How to Diagnose and Repair Rack and Pinion Bushings

This picture of a simple rack and pinion unit is an excellent illustration of how they work. As the input shaft is turned, the orange gear spins against the yellow rack, pushing it in the direction needed to make the car turn as desired.
rack and pinion unit
TRW illustration showing how the rack and pinion unit connects to the steering wheel and the front tires.

In this, Part Three of our suspension repair series, I’m going to discuss how to determine if your steering rack bushings are bad, and if they’re bad, how to change them.  Next we’ll go into how to diagnose and replace the steering rack itself.  I’ll also quickly rehash how to quickly and easily make sure both front tires are pointed straight down the road once you’ve completed the required repairs to your suspension.

rack and pinion unit
This picture of a simple rack and pinion unit is an excellent illustration of how they work. As the input shaft is turned, the orange gear spins against the yellow rack, pushing it in the direction needed to make the car turn as desired.

Checking Rack Mount Bushings

Rack mount bushings are semi-hard shaped pieces of rubber that go between the steering rack and the rack mounts.  Their purpose is to isolate the steering rack, and thus your hands, from oad vibrations which could over time cause your hands pain or numbness.  Determining their condition requires a multi-step visual inspection.

urethane rack mount bushings
Pro-Thane urethane rack mount bushings. Urethane is used because it lasts longer and has less flex as it ages, among other reasons.

After raising your car’s front end enough to comfortably and safely crawl under it, place jack stands under the frame behind the rear wheels and lower the car slowly onto the stands.  Slide under and use your Mark IA eyeball to look the bushings over.  You’re looking for cracking and fraying.  Just because you don’t see any obvious fraying or cracking doesn’t mean the bushings are good.

Energy Suspensions polyurethane bushings
Energy Suspensions polyurethane bushings. If you look closely, you can see the split where it fits over the rack.

Now you need to see if the rubber in the bushings has started to break down and weaken.  If this happens, the rack can move around in the mounts, causing control issues as well as some steering wheel vibration.

  • Have a helper yank the steering wheel back and forth while you observe the rack and bushings.
  • Any deflection in the bushings is cause for replacement.
  • If you can see the rack sliding back and forth, even slightly, replace the bushings.
  • Grasp the rack near one of the bushings and push and pull. Very minor, hardly noticeable movement is acceptable.

Replacing Rack Mount Bushings Is Easy

Replacing rack mount bushings should be done in pairs, not singly. You don’t want one good bushing and one borderline or partly worn bushing. Replace them one at a time.

  1. Loosen and remove the bolts securing the rack to the frame member. The nuts that the bolts thread into may be welded to the frame but there are some cars where you’ll need either two wrenches or a ratchet and a wrench.
  2. Remove the rack mount and set it aside.
  3. Pull the old bushing out paying attention to any keyways or grooves in the bushing, mount, and the rack that are used to align the bushing and mount to the rack.
  4. Place the mount strap over the bushing and rack and thread the nuts/bolts back in by hand.
  5. Tighten the nuts/bolts to spec. Some bushing kits come with instructions that will list this torque spec, but a good standard is around 50 foot-pounds.

Note: On some cars (Mustang IIs come to mind immediately), the rack and pinion mount and bushing are integrated with the rack itself.  These bushings, when worn, require the rack to be removed and the mount bushings pressed out. When putting it back together, the rack-to-frame bolts are torqued to between 80 and 100 foot-pounds.

How to Tell If Your Rack and Pinion Unit Is Going Bad

rack and pinion unit
Blown-up illustration of a typical rack and pinion unit.

There are a few ways that a rack and pinion unit can go bad.  The most common I’ve seen as a mechanic is for one or both of the end seals to start leaking.  If left unrepaired, this can cause you to lose all your power steering fluid, causing the steering to require more input force and finally destroying the power steering pump and the rack itself.  Of course, this is only applicable to power rack and pinion units.

The other way that rack units go bad is for the pinion preload spring assembly to wear out, causing excess clearance between the pinion and rack.  This condition will show up as the wheels not beginning to turn immediately when you turn the steering wheel.  You can fix this with the right parts and tools.  However, some of the tools required are specialized and the manuals say you’ve got to pull the rack anyway to perform this repair.  Checking this can be done in one of two ways:

  • Under the car, grasp the front and rear of the tire and push and pull as if you’re commanding right and left turns. Watch for the steering input shaft and yoke to wiggle as you’re doing this. If it’s not wiggling, you’ve got a worn preload assembly.
  • Have your helper turn the wheel side to side as you hold the tires. If the steering put shaft and yoke move more than the tire does, you’re also looking at a worn preload assembly.

I’m not going to go into rebuilding a steering rack in this article. It’s far too in-depth to cover in the space allotted here.

Mopar steering coupler
Typical Mopar steering coupler.

What You’ll Need to Replace the Rack and Pinion Assembly

 

Now that you’ve determined that your rack and pinion unit is worn and needs replacement, you need to know what tools you’ll need. These are:

  • Socket set
  • Wrench set
  • Tie rod separator
  • Small drift punch
  • Ball peen hammer
  • Adjustable wrench
  • Tape measure
  • Pliers or wire cutters
  • Drain pan or bucket (power steering units only)
  • Power steering fluid (power steering units only)

NOTE: If you’re working on a power steering rack, it is highly recommended that you use line wrenches to remove the power steering lines from the rack. Regular open-end wrenches can round the fittings off, making it near impossible to remove and reinstall the power steering hoses.

Power steering
While you’re at it, why not upgrade to power steering?

Removing the Steering Rack Assembly Step One: Disconnect the Tie Rod Ends

If your car is equipped with power steering, pop the hood and remove the cap on the power steering pump/reservoir and stuff a clean rag into the opening to keep dirt and debris out of the system.  Use the adjustable wrench (or an open-end wrench of the correct size) to break the tie rod shaft locknut loose at the outer tie rod end.  Count the number of threads exposed on the tie rod shaft and write this number down for when you’re putting everything back together.  Straighten and remove the cotter pin and remove the tie rod stud nut.  Use the tie rod separator to remove the tie rod end from the steering knuckle.  Put the nut back on loosely for safekeeping.  Spin the rod end off the tie rod shaft and set this aside.  Do this on the other side.

Step Two: Disconnect the Steering Rack from the Steering Input Shaft

GM steering coupler
Typical GM steering coupler.

Exactly how this step is accomplished will depend on what kind of car you’ve got.  However, most cars equipped with rack and pinion steering use a grooved shaft on the rack with a grooved coupler on the steering column.  The other type is a flexible coupling.  The flexible coupling separates easily simply by removing the nuts and bolts.  The grooved coupling separates by loosening but not removing the clamp bolt and wiggling the coupling while pushing upwards.  Quite often you will have to wait on this until the rack mounts are off.

Step Three: Removing the Power Steering Hoses

This part can get messy, so have rags handy.  Place the drain pan or bucket under the power unit of the rack assembly – this is where the hoses and bypass pipes are located.  Using a line wrench, loosen and remove the power steering hoses, paying close attention to which one goes where.  I prefer to label them, even after 30-plus years in the industry – front and rear or left and right.  DO NOT remove or loosen the bypass hoses.  Extra and unnecessary work will ensue and I’m not going to cover it.  If your car isn’t equipped with power steering, you can skip this step obviously.

Step Four: Drop the Rack Unit

We should now have the rack just about ready to remove from the car.  The input shaft should be disconnected from the steering yoke/steering column and the outer tie rods removed the tie rod shafts.  All that’s left is to remove the rack mounts by loosening and removing the bolts and nuts.

As mentioned above in the diagnosis section, cars such as the Mustang II have the rack mounts integral to the steering rack itself and all you need to remove the rack is a wrench or a socket.  However, on most other cars, the rack mount is a U-shaped bracket that is secured to the vehicle’s frame with two (sometimes four) bolts and nuts.

Pro-Thane polyurethane bushings shown in a blown-up drawing illustrating their use on a Mustang II-type rack.
Pro-Thane polyurethane bushings shown in a blown-up drawing illustrating their use on a Mustang II-type rack.

On these, you’ll need to hold the bolt with a wrench and loosen and remove the nut with a ratchet.  Leave the lower bolts in until you can get one hand on the rack to keep it from falling on you.  Pull those last two bolts and use that hand to help separate the steering coupler.

NOTE: Remember, when you bought the replacement unit, there was probably a pretty steep core charge that you paid.  If you don’t damage the rack taking it out, you’ll get that back, so don’t drop it or drag it around.

Step Five: Put It Back Together

Yep, you guessed it, putting the new rack in is simply the reverse of removing the old unit.  As you lift it into place, guide the coupler over the input shaft.  Then, while holding the rack in place with one hand, place the new bushings (if so equipped) over the rack in the proper locations and loosely install the rack mounts.  Once both mounts are tightened by hand, go ahead and torque them to about 50 foot-pounds.

When you reattach the tie rod ends to the rod shafts, make sure you thread them onto the shaft and leave the same number of threads exposed.  When reattaching the tie rod end to the steering knuckle, torque the tie rod stud nut to about 50 foot-pounds.  Tighten the nut enough to get the hole in the stud to align with the openings in the castellated nut and lock the nut with a cotter pin.  Raise the car off the jack stands and lower the car completely.

Making Sure Your Wheels Point Where You Want Them To

Hop in and start it up if you’ve got power steering, if not, just hop in.  Cycle the steering wheel from lock to lock a few times.  I usually do this three times.  Now center the wheel and lock it down.  If you don’t have a steering wheel clamp, use a tie down strap or rope.  Just make sure the wheel can’t move much.

Dorman steering couple/damper
Dorman steering couple/damper.

Use your tape measure to measure from inner sidewall to inner sidewall, about three inches up from the ground.  Do this both in front of and behind the steering knuckle.  You’re looking for the rear measurement to be slightly (no more than 3/16 of an inch) larger than the front measurement.  If not, turn the tie rod shaft to adjust it until it’s within this “shade tree spec.”  Lock the lock nut down securely and get at least the toe properly checked and set.  IF you’ve got a long enough straight edge, you could also lay it on the outside of the tire flat against the both front and rear tire sidewalls.  If the front tire isn’t flush against the straight edge, adjust the tie rod shaft until it is and lock it down.

Safety Note: You’re working on components that are above the level of your head with this repair.  If you’re working on a power steering system, you’re also working with fluids that can cause eye damage.  ALWAYS wear eye protection when doing any sort of suspension work.  Please.

About Mike Aguilar 200 Articles
Mike's love of cars began in the early 1970's when his father started taking him to his Chevron service station. He's done pretty much everything in the automotive aftermarket from gas station island attendant, parts counter, mechanic, and new and used sales. Mike also has experience in the amateur ranks of many of racing's sanctioning bodies.
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