Re: A-body dailydriver 1" torsion bar upgrade
[Re: jcc]
#1527538
04/22/14 01:59 PM
04/22/14 01:59 PM
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Joined: May 2012
Posts: 841 Santa Fe Springs, CA
Dan@Hotchkis
super stock
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super stock
Joined: May 2012
Posts: 841
Santa Fe Springs, CA
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Quote:
I agree with Mitch, go big.
Unless you have a proper cage and significant reinforcement to support the chassis, I would stick with 1.06 or lower for A bodies and 1.10 or lower for the B and E's. Any more than that and significant torsional load is transferred to the chassis; you begin to pop spot welds and tear sheet metal.
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Re: A-body dailydriver 1" torsion bar upgrade
[Re: Dan@Hotchkis]
#1527547
04/23/14 09:22 AM
04/23/14 09:22 AM
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Joined: Jan 2009
Posts: 813 Ontario,Canada
brads70
super stock
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super stock
Joined: Jan 2009
Posts: 813
Ontario,Canada
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In our experience, the three major fail points were: -upper inner fender wells where they "attach" to the firewall -Inner fender wells to shock tower -Rear shock tower to frame horn
That was with 2 above average chassis'; about 30k street miles driven mostly in CA, AZ and NV; and probably 500 track miles and 2000ish autocross laps split between the two. Your results may vary.
Thanks for sharing that! US cartool cowl brace should address the first two then?
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Re: A-body dailydriver 1" torsion bar upgrade
[Re: Dan@Hotchkis]
#1527548
04/23/14 01:15 PM
04/23/14 01:15 PM
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Joined: Jan 2010
Posts: 1,443 NW Chicago suburban area
Mopar Mitch
pro stock
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pro stock
Joined: Jan 2010
Posts: 1,443
NW Chicago suburban area
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I've owned my Chally since 1975, always been rust free (stored winters), bought it with 22K odometer; been autocrossing it since 1975; car went through major transformation in mid-80s, including progressive changes in suspension (TBs, leafs, bushings, shocks, etc) primarily for concentrated hi-level SCCA Solo II/autocross competition, as well as for some hi-speed road course events). Streetable, but mostly trailerd between mid 80s through mid 2000s. Odometer currently has ~78K (put ~5K miles between mid 80s~early 2000). Chassis/unibody has no cracks or weld breakage, no stress cracks, etc... I know every inch of the car. Best mod ever for improved suspension handling was progressing stiffer with the TBs... the 1.24 is simply the largest to fit within the factory hex openings.... and a 1.24 TB is still very reasonable to drive daily... other mods compliment the "package" to my car.... again, primarily intended, and following the SCCA class rules for "E/Street Prepared".... rules have since changed a little since my past heavy involvement up to early 2000s, so a few other selective mods could be done, including welding in SFCs (must attach to the front and rear frame rails, not the leaf spring point).
The original T/A-AAR race cars used something like 1.4 diameter TBs.... makes the 1.24 and smaller TBs really weak by comparison. I had the opportunity to talk "unibody stiffness" with some Chrysler engineers face-to-face in the early 80s.. they told me our Mopars (concentrating on my E-body) had the strongest unibody designs compared against any makes, and even the AMC Javelins were very strong. At the time I was considering the "SCCA-Solo allowed Bolt-In SFCs"... they told me unless they were welded in, not to worry or bother with them (and I still don't have any SFCs.. maybe/probably someday). Our unibodies can certainly be strengthened, but I've never experienced any unibody or weld cracking, despite extreme g-forces (soft/ultra-sticky compound tires, such as Hoosiers). The car is intended to be driven at autocross and road course events, and certainly avoiding bad roads, pot holes, etc when driven on the street/hwy... If I were concerned about the ride stiffness, I wouldn't drive it on the street/hwy... even with the 1.24 TBs in it now, as well as some friends of mine with A-bodies having 1.14 (even 1.18), driving on the street/hwy is just fine and compliments the handling for better personal enjoyment.
Big TBs aren't for everyone, but small TBs (1.0~1.6~1.10) only lend the question: "These aren't bad at all... what would larger TBs be like?" That's why I encourage at least mid-range TBs like ~1.12-1.18 for best moderate results (leaning towards street/hwy as a larger % of someone's driving)... and still other mods are needed to compliment (leafs, shocks, etc). Don't forget.. "the nut-behind-the-wheel" will make the biggest difference.
Mopar Mitch
"Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers!
Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!
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Re: A-body dailydriver 1" torsion bar upgrade
[Re: Dan@Hotchkis]
#1527549
04/23/14 01:51 PM
04/23/14 01:51 PM
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Joined: Apr 2012
Posts: 186
B-Body Bull
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member
Joined: Apr 2012
Posts: 186
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Quote:
Quote:
Unless you have a proper cage and significant reinforcement to support the chassis, I would stick with 1.06 or lower for A bodies and 1.10 or lower for the B and E's. Any more than that and significant torsional load is transferred to the chassis; you begin to pop spot welds and tear sheet metal.
My Duster has broken these while using mopar 1.14 bars: k-member at control arm/torsion bar pivot, torsion bar cross member at torsion bar socket. A bodies are flimsy so get out the welder. Get some custom rate leafs to match large bars or it's Plow city. For me, I like the .99 bars addco front and rear sway bars, monroe shocks, and Hotchkiss 130lb leafs for driving my Duster. My stock suspension factory bars and leafs Duster with just low profile tires, front and rear sway bars and edelbrock shocks handled like a boat, when autocrossing in comparison.
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Re: A-body dailydriver 1" torsion bar upgrade
[Re: jcc]
#1527551
04/26/14 11:15 AM
04/26/14 11:15 AM
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Joined: May 2012
Posts: 841 Santa Fe Springs, CA
Dan@Hotchkis
super stock
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super stock
Joined: May 2012
Posts: 841
Santa Fe Springs, CA
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Quote:
Boy, been on Moparts over ten years, and finally discover we should be picking our TB sizes based on possible spot weld failures. Who knew?
Some people get a little bummed when they just spent 50k on a freshly restored car and their front frame horn and inner fenders detach on a track day. Who knew?
We try to minimize failures as much as possible. We'd feel a bit liable if someone's car came apart because of a recommendation we made. Are you willing to be liable for it? Both of the cars we ran heavy TB's on began to see massive amounts of torsional loads shifted from the suspension to the body, and failures ensued. Not all of the cars out there are as well maintained as Mitch's car; and I would argue that my Road Runner is in about as good of shape as his Challenger. We didn't have any catastrophic failures, but sections of the frame horns started to come apart. I made the repairs needed and stepped down on the bars to our new production units.
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Re: A-body dailydriver 1" torsion bar upgrade
[Re: 68cuda440]
#1527553
04/27/14 10:53 AM
04/27/14 10:53 AM
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Joined: May 2012
Posts: 841 Santa Fe Springs, CA
Dan@Hotchkis
super stock
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super stock
Joined: May 2012
Posts: 841
Santa Fe Springs, CA
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Quote:
Would the A-body then fail elsewhere? The shock towers on the A body appear to be a lot more stout and better attached to the frame rails. Any experience on the A body cars? My car has had some reinforcement and some additional welding, but nothing compared to the car you posted the link for that has a full cage being fabricated. The A-body has a lot of differences dimensionally, and has some design differences. Does it have more torsional rigidity than an E-body?
An excellent question. I"m trying to recall, but the only thing I've personally noticed is about twice as many LCA pin hole failures on the K-Mmember. We are building 3 A-Bodies right now that should start hitting the streets in the next month or so. These will be the cars to watch.
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