Poly Seat or Aluminum??

Scenario - Full body car (A,B,E Body) seats at OEM stock height and near OEM stock position...what aftermarket seats and mounts are you guys using & why....poly seats or aluminum and if aluminum...what angle? Looking on line, it appears that the aluminum seats are offered in 18° and 20° lay-back and have seen a couple at 10°...

Just my own experience: if the seat is too vertical it's a bit confining, especially if you have to wait in staging lanes.
OTOH, too much lay-back makes me nervous - I have a tendency to lean forward, and not use the seat back: the dreaded "air gap".

I used Kirky Pro Strteet aluminum seats in my Dart.

https://www.summitracing.com/parts/kir-41900

While many of us did most of our drag racing with a poly seat IMO No racer should use such an unsafe piece of equipment--a seat IS a piece of safety equipment---In a crash the inserts pull out of the seat bottom and you are toast--Kirkey makes aluminum seats cheap enough now days--and when mounted correctly ( a very big deal) you are much safer than in a poly seat. Poor seat mounting is very common and puts you at great risk in the event of a crash.

Im a big fan of the BAJA style seat from Corbeau. there is a big selection and all good for racing applications.

http://corbeau.com/catalog/product/view/id/133/category/78/

I've always used the poly seats with the cover. The seat itself is too light to worry about pulling out the inserts. The harness is what keeps you in place. As long as you have good mounts on the straps, you aren't going anywhere. I use the 2 piece mounts and angle the seat to where is comfortable for me. I can almost fall asleep in my seat.

This is just me ....but I never was a big fan of the aluminum seats they look uncomfortably for me, the poly does it for me.

... the proper way so set up a seat is to angle
the front up to support your legs... with your foot on the
pedal... the back of the seat can be back a little from 90*
from the seat itself... but the front is the important part..
if the back of the seat is against the cross bar its not going
anywhere... the belts hold you from going forward and up

X100

Those who say other wise have never crashed and it should not even be a question now a days like said above. GO Aluminum!

This reminds me of this...

I've never been in a wreck at the track, but I have to side with crabman173 and Challenger 1. I'm also concerned about the inserts pulling out of a poly seat. I'm not saying that poly seats are "unsafe", because they do help "confine" you within them and the belts help by being routed through them. I had poly seats in my bracket car. They have many benefits over OEM buckets and bench seats. But I believe aluminum is much safer and stronger. As for comfort, you can always add padding.

You have to remember, the seat belts DO NOT stop you from moving forward, up, laterally, etc. They LIMIT your movement! Seat belts WILL stretch, the seat can move around due to your weight and poly is weaker than aluminum. To me, it seems that insert "wallowing & pull-out" in poly appears easier than "wallowing & pull-through" in aluminum.

Of course, there are no guarantees. Each wreck is unique and weird things can happen. The severity of the accident, proper mounting and many other variables come into play. But I decided on aluminum Kirkey seats for one of my two 11-12 second cars to replace the OEM seats. I just haven't had the time or decided which one to put them in.

Anyway, that's my perspective.

I have had the inserts pull from a poly seat on a launch years ago BUT....that was because the seat was not as secure as it should have been and at that time.....the crotch strap was not properly installed....

If you lived closer and wanted a alum seat I have one
thats never been in a car... I didnt like it and bought
a poly one.. if anyone wants one cheap..$70.. come get it
its up in the rafters in my pole barn.. along with some
other stuff that never made it on a car.. like a hood scoop

The seat mounts DO NOT hold the seat in the car. For Christ sakes, Pro-Mods and similar have the damn seats held in with dzus fasteners. You think those keep the seat in the car in the event of a crash? The BELTS hold you AND the seat in the car. If your belts let you and the seat move around a lot in the event of a crash......either the belts are not mounted correctly OR you did not have them tight enough

The poly seat only weighs a few lbs. which is a very small percentage of most of our body weights.
It's not going to matter what kind of inserts it has.

If you look at how complicated the seat mounting is in a NASCAR ( they are installed RIGHT!) and then you look at the lame A$$ way most drag racers mount the set and belts you will then see my point--Drag racers usually do a crappy job --follow no instructions --or even care--Until--they have a crash and learn the hard way just how much you can move around in a car with belts tight as all get out--YOU MOVE a LOT!
Minimizing the chance for injury is all about a well designed seat that fits YOU not the average guy--all circle track seats are custom in NASCAR for a reason--you go get fitted then seat is built for you--then..more attention goes into mounting than than almost anything else.
Read, study, ask the makers of safety equipment and make your car MUCH safer! Or not...
Every violent bracket car crash I have ever seen the seat and belts did not do the job and were detached, deformed, etc which for sure added to injury--
I run a front engine dragster with a very snug drivers compartment to say the least--I am belted in so tight I can hardly breathe--I had a rough shut down on a crappy/ bumpy track recently and was VERY surprised how much I moved in the cockpit--a ride like that in a door car and poly seat and I would have been in the back seat
FWIW many Pro mod type cars fly all to pieces during a crash--everything leaving its original mounting spot--they may follow NHRA specs but those do not promise or mean it will not bust into a 1000 pieces and save you --it is not much more than a little common sense --it is not all "scienced" out so yea--they have Dzus fasteners and most everything else on them is too light and prone to break off with the least little bump
One out of 20 bracket racers can tell you what seat belt mounting angles and shoulder belt height etc should be the others are just lucky they have not crashed.

That is very dangerous advice in the op's context.

The OP car is not a pro mode and I am betting it don't have a funny car cage in it either.

I disagree... the weakest point in a seat mount is the stanchions
itself... not the seat holes... the stanchions would be the first
to go... 99% of use make them out of alum for weight.. the seat
belts do their job of containing the driver... they always have..
it you have a taller seat frame its the first thing to break.. but most of use keep the seat close to the floor with only the
front raised up for angle... I've seen multiple cars roll and the
plastic seat was still in tact when it was over... because the
belts held it there(with the driver)

I would say set in one before you buy. The poly seats are one size fits all. I'm here to tell ya my butt don't fit that well in a poly seat, very uncomfortable .It might be OK for a few minutes at the track but I drove my daughters Jeep about 1/2 mile and couldn't wait to get out of it. Kirkey aluminum fits and is comfortable in the proper width, 20 lay back for me. Just my opinion, others my differ.

Love my aluminum Kirky, I can sit comfortably in it during numerous Chevy an Ford oil downs, no problem.

NO it's not and if you don't understand, you have ZERO clue about building a REAL race car. All you internet know it alls and wannabe engineers do more harm than anyone. You can't possibly mount a poly or an aluminum seat well enough that the seats mounts alone will contain the seat and a 200 pound driver in the event of a hard crash. As far as seats not fitting, if yours doesn't, it's your own damn fault for not buying the right seat. They also make "pour in" kits that are required by the rules in faster classes. It's a mixture in a bag, you sit in the seat suited up, it conforms to your exact shape and hardens.

And what I said above about the belts and mounts is 100% true and I could really care less if you think it is bad advice or not.

The fact that Pro-Mods, Pro-Stocks, whatever, shed parts during a crash is irrelevant to this discussion. Anything that is outside the drivers compartment doesn't matter. The carbon body weighs 40lbs and is mounted with tiny tubing and dzus fasteners. Well of course it is coming off......it's supposed to. But at the end of the crash, when the fully intact drivers compartment is sitting there with the driver and seat still held in by properly mounted belts, the rest simply doesn't matter

And in this context, it doesn't matter if the car is a street car, a pro-mod or a dragster, the MOUNTS do NOT contain the seat. It's the BELTS and always has been

A seat belt only restrains a person AGAINST a surface (seat/mountings). If that surface does not resist the forces the body presents AGAINST the seat, a seat belt's usefulness is of reduced benefit in a dynamic multi impact typical crash.

I hope our readers care, its their well being at stake.

This poly seat stayed in my 66 Dart when it rolled about 6 times at about 114 mph. The safety belts did their job and kept me in the seat in the car. I did slide down in the seat some as this was in 1982 and I did not have a crotch strap in it and I slid down in the seat some and broke my ankle. My shoulder harness was hooked to the rollbar center bar behind the seat and the rest of the safety belts were hooked into the stock seat belt mounts. Ron

wow
folks use what you want just please mount it right and mount belts correctly per makers instructions

[quote=Adobedude]Love my aluminum Kirky, I can sit comfortably in it during numerous Chevy an Ford oil downs, no problem. [/quote

+ + +

The biggest concern I have now with my plastic seats in the Demon is the rear brace just being a tube ended with a 2 sq inch plate that ponts right at my backbone. In a rear impact it would skewer my back. I will be putting a formed plate there before it hits the street / track again - both seats.

My buddy was "big" In the bottom area so I heated the poly seat with a torch, then he would set in it to "form" to his butt. Had to water down his butt after each fitting. LOL

Poly, 6 bolts through the floor and one to roll bar. Aint coming loose. Close to stock position ( height and angle ). Within roll bar parameters. Very comfortable- a biggie if you are stuck in staging for any length of time. Make sure you can reach all controls after you are cinched in. Belt mounting = Factory floor mounts for lap belts, fish plated ( floor )dive belt, roll bar for shoulder belts.

Thx for all the feedback on this subject!! There are a lot of good points here and Monte brought up something that a lot of us may not have thought of in that the pro cars, their seats are held in by fasteners that allow the seat to be easily removed between rounds for maintenance accessibility and that the belts are largely responsible for holding the driver in place in the event of a roll over.....

My main concern is "safety" first, function, then comfort and then appearance in that order and I appreciate all replies.....

Aluminum, specifically the Jaz or the small Kirkey over the big pro street Kirkey. Or on a tube chassis, street roaster, dragster type car, the single panel carbon or fiberglass seat that attaches or Dzuses into a tubular seat frame that is part of the chassis. I've tried to steer guys away from the plastic bucket seats. Whatever way you go, the mounting is critical. The best seat in the world is no good if it comes loose.

We even mount the alum seats with dzus fasteners. You build a front loop off the floor that supports the front of the seat out of usually 1/2 tubing. Also bend a loop off the rear crossbar from same tubing to support back of seat. Then you can also run some pieces of 1/2 tubing from rear loop to front loop, bent to seat contour. Seat is basically sitting in a tubing frame and mounted with dzus fasteners. With the belts mounted right, you could just sit the seat in the frame and it isn't going anywhere. This type mount can be built in ANY car with ease and is 10 times better than some bolts through the bottom of the seat. You can also mount a poly seat the same way, by cutting a large enough hole in the inner shell to mount the dzus. Just because a poly seat has some weak threaded inserts in the bottom, doesn't mean you have to mount it with them. With this setup, the seat sits in a cradle. VERY safe, VERY strong, VERY secure

Many ask "whats the point of the seat dzusing out quickly"......answer that question after you need to lay in the floor to work under the dash on a car with a cage

Monte can you post some pics of mounting cradle or pm me some. Ill be doing some chassis mods over the winter and I like the idea of being able to remove the drivers seat.
Thanks in advance

http://timmcamis.com/shop/carbon-seat-frame-kit.html

Similar to pictured above, but instead of lower loop hanging from cage structure, you simply flip it over and attach it to floor. A loop on back bar to support rear of seat and bars under seat to connect two loops. Very simple. I doubt I have any pictures because seat mounts are not something I usually take pics of

My favorite is when someone installs the shoulder harness/belts through the stupid holes in the seats and they come out below your shoulders, during an accident, you will get spinal compression. Always have your belts positioned above the shoulders just slightly to minimize the angle and stretch in an accident.

I will agree, the belts should not be excessively pulled up or down by the opening in the seat. Ideally the belts should be deflected very little by the seat between the drivers shoulders and the mounting point and I've changed the openings in the seat to correct this for tall or short driver situations. Beyond that, the mounting locations for belts in racecars are pretty specific and spelled out in the rulebooks.

Well mine go thru that slot... it keeps them on
your shoulders .. see what happens if they slide
off your shoulders

That's incorrect and will get you bounced in tech. The belts have to hold you and the seat DOWN in a rollover, so therefore have to be below the shoulder or at a minimum level with

Wrong, if you are referring to the shoulder belts in your quote.
Tell us again how many cars you built.


Trevor Ashline, "Hutchens":
"The key to all restraint is the pelvis. Federal government safety studies indicate the pelvis can take loads up to 130gs, compared to 80gs for the chest and 60gs for the head. If you can control the pelvis, it is easier to control the movement of the torso and then the head and neck. A properly mounted lap belt and six-point harness can reduce the pelvic movement by 40 to 50 percent over a standard five-point system."

Butler Racing seats:
"Shoulder Harness
Shoulder harnesses should be positioned in such a manner to pull perpendicular to the drivers spine. "

Scroll down to the middle of the page :
https://simpsonraceproducts.com/pdf/inst/Seat_Belt_Mounting.pdf

I don't know the answer, but are they suggesting the 0 to 20- angles in order to make the Hans/neck restraints more effective? Because the down angle is a proven spinal issue in accidents, but think the increase in the neck restraint effectiveness might be a better trade off for their design, so I guess we should be noting with or without neck restraint in this discussion.

Some of you guys just give plain scary incorrect advice, my guess based on nothing more than your opinion.

This is the internet. That's what you're supposed to do.

I have built 6 sec Pro-Mods JCC and they pass tech. Because I do what the rulebook and belt makers say. See the link above for how Simpson says to mount their belts.....either level or below shoulder line, which is EXACTLY what I said. Hans or not, the angle is still the same but changes the relative shoulder placement, because of the added height. But I guess Simpson has no clue either. Is that what you are saying JCC?

According to you, block makers, the NHRA, SFI, chassis builders, belt makers and about everyone else has no idea what they are doing. Apparently all they need to do is call you and you could solve all the problems.......Hell, maybe you should run for president and fix that mess as well

The problem here is you only seem to get about 40% of what I write. You have yet to address the serious already noted spinal compression issue. Not sure if you even understand how that actually occurs, Additionally, most, if not all the current online references describing harness angles with a picture/diagram and a seated helmeted driver, are showing a neck restraint system (hans, etc), that is a relatively new development, especially in the lower classes. It would be interesting to know what percentage here have/use a neck restraint. Before and during the roll out of neck restraints, shoulder harnesses were instructed to be level (perpendicular to spine), or even slightly higher angle, after the spinal compression issue arose. However it is easy to see with current neck restraints to function properly, they are in a more preferred orientation if the shoulder harness is angled lower with a neck restraint then without. I already mentioned there is likely a benefit of head restraint with potential spinal compression vs no head/neck restraint. I also suspect for legal liability, and sales, all drawn references show a head/neck restraint, ask the lawyers why.

I stand by my original statement, that you were wrong in your statement if you were implying shoulder harnesses are intended to keep you down in the seat. I never commented on the NHRA (the guys with the 2 year rule), SFI, etc

shoulder harnesses were instructed to be level (perpendicular to spine),

Can't be both. Level to shoulders would put the mounting point much higher than perpendicular to spine since seats are always tilted back. If mounted perpendicular to spine, and lap belts were cinched down properly, in the event of an abrupt stop, the torso would act as a pivot point, head and shoulders trying to go forward. There would be no compression force on the spine since that would be a perpendicular motion to the straps.

You are right, can't be both if spine is off vertical, I think the point was anything lower then perpendicular was too great of risk of spinal compression. The more reclined the seat however, in a frontal impact, more force goes into seat bottom, and less into shoulder harness. I think we all also understand we are normally speaking upright seating, not formula reclining stuff here.

http://www.sfifoundation.com/wp-content/...%2006-05-12.pdf

"Butler Racing seats:
Shoulder Harness
Shoulder harnesses should be positioned in such a manner to pull perpendicular to the drivers spine."

Per SFI:
"The Anatomy of a Seat Belt

A restraint assembly consists of several components, each with a specific function. The shoulder harness is a belt assembly, one strap for each shoulder, intended to restrain movement of the upper torso and shoulder regions. An optional cross strap across the chest can be used to hold the shoulder harness together. The lap belt restrains movement of the pelvis and the anti-submarine strap prevents the pelvis from slipping forward from under the lap belt in the event of an accident."

The harness assembly is intended to keep you from moving in the seat; up, down, sideways, whatever direction you consider.

All of the information specifies that the mounting point should be no higher horizontally than the top of the shoulders and no lower than perpendicular to the spine, which if the seat is laid back 25 degrees would be a few inches below the top of the shoulders. Which brings us right back to the drawing in the rulebook which indicates the same thing. No one is specifying (or advocating) the mount to be lower than 90 degrees beyond spine angle, nor higher than level with the shoulders, which would be 65 degrees if the seat is laid back 25.

I have just fitted this seat to my sons street strip car, just setting it up but the hole for the belts in the seat is way to low.

Looks like it's laid waaay back. Is that where it goes? Getting the right seat angle is a combination of getting the height, visibility, arm and leg room, head room (don't want the top of the helmet above the hoop), and comfort right for the driver. Beyond that, the harness mount and/or crossbar will need to be at the correct height in relation to shoulder height. You may need to move the crossbar up or down or fab a new harness mount. If the opening in the seat is lower than the shoulders and would cause the belts to be deflected, a different seat may be needed. Also, the belts need to be beside each other on the crossbar and some type of retainer used to keep them in place.

CMcAllister, pic is a bit deceiving, seat position is great, top of rear bar is only about 1" below shoulder, just the hole in seat is low, we are not tall guys either. is it a big NO NO to have the belts over the seat as in the pic ? when strapped in it feel good.

I always thought the lap belt keep one from going up and foward, shoulder belts keep the upper body from going foward. The lap belt being the most important part. But I can see the belts should be custom fit for each driver, not one size fits all. Glad this post came up, now I know a little more when I put my belts in, thanks

Other than me and one other, I see no one posting pics on this subject - although lots of discussion - and interpretations of "the right way".

I believe you have the most correct understanding. Shoulder harnesses do a very poor job of restricting any upper body motion other then forward. A well designed racing seat restricts the other directions much better, Surprised a racing seat manufacturer doesn't plainly state that. I also believe one if the reasons the "Y" shoulder belt was no longer approved is, in a sideways incident, the Y shoulder harness induced a lot of forces on the neck in trying to restrain sideways body movement. the neck is not a good place to apply force to restrain body movement. Same applies to our typical shoulder harness today. The Lap belt is the key component here.

The BUtler quote also mentions the submarine belt purpose. Consider, if a typical belted driver weighs 200lbs, the upper torso/head has approx 40%? of the upper body mass restrained in a forward direction by the shoulder harnesses, or 80lbs. In a 10g forward impact, that stresses the two shoulder harnesses with 800lbs of force. Assuming no frictional loss going over the shoulder, that means ea end (4) of ea shoulder harness sees 200lbs of force during the impact. That means the lap belt has additional forces pulling up (parallel to to the spine?) of 400lbs. If the lap belt is mounted at its intended angle, the lap belt wants to rotate upwards with this lower shoulder belt induced force. The abdomen, above the pelvis, is very delicate with a lot of fragile organs, and a dangerous area to impact. That upward movement is mainly resisted by a properly positioned "submarine" belt. IMO a submarine belt is mis labeled for upright seating.

I went to the other post on proper seat belt position and read the FAA guidelines from the test they did. Very interesting read, good pics, same as what you're saying, crotch belt is very important in keeping the other belts, and the person, in the right place. NHRA rules have been out a long time and I don't know if they're up to speed with the new info of today. I mean, who has more money and clout, NHRA or the FAA to do all the test?

1" below the shoulder should be fine. The problem with your current setup is it would easy for the driver to get out from under the shoulder harness in an accident situation. The shoulder belts should come together behind the neck and be side by side at the mounting point. I use a combination couple of short "D" shaped loops with a mount for the seat brace. I've seen people use something as simple as a couple of muffler clamps to keep the belts in place. The last one I did I also had to move the hole in the seat to get a straight shot to the shoulders and prevent the belt from being deflected. Not hard with an aluminum seat. Another reason I like to use aluminum. It could be done with a poly seat, but I would want to reinforce it once I had a hole in the correct place.

I meant to quickly clarify my comment above on submarime/shoulder harness belts loads, but was not able to get back online. Mainly, the loads/numbers I used above were more for illustration that the shoulder harness applies forces on both ends, the roll bar mount and the lap belt. The numbers I used are from the hip and likely not very precise, the variables in trying to exactly calculate, are many, and if precise numbers were needed in the real world, they could only be verified by actual testing. I hope I did get my point across even taking this liberty.