Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: migsBIG]
#1906862
09/05/15 01:19 PM
09/05/15 01:19 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Pic #60 shows some of the completed solutions I devised. Other pics may show more info in the process. https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1553823/1.html
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: migsBIG]
#1907908
09/07/15 10:45 AM
09/07/15 10:45 AM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
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The Kit Car cage pretty much does what you are asking about, but from the top not the bottom.
I don't think I've seen anyone build a cage underneath with the idea of stiffening the rear suspension. Dunno if it's a case of not enough room to do it right or that cages in compression are easier/lighter to build than ones in tension.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: migsBIG]
#1908138
09/07/15 05:15 PM
09/07/15 05:15 PM
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Joined: Jan 2010
Posts: 667 Los Osos, Ca
CKessel
mopar
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mopar
Joined: Jan 2010
Posts: 667
Los Osos, Ca
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PHJ426, do you have any drawings or pictures of what you are talking about under the package tray?
Carl Kessel
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: CKessel]
#1908264
09/07/15 09:16 PM
09/07/15 09:16 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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I suspect the OP is intent on doing something, however this is all based on the assumption that there is a lot of distortion rear? of the drivers seat, and it effects spring rates?, and optimum rear axle alignment during cornering, and this is not a wheel to wheel race car?. So all rear chassis input forces originate first thru the tires, and connect into the chassis at the front leaf spring hangers, the upper shock mounts, and the rear leaf hangers. The only significant sprung mass in this area besides the chassis is the fuel tank, and that is variable. The efficiency of any stiffening mods mainly depends on how an efficient design is incorporated to connect these 6 points, and then how they connect to the front suspension. The amount spring rate lost due to flexing can be compensated slightly by spring choice, shock settings, and or swaybar. The amount of rear live axle misalignment due to chassis flex I suspect is minimal. Chassis responsiveness for driver comfort is extremely subjective, but also very worthwhile. I don't see a lot of bang for buck stiffening the area around the fuel cell for handling purposes. Did I miss anything?
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: migsBIG]
#1908334
09/07/15 10:49 PM
09/07/15 10:49 PM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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In my experience, a reduction in chassis compliance is always a benefit in any performance application. The amount spring rate lost due to flexing can be compensated slightly by spring choice, shock settings, and or swaybar. I think this is quite underestimated, it's very difficult, if not completely possible, to tune a suspension to accompany chassis compliance. I would say that properly tuning a car for anyone here is challenging enough, adding a another variable that is not consistent isn't going to help things. Also, while steel does have excellent fatigue resistance, I'd rather not use my chassis as a point of wear at every turn, if I can help it. Just short of a cage, I'm doing as much as I can to knock the compliance out of the chassis. With my car supported by the subframes and the front rail, the rear of the car is not as solid as I would like, and is all factory at this point. I do agree that there shouldn't be a significant amount of load in the chassis past the front hangers and most roll will be handled by the sway bar. Upgrading the crossmember behind the bumper mounts wouldn't be a terrible idea however.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: GoodysGotaCuda]
#1908511
09/08/15 09:33 AM
09/08/15 09:33 AM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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For the OP, I mentioned earlier 6 points that loads are transferred into the chassis, it should also be noted, the two shock connections are mainly a vertical load input, if one discounts the fact most shocks are leaning slightly, the two rear leaf hangers have vertical and a lateral inputs, which because mopar springs are asymmetrical, these loads are always proportionally less then the front spring hangers, and then the front hangers induce, vertical, lateral, and longitudinal loads to the chassis. It should be obvious where most efforts would give the most result. And yes I agree, chassis compliance has little upside, but always exists no matter what we do, including filling the car with solid concrete.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: GoodysGotaCuda]
#1908741
09/08/15 05:20 PM
09/08/15 05:20 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
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Posts: 14,889
up yours
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Upgrading the crossmember behind the bumper mounts wouldn't be a terrible idea however. Dunno, polar moment of inertia is affected negatively if I understand where you are thinking of adding a cross member. Not sure any stiffening benefits would outweigh the negative change in inertia.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: Supercuda]
#1908833
09/08/15 07:54 PM
09/08/15 07:54 PM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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Upgrading the crossmember behind the bumper mounts wouldn't be a terrible idea however. Dunno, polar moment of inertia is affected negatively if I understand where you are thinking of adding a cross member. Not sure any stiffening benefits would outweigh the negative change in inertia. I don't think we're talking about a signifiant amount of weight here. I'd be more worried about the fuel level and the sloshing of it than the ~4# added from a crossmember reinforcement. Or the 40# battery that is usually put in that same area, behind the axle. I certainly agree it's not the best place to add weight, but on a nose heavy car, it could be worse.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: migsBIG]
#1908845
09/08/15 08:09 PM
09/08/15 08:09 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
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up yours
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Most that put the battery that far back aren't into handling, just straight line. If I was gonna relocate my battery it'd be pass side, just behind the seat or under it if I could.
Last edited by Supercuda; 09/08/15 08:12 PM.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: CKessel]
#1908958
09/08/15 11:52 PM
09/08/15 11:52 PM
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Joined: Nov 2005
Posts: 3,456 Fly Over States
PHJ426
master
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master
Joined: Nov 2005
Posts: 3,456
Fly Over States
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PHJ426, do you have any drawings or pictures of what you are talking about under the package tray? In this thread there is a post from Tom Quad take at look at the package tray here and the mounts for the belts, there is a reinforcement underneath. Read his other posts on We ran hot laps, the Black N Blue Charger at Watkins Glen https://board.moparts.org/ubbthreads/ubbt...tml#Post1183866
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: Supercuda]
#1909138
09/09/15 11:53 AM
09/09/15 11:53 AM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Most that put the battery that far back aren't into handling, just straight line. If I was gonna relocate my battery it'd be pass side, just behind the seat or under it if I could. That's where mine is, but expecting to soon switch to a lightweight battery, makes one start to question the effort and the downside of the extra wiring/switch. Having a single exhaust also helps in lowering the battery thru the floor if muffler(s) are in stock location. On this thinking, does a busted rear section of driveshaft always self disconnect and fall off, there is a front safety loop, but I am not excited about the DS flaying around and causing battery damage, especially a new light weight one (read expensive and maybe explosive?). I'm debating adding a rear loop, but this starting to get complicated.
Last edited by jcc; 09/09/15 12:23 PM.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Rear frame rails/gas tank brace. Anyone build one?
[Re: migsBIG]
#1913984
09/16/15 08:03 PM
09/16/15 08:03 PM
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Joined: Jun 2007
Posts: 2,432 NorCal
RylisPro
top fuel
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top fuel
Joined: Jun 2007
Posts: 2,432
NorCal
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