just one guy's opinion, YMMV.
 

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To put things into perspective. I've only had one passenger using the rear seat once as my car is not a daily driver. My 66 pony though it can seat four persons, is in reality a small coupe. My car sagged in the rear with a person in the back and the performance suffered. This reality has not caused me to focus too much energy on the rear seat safety aspects. Instead I have place headrests on the buckets and insured my emergency brakes work.
 
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