XJ40 ( XJ81 ) 1986 - 1994

Steering Rack Stiffening Bushes DIY

 
  #1  
Old 01-08-2015, 10:27 PM
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Default Steering Rack Stiffening Bushes DIY

A few years ago, a U.K. Jaguar parts vendor and eBay seller began offering a “Steering Rack Bush Repair Kit,” said to fit the XJ40 and X300 racks. The “kit” was a pair of claimed "New Old Stock" nylon steering rack stiffening bushes, Jaguar part SPC1059.
A little research revealed that these bushes were among the upgrades installed on XJR and XJR-S models beginning in 1988. Apparently, Jaguar never offered these bushes separately as service parts. Below is a link to the special parts list:


http://www.jag-lovers.org/xj-s/xjrs/parts%20list%2088.htm


The bushes are thin plastic rings that slip into the gaps between the ends of the steering rack body and the mounting brackets. The bushes prevent side-to-side movement of the rack due to the rubber bushings molded inside the mounting brackets. In the past, I've read about owners who have used several wraps of wire or even thin U-bolts to serve this purpose, but I liked the simple elegance of the plastic bushes.

Here’s the eBay seller’s photo of the Jaguar OE bush:






The eBay seller offered a limited number of sets at 36.64 / $55.41 (plus shipping outside the U.K.). I was tempted, but suspected I could make my own bushes for less than what would probably have been more than $65.00 with shipping costs to the U.S. All I needed were the dimensions of the bushes. Those came from Richard, a fellow Jag owner in the U.K., who ordered a pair for his X300 and kindly took careful measurements. I also learned from him that the bushes have a groove around their outer circumference to receive a wire to secure the bush in place, something I couldn’t have known from the eBay photo alone. With this information, I created a simple part diagram:




The next step was to find a suitable material from which to machine my bushes. Richard said that despite the fact that the OE bushes were made of a white plastic Jaguar called Nylon, he was concerned that real Nylon might not be sufficiently flexible to spread apart to slip around the steering rack. When I began installing my own bushes, I could see what he meant. The steering rack is the same size as the inside diameter of the bush, so the bush must be highly flexible to bend around the rack body. Richard suggested I look at polyethylenes, and after some research I opted for a High-Impact Resistant, Ultra High Molecular Weight (UHMW) Polyethylene made under the Tivar brand. Here's a link to Tivar specifications:

http://www.quadrantplastics.com/na-e...-products.html


Given the 3.3mm thickness of the OE bushes, I ordered a section of rectangular bar 4 in. wide X in thick, item number 8702K472 at McMaster-Carr (mcmaster.com). The price was $6.76 per foot. I only needed 1 foot, but I ordered 2 in case I made a mistake. The mistake I made was to order in. material with the plan of planing it down to 3.3mm (0.1299 in.). After discovering just how tight the 3.3mm bushes were to install, I would highly recommend ordering 1/8 in. (0.125 in.) material, McMaster item 8702K446 at $4.69 per foot. The bushes will work fine and be just a little easier to fit. Here’s the plastic I ordered:







This is the part you don’t want to trouble yourself with, but I’ll show the photo for the historical record. I machined the poly bar using the surface planer. Even taking very light cuts, the planer did not like this thin, flexible material, resulting in bad sniping on the trailing end. A solution would have been to adhere the poly to a board with double-sided tape, but truly, you don’t need to mess with this at all:






With very light cuts, I snuck up on the final thickness:






With double-sided tape, I fixed the poly bar to a sacrificial board, then drilled appropriately-spaced center holes in the plastic for my router guide pin. I drilled holes in a router base at the correct radius points to rout inside a 58mm circle and outside an 83mm circle. I cut the outer diameters first, then the inners, so the bush rings would remain connected to the plastic with the center holes until all cuts were complete:






I used the edge of a small jeweler’s file to scrape the burrs from the edges of the rings:






I considered several ways of machining the groove in the outer edge of the bushes. I could have simply used a jeweler’s file to form the groove by hand. I could have used a luthier’s purfling tool to define the outer edges, but then would have had to remove the remaining material. I could have used a slot-cutting bit in either the drill press or router table, but I would have had to devise a means of controlling the depth of the cut. In the end, I opted for the Dremel router table mounted with a small spherical carving burr with a diameter about 1/3 the thickness of the poly bush rings (I just chose the burr size by eye):






By adjusting the position of the Dremel tool below the table, I set the depth of cut. The board clamped to the table served as a second guide fence to prevent the flexible plastic from deflecting. By rotating the poly rings over the spinning bit, I cut the grooves:






The bushes have a slot cut across their width. The most obvious reason is so they can be spread apart to fit around the steering rack. But why is the slot about 1/8 inch wide, instead of being narrower, like the kerf of a bandsaw? My suspicion is that the wider slot is intended to allow a small range of adjustment to ensure the bush can be tightened so there is no gap between the inner diameter of the bush and the body of the rack. The simple solution was to use the table saw to cut slots that are about 1/8 inch wide, using a push stick to help hold the rings securely while making the cuts:






Given the function of the bushes, there's no need to polish the rough surfaces. Here are two views of the finished bushes:










For the security wire that fixes the bushings in place, I could have purchased some nice stainless steel brake safety wire, but I had on hand some standard steel wire in 19 gauge, so that’s what I used:






Installation began with clipping a couple of wire ties so a hydraulic line could be moved out of the way:





When I tried to install the first bush, the fit was too tight, so I started the engine and turned the steering wheel until the gap between the rack and mounting bracket increased to its maximum. The fit was still tight, so I used a piece of thick twine to first clean the gap, then to lubricate it with plastic-safe dielectric grease:






I lubed both sides of the bush with dielectric grease and worked it into the slot:






Working from below, I struggled to push the top of the bush down into the gap, so I used a long wooden dowel from above (in the engine bay) to work it into place:






I used a wide prying lever to fully seat the bush all the way around, then looped a section of steel wire around the bush:






I used lineman’s pliers to twist the wire snug but not so tight the metal of the wire might be weakened:






With the right end of the rack now immobilized and its play eliminated, installing the left bush was even more difficult. I adjusted the steering wheel to maximize the left gap, but still had to loosen the rack mounting bolts to gain enough clearance to fit the left bush. That’s another reason to use 1/8 in. plastic and not worry about the 3.3mm thickness of the OE bushes, which the factory would probably have fitted on the rack before it was installed in the car, making the job far easier.

Here’s the final result, the bush installed and secured with wire (my wire twisting skills won't win any awards):







So was it worth it? For me, yes. The steering on our ’93 has always been more limousine than sports sedan, and these stiffening bushes remove a little of that frustrating imprecision. If your steering rack is worn and in need of replacement, these bushes won't solve the problem (or even make a noticeable difference). But if your rack is good, I think you’ll notice a worthwhile improvement in steering response, with no discernible increase in harshness.

I do not know whether these bushes, or similar ones of different dimensions, might fit the X308 or later racks, or Series III or earlier racks. Nor do I know if those racks have the same room for improvement.

The eBay seller appears to be sold out, and all of the OE Jaguar parts sources I've checked with either can't find the part number or list the bushes as unavailable. Fortunately, it's not too hard to make your own for about $10.00 and a little time
.
.
Cheers,

Don
 

Last edited by Don B; 06-11-2019 at 05:24 PM.
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  #2  
Old 01-09-2015, 03:47 AM
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Greate write up, and nice solution!
 
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Old 01-09-2015, 05:00 PM
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Great write up and another great DIY solution to an OEM mystery part!
 
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Old 01-13-2015, 08:39 PM
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Don,

You simply amaze me at times.
 
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Old 01-13-2015, 08:58 PM
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Originally Posted by Rob Evenson View Post
Don,

You simply amaze me at times.
+1 superb solution Don

Only question is, why haven''t you FAQ'd it ( added as a how to ) ??

I'm sure it'll be of help to someone at some point

Many thanks for the write up
 
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Old 04-05-2015, 08:01 PM
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BTW, did we every verify that these bushes are already in place from the factory on X300 XJRs?

.
 
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Old 04-07-2015, 10:15 AM
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Originally Posted by al_roethlisberger View Post
BTW, did we every verify that these bushes are already in place from the factory on X300 XJRs?

Al,

You are the perfect candidate for crawling under your XJR to look for them! Please let us know what you find!

Cheers,

Don
 
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Old 11-30-2017, 08:04 AM
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Got a link?
 

Last edited by Don B; 06-11-2019 at 05:13 PM.
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Old 11-30-2017, 05:21 PM
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Ya, link please. My planer is buried under too much other junk!
 
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Old 06-11-2019, 03:00 PM
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Is anyone making these anymore?
 
 
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