PST 1.03 torsion bars

[JR_Charger]

You got a 10.5" rim into the front of an A-body?! 8.5's look dubious in the front of my B-body.

I found the Dr. Diff hub on their website. It looks thicker than the factory hub, but not enough to make up for the backspacing on an 18X10.5 rim. Are you using a spacer with it? How thick? Is your setup hub centric?

Have you experienced any issues with scrub radius?

 

[j-c-c-62]

In Mopar B-Body Performance Upgrades 1962-1979 Andy Finkbeiner says the Magnum Force 2" drop spindles allow for full suspension travel and don't affect the alignment. The only issues he mentions are interference issues with small rims that have big backspacing. He doesn't say anything about changing the roll center. I don't understand how lowering the roll center would change anything in a negative way, but suspension design is a complicated subject.

FWIW I'm in the build stage, but I've got the QA1 Kmember, adjustable strut rods, tubular LCA's, 2" drop knuckles (not yet installed), the QA1 front sway bar (planning to replace with one that can run through the Kmember), 18" rims. I've currently got the factory upper A arm installed, with reversed offset bushings, but I'm considering replacing with a tubular A arm. Not sure which one to get, there are a few on offer.

Needless to say, I'll be big disappointed if the 72 Charger doesn't handle well.

Roll center is not an alignment setting, It is a design solution/choice. Most simplistically its effect is best visualized by the distance between the geometric roll center and the center of gravity, possibly resulting in the greater the distance, the more the COG acts as a lever to make the car roll due to centrifugal force. COG always must be above the road surface obviously, but lower is always better, but still based on other compromises. It is not a simple subject.

Handling is always closely related to tire choice, you can never escape that, and a topic not yet covered here in this discussion that I remember (it's 4Am)
Here is pic of a mockup on my knuckle brake rim/tire set up, You see the TR clearance issue, which is mainly from a wide rim with a lot of BS with the dropped spindle.

 

[j-c-c-62]

You got a 10.5" rim into the front of an A-body?! 8.5's look dubious in the front of my B-body.

I found the Dr. Diff hub on their website. It looks thicker than the factory hub, but not enough to make up for the backspacing on an 18X10.5 rim. Are you using a spacer with it? How thick? Is your setup hub centric?

Have you experienced any issues with scrub radius?

My biggest issue is with the fenders, I'm going to FG fenders to ease getting/making the tire clearance I need.
Scrub radius is what is unfortunately. 1/4" spacer so far gets me in the game. Hub centric is not a deal breaker for me.
I don't remember the Dr Hubs changing wheel offset, all the extra thickness in the flange is inboard.

 

[JR_Charger]

Interesting thread. Good to know the govn has the resources to send a half dozen agents from a half dozen agencies to check the legality of a car that probably wasn't worth much when you bought it.

It's hard to believe you got a 10.5" rim in the front. I'm not sure I think I can get 8.5" in the back o.k. on the Charger, but I'm not 100% confident.

Mancini Racing used to have a hub for modern rims, but it looks like they're no longer available. I wish I hadn't missed out on that.

I assume by now you've raced the Dart with spacers and the rims mounted lug centric, and it survived?

 

[70ChargerRT]

That bracket ONLY fits a drum knuckle.
Remember guys, the proper term is NOT spindle. The spindle is the horizontal portion that the hub attaches to.

View attachment 1766902

I’m probably wrong but I thought the knuckle part where that bracket bolts on to was the same for disc and drum?

 

[Kern Dog]

I’m probably wrong but I thought the knuckle part where that bracket bolts on to was the same for disc and drum?

Here is a picture showing the top two and bottom two of the holes being filled with the gold colored bolts...

....The gold bolts attach the bracket to the drum knuckle. The top two bolts attach to the knuckle, the bottom 2 holes of the bracket attach to where the lower ball joint usually attaches. THEN you see the alternate 2 holes at the very bottom to relocate the lower ball joint to a lower position. The top two smaller bolts attach to a location that isn't there on a disc knuckle.

 

[70ChargerRT]

Here is a picture showing the top two and bottom two of the holes being filled with the gold colored bolts...

View attachment 1767159
....The gold bolts attach the bracket to the drum knuckle. The top two bolts attach to the knuckle, the bottom 2 holes of the bracket attach to where the lower ball joint usually attaches. THEN you see the alternate 2 holes at the very bottom to relocate the lower ball joint to a lower position. The top two smaller bolts attach to a location that isn't there on a disc knuckle.

View attachment 1767160

Thanks for those pics. I just don’t know how I feel about that set up.

 

[themechanic]

Purchased from Hotchkis some 10 yrs ago. They take off the shelf Bilstein shocks and modify the valving so they respond better for the weight/balance of our cars. Some estimates I've read say 15% stiffer. Later Hotchkis switched to offering tuned Fox shocks and not sure if they still offer the Bilsteins. I've never tried tuned vs non-tuned back to back to I have no idea how they compare, but they work well for my car.

Bilstein does not make a Mopar specific shock. They are sort of remanufactured/upgraded to fit a Mopar. Try using their "Search By Vehicle" on their website if you doubt what I'm saying.

Home page

cart.bilsteinus.com

 

[j-c-c-62]

Thanks for those pics. I just don’t know how I feel about that set up.

It's clever, untested, simple, improves some geometry, and if I had to do it all over, I would have tried it.
And for the talented, replicable, maybe out of Inconel, just to step it up a notch.

 

[Rennkafer]

It's clever, untested, simple, improves some geometry, and if I had to do it all over, I would have tried it.
And for the talented, replicable, maybe out of Inconel, just to step it up a notch.

Chris has tested them on his Charger. My quibble with them is the unsprung weight gain, but the geometry revision is probably worth the tradeoff. I'd try a set (or make a set, as you mention it's certainly DIYable), but I have disc brake knuckles. At some point I'll have a closer look at those to see if something similar can be made to work.

 

[j-c-c-62]

Chris has tested them on his Charger. My quibble with them is the unsprung weight gain, but the geometry revision is probably worth the tradeoff. I'd try a set (or make a set, as you mention it's certainly DIYable), but I have disc brake knuckles. At some point I'll have a closer look at those to see if something similar can be made to work.

I'm usually not fond of being able to grade one's own spelling test.
Why can't the other, albeit smaller threaded existing holes in a disc knuckle be used (3/8"?) or slightly enlarged for the other pair of grade 8+ fasteners? Didn't seem like there was a lot of meat to go the full 5/8"? Maybe on a mill offset the larger hole. and I admit, the vertical bolt spacing is reduced no matter what vs the solution being offered here.

 

[Rennkafer]

I'm usually not fond of being able to grade one's own spelling test.
Why can't the other, albeit smaller threaded existing holes in a disc knuckle be used (3/8"?) or slightly enlarged for the other pair of grade 8+ fasteners? Didn't seem like there was a lot of meat to go the full 5/8"? Maybe on a mill offset the larger hole. and I admit, the vertical bolt spacing is reduced no matter what vs the solution being offered here.

That's kind of the same direction my thinking was going for attaching one to a disc brake knuckle. I'm in the middle of building the engine for an engine swap on the car at the moment though, so that's back burner.
As far as "grading one's own spelling test"... if he just said "ya, it works better" without showing us the geometry, I'd agree. But he does show it, and it's arguably better. Again though, whether it overcomes the unsprung weight addition is anyone's guess. I'd love to see him run some instrumented testing optimizing his alignment both with and without that mod, but I doubt we're going to get that.

 

[j-c-c-62]

But everybody was afraid if they went from OEM HD .88 to ,96, their ride would be harsh, ride like a dump truck etc . Nobody would listen to Mitch. Of course, Mitch was on track competing, so no sweat off his back if they ignored him. IMO it's the best first initial most impactful upgrade followed by tires and then shocks.
My latest custom built TB is C body hex, B body length. 1.38", hollow.

 

[Kern Dog]

That is interesting. Bigger bar for more spring rate while weighing less due to the hollow center.
Hmmm…..

 

[JR_Charger]

View attachment 1768680

What is the name of the corresponding part on the LCA? Are you using QA1's tubular LCA's?

 

[j-c-c-62]

What is the name of the corresponding part on the LCA? Are you using QA1's tubular LCA's?

No, my LCA's will be custom modified OEM's, and as Kern noted the TB rate will increase, but it will be slightly offset by the slightly longer LCA's I'm using for a wider track.
I have I believe a trick solution; and I'll share when finished.
A big hold up here has been getting a vertical Heat Treater for the 41" T bars to stave off distortion issues.
They have been found, but the price is still an unknown. My fingers are crossed

Edit: I am not trying to be "coy" here on my supposedly undisclosed "trick" solution. Talk is cheap, and it's a design problem I have been tossing around for years, and I like to fine tune any solution, you know, overthink it, and when you start to share it you kind of get locked into finishing more for reveal's sake rather than changing one's mind/solution as ideas work out and evolve

 

[JR_Charger]

Huh. I thought you were not a fan of the boxed factory LCA's?

 

[j-c-c-62]

Huh. I thought you were not a fan of the boxed factory LCA's?

They will not be boxed, I have another better solution I believe I am pondering for helping a longer LCA's task, and for the thread's sake, I will leave it at that.

 

[Kern Dog]

The A bodies actually used a LCA approximately 1/2” longer than the B bodies. I was surprised to learn that.

 

[icetech]

The A bodies actually used a LCA approximately 1/2” longer than the B bodies. I was surprised to learn that.

didn't know that... probably a late repair for designing a-bodies so bad... "Oops... hang on i got a fix"