Appendix “A”: Replacing the Steering Rack on a 993

Disclaimer: The content of this document relates to the Porsche 993 (911 1995 to1998) I am not a professional automotive technician and some of the opinions expressed in this document are just that, opinions, therefore, please feel free to use this document at your own risk. Many times a lot can be learned by simply watching qualified professionals work on your 993

Appendix “A” Replacing the Steering Rack on a 993 using Jack Stands.

Get a copy of the section of the Porsche 993 shop manual on how to do this procedure and read it. Key information in the shop manual covers the sequence and torque values when reinstalling the U Clamps. Since you will be putting your entire body under the car make sure you suspend the vehicle safely and work in a safe way. See Appendix “L” Safely Lifting your 993.

Removing the Old Rack:

• Remove the floorboard covering the peddle cluster in the driver-side footwell. Getting to the bottom left-hand floorboard screw involves pulling back on the throttle peddle until it releases (pops) from its plunger shaft allowing you to fold it rearward gaining access to the last screw.
• Rotate the steering wheel so the split in the clamp that holds the steering rack to the steering column Slider joint is facing rearward and then shoot a little spray paint into the split onto the steering shaft spline to record the steering Slider joint orientation on the steering rack’s spline shaft.
• Loosen the Slider joint’s clamping bolt but do not remove it.

  

  Footwell Slider Joint

• Rotate the steering wheel to the center position with the wheels pointing straight forward and tie up the steering wheel loosely in this center position. I used a bungee cord looped through the steering wheel spokes and tied it up to the above sunshade. No need for precision here as you are only trying to preserve the relative rotation center position to avoid clocking the steering wheel 360 degrees and with it moving the airbag electrical contact unit out of its correct center position. Otherwise, the airbag contact unit is easily broken.

A digression caused by not tying the steering wheel up in position:

Now you get to learn from my folly of not tying up the steering wheel in the center position and having to remedy the results:

• With the slider joint detached and flipping the steering wheel around past its extreme left or right turn clocking range I broke the airbag contact unit’s pins (callout 2 in the image below) that engage the steering wheel and had to repair them, OUCH!. Before you loosen the steering wheel’s hold-down nut to get at the contact unit don’t forget to disconnect the negative terminal on the battery and mark the steering wheel’s position to the top of the steering shaft so your steering wheel can be put back on straight.  Fixing the snapped-off pins is done by retrieving the snapped-off pin’s head and reattaching it with a short piece of fish tank air hose filled with flexible car molding adhesive – better than new! If you can't find one of the pins the system works fine with just one of the pins reattached.

• Once repaired re-clock the airbag contact unit according to the directions printed on the unit or in the shop manual. If you do end up re-clocking the airbag contact unit a good trick is to remove the grossly over-engineered small metal spring-loaded “Rotation Lock” (call-out 3 in the image below). On my car, it was bent and had broken free from the contact unit sometime in the past.  Instead, just use a long piece of electrical tape to hold the contact unit in the proper position.  Thread the tape through the steering wheel using the same hole the wires from the contact unit pass through. Once the steering wheel is placed over the correctly positioned contact unit and the airbag contact unit’s pins (2) are in their slot on the steering wheel at 12 o’clock and 6 o'clock just pull the tape out through the wheel. Extra steps, extra time, I just love this kind ‘a work! 

  

  The Airbag (SRS) Contact Unit

Let's get back on topic and continue:

• Now while holding the slider joint up in the footwell, so it doesn't slip down off the steering shaft above, completely detach the slider joint’s spline clamping bolt to release the rack from the slider joint. 
• Tie the slider joint up with some wire to hold it in place. 

• If the slider joint falls off the upper spline shaft putting it back on in the proper orientation involves pulling its shaft alignment spring pin out slightly and aligning the spring pin to its matching groove on the upper steering shaft spline. Pulling the pin out slightly makes it easier to fit the joint over the upper spline shaft.  A task done way under the dash. Not fun at all.

•  As a precaution wrap, the rack’s now exposed steering shaft spline end in electrical tape to avoid dinging it in the removal process.
• With the car now on Jack Stands, remove the front plastic underbody cover and save the fasteners that hold it in place.
• Unbolt and release the outside tie rod ends from the wheel carriers. Use a generic tie rod end removal tool if required.
  
  Do not detach the outer tie rod ends from the inner tie rod ends. Leaving them in one unit preserves your car’s alignment upon reassembly
• 
• Now under the car push back the boots and release the inside tie rod ends. Use two wrenches and use care not to put rotational force on the rack. I found that if the inner tierods seem to not want to break free use a pair of longer box wrenches close together on the joint's wrench pads in a scissors-like action squeezing them together to break it free. Conceivably, in a pinch, one could use a C-clamp like a vice against the two wrenches pressing them together to free things up.
• Unscrew the inner tie rod ends from the rack by rotating the entire tie rod assembly and remove the inner/outer tie rod assembly in one piece.  Note the orientation of the thick washers that are held to the rack ends by the inner tie rod end. Save these washers for reinstallation on the rebuilt rack later. Also, mark the assemblies as left and right so you can reinstall them on the same sides of the car as they were removed. My car’s tie rod ends were good (no play) but the outside rod end grease boots looked a little dried out so I cut the boots off and replaced the little booties with aftermarket ones and repacked them with wheel bearing grease.
  
• Under the car unbolt the socket head capscrews holding the U clamps in place and release the old rack, not too complex just involves spending quality time on your back under the car. You will not reuse the mounting capscrews.
• Most 993s have a removable cross strut that comes off with the longer (80mm) rack hold-down capscrews. Note which positions the longer capscrews were removed from to assist you in reassembly later. 
• Save all the pieces-parts. You will reuse the metal U clamps but not the rubber mounting bushings or the capscrews. 

  

  The Rack Mounting Capscrews
• Also, there is a sealing grommet about the size of a Dunk' in Donut pressed by the rack against the pass-through hole into the driver-side footwell. You can reuse this or replace it. It may be easier to just leave it stuck in place for when you reinstall the rack after it is rebuilt. Using the old donut you will avoid having to compress a new one when trying to bolt in the rebuilt rack.

Part numbers of 12.9 Metric Cap Screws from Pelican Parts Catalog:

Socket head cap screw M8 x 60mm = 999 218 102 01

(4 on vehicles without cross strut, 2 on vehicles with cross strut)

Socket head cap screw M8 x 80mm = 999 218 103 09

(2 on vehicles with cross strut)

Washers 900 031 105 01

(Four screws above 4 on vehicle)

If you or someone has already put the 18" wheel option on your car and the cross strut/brace update is not in place I would consider updating and adding it at this time. The strut is part number 993 347 131 02 and also swap out two of the mounting capscrews with the 80mm mounting capscrews, part number 999 218 103 09.

Rack strut in place

Rack strut and
longer 80mm cap screws

• Take a break, clean yourself off now replace the steering fluid reservoir in the engine compartment Pelican Number:  993-347-015-01-M103.
  
  It has an integrated power steering fluid filter and therefore should be replaced. I used a turkey baster to draw most of the fluid out of the reservoir before removing it. I stuffed lots of rags under it so when removing the old one I avoided spilling fluid all over the engine.
• One of the clamps holding the hoses to the reservoir is not reusable. So you will need to cut it off and get a substitution replacement at your local auto parts store. While you are there get three or four large cans of spray CRC QD Electronic Cleaner or another brand of the same as you will need to clean up under the car at several points in the process, also call your local VW Dealer and have them order some steering rack grease, VW part number AOF 063 000 04 specified by Porsche has been superseded to the new part number G052168A1 or really any branded grease made specifically to work with  ZF hydraulic power steering racks should work fine, for example, BMW's  FB-1 grease  #83232208093
  
  
  

  
  
  

Now for the messy part! 

• Go ahead and detach the hydraulic lines from the rack now that it is loosely held in place by the car’s frame. Save all the pieces-parts.
  
• At this point, you should be able to push the rack’s shaft ends in and out of the unit by hand, to the left and right as needed to clear the car’s frame. I pulled off the tie-rod end boots before I did this step.
• You now have the removed rack in your hands. Remove the attached small hydraulic line bracket with clips and save it for reuse. Observe its placement and orientation.

I sent my rack out to www.steeringgearsuperstore.com to have it rebuilt and returned, with no core charge.

When sending out your rack add the following instructions on the packing slip:

• Asking the rebuilder to return the rebuilt rack made from your core, note the serial number, not from his stock of cores.  A rack freshly taken out of service such as the one from your car should likely just need soft parts switched out. One built from a salvage rack can result in a rebuild job with a much shorter service life because it may be made from a damaged rack or have welds done on its hard parts to fill corrosion pitting from sitting around on a salvage car.   There are very few good 993 rack cores floating around as the rack for the 993 is a model unique configuration, not too many 993s were built and those built are mostly still on the road.

  

  A rack back from a rebuilder.

  
  
• Ask him to use care to not remove the paint alignment mark on the steering spline shaft;
• Ask him to protect the spline shaft with a piece of rubber hose for return shipping. I would go as far as to provide the hose installed on the rack when you send it in so he has the provided hose on hand to use on the return.

Above are critical instructions as even a minor ding on the spline will not allow the steering Slider joint to slide over the rebuilt rack’s steering shaft.

 My rack came back with two small dings I had to remove with a Moto-Tool to allow it to reinstall. Fixing a ding is easy however it also adds a trial fitting step that requires that you remove and reinstall the steering Slider joint under the dash. The Slider joint slides off easy enough but to put it back on in the proper orientation involves pulling its shaft alignment spring pin out slightly and aligning the spring pin to its matching groove on the upper steering shaft. A task done way under the dash. Not fun at all.

Reinstalling the Rack:

• Put a pan under your car during the one-week turn-around otherwise old steering fluid leaking out of the lines creates a mighty handsome puddle on your garage floor!
• Once the rack is returned to you clean any rebuilder-applied paint from the original ZF/ Porsche part number/ serial number plate. Look at the part/serial number to ensure you have your original rack in your hands. 
• Use extreme care not to scratch the hydraulic port faces when removing the rebuilder’s dust plugs as leaks will result later. Use solvent to clean any rebuilder-applied paint overspray from the hydraulic port faces and loosely reinstall the dust plugs to keep the ports clean as you position the rack under your car.
• Consider using a solvent to clean any rebuilder-applied paint from the ends of the rack cast body up to and including the rack end boot mounting grooves to avoid paint contamination of the rack end seals on the casting inside the boots potentially shortening the rack’s life.
• Use care to not get any solvent on the rack shaft seals as it may soften them resulting in a future premature failure.
• Prepare the new rack with:
•  New dust boots usually come with the rebuilt rack;
•  New rubber rack mounts Pelican part number: 964-347-137-07-M136 and;
• Special WV rack grease, VW part number AOF 063 000 04. Be sure to use only VW hydraulic rack grease or other rack compatible grease to lubricate the inside tie rod ends and to coat the geared rack shafts to avoid contaminating the rack with incompatible chassis greases;
• Make sure the centering observation port on the rack has the rubber plug in place, Pelican part number: 477-419-115-OEM;
• Reinstall the small hydraulic line bracket to the rack removed earlier.
• Use care not to punch any holes in the boots when mounting them to the rack or later on when pulling them over the inside tie rod ends.  Pulling the boots onto the rack’s casting is not easy. I rolled the boot ends back like rolling the cuffs on a dress shirt and then rolled them down over the racks boot mounting grooves.

• Before bolting up the rack reattach the two hydraulic lines each with two size 12 x 15.5 sealing washers, Pelican part number¨12-X-16-X-1.5-CU-M131 one on each side of the hydraulic fitting where it mates to the port and under the banjo bolt’s head. Take your time as you will drop the sealing washers several times before you sort this task out. Use care not to cross-thread the ports with the Banjo Bolts. You will know when they are started in properly and not cross-threaded as they can be screwed in almost all the way by hand with a very light touch without binding. Avoid over-tightening the Banjo Bolts. They only need to be tight enough to cause the soft copper sealing washers to mate snuggly with the port and fitting faces.
• Bolting up the rack in the final position takes upper body flexibility and ingenuity.  I used a scissor jack on the floor and a block of wood to gently force the U-clamps into position as the new rack mounting bushings and the rack-to-body sealing donut needed to be compressed slightly for the U-clamp capscrews to line up and thread in. 
• Install the proper new capscrews and washers, with the washer face with the rounded-off edges facing the capscrew head. This is standard procedure with any washer used with a cap screw. Washers have sharp stamped edges on one face that can score the small fillet on the bottom of a cap screw head where it meets its shank significantly weakening the screw.
• In the proper position reinstall the strut that came off with the capscrews if your car came with one of these. The strut is placed across the two capscrews closer to the front of the car with the part number facing away (down) from the car body installed in conjunction with the two longer 80mm cap screws and washers.  Do not reuse the old cap screws and use care to observe that the U clamps are in contact with their mountings and torqued to the proper value as listed in the shop manual when the rack is fully in place. Read the shop manual instructions carefully on this:
• Tighten the fastening screws of the rack as follows.“First, screw down the screws evenly until the fastening brackets almost touch the cross member. During final tightening, start with the screws for the short leg of the cross member and pull them tight, so these surfaces will be the first to fit tightly. Tightening torque: 45 Nm” or (33 ft.lb.). Using a torque wrench to seat the capscrews is very important as the OE fasteners’ threads have been treated with thread-locking compound and this in conjunction with the elastic nature of the rack mounting bushings makes it very hard to tell when the cap screws have fully seated in the U-clamps by feel. The capscrews are also threaded into what appears to be soft aluminum and using too much force can easily strip the mounting threads. In my case, one of the capscrews made a galling (loud creaking) sound as I tightened it so I removed it and used a very small amount of anti-seize on the capscrew. It seemed that the pre-applied thread locker still offered considerable resistance even with the anti-seize applied. For this reason, I used anti-seize on the shafts and threads when installing the remaining capscrews.
• Shift the rack steering position as needed to attach the inner and then the outer tie rod ends and pull the boots over the inner tie rod ends.  When complete adjust the rack so the wheel hubs are in the position so if the wheels were attached they would point straight forward. Getting the boots over the inner tie rod ends was the hardest part of the entire job.
• I learned from my friends who have done this before that a pair of tools made from coat hanger wire with small hook-shaped bends on the ends does the trick here to avoid poking a hole in a boot by using other tools during this installation process.
  
• With the wheel hubs pointing forward reattach the steering column Slider joint under the dash to the rack’s spline shaft; be sure to line up the painted spline alignment mark you painted when you initially removed the rack and preserve the relative rotational position of the steering wheel as not to damage the airbag connection. You will probably need to turn the steering wheel a ¼ turn to the side to allow you to see the slot necessary to line up the spline paint mark.  This is why the steering wheel should only be loosely tied up in the center position earlier in the process.

Buttoning Things Up:

• Clean the rack, the underbody, and the underbody cover of steering fluid with CRC QD or similar Electronic cleaner described above. Use care to clean off the hydraulic connections so they appear dry.
• Fill the reservoir then run the engine for a moment while rocking the steering back and forth.
• Check the reservoir and top it off again.

• Run the engine for 60 seconds or so and shut it off.  Get under the car and look for leaks around the hydraulic line connections. If the copper sealing rings look wet with fluid tighten them up just a hair, clean them off again with the spray cleaner, and run the test again until nothing leaks. In the unlikely event that you are using greater force or things are still leaking after three tests something else is at work. Never use high levels of force on the Banjo Bolts.
•  Put the underbody cover and wheels back on the car remove the jack stands and properly torque the wheel nuts. Reassemble the foot well, and enjoy the mess on your garage floor.
• You might find that you need to add more fluid after test-driving a short distance. If you hear the power steering pump whining immediately stop and top off the reservoir again.
• Think about what you will do with the thousand if not thousands of dollars saved over having someone else do the job.
•  If you’re over 50, as I am, be sure to take two Tylenol or better yet Ibuprofen before you go to bed or it's going to really hurt in the morning! No pain no gain!
• If you did not take your tie rods apart, you tied up the steering wheel in the center position and you reinserted the steering rack’s spline in the paint-marked position on the steering Slider joint when you remove it, your car’s alignment will be preserved and your steering will be properly centered when you are done.

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Andy