Fiat Punto GT
I've been trawling the internet over the last few weeks looking at the tonne of information relating to proper harness mounting. I also had a good look at the instructions that came with my Schroth harness.
I've now come to the conclusion that my harnesses are complete unsafe and that they need remounting.
The distance between the back of the seat and the mounting points is far too long, this needs to be as short as possible to prevent slack. Most modern cars and especially Fiats crumple in an impact. If I was to be involved in a rear end shunt, it's likely that the mounting points I have use will spring forward causing slack in the harness. To solve this you would use a harness bar, either independent or as part of a roll cage.
Shown here is one fitted to a 911:
The mounting angle is also to much, they need to be within 15-20 degrees of a horizontal line from the holes in the seat back. This is to ensure that the harnesses stay on your shoulders and do not put too much pressure on your shoulders.
This image shows the shoulder belt and lap belt angles:
The lap straps must be routed so that:
· lap belt strap length must be as short as possible. The distance between the lap belt anchor points should not be greater than the width of occupant’s pelvis or the outer width of the occupant’s bucket seat. The distance of approximately 400 mm [16”] is recommended. If there are choices of several anchor points choose those that come the closest to these recommendations.
· Lap belt straps must be routed over the pelvic bone to stay firmly and tightly in the crest between the pelvic bone and the upper thigh.
· Lap belt downward angle should be approximately 60° measured from the horizontal, passing through the occupant’s hip joint. This is the suggested angle for upright seating [15-20° backrest declination]. A higher backrest declination, e.g. 30° – 40°, as is common in open wheel race cars, requires a belt angle of 70° – 80°.
· Make sure there are no sharp edges [seat structure, seat mounts, chassis] that may tear or cut the lap belt webbing.
Also, in the above image note that the shoulder belts should not be straight from each shoulder when the distance is greater than 500mm [20“] behind the seatback.
POSITIONING OF SHOULDER STRAP ANCHOR POINTS
X = Distance from Shoulder Points to attachment. Take the measurement from the highest shoulder point.
Z = Distance from the middle of the left shoulder point of the webbing to the middle of the right shoulder point of the webbing.
Y = Approximate distance between anchor points. [measured from the middle of the webbing at the left anchor point to the middle of the webbing at the right anchor point]
Approximate result: the shoulder belts will cross over when the anchor points are located more than approx. 500 mm [20”] behind the seat backrest.
And finally, the mounting points themselves.
Tightening Torques by Bolt Dimension
• Each bolt diameter and type of thread requires an individual torque for proper tightening. These torques as listed below are defined by national or international standardisation organisations.
• For safe installation always tighten bolts to the recommended torque.
• For any installation use e.g. “Loctite 243” or spring washers where recommended to secure bolt fastening.
Bolt size - 7/16” 20 UNF / Torque in Nm 40 / Torque in lbinch 30
For new attachment points to the chassis you should use a FIA specified reinforcement plate.
• Drill a hole of 12 mm diameter for lap- & shoulder belt and 5-point anti-sub strap attachments.
• Use seal compound and stick the reinforcement plate from underneath to the floor panel. The seal also helps to prevent water intrusion.
This is just my take on the guidelines I've been reading and some of the reports I've read when people haven't followed this. I am not by any means an expert on this, so if anyone knows more than me, please feel free to speak up.
I know I'll be redoing my harness mountings ASAP to fall in line with these guidelines.
Hope this helps.
I've now come to the conclusion that my harnesses are complete unsafe and that they need remounting.
The distance between the back of the seat and the mounting points is far too long, this needs to be as short as possible to prevent slack. Most modern cars and especially Fiats crumple in an impact. If I was to be involved in a rear end shunt, it's likely that the mounting points I have use will spring forward causing slack in the harness. To solve this you would use a harness bar, either independent or as part of a roll cage.
Shown here is one fitted to a 911:
The mounting angle is also to much, they need to be within 15-20 degrees of a horizontal line from the holes in the seat back. This is to ensure that the harnesses stay on your shoulders and do not put too much pressure on your shoulders.
This image shows the shoulder belt and lap belt angles:
The lap straps must be routed so that:
· lap belt strap length must be as short as possible. The distance between the lap belt anchor points should not be greater than the width of occupant’s pelvis or the outer width of the occupant’s bucket seat. The distance of approximately 400 mm [16”] is recommended. If there are choices of several anchor points choose those that come the closest to these recommendations.
· Lap belt straps must be routed over the pelvic bone to stay firmly and tightly in the crest between the pelvic bone and the upper thigh.
· Lap belt downward angle should be approximately 60° measured from the horizontal, passing through the occupant’s hip joint. This is the suggested angle for upright seating [15-20° backrest declination]. A higher backrest declination, e.g. 30° – 40°, as is common in open wheel race cars, requires a belt angle of 70° – 80°.
· Make sure there are no sharp edges [seat structure, seat mounts, chassis] that may tear or cut the lap belt webbing.
Also, in the above image note that the shoulder belts should not be straight from each shoulder when the distance is greater than 500mm [20“] behind the seatback.
POSITIONING OF SHOULDER STRAP ANCHOR POINTS
X = Distance from Shoulder Points to attachment. Take the measurement from the highest shoulder point.
Z = Distance from the middle of the left shoulder point of the webbing to the middle of the right shoulder point of the webbing.
Y = Approximate distance between anchor points. [measured from the middle of the webbing at the left anchor point to the middle of the webbing at the right anchor point]
Approximate result: the shoulder belts will cross over when the anchor points are located more than approx. 500 mm [20”] behind the seat backrest.
And finally, the mounting points themselves.
Tightening Torques by Bolt Dimension
• Each bolt diameter and type of thread requires an individual torque for proper tightening. These torques as listed below are defined by national or international standardisation organisations.
• For safe installation always tighten bolts to the recommended torque.
• For any installation use e.g. “Loctite 243” or spring washers where recommended to secure bolt fastening.
Bolt size - 7/16” 20 UNF / Torque in Nm 40 / Torque in lbinch 30
For new attachment points to the chassis you should use a FIA specified reinforcement plate.
• Drill a hole of 12 mm diameter for lap- & shoulder belt and 5-point anti-sub strap attachments.
• Use seal compound and stick the reinforcement plate from underneath to the floor panel. The seal also helps to prevent water intrusion.
This is just my take on the guidelines I've been reading and some of the reports I've read when people haven't followed this. I am not by any means an expert on this, so if anyone knows more than me, please feel free to speak up.
I know I'll be redoing my harness mountings ASAP to fall in line with these guidelines.
Hope this helps.
