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IDK if I would mess with the seat frame at all. You do not want to weaken it any, could end up being detrimental to your health.

If you were to do anything replace the steel with Aluminum. It is 1/3rd the weight of steel and a good rule of thumb is the Aluminum will need to be 1.5 times the thickness. it looks like the seat frame is close to 0.125" thick. so you would need to use 0.1875" (3/16") Aluminum. By doing that you would reduce the weight by 50%. Because it is the seat I would suggest to go 2.0 times thicker with the aluminum and make it 1/4". you will still have a weight savings of 40% and you will end up with a stronger seat base. 1/4" aluminum stock is not that expensive. I would use 4 steel rivets that are 3/16" diameter at each end of the flat stock. I would then set the rivets using any large chunk of steel and a 5lb hand sledge. I have a piece of railroad track that I use as an anvil which works. You want to flatten the rivet to tighten it up. No need to weld the cross bars at all.
 

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and your car is going to look like a roller skate!!!!


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Yes that is a steering wheel at the top. LOL


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I have a question regarding the seat.. The Solstice/Sky has a pretty flat floor pan where the seat bolts in. why the need for 2 mounting frames?

The brackets that are on the sides of the Sparco do come off yes??? and those brackets should have mounting holes in them. bolt them to the floor then put the seat in and put the screws in on the sides. It looks like there is the ability to adjust the height of the seat, 4 different levels and you have it at the second to the lowest setting. So if the second bracket was so that you could get the seat to sit up higher this can be accomplished using the adjustments on the seat.

If your concern is bolt location this is an easy thing to handle. Use 2 pieces of 1/4" aluminum flat bar and bolt them under the car in the same location that the stock seat rails bolt down to. then you can set the rails in place and drill a pilot hole through the floor and through the aluminum. then take the flat bars out and drill them so that you can press some wheel studs into the bars. drill the holes in the floor pan so the studs will fit through and put the bars back in (studs up).. there is no way that seat would pull loose from the floor if you did that.
 
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Also I can walk you through how to get rid of the "blob" under the steering column. It is not that hard to do. Amazon has the part for 50.00 USD that will enable you to move the immobilizer module



Here is the schematic of the part that sits in that "blob"

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the part marked "1" is what you would need to move. The ring you see in the image on the part is an antenna, it wraps around the key cylinder to read the microchip in the handle of your key. If you move it the car will not start. That is where that piece i mentioned above comes into play. It wires into the wiring that plugs into the Theft Deterrent Control Module when that "bypass" is activated it will send the information the BCM needs to allow the vehicle to start. Since the bypass is taking over the function of what the microchip in the key would do you can then move the Theft Deterrent Control Module to under the dashboard along with the bypass module. then you can leave the bottom half of the column off or you can cut the "blob" off if you want.

I helped design and test this module. It was originally made by a company called Trilogic, Directed Electronics (DEI) bought them out some years ago. That module has been around for 14 years and is bulletproof.. It is wicked easy to install too...
 

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Discussion Starter #65
It was that the width of the seat and seat rails was close but not close enough to width of the floor studs. Floor studs 17-3/8 inch wide iirc and seat rails 17. So how to make wider when they overlap an odd amount? I don’t have a big metal bender.
 

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Yeah I know what you are saying. I think that attacking the problem from under the car using the flat bar and studs like I described would be the the strongest way and also the lightest way. you can grind down the edges of the flat bar so nothing could get hung up and the use of pressed in studs make it hard for anything to get hung up. you could even countersink the studs 1/16" to reduce the change even further.

I don't know of any better way to go about it other then what you have done. but that frame has got to weight quite a bit.
 

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The flat bars running laterally seem unnecessary to me, and I wouldn't be putting much faith in that seat belt mount tab to hold up in even a minor crash.

I've had the luxury to make my own (you've seen them elsewhere at this point,) but I bolt them to the seat, then drop the seat and brackets into the car together. There is more than enough room to access the studs/nuts to bolt it in, and I have a few inches of fore/aft adjustability built in so you can "quickly" unbolt, move, and re-bolt if needed for different drivers.
 

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Discussion Starter #68
The tab welded on the rear of the frame is 1/8 and the L channel is 1/8, and the bolt goes through both. The 4 inch piece is just 1/8 inch but I can easily make that 3/16. The stock seats are using 1/8 steel plus the nut is welded to that part.

KG yeah it does weigh a bunch, but I think its still not as heavy as the stock seats altogether. I will have to re-weigh everything soon.
 

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IDK what the material the seat pan is. It looks like fiberglass. If it is fiber glass then the seat and the brackets that came with it should weigh 1/3rd what the original seat weighs. I have never done a weight comparison so I couldn't tell you exactly. I can tell you that the frame you made has got to weight a pretty decent amount. the thing is built like a brick poop house. As @phil1734 said, you can probably get away with only using the L channel on either side and there is no real need to have the bars connecting the 2 together. it looks like the width difference between the mounting locations in the car and the mounting locations on the seat are way more then 3/8" difference, it's hard to tell from the photos.

You can also make the edge of the L channel that is vertical 50% - 75% shorter. that will also save quite a bit of weight.
 

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1"x1"x1/8" L channel with a span of < 2 feet can hold at least 2,000 lbs with the weight centered in the middle of it (this is a guess I would have to check to know exactly). those are some pretty high G's needed to cause the bars to bend from your body weight. that is why I said you can shorten the vertical sides of the L channel.

So as far as weight reduction goes between getting rid of the flat bars that connect the 2 rails and shortening the sides you would have a 40% - 50% reduction in weight for the frame, possibly more then that. because the holes for where the seat mount are so far away from the side, I would add enough metal to the bottom next to the mounting holes so the L channel makes contact with the floor. doing that will keep the L channel from twisting.

I know you want to keep the weight in the vehicle down, How long did it take you to shave 5lbs by removing the sound deadening material?
 

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Discussion Starter #71
Taking out sound stuff took like 45 mins.
I'll think about a redesign for the passenger side seat, I haven't done that one yet. Redoing the driver side might be a "later" project to do since time is running out before start of the season.
 

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Just some suggestions, you did ask about cutting holes in it to reduce the weight. 🤪
 
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Discussion Starter #73
Just the seat: 15 pounds, seat with Sparco side brackets 22 pounts, seat with brick-house mount 32 pounds. Still 10 pounds lighter than stock seat!
 

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Discussion Starter #74
2021.03.19 Wheels arrived!

BCForged style KL01, I chose these because they have the look I wanted, and they specifically have the lug nuts not inside of the spokes, they are more exposed so easier to get to with the impact gun. Silver finish has a LOT of metal flake, looks great, matches the windsheild surround/tulip area too.

I made sure to check with them so there is at least 1.5 "fingers" of space for the Brembo calipers.
+50mm offset
not cheap, around $3000
from Sam Strano <- my main man, literally multi time SCCA autocross national champ, and local to me, ie comes to some of my local events. Helped me out a lot on my TA.

LIGHT WEIGHT OMG!
Just the rim is 18.5 (maybe 19, my bathroom scale is only good to 1/2 pound)
BFG Rival 315 tire is 29.5
So.... stock wheel with tire: 54 pounds
BC + BFGs: 48 pounds!

In the rear I will probably have to use the BFH to get a little bit of clearance. :giggle:

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Discussion Starter #75
2021.03.20 Rollbar update

The RPM Rollbar got taken last week to a guy who works on them as practically his 2nd job and came highly recommended. I wanted to get rear bars added to mount shoulder harness straps on. It was more than a day job, as there were 3 simultaneous angles to bend and notch for. While I was there he did a lot of hand grinding to make it fit. A week later it was done and ready. The sizing is just right, it fits in front of the rear wall and panel just right.

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This piece was sort of the lynchpin to the whole car. I could certainly drive/autocross it without, but I really wanted a harness for competition, and with the completion of the welding, I can install the bar and the seat placement can get totally finalized and installed. And also double confirmed the top still goes up and clears it nicely, lots of space except for about 4 inches down from the top, one member gets really close, like 1 pinky width, to the bar.
 

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Discussion Starter #76
2021.03.28 Roll Bar installed!

Finally the bar is in. Thanks to RayGun (since left for Corvette world) for the post on this thread [RPM Rollbar install] and specifically this post #48 [RPM Rollbar install] to spell out a lot of details. I'll reiterate some of my favorite ideas:

  • The bar isn't sized exactly right. The width of the feet is about 1/2 inch too narrow so you really need to stand on the passenger side foot to get it into the floor depression. I feel this is sloppy design or QC.
  • I decided to use the inboard floor hole as my harness ring point. Easy peasy to just make that hole a touch bigger.
  • I was going to use the raised crossbar area where the seat mount was, but that pinched the harness behind the seat and created a rub point, so I ended up not using that. So I just used it as an additional plate mount bolt, though of course not as tight as the others so as to not squish that area. I had a friend weld the original under car foot plate to another plate to expand the size of the reinforcement.
  • Don't drill holes for the transmission tunnel until you get the feet situated.
  • Inside the transmission tunnel, at the top edge there's a double wall rib, the same as below where the cover plate mounts to. The inner tunnel plates ride in the "single wall" area.
  • The tunnel plate holes ARE AT THE TOP when oriented correctly! Very important.
  • You totally need to clean up the holes on the tunnel plate that has the welded nuts. They are probably off center, and means you can't actually get a bolt started in them properly. Some patience with a dremel griding bit to make sure they are free of impediment really helps out.
  • Inserting the driver side tunnel plate is "easy" if you're experienced with car repair/building. Its tight if you have big hands, but doable with medium hands IMO. You need to pull back the insulation of course but the holes are not too far away, easy to see and reach to put a wrench. Probably an open box wrench.
  • The passenger side: you might want to make the holes a little bigger, like 7/16.
  • The passender inner plate was actually very easy for us to install. We used twistie tie and fed a long length of it down the #1 hole, and it passed between the insulation and the tunnel metal (and where the torque arm is in the way) pretty easily. Then we passed some of it down the #4 hole. Then I put the twist tie ends through the holes and nuts on the inner plate, twisted them together, and pulled it up into place. So then the place was a little too low still, so in the holes I used a very small rod in holes 1 and 4 to lift a bit more, to get the bolts started in holes 2 and 3. Then we snipped and pulled out the twisty tie, and inserted the other bolts. Then snugged them down a lot. I had estimated it would have taken an hour to do that side with multiple attempts. But really it was quite smooth.

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Discussion Starter #78
My understanding is the yellow is zinc coating.
 

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If you take mechanics wire and wrap it around the threads of the stud (10 threads worth) and leave a pig tail of wire. Unscrew the bolt from the mechanics wire and feed the wire from the inside of the car. then screw the bolt back into the "spring" on the end and pull the stud up into place. use your fingernail against the side of the stud to hold in in the hole while you unscrew the wire and get a nut on it. When you tighten the nut it will pull "press" the stud into place. It would be more aerodynamic 🤪, and it would also have less of a chance of getting hung up on something.
 
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