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Rebuild Your C4 Corvette Rack-and-Pinion Steering

Refreshing Your Rack

Chuck Vranas Feb 28, 2018
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There’s nothing more magical than settling into the driver’s seat of your Corvette to hit the open road. One of the finest feelings you get to experience is the way it holds the street and carves through the turns with its low-slung dynamics operating at an optimum level.

What happens though when the miles start piling up from all the driving and the steering starts to feel like it’s not as crisp as the factory’s original specifications? When the performance you expect starts to deteriorate there’s one way to recapture its original precision. Recently, we made a trip to Saginaw, Michigan, to stop by Turn One High Performance Steering Systems to see just how they breathe life back into a tired C4 Corvette rack-and-pinion while infusing their years of experience into its rebuild.

To give you little bit of background on Turn One let’s start with company founder Jeff Roethlisberger who spent 14 years working at Saginaw Steering Gear, GM’s steering division, as a ride and handling engineer till starting Turn One in 1997. For years, Turn One has been building steering systems for many highly recognized NASCAR teams, earning 28 championships to date with teams utilizing their exclusive products. During our visit we followed along during the complete rebuild and restoration of a 1990 Corvette (C4) power rack-and-pinion unit. Since the units are no longer produced your only choices are to source a used one and hope its better than the one you have or rebuild the one you have. The talented technicians at Turn One have over 60 years of combined experience in rebuilding services for C4 and later Corvette racks. Following the images in the story will give you a great in-depth view of just what it takes to bring your rack back to better than factory specs.

There are a number of comprehensive rebuilding services available from Turn One, including ones for your rack-and-pinion, power steering box and power steering pumps. Regardless if your needs encompass bringing your parts back to full restoration specifications or modified for high-performance applications they have you covered. They also offer their own performance lineup of custom power steering boxes and pumps, billet aluminum pulleys, fittings and accessories. Give them a call to talk with them directly about an application and speak with one of their expert technicians on how they can customize a steering solution for your needs. Vette

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1. Here is a newly arrived 1990 C4 power rack-and-pinion unit that’s ready for a full rebuild by the team at Turn One to return it to better than new condition.

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2. Once the unit has been disassembled all of the parts will be thoroughly cleaned and closely inspected for normal wear and tear to determine which internal parts will need replacing during the rebuild.

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3. The bare rack-and-pinion housing is then secured in a vise, blown clean to remove any final debris and prepared for reassembly.

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4. One of the first internal parts needing replacement was the well-worn plastic pinion bushing (left) with a new bushing (right).

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5. The new plastic pinion bushing was then carefully installed into the housing.

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6. A special tool is then used to install the new pinion seal to the housing.

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7. A press is then used to complete the installation of the new pinion seal.

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8. The new pinion bearing was packed with grease top prepare it for placement in the housing. To the left you can see the special installation tool.

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9. Using a press, the pinion bearing was installed into the housing.

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10. The snap ring was then installed to keep the pinion bearing in place.

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11. The rack shaft was placed into a lathe to first be reviewed for straightness where it was spun and checked for perfect runout.

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12. It was then spun again to polish it. This step ensures a perfect inner seal.

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13. The shaft teeth are then treated to a well-balanced coating of grease. A new inner rack seal was then coated with grease and installed.

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14. From there, the rack shaft is carefully installed into the housing.

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15. The housing was then secured in a press and a special tool was used to install the new seal.

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16. A new bulkhead seal and O-ring were then installed to the bulkhead.

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17. The new bulkhead seal and O-ring were then treated to a healthy coating of grease using a brush.

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18. The bulkhead is then installed into the housing.

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19. Once the bulkhead was eased into final position, a snap ring was then used to hold the unit in place.

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20. At this time, the rack shaft was centered in the housing. This may vary with individual units and our measurements were 1.825 inches per side.

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21. The valve and pinion assembly was then installed into the lathe to be polished. It then received a final inspection prior to installation.

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22. A coating of grease was applied to the gear end of the valve and pinion assembly to prepare it for the install. A special assembly tube was then used to allow smooth entry for the Teflon rings to the inner housing.

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23. After hand seating the valve gear to mesh together with the rack teeth, the bearing was installed to the input shaft followed by a new spool shaft seal and dust seal.

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24. Everything was then tapped into place using a press tool with face and a rubber mallet. To keep everything secure, a snap ring was the installed.

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25. The valve and pinion assembly was then final torqued to manufacturer specifications.

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26. Here you can see the adjuster lock nut, spring adjuster and rack bushing as they await reinstallation. The adjuster allows the unit to be set to the factory specifications preload.

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27. With the inner housing well greased, the rack bushing and spring are first set in place followed by the lock nut.

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28. Using a torque wrench, the adjuster was set to manufacturer’s specifications and then set to the factory preload using a pair of specially designed wrenches.

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29. The hydraulic lines were then reinstalled onto the rack.

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30. The completed rack-and-pinion was then hooked up to Turn One’s exclusive Steering Box Analysis System to check its performance under load. Here you can see that the rack performed at its ultimate level for the left and right valve pressure effort’s perfect balance.

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31. This closeup lets you see the actual lock-to-lock pressure readings of 1,450 psi under full load rotation where the internal leakage percentage is perfect, at under 0.3 gallons-per-minute (GPM).

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32. Here you can see a Turn One team member at the controls of the dyno putting the recently restored C4 rack-and-pinion through its paces at full operating temperature.

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33. To complete the assembly, the final steps include the installation of the tie-rod ends and a fresh set of rubber boots with clamps.

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34. The completed rack-and-pinion unit is now ready to bring your C4 Corvette’s steering system back to perfect balance thanks to the team at Turn One.

Photos and video by Chuck Vranas

Sources

Turn One Steering
Saginaw, MI 48601
877-468-8761
www.turnone-steering.com

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