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Discussion Starter #1
Hey everyone.

I have a 1993 Honda Civic del Sol Si. It's built for street and track duty - mostly weekend open lapping sessions during the spring/summer/fall months. I recently swapped a JDM OBD1 GSR with an S80 ITR LSD transmission after blowing up my NA d16z6 this past May (still stings deeply...). I will be selling the custom built S40B000 5-speed soon. I plan on installing a BuddyClub P1 racing seat this spring. I already have a Takata 4-point harness and plan on getting a bar installed behind the seats.

I wanted to know if it's possible to install the racing seat and still be able to keep the OEM seat belts. I would like to keep and use them for normal street use (which is very infrequent) so that I'm not strapping into a 4-point harness every time I go for a short drive.

​​​​​​​Thanks.
 

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Discussion Starter #3
I've been researching this topic and I think I've come to the conclusion that I won't be going this route.

I could install the bucket/racing seat and use the OEM seat belt with certain modifications but the seat belt would not work as effectively. The high side leg bolster would create too large of a gap between the lap belt and the pelvis. The belt should be firmly against the pelvis to hold in into the seat. Even if you are able to feed the buckle through the opening at the side bolster, the shoulder strap would run into a similar problem with the side shoulder bolster. The three point seat belt is designed to work with a seat that is not a fixed bucket. I contacted Buddy Club and they told me that I could use the OEM seat belt with the seat but I would need to relocate the buckle to the seat side rail. The issue with the gap between the seat belt and the body remains however.

The next option would be to use the Takata Drift II 4-point harness that I already own. I was looking into how I would install this and how it would work. The harness is designed to keep the torso firmly planted in the seat at the level of the shoulders and the waist. However, in circumstances where the inertia from an impact wants to throw the body foreard, the torso doesn't move but the head does. Unless you're using a HANS device or a neck roll, your head will be thrown forward with significant force and forward flexion of the neck causing vertebral injury, spinal cord injury or significant brain injury. You shouldn't use it for street driving because of this.

The other thing that can happen unless the harness is designed to prevent it, like the Drift II is, is a phenomenon called "submarining". Some people believe that it's what happens when you slip under the harness and fall into the foot well. In actual fact, what happens is that the shoulder harness pulls the waist harness upward into the abdomen rather than keeping it at the pelvic bones. This can lead to significant internal organ damage. The other thing that can happen is the harness can forcefully pull the torso down into the seat creating an axial load leading to compression fractures of the vertebral bodies.

I also contacted Takata to inquire as to how I would install the harness if I decided to use it. Since I have a del Sol with only two front seats and no rear seats to use the rear seat belts to fix the harness to as an option, I was advised that I would need to install a roll bar or roll cage. This is another dangerous modification. A roll bar to fix the harness to can and will warp and fail. A bar failure will result in the harness failing to keep the occupant fixed to their seat. The bar can impact the driver's head or the driver's head can impact the bar. Unless you're always wearing a helmet, this is a very dangerous and potentially life threatening situation. The same goes for a roll cage. Serious injury or death can occur if the head or neck hits the bar or cage.

So what I've learned is that a bucket seat and harness are not suitable for a vehicle that will also be driven on the street. An OEM seat belt doesn't work well with a fixed bucket. The only time it makes sense to install a roll bar or cage is when you install the safety equipment as a whole system. Bucket, harness, HANS, cage/bar.

I think I'll end up returning the harness and opt for a seat option that allows for movement of the upper torso portion and use of the OEM seat belts.
 

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Asshole
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I think you're way over thinking things. Where in the stock restraint system is the restraint that keeps your head in place during a crash? There isn't one.
 

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Discussion Starter #5 (Edited)
I think you're way over thinking things. Where in the stock restraint system is the restraint that keeps your head in place during a crash? There isn't one.
The stock restraint system is designed to allow the torso to move forward enough to reduce the amount of forward flexion of the neck. The stock seat belts are also designed to work with the airbags. The torso is allowed to flex forward enough to make contact with the airbag which in turn forces the torso back into the seat and further reduces the forward flexion of the neck. They are designed to work as a system.

Even the Takata Drift II system is designed to allow for just enough slack in the waist straps to reduce the amount of forward flexion of the torso and prevent "submarining".

Here's a great video that shows the effects of submarining but you can also see how the harness causes significantly increased forward flexion of the neck.
https://youtu.be/0Dv_zeveYR4

This forum was also a great source of information:
http://www.clubwrx.net/forums/interior-mods/134349661-seat-belt-harness-bar.html#/topics/134349661
 

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I've got the buddy club P1 seat and I use a factory belt. Yes it doesn't hug my pelvis, but hopefully I never get into a major accident either.
 

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Discussion Starter #7
I've got the buddy club P1 seat and I use a factory belt. Yes it doesn't hug my pelvis, but hopefully I never get into a major accident either.
I wonder if there's a way that you could disconnect the belt from the mounting points and route them through the openings at the sides of the seat - unless you've already done that.
 

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88 RT4WD wagon
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i use the stock belt in conjunction with a schroth ASM rallye 4. it has the extra fold of strap to allow you to rotate and not slide under the lap belts. you need to thread your stock shoulder belt through the seat harness hole as well as get an extender or find a way to bring the buckle through the other side but you should be able to have both bolted into the car and just pick one as necessary. This is all just a compromise until i can get some bars in there anyway though.
 
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