Sheared Shoulder Pt. Seat Belt Bolt

[Walnuts]

The bolt that mounts the driveer's side shoulder Pt. (upper corner into roll bar) of my stock harness sheared off while I was putting it back in. WTF do I do now. Any suggestions? Did I just run myself a few $k into the ground and have to have the entire roll bar replaced? Its a good 1/4" below the outermost part of the threaded piece on the roll bar that it screws into so I can't really see how anyone would be able to weld anything to it. The only sollution I can think of is a bolt extractor bit, but I know those have a tendancy to break off and it it does, I won't be able to do anything else to it. What about drilling it out and trying to break it up with a chisle?

The only good thing I can see is I just finished intalling a harness bar so I should be able to purchase a 4pt. and use that for the time being, but AUGH! WTF.

[RoadDad]

Get a screw out set and take out the remainder of the bolt.

[Walnuts]

Hmm... so after a little bit of thinking to myself "what the hell did i just do?" and a quick trip to Sears, I got what was left of the bolt extracted with a little elbow grease and a knew tool

Thanks for the advice RoadDad. I just had read a lot of negative things where those actually make the situation worse. Time to order some new bolts

[Walnuts]

Does anyone have a part number for the bolt I broke? I cannot find anything other than an indication that it may be part of the Seat Belt Assembly B121B0013F. Not having any luck getting a hold of LotusGarage and my local dealer doesn't seem to be finding anything either.

If I HAVE to buy an entire assembly, the so-be-it. I'd rather not though. I'd really rather not buy an entire assembly and find out the bolt is not part of it.

[RoadDad]

Advance Auto, Auto Zone, Kragen's, your hardware store, etc. can supply you with the appropriate bolt. Take the two pieces of your broken bolt with you for size matching.

[chromedome]

Make sure to match the grade of the original bolt too.

[Walnuts]

in case anyone else has this issue, the bolt is a 7/16"-20 thread, with a 17mm head, and from what I can tell, it is an SAE grade 5 fastener (standard spec for seat belt bolts). Yes, a metric headed, english threaded bolt. It has a 14mm diameter, 10 mm long shoulder and is 38mm long (1.5")

[RoadDad]

Originally Posted by Walnuts

in case anyone else has this issue, the bolt is a 7/16"x20 thread, with a 17mm head, and from what I can tell, it is an SAE grade 5 fastener (standard spec for seat belt bolts). Yes, a metric headed, english threaded bolt. It has a 14mm diameter, 10 mm long shoulder and is 38mm long (1.5")

That makes no sense at all. I'm not sure I'm following your measurements here. Maybe I'm just misreading it .

You say both 7/16" and 14mm for the diameter of the bolt? That's not possible. 7/16" and 11mm would make some sense as they are very close. 7/16" and 14mm are not. 14mm is close to 9/16".

US fasteners are indicated as diameter - thread count (threads per inch) x length. Metric fasteners are indicated as diameter x thread pitch (distance between threads in mm) x length. So you have either a 7/16-20 x 1.5 bolt OR a M14 x ?(most likely 1.5) x 38 bolt. But those bolts are not close except in length.

What did you measure to get the 7/16" and the 14mm readings? You have a 7/16" what? Root (aka minor diameter)? And a 14mm shank or thread (aka major diameter)? That could be but I somehow doubt that you measured the root.

I'm just not following your measurements here. It's either SAE or metric, not both. If it is a 7/16"-20 x 1.5"(length) bolt, fine. If it is an M14 x 1.5 x 38 bolt, fine. But you can not have a 7/16-20 bolt with a diameter of 14mm, etc.

And my bolt is a Class 8.8 which is similar to a SAE Grade 5 bolt. Not exact but close. You will need to look up the torque value for the particular bolt that you have chosen to use.

[Walnuts]

I know it doesn't make sense, that's why I'm scratching my head.... the major diameter of the thread is .430" (10.9mm) The shoulder is 14mm (.548") diameter and 12mm (.475") long. The head is 17mm (.6720" on my calipers) face to face. Searching all over trying to find the spec for it, I kept seeing 7/16-20 being the thread for seat belt bolts (even on SELCO for the S1 Elise. I guess I've been blinded by my Google Goggles. The M11x1.5 does make more sense. Looking at how far my .430" measurement is off of 7/16 vs. 11mm I see that you are more than likely correct. Have you replaced yours? Mine don't have an grade indicator on them, but I had planned on 8.8 or higher.

Sounds like I'm looking for an M11x1.5 x 38mm shoulder bolt (17mm head, 14mm x 12mm shoulder)

Will be going to the auto parts store after work.

[JWA]

Seat belt bolts are all SAE as they are spec'ed by the DOT. (Something new that I learned from tesprit recently). That isn't a 17mm head, it is 11/16", I believe. You are much better off finding one from a parts store, as they are incredibly expensive from Lotus. The shoulder bolt for the lower outer mounts are $32 from Lotus and under $2 everywhere else.

[Walnuts]

[RoadDad]

Originally Posted by Walnuts

I know it doesn't make sense, that's why I'm scratching my head.... the major diameter of the thread is .430" (10.9mm) The shoulder is 14mm (.548") diameter and 12mm (.475") long. The head is 17mm (.6720" on my calipers) face to face. Searching all over trying to find the spec for it, I kept seeing 7/16-20 being the thread for seat belt bolts (even on SELCO for the S1 Elise. I guess I've been blinded by my Google Goggles. The M11x1.5 does make more sense. Looking at how far my .430" measurement is off of 7/16 vs. 11mm I see that you are more than likely correct. Have you replaced yours? Mine don't have an grade indicator on them, but I had planned on 8.8 or higher.

Sounds like I'm looking for an M11x1.5 x 38mm shoulder bolt (17mm head, 14mm x 12mm shoulder)

Will be going to the auto parts store after work.

I haven't swapped mine out. They are the Class 8.8 OEM bolts (again which is close to Grade 5). I've removed them several times but never removed the bolt from the seat belt unit itself to look at them.

It sounds like you are looking for a 7/16-20 x 1.5 shoulder bolt with a 9/16" shoulder.



$1.95 here: Seat Belt Hardware

[RoadDad]

Originally Posted by JWA

Seat belt bolts are all SAE as they are spec'ed by the DOT. (Something new that I learned from tesprit recently). That isn't a 17mm head, it is 11/16", I believe. You are much better off finding one from a parts store, as they are incredibly expensive from Lotus. The shoulder bolt for the lower outer mounts are $32 from Lotus and under $2 everywhere else.

The head may still be 17mm even if the bolt is the seat belt standard SAE 7/16-20 (which is the worldwide standard as tesprit has pointed out via JWA).

EDIT: FWIW, my '90 Honda Civic bolts are not the standard 7/16-20 size.

[Walnuts]

SAE document number J141 issued by the Belt Systems Standards Committee describes performance requirements for hardware used in motor vehicle seat belt assemblies. Issued in June of 1995.

I believe everyone, industry wide adopted it following that issuance. I've seen on SELOC that the S1 Elise seat belt anchor bolts are also 7/16"-20. ReVerie Ltd has listed on one of their spec sheets that the Lotus spec bolt is a 7/16"-20 x 38mm bolt... I'm going to check the store on my way home, hope I can find something close. If that doesn't work, I'll order the ones you found for me RoadDad. If that doesn't work, I'll have to get a new assembly or find someone that is removing/removed their 3pt belts which had not been in an accident prior to removal.

[Walnuts]

Well, its not a 7/16-20 bolt and I'm pretty sure the threads in the roll hoop on both sides are screwed up. Looks like it is going to have to go to the dealer to see what can be done (if they can fix them or have to replace the hoop).

Thanks for the help guys.

[RoadDad]

what was wrong with the size? too big? do you just need to run a tap through to get the little chunks of sheered prior bolt out of the threads?

[Walnuts]

Originally Posted by RoadDad

what was wrong with the size? too big? do you just need to run a tap through to get the little chunks of sheered prior bolt out of the threads?

the pitch was too large. I think an M11x1.5 might be right but I really don't know anymore. I have no idea if I just need to run a tap through. I don't think there are bits of bolt left in it, I think rather the threads themselves are messed up. At this point, I'm so mad at myself for causing this big of a headache that I'd rather have a mechanic look at it and figure out what should be done instead of screwing it up worse myself.