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Discussion Starter #1
Copying from Coupe forum

Kirkey Adjustable Seat Mounting Copy Cat
Learned/Borrowed extensively from Rich A under coupe forum, as well as Jeff Kleiner (thanks), and will do my share by providing part numbers:

-Seat tracks are Summit # SUM-G1153 (@$27.95 ea pair)
-Kirkey base mounts are Summit # KIR-99204 (@$42.95 ea pair)
-as Rich mentioned, stock latch cross connect wire is too short for our application, used 13" of 1/8" x 1/2" aluminum flat (@$7.47 for 8' at Lowe's)
-for mounting to chassis, purchased several 3/16" x 1.25" x 3' steel flats (@ 7.67 at Lowe's). intend to mount them fore and aft on the two tracks using the seat track bottom studs under the black round plastic hat covers, adding any additional bolts necessary to connect with the chassis steel (plate and 3/4" square tubing) under the cockpit floor
-about $6 of miscellaneous bolts, flat washers, nuts, and lock nuts out of Lowe's hardware bins to complete the job

Used a step drill bit for the first time ever, and found this to be the second most favorite tool discovered on this car project, second only to the angle grinder with cutoff wheel (which will be used to sheer off the extra lengths of the screws mounting the seats to the side brackets, once body is mounted and am sure seat orientation is good).

Went with adjustable seat tracks as I have no plans to road race, only occasional auto-cross and track days. Assuming that these strong seat mountings, plus 5 point safety harnesses, plus dual roll bars will be considered sufficiently safe.
 

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Discussion Starter #3
Mark,
That is a very good question (which I hadn't thought of)! The driver's seat did work over a short test range, but I'll give them a full span test today. If needed, will shim the brackets against the seat with washers. Thanks for the thought.
 

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I have no intention of being a safety Nazi but everyone considering this needs to know.

Kirkey seats are designed to be installed with a back support. They are not designed for impact from any direction, nor use in any arena without a proper back support installed. Installing the seat in this manor should be done knowing you are operating outside design parameters and installation instructions.
 

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Understood. and appreciate the input. No doubt Kirkey's lawyers rightfully mandate that statement. My (non scientific) observations:
1. The thick gauge, multi-welded, non pivoting back rest, three dimensional, semi-monocoque nature of the seat sure seems stronger than any car seat in any car I've owned over 40 years.
2. Again, won't the 5 point harness hold me tightly in fore & aft space, regardless of the seat's "inadequate" strength?
3. It sure seems that any physics application that can penetrate the roll bar, 5 point harness, seat base and roadster chassis integrity will sure do a number on human protoplasm, regardless of whether there's a seatback mount or not.

Nevertheless, even if all of the above is wrong, after 40+ years and ~ 200,000 miles of motorcycle trail biking, enduro riding, closed course roadracing, desert riding/racing, and street riding (current bike is an R1, on which I've occasionally hit 175 indicated and regularly "exceed the speed limit", while still in 2nd gear on the way to 6th), it just doesn't strike me as that risky to drive without a seatback mount.:001_smile:
 

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Like I said, I'm not the safety police. Lots of guys here don't know the risks or how to properly install a seat. My only intent is to make sure they are informed.

IMO, the biggest risk is a rear hit, folding the seat back halfway up and breaking the back, but I'm not the engineer.
 

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Nevertheless, even if all of the above is wrong, after 40+ years and ~ 200,000 miles of motorcycle trail biking, enduro riding, closed course roadracing, desert riding/racing, and street riding (current bike is an R1, on which I've occasionally hit 175 indicated and regularly "exceed the speed limit", while still in 2nd gear on the way to 6th), it just doesn't strike me as that risky to drive without a seatback mount.:001_smile:
Wait till for some reason ya get hit by another car or truck or it gets away on ya and ya find your self bouncing off of gaurd rails and that seat back folds up and your flung out of your shoulder straps... I to talk from many years of competition in the 1/4 mile and some auto cross. and the NHRA and IHRA will not allow you to run without a race seat been suported properly.
(P.S. my bikes faster than your's LOL...:001_tongue: ) >>>>

 

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Wait till for some reason ya get hit by another car or truck or it gets away on ya and ya find your self bouncing off of gaurd rails and that seat back folds up and your flung out of your shoulder straps... I to talk from many years of competition in the 1/4 mile and some auto cross. and the NHRA and IHRA will not allow you to run without a race seat been suported properly.
(P.S. my bikes faster than your's LOL...:001_tongue: ) >>>>

I've settled down myself. Way back when, I was the only MSF instructor in California doing sub 1:30 laps at Willow. Back then my weapon of choice was a prepped FZR1000. Now days I've settled down and ride a nice slow put put bike.
 

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We make choices every day that can have an impact when "what if" happens. I appreciate others providing factual information. What you do with it is up to you.

I opted to mount my Kirkeys on a (DS only) slider which I borrowed from a junkyard donor. Used a couple of 3/4" x 3/4" steel tube to tie the members together and give me a solid platform to bolt to. It's definitely not racetrack approved, but I wanted a little flexibility in driving position. Mostly for myself as it helps to be over top of the wheel sometimes but on longer drives I like to be a bit more relaxed, farther back.

One warning about the Kirkeys though. The upper 'wing' or support will be very close to the driver's door and you may not get as much track movement as you would like if you don't angle the mounting positon.

You don't have to angle the seats, they can still be straight front to back. But if you parallel offset your tracks slightly so the seat moves away from the trans tunnel just a little bit, you will be able to slide them all the way back (until the touch the rear cockpit) and still have a decent sliding range forward.

Sean
 

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Seat back support

MikeinAtlanta and all:

Mike has got a valid point and in a competition setting where only one driver uses the seat, it makes great sense to have the seat braced in all directions. But SCCA and most racing organizations that have rules on this let just about anything pass for a back support. One that passes is just a "T" shaped piece with a plate that bolts on the back of the seat and has a rod that goes back to the cage. A big side hit and it would bend like a cornstalk. Front and rear impacts are not too bad, as it spreads the load out anyway. The only real smart way to brace the seats is some diagonal braces that prevent both front to rear and side to side. I have seen 3 Kirkey seats that have been in wrecks in the NW at track days and competition events and they all were bent a little. On inspection 2 of them had no bracing and they just kind of leaned over about an inch and stayed that way. No cracking, just deformed. The one that had the back brace was still bent a little just above the brace. All of these seats were using Kirkey style mounts, except one that was bolted to the floor. The mounts bent a little also. My read was that the seat actually absorbed some of the shock load like the foam in a helmet and kept the total "G" loads on the driver down a little lower. A lot of the FIA rated racing seats that use a steel tube or sheet metal frame are not required to have a back brace by SCCA and there are FIA rated adjustable seat tracks available from Sparco and others. Here's what SCCA has to say about seats and mounting. Anything goes and most tech inspectors wouldn't know a good brace anyway as they are not engineers.

"9.3.41. SEATS
The driver’s seat shall be a one-piece bucket-type seat and shall be
securely mounted. The back of the seat shall be firmly attached to the
main roll hoop, or its cross bracing, so as to provide aft and lateral support.
Seats homologated to and mounted in accordance with FIA standard
8855-1999, or FIA.Standard.8862-2009 or higher need not have
the seat back attached to the roll structure. Seats with a back not attached
to the main roll hoop or its cross bracing may not be mounted to
the stock runners unless they are the FIA homologated seats specified in
an FIA homologated race car. The homologation labels must be visible.
Seat supports shall be of the type listed on FIA technical list No.12 or
No. 40 (lateral, bottom, etc). Passenger seat back–if a folding seat, it
shall be securely bolted or strapped in place.
Mounting structures for racing seats may attach to the floor, cage
and or center tunnel. Seat mounting points forward of the main hoop,
between the center line of the car and the driver’s side door bar and
rearward of the front edge of the seat bottom are not considered cage
attachment points in classes with limitations on the number of attachments.
A system of head rest to prevent whiplash and rebound, and also to prevent
the driver’s head from striking the underside of the main hoop shall
be installed on all vehicles. Racing seats with integral headrests satisfy
this requirement.
The head rest on non-integral seats shall have a minimum area of 36
square inches and be padded with a minimum of one inch thick padding.
It is strongly recommended that padding meet SFI spec 45.2 or FIA
Sports Car Head Rest Material. The head rest shall be capable of withstanding
a force of two-hundred (200) lbs. in a rearward direction. The
head rest support shall be such that it continues rearward or upward
from the top edge in a way that the driver’s helmet can not hook over
the pad""

And that's it for rules. I have seen some adjustable back supports that actually work well but I'm not sure how to do a picture here. PM me and I'll get you a sketch of how they work.

Ron
 

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Great post Roadracer83. I've seen lots of reminders about the back brace requirement, but you are the first to share actual accident results. I'm surprised the seat without the brace held up as well as you describe. Great post.

Jeff
 

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My seat back mounts are very rigid but also made to bend up to and inch in any direction. We are using seat inserts for different height drivers.
 
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