The Pantera Place
"Your de Tomaso Connection"
Pantera Steering Rack Rebuild and Bushing Install
By Mike Drew
All of the technical information and product information posted on this website is offered as general information and is not recommended, endorsed, guaranteed or presented as professional technical information. It is recommended that you seek professional help for the repair or maintenance of your car. Improper self-maintenance or repair of your car can result in serious injury and or death. Use of this information is done at your own risk.
At the left are a variety of prying tools, custom chisels (narrowed on a bench grinder to fit into the slots machined into the rack and the tie rod nut), a pointed punch (most useful for lifting up on the indented portion of the ring in the center, rendering the ring circular again), and a flat punch (used to stake the ring during reassembly).
Alongside are a specialized adjustable pin wrench, and an adjustable spanner, which are used to remove and install the tie rod. Should you choose not to buy those tools, simple pipe wrenches can be substituted, although they will mangle the locking ring and tie rod.
The next tool is actually a sprinkler tool by Rain Bird, which happens to be absolutely perfect for removing the spring-loaded plunger from the rack housing.
At the top is is a 10/24 tap welded to a 1/4 inch drive socket (for tapping a hole in the rack housing if the secondary type of replacement bushing is used) and a bushing malletizer (PVC pipe turned on a lathe to match the inner diameter of the rack housing, and set up to sink the new bushing to the proper depth). A deep-wall socket is an acceptable substitute, but you must take care to drive the bushing to the proper depth.
The pin wrench is made by J.H. Williams, which is a 19th century tool manufacturer that recently has been absorbed by Snap-On. Both Williams and Snap-On offer similar tools, with the Williams tools being quite a bit less expensive.
I was able to download their PDF catalog, find the appropriate (smaller) wrench, and buy it from a local distributor for only about $20!
The hook spanner should be available locally, but J.H. Williams sells them too.
The above photo clearly shows the relationship between (from top to bottom) the rack housing, the rack, locking ring, tie rod and rubber boot. Ordinarily, the end of the boot is clamped into the groove in the end of the rack housing, so all these guts are hidden from view.
This photo clearly shows how the locking ring is peened into a groove machined into the threaded portion of the tie rod. Disassembly requires prying up that peened portion, then carefully turning the locking ring and tie rod in opposite directions to free them up from one another, then unthreading them to remove them both from the rack.
Barely visible on the right side is a second indentation on the other end of the locking ring, where it is peened into a groove on the rack itself. It is especially important that this indentation is removed fully, because otherwise when you remove the locking ring, it will mangle the threads on the rack, potentially compromising safety.
The tool for the Pantera rack is the top one pictured on page 30 of the wrench section of the J.H. Williams catalog; you can download it here:
Part number is 0-471 and the cost was $20.01. Such a deal!
Unfortunately, Williams doesn't sell directly to the public; you have to call their customer service hotline to find the nearest distributor:
Continental U.S.A. and Canada
International Phone: 706-563-9590
International Fax: 706-563-1820
Buying this tool is money well-spent, I believe, if you ever envision doing more than one rack. The pipe wrench method works fine too though, and since all these parts are hidden under the boots, nobody will know you brutalized the thing.
The job of disassembly begins with removing various bolts with a 13mm socket. There are three bolts with nuts which secure the rack support (sheetmetal piece to the right of the rack housing) to the chassis, and four bolts (shown here) which thread through the rack mounting clamps directly into captured nuts welded to the back side of a main chassis structure. If you should happen to snap those nuts off inside the chassis, you are doomed. Sell the car! To prevent this, spray Liquid Wrench liberally into the nooks and crannies in the chassis piece, with the faint hope that some will get onto the end of the bolt.
The steering coupler must be removed from the rack pinion. Often itís rusted in place, so plenty of Liquid Wrench must be employed here also. After removing the pinch clamp bolt and nut, hammer a sharpened screwdriver into the pinch clamp to hold it slightly open, and tap against the coupler from beneath the car with a hammer and a long punch. Tap the coupler back towards the rear of the car until it slides off the pinion input shaft.
Here are the rack mounting clamps as seen in the photo above. The late L-model cars (and later cars, presumably) came with about a 10mm shim between the clamps and the chassis of the car; this shim was developed and used on the factory Group 4 and GT3 race cars to improve bump steer characteristics. Since this 1972 L-model Pantera was lacking these shims, we fabricated our own using aluminum strip measuring 1/8" x ĺ". Three layers of shim equals almost exactly 10mm, and provides great adjustability in the event the suspension geometry is changed at a later date.
The factory boots are secured with twisted stainless steel wire. Most earlier cars had very special, unusually thin hose clamps instead of wire securing the boots; if these are in good shape they can be reused. Note that they are slightly too large in diameter, and even when fully compressed, the boot will probably be loose enough to rotate by hand. Use a pair of dykes to snip the wire close to the boot and discard it. Be careful if you plan to save the boot! The presence of this wire is absolute proof that the rack boot has never been removed before.
The tie rod is threaded onto the end of the rack, and is secured with a smooth lock ring. The two are peened together and the lock ring is also peened into an indentation in the rack. You must un-peen both places to remove them. It is especially important to make sure you thoroughly un-peen the indentation into the rack, because the steel is rather soft, and an other-than-round lock ring will seriously demolish the threads if you have to muscle the ring off of the rack. The ring should turn reasonably easily; if you have to force it, STOP and attend to your un-peening duties! Here a customized chisel is used to start un-peening.
An L-shaped prying tool can be used to perform this job but a small, round punch is the most effective means of raising the indented portion of the locking ring without damaging it. As these punches are hardened, they should not be used as prying tools; rather, the punch should have sufficient taper to lift up on the indented portion of the ring as it is gently tapped with a hammer.
If you do not have access to the proper wrenches as shown in the tools image, pipe wrenches can be substituted, but recognize that they will mar and damage the exterior surfaces of the locking ring and tie rod. With the un-peening complete, two pipe wrenches are used to break the tie rod and lock ring free from one another. Turn the tie rod to the left and the lock nut to the right, facing the rack. Place the wrenches as shown and then pinch them together to get maximum torque. Avoid spreading the wrenches so that you are placing undue pressure upon the rack itself.
If the rack has been allowed to run dry for any length of time, it is likely to suffer extensive corrosion, as well as severe build-up of dried-out oil which turns into a very stubborn solid substance. Attempting to install a rack bearing with any obstruction on the rack will result in the rack actually binding up. You do not want to go through the whole installation procedure, get everything buttoned up and then discover that you can't turn the steering wheel! Fortunately, dismantling the rack for cleaning is a simple affair once the rack is removed from the car.
The rack pinion is supported by two ball bearings. In extreme cases, these bearings can be rusted beyond salvation, and they are impossible to find through conventional bearing supply sources. Fortunately a few of the Pantera vendors in the USA have found a source. These bearings should be removed, and thoroughly greased prior to reassembly.
The rack is pressed against the pinion by a steel plunger which is compressed by a small spring. Often, removing the cover and spring will enable the plunger to fall free; in this particular rack, the O-ring seal was excellent and the plunger didn't want to budge. If this is the case, go to your local hardware store and buy a Rainbird sprinkler tool, which is basically a pair of thin pliers with the jaw on the outside. This will fit perfectly into the indentation on the plunger; squeezing and pulling will easily extract the plunger.
Tension between the rack and pinion is controlled by the use of one or more extremely thin sheet-metal shims between the spring's cover and the rack housing. Remove the spring cover which resides at a 90-degree angle to the pinion using a 1/2 inch socket, taking care not to damage the shims or the spring.
Then remove the bearing cover opposite to the pinion, again using a 1/2 inch socket. A circular spacer resides between the cover and the face of the bearing. Note that although the covers look very similar, the bearing cover is slightly larger and thus they will not interchange. To pop the bearing free, lightly tap against the opposite end of the pinion (where the steering coupler was attached) with a plastic or wooden mallet. This will drive the bearing out of the rack housing.
The pinion can not be removed until the rack is turned to the end of the toothed portion, where a notch is cut in the face of the rack. It will probably be impossible to turn the rack by hand, so use a pair of Vice-Grip pliers (or a handy shift- or steering-linkage u-joint) to turn the pinion. Be extremely careful not to damage the fine splines. Turn the pinion so the remaining tie rod moves away from the rack housing, and the toothed portion of the rack becomes visible. When turning no longer moves the rack, you're there. Now, by maintaining the orientation of the rack within the housing (it may want to rotate, which will cause the notch in the rack to hit the pinion and prevent it from sliding out), gently tap against the pinion, and it should pop out. The above photo shows the notch in the rack lined up with the pinion and the bearing on the opposite side.
Ideally, if you've gone this far, you should remove the rubber pinion seal from the other side and replace it. These seals are another DeTomaso-vendor-specific part, very difficult to find through conventional channels, but fortunately cost only about $12 from the Pantera vendors. Should you elect to re-use it, be especially careful not to damage it during removal and installation of the pinion.
This shows the rack dismantled to the extent necessary to perform the job. At top is the bottom pinion bearing cover, spacer and bearing. The rack housing contains the upper bearing, and the plunger which presses against the underside of the rack. The rack itself is hardened only along the toothed portion (hence the discoloration) and still has the driver's side tie rod and boot affixed. Beneath that is the plunger cover, shim and spring, the pinion, and a handy U-joint I use to turn the pinion.
The extensive buildup on this rack would have prevented free movement had the bearing simply been hammered into position. Although it looks like severe rust, this rack had considerable foreign matter stubbornly clinging to it, but only mild pitting and no real rust.
The majority of the debris was removed using a gasket-scraper. The final clean-up was performed using a Scotch-brite pad (steel wool also works well.) Be advised that the rack itself is made of extremely soft steel and is very vulnerable, so use care when scraping or filing.
The end of the rack has a tendency to swell or mushroom when the threads are cut; as a result, most bearings will slide over the threads but will not be able to pass onto the shaft itself without some work. Carefully file the sharp shoulder at the end of the threads, and perhaps the first inch or so of the smooth portion of the rack, being careful to avoid filing on the threads themselves. Periodically stop and test-fit the bearing. The goal is for the bearing to slide up and down the rack without binding, yet not to the point where there is unwanted slop.
Frequently, there will be corrosion and residue on the rack itself. This is a combination of rust, dried oil and decomposing nylon from the bushing. If the rack was rebuilt on the car, this residue would prevent the rack from operating smoothly (or at all!). This shows the importance of fully dismantling the rack to service it.
The preferred technique is actually to remove the old bushing and replace it, rather than using the other style of bushing which supplants the stock, worn-out one.
In order to remove the old bushing, first the set-screw must be removed. Then, a very thick, strong washer is ground down to the appropriate diameter. The washer should be larger in diameter than the inside of the bushing. Grind two flats on it, which will let it slide vertically through the bushing. Once it's through, it can be rotated and it will then 'capture' the inner edge of the bushing. Using a long piece of all-thread rod with a nut a few inches from the end, insert the rod from the driver's side of the rack, through the center of the washer, and then liberally whack the end of it, to drive the bushing out.
Using a Scothbrite pad, carefully sand the surface of the rack, to remove all residue. Slide the new bushing over the rack and make sure that it moves freely; there should be some clearance between the inside of the bushing and the outside of the rack, because the bushing will 'shrink' somewhat when it is pressed into the rack housing.
A very slight bevel should be put on the edge of the bushing, to make it easier to insert into the rack housing. The bushing will index against a step inside the rack housing, so if you make your bevel too large, it might allow the bushing to travel too far, or actually be compressed by the rack housing when the bushing is driven into the step. Test-fit the bushing on the rack housing and only put enough bevel on it to let it get started into the end of the housing.
You will need to use a mallet and a piece of pipe, or a deep-wall socket to drive the new bushing into position. There are two different-sized bushings on the market; most vendors sell bushings which are designed to replace the stock bushing entirely. (There are a few vendors that size their bushings about .020" larger; these are designed to augment (rather than replace) the stock bushing. The procedures for using these bushings are at the bottom of this page.) Once the new bushing has been fully seated into the rack housing, carefully use a very small punch, insert it through the threaded set-screw hole, and with a hammer make a clear indentation in the center of the exposed portion of the bushing. Then, using a very small drill bit, so as not to touch the threads on the rack housing, drill straight through the bushing. This will give the set screw a place to 'bite' into the bushing, without deforming it unduly. Use Loc-Tite to secure the set screw.
Although the Pantera rack was originally filled with 90-weight gear oil, TRW (the company that bought out Cam Gears UK, the manufacturer of the Pantera rack) now recommends 0-weight grease, instead of oil. Although 0-weight grease can be purchased in 10-gallon tubs, only a fraction of that is necessary for this job. The nearest thing you can find at the retail level is CRC Engine Assembly Lube, which is 0-1/2 weight.
With the new bushing installed, the teeth on the rack are liberally lubricated with this grease; the bearings, and pinion, and the other end of the rack where it passes through the bushing, should all be similarly lubricated.
When it's time to reassemble the rack, simply perform the above steps in the reverse order. It is far easier to install the bearing with the rack entirely removed from the housing. Remember to rotate the rack within the housing so that the toothed portion faces away from the plunger, and line up the notch to enable the pinion to slide freely. Once you've got the pinion in place, slight pressure on the end of the rack will allow the teeth to engage, and you should be able to then turn the rack side-to-side with the pinion.
Be advised that if the hole that you drill in the bearing for the set screw isn't deep enough, tightening the set screw will actually deform the bearing and cause the rack to bind up. It's best to drill straight through the bearing, so that the set screw will completely thread into the bearing.
This photo shows the two spanners in use. The tie rod is threaded onto the rack to the appropriate point, and then the locking ring is tightened against it using the pin wrench. When finished, the peened portions of the locking ring should once again line up with both the indentation in the tie rod, and the groove machined into the rack itself. This is a good quality check to ensure that you have tightened the tie rod to the appropriate degree.
The rebuilt rack is in place with the spacers holding it in a new position without the mounting bolts installed yet. The rack support will also have to be re-positioned downwards. Use the existing chassis hole "A" and drill a new hole in the support. Drill a new hole "B" in the chassis (approximately where marked) to use the existing hole in the support. On the driverís side, use the existing hole in the chassis and drill a new hole in the support. Secure the rack clamp bolts using lock washers, and the rack support bolts using locknuts. Reconnect the tie rod ends, eyeball the toe setting, and drive as little as possible until getting an alignment.
Oversized Bushing Option
If you choose to buy an oversize bushing which is designed to augment rather than replace the stock one, do not remove the stock bushing. With this option The old plastic bushing is not removed from the rack. The new bushing is seated to the outside of the old bushing.
You will have to drill a hole using a 5/32" or No. 25 drill bit, to hold the bushing set screw. Use a hammer and a punch and strike the rack housing in the letter "E" in the word "PATENTS"; this equates to 1 Ĺ" from the end of the rack housing.
After the hole is drilled, use a 10/24 tap to thread the hole, and thoroughly clean out any metal shavings which will have entered the rack housing. This tap is welded to a socket which makes it extremely easy to use a ľ inch ratchet if the rack is still in the car. Tapping the hole with a conventional tap with the rack in the car is very difficult.