The FFR build manual is a little short on detail regarding how to properly install and set up the Mk4 steering rack. There is interaction between the rack, the front end alignment, the steering wheel alignment, the steering shaft position, and the number of turns center to full-lock-left and full-lock-right that isn’t immediately obvious. After struggling for a couple weeks to set mine up properly I wanted to write down what I learned in the hopes that it saves someone else some time and trouble. My particular build uses the manual steering rack but the install procedure should be common to both manual and power racks. I acknowledge that there are multiple ways to do this. This is intended to be a somewhat systematic approach that should get all the important parameters in the box.
The single most important thing to get right is the concept of what is meant by ‘centering the rack’. Note particularly that this does not mean centering the housing of the rack in the chassis, nor does it mean centering the gap between the housing and the rack internals, nor does it mean centering the steering wheel at the midpoint between full-lock-left and full-lock-right. What it refers to is centering the position of the rack’s inner tie rod ends in the suspension. This is best illustrated with a few pictures.
A properly centered rack will center up the distance to the inner tie rod ends as shown below. Note that you’ll have to slide the boots back in order to measure this. The threaded connection between the inner tie rod ends and the moving part of the rack itself is a convenient place to take a measurement. You’ll also need a reference point on the chassis to which to measure. In the photo below the reference point is the outside wall of the vertical frame member. There are a couple of paint sticks clamped to the frame as a way to extend the surface in order to take a measurement.
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Set up in this manner you’ll notice that there is unequal extension as measured to either side of the rack housing. This is normal (and a reflection of the fact that the rack housing is not perfectly centered in the FFR chassis).
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With the rack centered the outer tie rod ends can now be threaded on. You should end up with very close to the same number of threads showing on both sides with the wheels pointed straight ahead. Here’s a convenient way to get the wheels close to straight: tie a string to a spoke on the rear wheel and pass it through the wheel, around the back of the tire, and then extend it to the front wheel as shown. Adjust the outer tie rod ends as required to get the string to just touch the sidewall at the back of the front tire.
So at this point we have the rack centered, the front wheels are straight with respect to the rear wheels, and we have (mostly) equal thread engagement on both outer tie rod ends.
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Unless you’re very lucky, you’ll most likely find that that the steering wheel is now off center (crooked). There are a couple ways to fix this. One way is to remove the steering wheel from the hub it’s attached to, center it up, and then redrill the hole pattern in the hub as required. Another way is to take advantage of the fact that the steering shaft is splined where it attaches to the steering rack. The splines are fairly small and therefore provide for relatively fine adjustment. The problem with this approach is that the shaft on the rack has a flat that is intended to match up with a set screw on the steering column. And most likely the flat and the set screw won’t line up with the shaft rotated as necessary to center the steering wheel. So what you need to do is to mark the location where the set screw ends up and grind a small indentation on the shaft to provide purchase for the set screw. No need to remove a lot of material; the splines resist the torque (not the set screw), so all you need is a small indentation to help the set screw resist the fore/aft motion. I added the indentation shown with the help of a Dremel plus a carbide tungsten bit.
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So we now have the rack centered, the front wheels straight with respect to the rear wheels, equal thread engagement on both outer tie rod ends, and the steering wheel is centered. At this point you can go ahead and set toe-in to specification (typically 1/32” per side, 1/16” total) per any of the techniques described in the FFR FAQ. Finally, we need to verify a roughly equal number of turns on the steering wheel from center to full-lock-left and center to full-lock-right.
Part of the reason it took me a couple weeks to complete the steering rack install/setup was because I was under the mistaken impression that an equal number of turns both ways was the starting point for the overall installation. This is not the case. In fact, equalizing the number of turns left and right is the final step in the sequence and is accomplished using the specialized set of spacers shown below.
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Ford “steering travel restrictors” part number N804842-S (about $15 for a package of 4). The rack as supplied by FFR most likely already has travel restrictors installed. On my particular sample, there were actually two of them on each side as shown below. The separately available Ford parts are a split design and can be easily installed with no disassembly of the rack required (other than moving the boot back to expose the innards). Simply install however many spacers are required to even out the travel on both sides. In my case I needed one additional restrictor on the passenger side, at which point I had about 1-1/4 turns from center to full lock on both sides.
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So at the end of all this we now have the rack centered, toe-in set properly, equal thread engagement on both outer tie rod ends, a centered steering wheel, and approximately equal travel from center to full-lock-left and full-lock-right. Whew!
Hope this helps someone else out there save some time and frustration.
-Karl
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Originally Posted by hjoensy
How do I set caster
