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Swivel Harness bolts.


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So I understand this is a new thing that tech is checking.  We make sure that our belts are in tension on the proper angle but we bolt them tight.  I understand why tech wants them to swivel, but how is everyone doing this?   I have the lap belts bolted in with grade 8 bolts and mechanical locknuts.  Can I just loosen them a bit so they swivel?  From an engineering standpoint this makes me cringe.   I could also make a spacer that tightens up but that would require going down a bolt size and that’s counter intuitive too. 

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11548 bolted to the chassis. Lap&sub belts with 11546 D clip( don’t forget the cotter pin). This allows the belt to “swivel”. If mounted properly any of these types of hardware can be used. Be sure not to have anything pinched or not at correct angle to driver. 

image.jpeg

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I did the locknut+red and backed off just barely to allow it to swivel for years. I’m picky and was comfortable with it. 

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3 minutes ago, ETR said:

I did the locknut+red and backed off just barely to allow it to swivel for years. I’m picky and was comfortable with it. 

red?  As in painted it red so you can see if it’s loose or red loctite?

 

Has this passed tech inspection recently? 

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Look at your stock seat belts.  Perhaps not in all cars, but in many, the bolt has a sleeve that goes through the tab allowing the bolt to be torqued, but without pinching the tab that holds the nylon belt. 

 

Might not be the quite the right size, but something like this:

 

https://www.mcmaster.com/sleeve-washers/system-of-measurement~inch/for-screw-size~1-2/material~steel/

 

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8 minutes ago, petawawarace said:

red?  As in painted it red so you can see if it’s loose or red loctite?

 

Has this passed tech inspection recently? 


Just red loctite with a pretty substantial locknut.  Passed last 3 years like that. 
 

I just pulled them for new belts (expiration rule change) and went with snaps w/cotter pins this time, but the locknuts hadn’t budged till removal and there’s not really any reason for them to. 

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Posted (edited)

There are a couple of best practice options here. One is mentioned above using a shoulder sleeve over the bolt. Most of the racing seatbelt harness tabs have 1/2” holes in them. In the picture, The method on the right uses a 7/16-20 bolt with the shoulder sleeve, allowing the seat belt to rotate with the bolt fully tightened.  
The OEMs use shoulder bolts like the three in the center of the picture. The shoulder is a half inch, with 7/16 threads. You can torque it down fully and the seatbelt tab rotates on that. 

All of the bolts here have 7/16–20 threads. 
 

To do it right, I’d find some of the shoulder sleeves or shoulder bolts at a fastener store, or Go to the boneyard and try to find some of these OEM bolts that are shown in this picture.

DD612FD8-601E-4DF3-AC7C-70ED47026A98.jpeg.fc1aa4ee22eb0261ee5feedebf7f205a.jpeg

Edited by mcoppola
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Schroth has a few different options for this. For our car, we didnt have enough room between the tub and the seat to run swivel sleeves. We went with the dog bone to clip in solution.

 

01324 - Bolt-in B23A Kit "Rallye End"

 

Swivel Sleeves

Pivot sleeve in use (with optional washers and bolts)

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A quick Public Service Announcement on this subject - Many cars from both sides of both oceans use a fractional size bolt for seatbelt anchors.  I THINK it is 7/16-20. 

 

What I do know is that it is so close to a metric size that it can be confused and also will work enough in one direction (bolt into nut, but not nut into bolt) that it will drive you batshit crazy trying to figure it out.  No need for others to suffer my fate.

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21 hours ago, MMiskoe said:

A quick Public Service Announcement on this subject - Many cars from both sides of both oceans use a fractional size bolt for seatbelt anchors.  I THINK it is 7/16-20. 

 

What I do know is that it is so close to a metric size that it can be confused and also will work enough in one direction (bolt into nut, but not nut into bolt) that it will drive you batshit crazy trying to figure it out.  No need for others to suffer my fate.

That sounds like 12mm x 1.25, which is very close to 1/2"-20.

 

The metric bolt will go into the standard nut but the metric nut won't go onto the standard bolt. There are probably others that are similarly close. 

 

P.S. A quick check of the numbers shows that 7/16"-20 could also work but in the opposite combination, i.e. nut on bolt but not bolt in nut. 

Edited by mender
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17 minutes ago, mender said:

That sounds like 12mm x 1.25, which is very close to 1/2"-20.

 

The metric bolt will go into the standard nut but the metric nut won't go onto the standard bolt. There are probably others that are similarly close. 

 

P.S. A quick check of the numbers shows that 7/16"-20 could also work but in the opposite combination, i.e. nut on bolt but not bolt in nut. 

Off the subject but…

The closest metric vs SAE fastener size, and thus the easiest to mix up, is M8x1.0 vs 5/16-24. (Thank goodness neither size is used much.) 

5/16” = .3125”

The 24 = 24 threads per inch. 

8mm = .315”

1.0 thread pitch = 25.4 threads per inch. 
almost impossible to tell these 2 apart. You get used to looking at the markings on the hex head. For SHCS, good luck telling them apart. 

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20 minutes ago, mcoppola said:

Off the subject but…

The closest metric vs SAE fastener size, and thus the easiest to mix up, is M8x1.0 vs 5/16-24. (Thank goodness neither size is used much.) 

5/16” = .3125”

The 24 = 24 threads per inch. 

8mm = .315”

1.0 thread pitch = 25.4 threads per inch. 
almost impossible to tell these 2 apart. You get used to looking at the markings on the hex head. For SHCS, good luck telling them apart. 

FYI, the metric SHCS have the grade markings on them so they are easier to spot.  The button heads are the tough ones.

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35 minutes ago, mcoppola said:

almost impossible to tell these 2 apart. You get used to looking at the markings on the hex head. For SHCS, good luck telling them apart. 

A metric SHCS will always have the property class stamped on the rim, typically 12.9, or if it's stainless, A70, something like that. A 'standard'/'american'/'SAE' SHCS typically won't have a grade stamp on it because it's assumed to be alloy steel if no stamp is listed, only a manufacturer mark will be there.

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1 hour ago, takjak2 said:

Tech looking for new things not in the rulebook?

 

I'll keep installing according to my manufacturer (Schroth) instructions thank you. Eye bolts should NOT be required to swivel.

The eye bolts themselves should not swivel (AFAIK). They allow enough 'swivel' in the system by being eye bolts. Was anyone saying that the eyebolts themselves should be "loose"?

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Posted (edited)
14 hours ago, enginerd said:

The eye bolts themselves should not swivel (AFAIK). They allow enough 'swivel' in the system by being eye bolts. Was anyone saying that the eyebolts themselves should be "loose"?

NO type of seat belt fastener should be left loose or not torqued/tightened down. 
It’s scary that some of y’all would do that, much less recommend it to others, as previous posts stated. 
Everybody who gets in a motor vehicle ought to watch a few crash tests. Even at 35mph, the devastation, destruction and violence are eye opening. 
 

Edited by mcoppola
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21 minutes ago, mcoppola said:

NO type of seat belt fastener should be left loose or not torqued/tightened down. 
It’s scary that some of y’all would do that, much less recommend it to others, as previous posts stated. 
Everybody who gets in a motor vehicle ought to watch a few crash tests. Even at 35mph, the devastation, destruction and violence are eye opening. 
 

 I was impressed how hard my 45-50 mph hit was at Ozarks. Never had more than a fender bender before, the deceleration was surprising even as someone who understands the forces at play when coming to a stop over the course of a half second.

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30 minutes ago, BollingerChump said:

 I was impressed how hard my 45-50 mph hit was at Ozarks. Never had more than a fender bender before, the deceleration was surprising even as someone who understands the forces at play when coming to a stop over the course of a half second.

Hopefully you’ve made a full recovery and didn’t suffer serious injuries. Having witnessed thousands of crash tests at an OEM, seeing the devastation (and designing to reduce it) became routine. But everything changes emotionally in a real life impact with real people, not dummies.  Anxiety kicks in because I’ve seen what can happen. 

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5 minutes ago, mcoppola said:

Hopefully you’ve made a full recovery and didn’t suffer serious injuries. Having witnessed thousands of crash tests at an OEM, seeing the devastation (and designing to reduce it) became routine. But everything changes emotionally in a real life impact with real people, not dummies.  Anxiety kicks in because I’ve seen what can happen. 

All good, just a dented car.  Now I'm part of the "those who have crashed" club...  Amazing how well all the saftey stuff works together!

Edited by BollingerChump
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18 hours ago, takjak2 said:

Tech looking for new things not in the rulebook?

 

I'll keep installing according to my manufacturer (Schroth) instructions thank you. Eye bolts should NOT be required to swivel.

 NO 

  And that is exactly what we want, mounted as the manufacturers require.

  No one has recommended loosening non locking fasteners. 

 

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10 hours ago, mcoppola said:

Having witnessed thousands of crash tests at an OEM, seeing the devastation (and designing to reduce it) became routine. But everything changes emotionally in a real life impact with real people, not dummies.  Anxiety kicks in because I’ve seen what can happen. 

 

Yeah, the forces in a crash are rather amazing. My day job involves a lot of the real-world results of collisions, typically on highways at higher speeds. Crash safety is no joke. Definitely don't want to cut corners there!

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