Harness Bars

[griffiths_r]

Alright, one of the first mods I want to do to my car (no, it's not on the road yet, but I have to start improving it sometime!) is to put in 4pt harnesses... this should provide a greater sense of security for passengers (and myself), especially when I get around to putting in some new seats as well.

There has been a few posts elsewhere (http://www.typ901.org/showthread.php?t=531&page=4), but I thought a central resource might be useful.

OK, the basic questions:
- How much does a harness bar cost?
- How hard are they to fit and where do you get them?
- What are the best 4pt harnesses to get?
- Are there any traps for beginners (like not being compatible with original seats)?

Thanks

Rich

[OBRUT]

- How much does a harness bar cost?

few hundred from memory.

- How hard are they to fit and where do you get them?

very easy. pelican and all the usual online vendors. don't know of any aussies vendors

- What are the best 4pt harnesses to get?

i find wider more comfortable (i use 3"). i'd go for something FIA or at least CAMS approved. i've had no problems with my sparcos.

- Are there any traps for beginners (like not being compatible with original seats)?

none that can i think of for the old style seats with separate headrests. if you use eyelets as mounting bolts they are easy to get in and out.

[e72phil]

The old style seats usually have the belts attached to the seat frame.

If your car does not have any belt mounting points elsewhere, then you have to create some solid points to attach the eye-bolts to attach the harness ends to.

The shoulder straps should be attached to a harness bar or a strong point on the rear parcel shelf. Drilling in new holes etc to accept the waist straps of the harness will need to be done properly. the existing seat belt mount points on the std Porsche "Comfort seat" will not work.

I suggest you try the USA for harness bars unless you get one custom made out here.

[OBRUT]

i don't agree phil

the seat mounts are designed for the same level as strength as the floor mounts - you can user either for the lap belt.

also, you should not attach the harness to the harness bar. the shoulder straps of the harness must mount to the car. it is only guided to the correct position above the driver's shoulders by the bar. the easiest way to do this is to place eyebolts in the rear seat belt lap mounts. if not, most speed shops sell a CAMS approved nut/washer combination for this purpose.

[e72phil]

Hi Ryan,

I was thinking more that the way the std seat belts attach to the seat does not lend itself to easily attach a harness that has a metal clip on the belt end. The inner stalk for the lap belt is very close to the seat and the bracket it attaches to doesnt allow a lot of room for attaching anything other than the normal short stalk. I am , of course, referring to the brackets that come on the old "comfort" seats whereas some cars also have extra mount points for the bels into the floor (as does my 72E) .

if you look at the pics of the harness bar I posted in another thread, its not the type that attaches to the B pillars to guide the belts, rather a flat bar to mounts to the rear parcel shelf using both rear seat belt bolts either side. This means the pull is more even across the rear shelf rather than a single point. I always thought the rear shelf was a bit flimsy to take the full strain of the harness at a single point, unless its reasonably reinforced underneath with an extra steel plate.

here are some pics to help.

[OBRUT]

hey phil

on the seats you can just remove the stock bolt for the standard seat belt stalk and replace it with an eye bolt - this leaves the stock belts unaltered and provides a mount for clipping on the harness lap belt.

the pic you provided is of a very old style arrangement. most harness bars are of the other type you mention which fix between the A pillars. for the A pillar type your best bet is to screw an eye bolt into for the shoulder belts to the stock (reinforced) mounts for the rear lap belts.

[e72phil]

Ryan, you are right in that you could screw the eye bolt into the same thread that the bolt holding the belt stalk but i would be a bit concerned about the fact with an eye bolt, under load, the setup puts extra pressure and leverage on the bracket rather than having the belt under a straight, shear load with the original setup. Also, you cannot tilt the seat back forward as the eye bolt will hit the seat tilt bracket.

I have added some pics of some eye bolt placements in my 72E where I substituted the original plain bolt with an eye bolt (same thread). My car already had these belt mount points installed a long time ago.

I guess my main concern here for safety and good engineering of the seat belts mounts to ensure they can withstand the shock loads of an accident.

Brey-Krause in the USA does make a harness bar for later model 911's (964/993/996) which mounts to the B pillar points where the shoulder sash of shoulder attaches. They show the belts mounted directly to this. keeping the shoulder belts short. i think this is the recommendation in the CAMS manual as belt can stretch under impact load and keeping them as short as possible is advisable. Shoulder belts should not be attached to the floor where the pull is down at an angle.

Have also added a pic of the rear passenger footwell in my 72T (in the USA) where the PO had made a plate with 2 eyebolts bolted thru as well as thru the floor pan with another matching plate under neath for strength. he attached the lap belts and also anti-submarine, crutch belts to this also. Its hidden by the carpet when not in use. A relatively simple way to add a strong attachment point with easy to drill holes.

Hope these pics help other understand the optins for seat belt and harness mountings.