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Part 18: Traction Tales - Improving 60-Foot Times

Cutting 60-foot Times with Competition Engineering
By Randy Bolig
Photography by Randy Bolig
1967 Plymouth Valiant Traction Bars Underside View
It's a common thought that... 
   
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1967 Plymouth Valiant Traction Bars Underside View
It's a common thought that traction bars do not belong on Mopars. Countless enthusiasts depend on Super Stock springs and pinion snubbers to control axle wrap-up. While that technology works, Competition Engineering Slide-A-Link bars have been gaining notoriety on Stock race cars for quite some time. For that reason, we decided to give 'em a try.
1967 Plymouth Valiant Rear Suspension Underside View
First thing, raise the back-end... 
   
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1967 Plymouth Valiant Rear Suspension Underside View
First thing, raise the back-end of the car enough to place jackstands under the framerails, and lower the jack to let the rear suspension hang loose.
1967 Plymouth Valiant Spring Removal Underside View
You will need to remove the... 
   
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1967 Plymouth Valiant Spring Removal Underside View
You will need to remove the rear springs to install the aluminum bushings into the spring eyes. First, support the rear end with a jack and remove the plates under the rear holding it to the springs. remove the springs at their front and rear attaching points. press out the soft bushing and install the aluminum one.
155 0404 Valnt 3 Z
The front of the spring now... 
   
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155 0404 Valnt 3 Z
The front of the spring now slides into the front pivot-point assembly. This pivot is a solid-mounted front plate installed inside the original front spring-pocket, and clamps to the leaf spring to provide a positive displacement for the torque applied during hard launches.
1967 Plymouth Valiant Front Mount Bar Underside View
With the bar's front mount... 
   
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1967 Plymouth Valiant Front Mount Bar Underside View
With the bar's front mount installed on the spring, you can now install the front of the spring back into the hanger. The short piece of the Slide-A-Link is then installed into the bar's hanger. install the spacers into the arm, slide it into the bracket, and install the bolt.
1967 Plymouth Valiant Spring Attachment Underside View
Raise the rear of the spring... 
   
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1967 Plymouth Valiant Spring Attachment Underside View
Raise the rear of the spring and reattach it to the car. If you left your rear end in place resting on the jack, you will not need to reattach brake lines, E-brake cables, and the driveshaft. Using the Slide-A-Link axle bracket, attach the spring to the rear end.
1967 Plymouth Valiant Traction Bar Underside View
Place the Durometer urethane... 
   
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1967 Plymouth Valiant Traction Bar Underside View
Place the Durometer urethane spacer onto the short arm of the bars, and slide the longer one into it. Make sure the longer-arm portion is on the rear of the assembly. The long arm is where all adjustments are made to dial in the bars for each application.
1967 Plymouth Valiant Traction Bar Underside View
Place the rear half of the... 
   
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1967 Plymouth Valiant Traction Bar Underside View
Place the rear half of the bar into the rear mount. For a starting point, Competition Engineering recommends tightening the driver side only until the urethane spacer contacts the arm at both ends. adjust the bars on the passenger side until the spacer touches. then give it another quarter turn.
155 0404 Valnt 8 Z
So, what are these bars supposed... 
   
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155 0404 Valnt 8 Z
So, what are these bars supposed to do? When properly adjusted, they will eliminate axle wrapup. Axle wrapup occurs when your car is launched hard, e.g., the start of a drag race. As the wheels turn forward, the axle housing will want to rotate in the opposite direction. When the spring has wrapped up as far as it can, the energy in the spring forces it to return to its normal location. This occurs violently, and the force of the returning spring can force the car upward, unloading the weight of the car off the tires. When the weight of the car is off the tires, they will spin. The diagram illustrates axle wrapup.
Competition Engineering, A Division of Moroso
moroso.com
Mickey Thompson Tires
Stow
OH
330/928-9092

www.mickeythompsontires.com

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