Racing seat installation... looking for advice !

[wildcat077]

Hey guys,

Caught the DE track bug real bad and i want to install some Sparco racing seats and harnesses in my 89 Coupe.
I have a Das roll bar already installed and i'm getting a real good deal on the seats,side mounts,bases and sliders.I plan on using six point harnesses.
Now what i need to know is concerning the tunnel mounts ?

I read something on another post that the 87 and up cars already have the threads in the tunnel for the eyebolts ?
Can somebody please enlighten me on the installation process ?

Thank you

Cheers !
Phil

[porschenut]

By "tunnel" are you referring to the center tunnel or the rockers? The rockers are where you install the eye bolt using the existing lower seat belt mounts.

All the SCs and Carreras and everything that came after that have the seat belt receptacles attached to the seat, not the center tunnel. There is no provision for an eye bolt on the center tunnel.

What you need is this 964 RS mount that goes between the inboard side mount and the seat slider:

[porschenut]

Here's more information about the part in this thread -> Recaro PP, mounting and where to buy?

Scroll down to Bill Verburg's post #15. These can be bought right here on Pelican.

[wildcat077]

Dave,

Yes i was refering to the inboard sides ...My supplier has a bunch of "eyebolt" receptacles in stock which i will mount on the rocker sides where my roll bar attaches,i was just wondering about how to attach the inners ?
Do you have any other pictures of how the 964 RS mount is installed ?

I kind of figured everything wouldn't be a direct bolt on ...

Cheers !
Phil

[Pazuzu]

Originally Posted by porschenut

All the SCs and Carreras and everything that came after that have the seat belt receptacles attached to the seat, not the center tunnel. There is no provision for an eye bolt on the center tunnel.

Not my SC, it has mount tabs from the factory on the tunnel for the inboard seatbelt mounts. I thought they switched over in 84 or 85.

[dad911]

The correct way is to mount the seat where it is comfortable, then install the harnesses per the manufacturers instructions.

For example, Schroth has installation instructions (pdf files) here: Schroth Racing Harnesses

[KTL]

964RS mount sounds like a good idea but last time I tried, Pelican couldn't obtain them.

Brey Krause makes an inboard seat adapter plate R-9005 that works nice. I used it for my Cobra Imola S seat install in my '87.

Brey-Krause Harness Installation Brackets for Porsche

[porschenut]

Originally Posted by Pazuzu

Not my SC, it has mount tabs from the factory on the tunnel for the inboard seatbelt mounts. I thought they switched over in 84 or 85.

Right you are! I checked PET and '85 was the model year when they made the switch to seat-mounted belt receptacles. I coulda sworn it was '78.

[Bill Verburg]

Originally Posted by wildcat077

Hey guys,

Caught the DE track bug real bad and i want to install some Sparco racing seats and harnesses in my 89 Coupe.
I have a Das roll bar already installed and i'm getting a real good deal on the seats,side mounts,bases and sliders.I plan on using six point harnesses.
Now what i need to know is concerning the tunnel mounts ?

I read something on another post that the 87 and up cars already have the threads in the tunnel for the eyebolts ?
Can somebody please enlighten me on the installation process ?

Thank you

Cheers !
Phil

If you go to the thread Porschenut linked to it pretty much lays it out for you,

If the RS mount isn't available thru Pelican it certainly is available at any dealer, be sure to order the matching 3x 3mm washers to keep the seat base level.

The only additional complication is if you want to retain the stock seat belts. On mine I use the RS tunnel side mounts for the stock seat belts and drilled holes for pad-eyes for the harness to clip to.

I second Dad911s recommendation to read the Schroth installation instructions, to do it right is not as easy as one might at first imagine

[chris.817]

I drilled holes in the top of my tunnel just forward of the access panel for the shift linkage. It's tight in there but easy enough. I used the standard eye bolts, nuts and big backer washer.

[don911]

If your passenger seat is non power, the inside mount can be used. The inside mount on non power seats is not welded to the seat slider/lift structure like the power seats.
I went through the inside mount issue on my 87 and ended up using the Brey Krause inside mounts shown in KTL's link.

This is rattling around in my "extra parts" box. I only have one but you're welcome to it if you want it.

[Bill Verburg]

Originally Posted by don911

If your passenger seat is non power, the inside mount can be used. The inside mount on non power seats is not welded to the seat slider/lift structure like the power seats.
I went through the inside mount issue on my 87 and ended up using the Brey Krause inside mounts shown in KTL's link.

This is rattling around in my "extra parts" box. I only have one but you're welcome to it if you want it.

Doesn't matter whether you use the factory RS or the B-K piece, you still need to use washers at the other 3 corners to keep the seat level. The factory RS base is 3mm thick and there are 3mm washers that go w/ it, you can also use the GT3 sub mounts to avoid drilling holes in the floor for the subs, coincidentally these are also 3mm thick at the tabs that go under the side-mounts.

[lateapex911]

Originally Posted by dad911

The correct way is to mount the seat where it is comfortable, then install the harnesses per the manufacturers instructions.

For example, Schroth has installation instructions (pdf files) here: Schroth Racing Harnesses

Agreed.
Also, the seat manufacturers are being very specific in their allowable methods for installing their seats. For example, FIA rated seats, like a good Racetech or higher end Momo etc are to be mounted with certain approved mounts in certain ways, and they must NOT have a back brace installed.
In my opinion, it's not something to be taken lightly.

[wildcat077]

Wow...
This isn't as straight forward as i expected !
I was going to pick up all the Sparco parts tomorrow from my local supplier but now i'll have to wait and see because it seems i will need a bunch on BK parts as well ...

From what i understand my 89 has the seat belt mounts threaded into the tunnel and the rocker side and i would need a BK bar for the 6 point anti submarine belts right ???

Thank you for the help guys
I would imagine it's pretty straightforward after you do it the first time ...

Cheers !
Phil

[don911]

Originally Posted by wildcat077

From what i understand my 89 has the seat belt mounts threaded into the tunnel and the rocker side and i would need a BK bar for the 6 point anti submarine belts right ???

The inside seat belt mounts are on the seats. There's no threaded mount on the tunnel side. Pre 85 (I think) had the inside seat mounts on the tunnel.

[lateapex911]

Originally Posted by wildcat077

Wow...
This isn't as straight forward as i expected !
I was going to pick up all the Sparco parts tomorrow from my local supplier but now i'll have to wait and see because it seems i will need a bunch on BK parts as well ...

From what i understand my 89 has the seat belt mounts threaded into the tunnel and the rocker side and i would need a BK bar for the 6 point anti submarine belts right ???

Thank you for the help guys
I would imagine it's pretty straightforward after you do it the first time ...

Cheers !
Phil

If they ARE on the tunnel, I think thats better, and I'd count myself lucky.

Are you mounting the seat on sliders? If so, inquire about appropriate sliders and mounts from the seat supplier.

As for the subs straps, typically they go through the hole in the seat, then back to the anchor points for the lap belts. Read the instructions to confirm. Your shoulder belts ...what were your plans for them? Mounting to the cage (roll bar?) cross car tube is a popular and good method. Some guys mount them to the rear deck, but I think that's sketchy in most cases, unless there is structure for, and specific to the belt anchor added.

Each setup requires quite a bit of thought to do properly.

[Bill Verburg]

Originally Posted by lateapex911

.....

As for the subs straps, typically they go through the hole in the seat, then back to the anchor points for the lap belts.......

That is absolutely and unequivocally wrong

Most sanctioning bodies will want through the floor mounts directly under to 20* back from the seat hole alternately a sub bar as used on GT3s can sometimes be used

Read the mounting instructions from a credible authority like Schroth

pads & reinforcements for through the floor

installed




GT3 subbar





another big mistake I often see is not having a straight fetch from the shoulder to the shoulder belt mount because the seat hole is too small or improperly located and not using a proper run on the belt attachment

[lateapex911]

From Simpson:

6-Point Anti-Submarine Belt should be anchored at an angle of 20 degrees behind the Chest Line as measured from the intersection of the Chest Line and the lap belt buckle. Mounts should be approximately 8 to 12 inches apart (approximately located under each hip and as close to the body as possible). Two routing holes in the seat or a special seat mount may be required. Using the 5-Point hole detracts from the effectiveness of this system.

on my race car, and my 911, the point refereed to (20 degrees behind the chest line/lap line intersection is also the lap belt anchor plane.) Granted, my RX-7 race car has the lap belts 18" apart, so that is 4" further than Simpson recommends. However, i followed the instructions that were with my harness set.
It's an FIA rated harness, installed in an SCCA logbooked racecar.



Main

see diagram B.
While it's rather small, the SFI diagram shows the sub strap anchors at a location in the same plane as the lap belts.

Further, G-Force, a maker of SFI and FIA approved systems, is rather open on sub strap attachment points, and advises that the sanctioning body has final say. (!)

Finally, the SCCA GCR (general Competition Rules) states that the sub straps may be bolted to the floor, or may attach to the lap strap anchors.


So, I appreciate your thoughts, but i think that stating that it's
"absolutely and unequivocally wrong" is a bit of an overstatement.

[Bill Verburg]

Originally Posted by lateapex911

From Simpson:


on my race car, and my 911, the point refereed to (20 degrees behind the chest line/lap line intersection is also the lap belt anchor plane.) Granted, my RX-7 race car has the lap belts 18" apart, so that is 4" further than Simpson recommends. However, i followed the instructions that were with my harness set.
It's an FIA rated harness, installed in an SCCA logbooked racecar.



Main

see diagram B.
While it's rather small, the SFI diagram shows the sub strap anchors at a location in the same plane as the lap belts.

Further, G-Force, a maker of SFI and FIA approved systems, is rather open on sub strap attachment points, and advises that the sanctioning body has final say. (!)

Finally, the SCCA GCR (general Competition Rules) states that the sub straps may be bolted to the floor, or may attach to the lap strap anchors.


So, I appreciate your thoughts, but i think that stating that it's
"absolutely and unequivocally wrong" is a bit of an overstatement.

This is the part I strongly object to

As for the subs straps, typically they go through the hole in the seat, then back to the anchor points for the lap belts

Please direct us to where Simpson outlines the sub belt arrangement, I sure can't find it

However, if you bother to look at Schroth's instructions it is clearly defined. On p15 & 16 as 0* to 20* back. An additional restriction is that the belt should not depend on the integrity of the f/g seat shell for support, in other words don't have the belt's pushing on the shell in any way. Usually you see this sort of mistake at the shoulder where there is not a clear fetch from the shoulder to the attachment point causing the belt to be deflected by the seat shell but it is equally important at the sub strap