Jdm/CDM Manual seat belt conversion question

Hey guys, in the process of getting the mounting points for the belts ready. I have most of the stuff I need but I’m stuck with the BPillar mount. The bolt is a 11x1.25 from what I understand, no hardware stores have them and I can’t find em online. I have a friend that may have a Civic parts car I can cut the b pillar mounts out of, but in the event He doesnt I noticed the factory USDM lap belt reel had 2 mounting points, and the thread happens to be the same as the JDM BPillar bolt. I’m not sure what the b pillar nut looks like, but for the reel it’s basically a tall nut welded behind the pillar. to do the conversion you only use one mount for the lower anchor point. I can potentially cut the second factory lapbelt mount out, weld it to heavier steel and place it on the b pillar for the JDM belt. What do you guys think?

Here’s a pic of what I have mocked up for the center mounts, still going to add some heavier steel obviously as the washer is too thin.

Ok so I’ve come to find out all USDM tegs ( and all USDM cars for that matter) come with 7/16x20 mounting hardware. Something about DOT regs requiring allseatbelt hardware to be SAE grade 8. Well since the belts are from OUTSIDE the US, the hardware is metric 11x1.25. You cannot buy 11x1.25 nuts ANYWHERE. so do I do what everyone else must’ve done and use 7/16 nuts to mount the b pillar stuff or try to source hardware from a USDM Honda that has manual belts, like a DC or 92-93 Accord (this hardware should be SAE a it’s a USDM car) an use that with the 7/16 nuts.

Basically, do I use the CDM/JDM metric hardware with 7/16 mounting nuts like everyone else or try to find USDM manual belt hardware?

Why bother with it being USDM or JDM specific?

If you know the DOT regs require Grade-8 stuff, why not find a size/length bolt you need at a hardware store, buy the corresponding nut, and go to town? Seems like more of a headache to source it from actual cars if it isn’t completely necessary.

Because the bolts For the belts aren’t a run of the mill bolt. They have a flanged head with a wider unthreaded section on the shaft that keeps the mount from having alot of free movement. Figure I should use the bolts that were designed to be used with seatbelts.

Use bolts that were designed for seat-belt use, on a b-pillar that wasn’t? Hmm… :wink:

From what i understand the b pillars are identical besides the threaded insert. They didn’t make special b pillars for the cars that were coming to the US, they just opted to not weld the insert in. On the other hand, looking at the mounting bolts and how they fit in the belt itself, they look to be designed to keeping mounts from pulling off the bolt, and to minimize the movements of the mounts when they’re bolted up.

I do believe I’ve figured it out.


The hardware seems to be 7/16x20. The metric equivalent is 11x1.25, and it an virtually unheard of size from what I’m told and what I’ve read. Search “7/16x20 seatbelt bolt” and other searches throwing in “11x1.25” and youll cone up with alot of sites referencing it. Saw it on an ATV forum, Porsche, Alfa Romeo, 4x4, Jeep. And everywhere I go i see 7/16x20 as the fastener. There’s a “how to” on EF Honda for the door to pillar belt swap. Then nuts he used are 7/16x20.

Took it to a local specialty hardware place, literally the top of a small warehouse filled with shelving units of hardware. I gave him the bolt that came with the belts and he says "you sure this is metric? Uh pretty sure “who told you that?”, goes over to SAE and a 7/16x20 grade 8 goes right on. This goes for all the hardware that came withthe belts as well as the existing holes For the USDM lap belt retractor. The lower mount of the manual belts bolts right up to either of those holes. It’s not a loose fit either, I’m very sure I can torque them.

So they’re interchangeable?

Good to know, makes things a ton easier I’m sure.

I guess they are. Here’s te differences between the two I found online.

"There seems to be lots of references on the internet to seat belt bolts being 11mm

Seatbelts are an NTSA/DOT mandated type of thing and guess what, they use SAE hardware, I think you will find the 7/16NF is what you are looking for."

7/16" = 0.4375"
11mm = 0.4331"

20TPI = 0.050"
1.25mm = 0.0492"

I figured the hardware that came with the belts would be metric, but a thread checker shows 7/16x20. Plus try to find an 11x1.25 nut, haven’t found one. And with all the people that did this swap, the nut size can’t be some super rare type, or there would be mention of it.

Jusy cut the inner piller out of a ef an weld it on to your inner piller there you go

That was my original plan. But No EF available to me. And the local pick a part doesn’t allow cutting tools.

um I might be able to cut you a set an send them to you depends on how soon you want them an whats in the yard let me know greazemunkey73@yahoo.com

I would need them ASAP.