Partial Tube Front End Using Stock Panels, Any pictures/ideas?
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From: 909 all motor mafia,, CA, USA
Partial Tube Front End Using Stock Panels, Any pictures/ideas?
This is for a 'weekend fun' drag car, no intention of being class legal in anything, just want to run it for fun at the track as I don't have the money to race competitively.
I'm sure everyone has noticed the severe amount of front end flex on a stock EG - most obvious when you jack the car from the center front, place jack stands at the factory jack points (front of each door), and set the car down - the jackpoints will come to rest on the jackstands, but the front of the car will keep going down maybe 3-4" further before its weight comes off the jack panel. This leads me to believe that a large amount of flex is going on between the firewall and the front end. I suspect this would contribute to wheelhop and just generally imprecise suspension action from the front suspension. First question: am I wrong?
I believe this is the reason that those 'JDM' fender braces exist, but I find it hard to believe that something like that is going to significantly increase front end stiffness.
Here is my plan, hopefully my description is accurate enough to allow you to form a mental picture:
- cut off the frame rail about 10" forward of the point where the frame rail projects from the base of the strut tower
- plate in a large section of the firewall in the upper corner, also plate a section of the top of the strut tower.
- run a tube the starts at the plated section of the firewall, comes forward across the top of the strut tower (welded to the plated section as it crosses it), then curves down and attaches to the top of the frame rail just at the end where it was cut off (this attachment point will probably have to be plated/boxed as well).
- Build a minimalist structure to support the required front end components (radiator, headlights, front bumper). Bottom tube will be a set of traction bars that doubles as support for the radiator, and will have a square steel plate welded to it in the center to act as a front jackpoint. Top bar will be just enough to support the radiator and a set of hoodpins. Was thinking I should probably run a pretty substantial bar right in the middle to directly connect the two framerails...
Anyone have any pics that show something similar, in all or in part? Anything I'm leaving out that is necessary to make this concept work, or is it just unworkable? I also plan to seam weld whatever seams I can find on the whole area (fenderwell/framerails/strut towers) forward of the firewall.
And before you ask, yes I understand the top tubes would be better if they ran through the firewall and attached to the front down tubes of a cage. However the car will almost certainly never run quick enough ETs to need more than it already has (six-point NHRA-legal roll bar with door bars) and I'm reluctant to add way more structure inside the car due to the weight it will add. The reason I can't afford to race competitively is because I can't afford to build crazy powerful motors, so I'm trying to build a chassis that will maximize what I have, and adding a bunch of weight runs counter to that objective...
I'm sure everyone has noticed the severe amount of front end flex on a stock EG - most obvious when you jack the car from the center front, place jack stands at the factory jack points (front of each door), and set the car down - the jackpoints will come to rest on the jackstands, but the front of the car will keep going down maybe 3-4" further before its weight comes off the jack panel. This leads me to believe that a large amount of flex is going on between the firewall and the front end. I suspect this would contribute to wheelhop and just generally imprecise suspension action from the front suspension. First question: am I wrong?
I believe this is the reason that those 'JDM' fender braces exist, but I find it hard to believe that something like that is going to significantly increase front end stiffness.
Here is my plan, hopefully my description is accurate enough to allow you to form a mental picture:
- cut off the frame rail about 10" forward of the point where the frame rail projects from the base of the strut tower
- plate in a large section of the firewall in the upper corner, also plate a section of the top of the strut tower.
- run a tube the starts at the plated section of the firewall, comes forward across the top of the strut tower (welded to the plated section as it crosses it), then curves down and attaches to the top of the frame rail just at the end where it was cut off (this attachment point will probably have to be plated/boxed as well).
- Build a minimalist structure to support the required front end components (radiator, headlights, front bumper). Bottom tube will be a set of traction bars that doubles as support for the radiator, and will have a square steel plate welded to it in the center to act as a front jackpoint. Top bar will be just enough to support the radiator and a set of hoodpins. Was thinking I should probably run a pretty substantial bar right in the middle to directly connect the two framerails...
Anyone have any pics that show something similar, in all or in part? Anything I'm leaving out that is necessary to make this concept work, or is it just unworkable? I also plan to seam weld whatever seams I can find on the whole area (fenderwell/framerails/strut towers) forward of the firewall.
And before you ask, yes I understand the top tubes would be better if they ran through the firewall and attached to the front down tubes of a cage. However the car will almost certainly never run quick enough ETs to need more than it already has (six-point NHRA-legal roll bar with door bars) and I'm reluctant to add way more structure inside the car due to the weight it will add. The reason I can't afford to race competitively is because I can't afford to build crazy powerful motors, so I'm trying to build a chassis that will maximize what I have, and adding a bunch of weight runs counter to that objective...
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From: Zoo York
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (revolt_allmotor)
If you're worried about the structural rigidity (say that 5 times fast) of the front end I would be concerned the rest of the chassis as well. If you want to undertake what you described and are capable of it there is no reason you should not be able to build a cage.
Back onto subject. I would worry about there being flex in the firewall portion of your concoction. Yes; you can stick a .125 steel plate there but the area in general lacks a proper "foundation." It's weak (compared to say an a-pillar bar/frame rail/etc.) Maybe you can add a smaller OD tube down from your "fire attatchment point to a bar crossing between the front frame rails towards the firewall. Kinda like in this picture. I'd imagine it would stiffen up the front end a lil'.
Attach diagnal bars to that from the upper bars. Just an idea. Did i lose ya?
oh, yes the motor is crooked; this is when we were making it fit!
Back onto subject. I would worry about there being flex in the firewall portion of your concoction. Yes; you can stick a .125 steel plate there but the area in general lacks a proper "foundation." It's weak (compared to say an a-pillar bar/frame rail/etc.) Maybe you can add a smaller OD tube down from your "fire attatchment point to a bar crossing between the front frame rails towards the firewall. Kinda like in this picture. I'd imagine it would stiffen up the front end a lil'.
Attach diagnal bars to that from the upper bars. Just an idea. Did i lose ya? oh, yes the motor is crooked; this is when we were making it fit!
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From: Dallas, TX, USA
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (revolt_allmotor)
The 3-4" of "flex" you're seeing is mostly the car resting on the new pivot point the jack stands provide, and the rear of the car coming up a bit vs. it being on a jack from the front...
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From: 909 all motor mafia,, CA, USA
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (bigTom)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigTom »</TD></TR><TR><TD CLASS="quote">Back onto subject. I would worry about there being flex in the firewall portion of your concoction. Yes; you can stick a .125 steel plate there but the area in general lacks a proper "foundation." It's weak (compared to say an a-pillar bar/frame rail/etc.) Maybe you can add a smaller OD tube down from your "fire attatchment point to a bar crossing between the front frame rails towards the firewall. Kinda like in this picture. I'd imagine it would stiffen up the front end a lil'. Attach diagnal bars to that from the upper bars. Just an idea. Did i lose ya? </TD></TR></TABLE>
That's the kind of info I'm looking for!
Will definitely take that into consideration.
Also thinking about a diagonal downtube from the rear (inside the car) portion of the plated firewall section to the front mounting plate where the single door bar of my six-point cage attaches...
Attach diagnal bars to that from the upper bars. Just an idea. Did i lose ya? </TD></TR></TABLE> That's the kind of info I'm looking for!Will definitely take that into consideration.
Also thinking about a diagonal downtube from the rear (inside the car) portion of the plated firewall section to the front mounting plate where the single door bar of my six-point cage attaches...
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From: b00sting my D16s, SoWis, USA
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (revolt_allmotor)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by revolt_allmotor »</TD></TR><TR><TD CLASS="quote">I'm sure everyone has noticed the severe amount of front end flex on a stock EG - most obvious when you jack the car from the center front, place jack stands at the factory jack points (front of each door), and set the car down - the jackpoints will come to rest on the jackstands, but the front of the car will keep going down maybe 3-4" further</TD></TR></TABLE>
I'm sure that you'd also see the incredible amount of flex in the unibody when you tilt the car 90 degrees and rest it vertically on it's front bumper support. Even more then you flip it 180 and rest it on the roof. That sheet metal up there will love to bend. To put it another way, you could have a solid block of berylium, conveniently the weight of a civic subframe, and jack one end up at the end of a spring-steel flat bar 12 inches long. Despite everything beyond that first foot being the made from the strongest metal for it's weight, it will appear to flex a considerable amount. Hopefully my point was conveyed mostly through my facetiousness.
The civic chasis is meant to be rigid through where the [driving] loads get placed on the car - the shock towers and the UCA/LCA mount points - and most vectors between them. When you jack it up from those points, you don't get much flex. The only way you reduce the flex that matters is by bracing said points. Brace the front to eliminate that 3-4" of flex you speak of, and you'll see no benifit besides reducing flex during that opperation.
You could always argue that placing supports far away from loads will benifit from using less material due to leveraging, and using less material to deal with the same amount of torque. Not many engineers try that approach though.
Integrating that cage to any places near the shock towers or suspension mounts will help make it more of an internal skeleton. The unibody is more of an exoskeleton, so in that way you'd get the best of both worlds.
I'm sure that you'd also see the incredible amount of flex in the unibody when you tilt the car 90 degrees and rest it vertically on it's front bumper support. Even more then you flip it 180 and rest it on the roof. That sheet metal up there will love to bend. To put it another way, you could have a solid block of berylium, conveniently the weight of a civic subframe, and jack one end up at the end of a spring-steel flat bar 12 inches long. Despite everything beyond that first foot being the made from the strongest metal for it's weight, it will appear to flex a considerable amount. Hopefully my point was conveyed mostly through my facetiousness.
The civic chasis is meant to be rigid through where the [driving] loads get placed on the car - the shock towers and the UCA/LCA mount points - and most vectors between them. When you jack it up from those points, you don't get much flex. The only way you reduce the flex that matters is by bracing said points. Brace the front to eliminate that 3-4" of flex you speak of, and you'll see no benifit besides reducing flex during that opperation.
You could always argue that placing supports far away from loads will benifit from using less material due to leveraging, and using less material to deal with the same amount of torque. Not many engineers try that approach though.
Integrating that cage to any places near the shock towers or suspension mounts will help make it more of an internal skeleton. The unibody is more of an exoskeleton, so in that way you'd get the best of both worlds.
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Thread Starter
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From: 909 all motor mafia,, CA, USA
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (HiProfile)
Your 'facetiousness' is completely missing the point of my entire post. I don't care about the flex when I jack the car up - what I was trying to convey was the fact that it seems like there is significant flex between the firewall area and the front strut towers, which I would assume would contribute to poor handling and wheel hop. You obviously didn't read the first post very closely, as I made that quite clear. I simply used the 'front jack point flex' as a visual aid.
And again you obviously failed to read what I wrote - reinforcing the strut towers connecting them more solidly to the central part of the chassis is exactly what I'm proposing.
I feel like maybe you only read the first paragraph of my original post?
And again you obviously failed to read what I wrote - reinforcing the strut towers connecting them more solidly to the central part of the chassis is exactly what I'm proposing.
I feel like maybe you only read the first paragraph of my original post?
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From: Zoo York
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (Fred Allen Burge)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Fred Allen Burge »</TD></TR><TR><TD CLASS="quote">Any more pics of that engine bay?
Fred</TD></TR></TABLE>
https://honda-tech.com/zerothread?id=1608977
Fred</TD></TR></TABLE>
https://honda-tech.com/zerothread?id=1608977
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From: 909 all motor mafia,, CA, USA
Re: Partial Tube Front End Using Stock Panels, Any pictures/ideas? (bigTom)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigTom »</TD></TR><TR><TD CLASS="quote">https://honda-tech.com/zerothread?id=1608977</TD></TR></TABLE>
Nice!
I am thinking if I use a similar rear crossmember, I can attach that to the plated section of the firewall as well, which should stiffen everything up even further...
Nice!
I am thinking if I use a similar rear crossmember, I can attach that to the plated section of the firewall as well, which should stiffen everything up even further...
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