ddd4114
forum member
I know this topic has been pretty thoroughly covered, but considering the importance of proper harness mounting, I wanted to get some feedback before diving into it. I'm probably being a little over-cautious, but... "better safe than sorry".
I already have a rollbar and a fixed-back seat installed, and I'd like to add a 6-point harness in the next couple of weeks. I took some rough measurements today so I can order hardware, and I realized that adding attachment points doesn't look as straightforward as I originally thought.
The shoulder belts are easy since they simply wrap around the harness bar, and I'll most likely use the OEM right-side lap belt location (provided on my seat bracket). However, the left-side OEM location is too far back. That side would have a much longer belt (more stretching), and it would be at too shallow of an angle per Schroth's instructions. Therefore, I'll have to add a new mounting point.
Based on Schroth's 60 degree recommendation, it looks like I'll have to add an eyebolt here, right in the corner of the floor:
I took some rough measurements, and it looks like that will end up somewhere around here on the bottom of the car (marked with the red circle):
However, due to the way the frame is shaped, it's pretty much impossible to add a standard reinforcement place there. My idea was to use an ~8" length of 1.0"x1.0" rectangular tubing (0.120" wall) and place it parallel with the frame rail to spread the load (see the blue outline in the image). However, the floor isn't very flat in that area, so I'm not sure how well that will work. There is as much as a 3/4" difference between the lowest and highest points, so I'd expect that it would deform a lot in anything more than a minor collision.
Next, appropriate locations for the anti-submarine strap mounting points seem limited. Once again, the normal reinforcement plates are too wide to use by themselves, so I'd have to do something different. Based on my rough measurements, the attachment points would have to be around the red circles in this picture to get a 6" distance between them:
It looks pretty difficult to get the attachments points closer to Schroth's 4" recommendation. Even at 6" apart, the floor near the transmission tunnel is (once again) very uneven, and the fuel lines might make the outboard point interesting. I think the 1.0"x1.0" tubing idea might work again here, roughly where I put the blue outlines.
Alternatively, I could make a structure that attaches to the seat bracket and has two eyebolts for the mounting locations. However, I'd rather not go with that idea because I don't want to load the seat bracket more than necessary. While the floor isn't very strong, I can reinforce it, and I'm not limited by the two M8 bolts and two M8 (I think?) studs that hold the seat in place.
Unfortunately, I don't have easy access to a lift or welder, so my options are a bit limited if I tackle this myself. Otherwise, I'll have to pay a shop to do it for me.
If I go with rectangular tubes for reinforcement, I'm also concerned about eyebolt length. I could probably use 1.0"x0.5" tubing with 0.065" walls and reinforce it with a section of 1/8" plate, but it would only give me another 3/8". Schroth only offers 22mm and 38mm eyebolts, so I doubt that I'll easily find something longer.
What have you guys done in the past that doesn't involve welding to the frame? Does my approach seem reasonable? I've spent hours reading things on the web, and I couldn't find any specifics for S197's beyond "drill into the floor".
Thanks.
I already have a rollbar and a fixed-back seat installed, and I'd like to add a 6-point harness in the next couple of weeks. I took some rough measurements today so I can order hardware, and I realized that adding attachment points doesn't look as straightforward as I originally thought.
The shoulder belts are easy since they simply wrap around the harness bar, and I'll most likely use the OEM right-side lap belt location (provided on my seat bracket). However, the left-side OEM location is too far back. That side would have a much longer belt (more stretching), and it would be at too shallow of an angle per Schroth's instructions. Therefore, I'll have to add a new mounting point.
Based on Schroth's 60 degree recommendation, it looks like I'll have to add an eyebolt here, right in the corner of the floor:
I took some rough measurements, and it looks like that will end up somewhere around here on the bottom of the car (marked with the red circle):
However, due to the way the frame is shaped, it's pretty much impossible to add a standard reinforcement place there. My idea was to use an ~8" length of 1.0"x1.0" rectangular tubing (0.120" wall) and place it parallel with the frame rail to spread the load (see the blue outline in the image). However, the floor isn't very flat in that area, so I'm not sure how well that will work. There is as much as a 3/4" difference between the lowest and highest points, so I'd expect that it would deform a lot in anything more than a minor collision.
Next, appropriate locations for the anti-submarine strap mounting points seem limited. Once again, the normal reinforcement plates are too wide to use by themselves, so I'd have to do something different. Based on my rough measurements, the attachment points would have to be around the red circles in this picture to get a 6" distance between them:
It looks pretty difficult to get the attachments points closer to Schroth's 4" recommendation. Even at 6" apart, the floor near the transmission tunnel is (once again) very uneven, and the fuel lines might make the outboard point interesting. I think the 1.0"x1.0" tubing idea might work again here, roughly where I put the blue outlines.
Alternatively, I could make a structure that attaches to the seat bracket and has two eyebolts for the mounting locations. However, I'd rather not go with that idea because I don't want to load the seat bracket more than necessary. While the floor isn't very strong, I can reinforce it, and I'm not limited by the two M8 bolts and two M8 (I think?) studs that hold the seat in place.
Unfortunately, I don't have easy access to a lift or welder, so my options are a bit limited if I tackle this myself. Otherwise, I'll have to pay a shop to do it for me.
If I go with rectangular tubes for reinforcement, I'm also concerned about eyebolt length. I could probably use 1.0"x0.5" tubing with 0.065" walls and reinforce it with a section of 1/8" plate, but it would only give me another 3/8". Schroth only offers 22mm and 38mm eyebolts, so I doubt that I'll easily find something longer.
What have you guys done in the past that doesn't involve welding to the frame? Does my approach seem reasonable? I've spent hours reading things on the web, and I couldn't find any specifics for S197's beyond "drill into the floor".
Thanks.