3-point seat belt install has begun ...

[KatoKato]

I've finally got around to installing the 3-point rear seat belts in my 86' targa. Thanks to those who helped me out in other threads regarding this project. I need some help just to finish the job.

I'm at the point where I've removed the old lap belt and am about to install the shoulder strap. Here's a pic of the pieces I am dealing with:



The "new" lap belt is the one with the black attachment, the old lap belt has the "gold" attachment.

Here's how the old one bolted in:





The only way I can see to install the new shoulder belt with the given bolt is this way:





Do I require a different size(smaller) bolt so it tightens in snuggly like the old belt did? (The gold attachment piece for the old belt has a larger hole in it).
Or should I just install as in the picture above?



Once the above question in answered how should I bolt in this new piece? (Pics below)







On a horizontal, 45 deg, or vertical like trajectory?
Should this be bolted in with no movement or should the piece be able to move from horizontal to vertical?


Sorry ... one final question:

Once installed should it look like this?



The reason I ask is that the seat belt label shows when in use. For some reason I feel like it should not be showing. (or does it really matter?)


Thanks in advance.
Kato

[Zef]

I want to install the same mod on my 1984 3.2...Can you tell me which seat belt P/N you installed??? I think but not sure than the front 944 three point seat belt will fit there...any idea about it...

[KatoKato]

Originally posted by zefsuper911
I want to install the same mod on my 1984 3.2...Can you tell me which seat belt P/N you installed??? I think but not sure than the front 944 three point seat belt will fit there...any idea about it...

I purchased two 964 shoulder belt reels. Left and right are identical and have the same part #'s. Not sure what that is though.

Check out the previous thread I started on this one.
Rear Seat Belt Upgrade

I couldn't get a hold of any plastic trim pieces cheap (used parts places wanted to sell the whole rear deck) so I've gone without. It looks o.k. - will post pics when done. If I get any negative comments I might fabricate my own metal trim pieces and paint them black.

One thing to note is that cutting through the rear deck is a PITA. Used an exacto knife. Had to remove the vinyl cover around the edges and shove a piece of particle board inside to protect the vinyl whilst I made the cuts.

Will keep you informed on progress

Kato

[Zef]

Thanks very much Kato...I need to check if front 944 seat belt are going to make the job...they are cheap and easy to find.This link is very good too...
http://911carrera.free.fr/article.php?id=28
Syl

[steve911]

Mark--
I just checked my rear belts. The shoulder belts mounts are fixed in place like in your first picture and the label does in fact show when the belt is pulled across. Not sure that it matters nor can I say that this is the way the factory intended it to be.

It works for my 9 year and gives me the necessary peace of mind.

[KatoKato]

Originally posted by steve911
Mark--
I just checked my rear belts. The shoulder belts mounts are fixed in place like in your first picture

Steve,

Thanks for the reply. Do you mean like in this picture (mounted on the horizontal)?



Do you know if these lower mounts are in fact fixed on the 964 (for which these belts were intended)? I'm asking because both of our family vehicles (Honda odyssey & VW Golf) have lower mounts that are variable, just like the original Carrera lap belts I just removed.

One more thing ... since the bolt is too big it'll stick out slightly. Does this little bit "poke" at the occupant?

As in this pic:



Thanks again,
Kato

[efhughes3]

I don't see how you can use that bolt. If you tighten it up, the shoulder that should be thru the hole will inhibit it's ability to pivot. Also, you'll have shear on a smaller diameter (the threaded area) which may or may not be a problem.

It looks like you need to open the hole up in the tang to accomodate the shoulder on your bolt.

[KatoKato]

Originally posted by efhughes3
It looks like you need to open the hole up in the tang to accomodate the shoulder on your bolt.

That's an option I'd like to consider last. That would mean taking them out and hauling them off to a machine shop to have them drilled. I'd hope to get two new bolts.

Does anyone know if the 964 seat belt bolts have the same thread size as the ones in my Carrera? Or did the thread size change in the "new" model.

Thanks,
Kato

[KatoKato]

Here are some pics of the original lapbelt setup:

From afar:



Closeup with plastic cover:



Closeup without the plastic cover:




1. Is the setup the same with the 964 rear shoulder belt attachment?

2. If so does the bolt have the same thread size but with a smaller radius in the "smooth" area where the belt anchor rotates?


Thanks for your help,
Kato

[efhughes3]

That's called a 'shoulder'. If you can see it in your mind, that shoulder adds some support in the event of shear load on the bolt. If you go to a smaller diameter shoulder, it will be weaker.

While I'm sure there is plenty of extra strength factored into the fasteners, why compromise?

I can only assume your upgrading the belts for rear passengers? How hard can it be to drill the tangs out to do the install correctly?

Do you have access to a drill press?

[KatoKato]

Originally posted by efhughes3
That's called a 'shoulder'. If you can see it in your mind, that shoulder adds some support in the event of shear load on the bolt. If you go to a smaller diameter shoulder, it will be weaker.....
How hard can it be to drill the tangs out to do the install correctly?.....

Ef,

That makes sense that a smaller shoulder would be weaker in the event of shear load on the bolt. However, the shoulder on the 964 bolt would have to be smaller to occomodate the hole on the attachment for the new belt.

I did some measurements to compare. (I'm assuming for the 964 since I don't have the bolt in hand)

------------Bolt Thread Size---Bolt Shoulder Size

Carrera--------27/64"---------------32/64"
964-------------27/64"---------------28/64"

It's interesting to note that in the 964 they decreased the shoulder size to basically the thread size.

Also ... I measured the outer radius length on the two different connectors:



The 964's measures 13/32" and the Carrera's is 11/32"

So ... in the 964 they reduced the shoulder and increased the outer radial length. I would assume then that the 964 bolt would suffice as that's how they designed it. (It would be nice to know if that's what the bolt it actually like)

Anyway...I'm thinking that if I drilled the holes larger it would compromise on the strenth on the attachment (and also be a PITA since the rear deck is installed, positioned, etc.)

If I could only get my hands on a 964 set of bolts I think I'd be in luck (assuming that the threads are the same).

Could I also just take the bolts to a machine shop and have them reduce the shoulder to 28/64"?

Thanks for your help, sorry for all of the questions. I am a novice if you haven't figured that out already.

Kato

[Icemaster]

Website for PEP is closed, any ideas on where to source the parts for this?

[KatoKato]

Just finished the job!

Went out to the local machine shop and had the shoulder reduced from 9/16" to 7/16" - the smaller shoulder fitted perfectly into the lower belt mount.

Here's the old bolt - new bolt:





And some pics of the install:









Thanks to all that helped out with this project. Nice and easy - even for a newbie. Took about a total of 4 hours.

Cheers,
Kato