Old Dec 5, 2007 | 08:05 AM
  #17 (permalink)  
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Cincinnati Slim
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Joined: Mar 2007
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From: Cincinnati
Default Auburn Posi-Pro...scary and expensive lesson for me!

The ESP/Traction Control system does indeed use the application of one-wheel brakes to limit wheel spin. The advantage of this system is it does not make the car loose directional stability in low traction conditions (rain, dust, gravel or snow/ice) when power is applied in a corner. In those circumstances a "tight" or highly biased/loaded posi/sure grip rear end can make a car dangerously "tail-happy" and prone to wild over steer. The Crossfire has a very short wheelbase in proportion to it's track. DCX didn't want these cars going *** first into ditches whenever it rained...

Here's my hard-learned experience. I had a '97 Cougar with a 4.6 SOHC "mod motor". I had adapted various Mustang hop up parts and got the engine running pretty strong. I had a 3,200 rpm stall torque converter and a TransGo shift kit which hit the gears pretty hard at full throttle.

But the factory open rear end limited the car. I could have installed a FoMoCo Eaton clutch type limited slip like used in the T-bird Super Coupe or Cobra Mustang. (both used the same IRS).

But I'm an old Mopar guy and am used to the "cone-type Sure Grip" limited slip unit like Auburn makes. I got greedy and installed their "Posi-Pro" unit; a very highly loaded/biased unit which is very resistant to differential wheel speed. On dry pavement it was great ! The car hooked and launched like crazy !

But the first rainy night...I tried accelerating on a uphill curving on-ramp onto a bridge on Northbound I-75. I kicked it down and all hell broke loose. The hard shift shocked the tires. The Posi locked-up and BOTH TIRES LOST TRACTION. With both rear wheels spinning the car fishtailed wildly. I attempted to correct and lifted but it was too late. I entered the expressway totally out of shape, skidded sideways across three lanes of traffic, the rear end smacked the guardrail...HARD !

Fortunately, since it was late at night and traffic was very light, there were no other cars involved. The impact actually got the car pointed in the right direction and I nursed my crumpled Cougar home. It was a very scary and expensive lesson for me!

That's my story, and I'm sticking to it !

Cincinnati Slim
 
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