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      07-19-2017, 02:39 PM   #1
dre99gsx
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Fixed bucket seats and roll bars

This discussion has been driven to the ground all around the internets, but here is my dilemma. Past HPDEs, my body is moving around way too much in the seat. I get soars on my knees and muscles from holding my body in place during cornering. I'm a skinny guy and need better seat support.

Wanted to get some fixed-back bucket seats (and save some weight as well), but the internet says I need to use 5-pt harness, which means I need a harness bar, which means I need a roll cage, and this, and that, and in the end, if you don't do it all, don't do it at all.

The theory about bucket seats without a roll bar is that during a roll over, you don't have the reclining seat's ability to "break" and tilt itself, giving your head some room before hitting the roof. On my car in particular, there is NO room for the seat to recline due to the rear bulkhead - thus I don't even think I get the benefit of reclining to save my head.

Having said that, wouldn't running fixed bucket seats without a roll bar work just as well (I'm talking rollover concerns, not any other safety concerns such as 3-pt harness use). I've been able to insert stock 3-pt harness through the right side access hole on the Z, thus it can work.

Ultimately, I need to find a way to secure myself into the seat better than with these M-seats.
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      07-19-2017, 06:05 PM   #2
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Good old CG lock?

Or use a reclining race seat but not because of the reclining feature, rather its compatible with factory 3 points and still provides better lateral support
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      07-19-2017, 06:09 PM   #3
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I just went through this.
I'll grab a couple of pics for what I did.

Racing seats + 4pt ASB harness + anchor points on bulkhead behind seats.
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      07-19-2017, 06:09 PM   #4
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Both good options. If retaining the 3-point system is 'safe' with a fixed back seat, there are options out there, some seats have a slight ingress for allowing the seat buckle to work with the seat. I've also seen short buckle extenders which can then fit through the seat hole.
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      07-19-2017, 06:29 PM   #5
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Ideally you'd want something like Recaro Sportster but if you're on a budget I'd consider the Corbeau a4's or Sparco R100's

(Note I have no idea how/if they fit our cars)
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      07-19-2017, 08:49 PM   #6
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Here's what I ended up doing...
Part of my issue was maintaining OE 3pt in the original location in order to remain street legal (local laws)

At the track I remove one bolt to remove the 3pt
& connect one half of the 4pt lap

I have 4pt ASB harness because I was originally going to try and make the OE seats work.
I plan to add the 6pt lower belts next time I have the seats out.

The harness bolts through the bulkhead are reinforced both sides and also have a pipe sleeve interior to the bulkhead.

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      08-02-2017, 02:35 PM   #7
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inTgr8r if I'm reading this right, you bolted harness points to the bulkhead instead of a harness bar right? I'm in the same position as OP, so interested in the various setups members are running.

Definitely don't like the factory seats, and common notion is that harness bar may as well be accompanied by roll bar. I don't mind half cage as long as I can street drive the car (only to and from track), but wonder if it adds any safety at all?
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      08-02-2017, 05:04 PM   #8
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Correct.
The problem with a harness bar is it gets mounted too high (above the bulkhead) for the shoulder straps to be at the proper angle.
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      08-03-2017, 01:31 PM   #9
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Quote:
Originally Posted by inTgr8r View Post
Correct.
The problem with a harness bar is it gets mounted too high (above the bulkhead) for the shoulder straps to be at the proper angle.
Gotcha. That's an interesting setup...are you able to adjust the harness straps as usual?
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      08-03-2017, 05:22 PM   #10
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Quote:
Originally Posted by bananabun View Post
Gotcha. That's an interesting setup...are you able to adjust the harness straps as usual?
Yes, full range.
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      08-05-2017, 03:58 AM   #11
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Quote:
Originally Posted by dre99gsx View Post

The theory about bucket seats without a roll bar is that during a roll over, you don't have the reclining seat's ability to "break" and tilt itself, giving your head some room before hitting the roof. On my car in particular, there is NO room for the seat to recline due to the rear bulkhead - thus I don't even think I get the benefit of reclining to save my head.

Having said that, wouldn't running fixed bucket seats without a roll bar work just as well (I'm talking rollover concerns, not any other safety concerns such as 3-pt harness use). I've been able to insert stock 3-pt harness through the right side access hole on the Z, thus it can work.

Ultimately, I need to find a way to secure myself into the seat better than with these M-seats.
I've never seen anything where the tilting seat back is supposed to "break" as you described. If it did that would negate the ability of the pretensioner for the 3 point OEM system to tighten the belt to hold you in place.
If anything there's a move to further strengthen the seat backs to ensure they don't break in an accident. The issue with "race seats" and the 3 point belt is the race seat changes the angles of the belt, potentially keeping it from securing you enough when the pretensioner fires. Instead of the shoulder strap catching your shoulder, as it would in the OEM seat, the side bolsters that project forward in the race seat cause the belt to slide down the side of the seat if the belt has just been put on over the outer perimeter of the seat. If you were able to route the OEM belt through one of the holes in the seat for the 4/5 point harness and maintained the OEM angles then it might still work close to as intended. You'll still have the issue of the belt not holding you securely in the seat during normal driving, so the CG Lock is still probably going to be needed. I use one and it works pretty well for at least keeping your butt from sliding around.
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      08-05-2017, 04:10 AM   #12
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I have pretty much exactly the same setup as Ian, minus the oem belts. I also have and additional roll bar set into the base of the rear partition. Works perfect, follows the roll hoops (roady) and provides sufficient roll over protection, and isn't in the way like some half cages I've seen (if your a tall guy with restricted movement for aft setting of your seat.)





Rubbish pic, I know, but shows what I mean.
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      08-30-2017, 11:35 AM   #13
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This may be a stupid question, but can the stock seats be modified to accept harnesses? Of course I know that anything can be done with time/money/effort, but has it been done here before and made to look good too?

I'm contemplating going back to a Street class in Autocross (Only my front wheel width upped me to Street Prepared), and the seats have to remain the same as stock, but can be modified for harnesses.
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      08-30-2017, 11:55 AM   #14
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Quote:
Originally Posted by Jackal View Post
This may be a stupid question, but can the stock seats be modified to accept harnesses? Of course I know that anything can be done with time/money/effort, but has it been done here before and made to look good too?

I'm contemplating going back to a Street class in Autocross (Only my front wheel width upped me to Street Prepared), and the seats have to remain the same as stock, but can be modified for harnesses.
Shipkiller Had a post from a couple years back showing his 4-point harness and OEM seat setup. Does this help?
http://www.zpost.com/forums/showpost...53&postcount=5
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      08-30-2017, 12:21 PM   #15
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Quote:
Originally Posted by Azeka1 View Post
Shipkiller Had a post from a couple years back showing his 4-point harness and OEM seat setup. Does this help?
http://www.zpost.com/forums/showpost...53&postcount=5
Harnesses are meant to be threaded through the seat itself to ensure it doesn't slide too far off the shoulders.

I was thinking more along the lines of someone cutting into the seats to allow the harnesses to pass through.
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      08-30-2017, 12:37 PM   #16
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Quote:
Originally Posted by Jackal View Post
This may be a stupid question, but can the stock seats be modified to accept harnesses? Of course I know that anything can be done with time/money/effort, but has it been done here before and made to look good too?

I'm contemplating going back to a Street class in Autocross (Only my front wheel width upped me to Street Prepared), and the seats have to remain the same as stock, but can be modified for harnesses.
I have seen pictures of an H pattern shoulder harness where the 2 straps are joined behind the seat to keep them from slipping off the shoulders.
I was looking into this before changing to racing seats, but I couldn't find a vendor for them.
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      08-31-2017, 07:25 PM   #17
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You might be able to make the Schroth E36 or E46 clip in harness work. Really depends on your head rest style.

https://www.schrothracing.com/products/quickfit
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