SRT Hellcat Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
1 - 20 of 21 Posts

·
Registered
Challenger SRT Hellcat
Joined
·
2,192 Posts
Discussion Starter · #1 ·
Anyone seen these yet? It’s a 4-link bolt in setup from a company called Acme Labs out of North Carolina. Buddy sent me a picture of this with no explanation. Looks like it effectively replaces the rear independent setup and converts it into a straight axle setup using your factory half shafts. Anyone using this or heard of it?

568199
 

·
Registered
Challenger SRT Hellcat
Joined
·
2,516 Posts
$6,900
Wow
I guessed $5,500.
 

·
Registered
Joined
·
52 Posts
Wesley Motorsports posted about it last year as they helped develop and test it while road racing their modern Mopars. Apparently that Acme Big Stick was on their Bilstein Challenger that competed in the Pike's Peak Hill Climb - that video was insane!
 

·
Registered
Challenger SRT Hellcat
Joined
·
2,192 Posts
Discussion Starter · #11 ·
I think the 60’ times are a tenth or two but the biggest thing with this setup is consistency. I watched them launch the car several times and your brain expects it to squat and go. Instead the thing catapults flat and straight and forward. Its pretty crazy because it’s not what your eyes are expecting to see on a hard Challenger launch.
 

·
Registered
Joined
·
4,608 Posts
Actually, that is known as a De Dion suspension. It was used on Gerald Wiegert's Vector W2 "supercar."
Automotive lighting Motor vehicle Automotive design Automotive wheel system Auto part


This particular version has a Watts link (as used on Gen 1 RX7's) to laterally locate the "De Dion tube." I prefer the Watts link to a panhard rod as used in this pic
Tire Hood Automotive tire Motor vehicle Vehicle

due to the potential for reduced lateral movement forced by the arc of the Panhard rod.
Ideally, the Panhard rod or Watts link linkages are as long as possible to minimize lateral movement of the De Dion tube during vertical motion.
Motor vehicle Font Automotive design Trigger Metal


(note: this illustration may not make it clear that the upper (right as viewed) end of the "lateral locating bar" also known as a Panhard rod, attaches to the De Dion tube, on the right side.)
The wheels are locked in camber etc. relative to each other, not relative to the car body, so the wheels are attached to a floating solid "rear axle" while the differential is bolted to the car. It's much of the benefit of a solid axle with about 100 pounds less of the bouncing drawbacks. If it were strong enough, you could use carbon fiber and/or kevlar or the part that locks the wheels in place relative to each other.

It will not tune the same as a four-link solid axle would, as a four-link solid axle uses the reactive torque of the rear axle on acceleration (or deceleration) to determine how much force is directed toward countering body squat or rise upon acceleration or braking.

This only applies if the four-links are either unequal length or non-parallel, or both.

With the De Dion setup, it is only the far lower torque number of the car pushing against its contact patch relative to the mounting points.

Note: one of the good things about this system is that if one so designed it, with adjustability, one could set the toe and camber for whatever one considered optimal for one's own setup and intended use in that circumstance. As an example, for drag racing, ZERO camber. For road racing, some static camber. (PS camber is ALWAYS STATIC on the De Dion suspension setup.

For maximum performance, the De Dion tube (not necessarily tubular, but that's what it's called) could be made of structural carbon fiber or some other lightweight material. It is just dead, unsprung mass, so the lighter it is, the more responsive your rear suspension will be in relation to the surface of the roadway. F1 suspension bits are tubular carbon fiber. I think the governing body (FIA) did not want blade-like chunks of metal flailing or flying around in case of a shunt occurring near the spectators, but in addition to that, the ideal unsprung mass is ZERO.

BTW, "Acme" has a similar meaning to "zenith" or, loosely "nabob." It means highest/best/most important.
 

·
Registered
Joined
·
4,608 Posts

An actual four-link live rear axle setup from Yukon Performance, if you like the idea of gobs and gobs of unsprung mass all slamming about under the rear of the car:

I have been trying to find this, for your benefits, but so far, no dice. I know someone makes a more complex bolt-in setup.
 

·
Registered
Challenger SRT Hellcat
Joined
·
2,192 Posts
Discussion Starter · #19 ·
The way the Acme guys explained it to me their Big Stick actually rearranged the IRS driveline into a live-axle format, where driveshaft input forces act upon the differential and use 4-link geometry to gain traction… it actually acts like a normal 4-link, but uses factory (or aftermarket) rear diff and CV’s. De Dion tubes only connect left and right wheel hubs to simulate a live axle connection but does not allow for successful 4-link operation.

The actual engineering of it is over my head but my eyes didn’t lie. It’s impressive to watch it work.
 

·
Registered
Joined
·
4,608 Posts
Yes, it seems that it has the predictable camber of a four-link solid rear axle, without the massive unsprung mass, but, obviously, can't use the torque from the IRS pumpkin for anti-squat.
 
1 - 20 of 21 Posts
Top