Install Problems, and Driving Impressions.

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4. Installation Problems

I encountered several  problems during the rack install process.

4.1 Installing the steering column bottom bearing adaptor.

On the 1970 models (and probably on 71-73 as well) with automatic transmissions, the steering column lock is connected to the transmission so the ignition key cannot be extracted till the transmission is in the PARK position. This function is achieved with a rotating inner shaft on the steering column, which terminates onto a small lever just above the steering box. See picture 1 below. From there a rod connects with a shaft protruding from the transmission housing. 

The standard TCP bottom bearing adaptor as supplied would not fit this steering column. There are two options:

1. Cut the interlock lever off flush with the outer column tube. (See photo 2 below). This enables the standard bottom bearing cap to be fitted. This option deletes the ignition key /transmission interlock function, (although it could be reinstated later by tack welding the lever extn back onto the column tube). 

2. A far better option is to install the specially designed bearing cap that TCP stock for this particular application. (See picture 3 below). This is longer, and has a slot cut in one side to enable the interlock lever to protrude and operate as intended. 

I used option 1. I also had to machine 1 mm out of the inside of the cap as it was too tight to fit comfortably over the outer tube. As the interlock lever had never been connected on my car I didn't at first realise what it was for. (I was also in too much of a hurry to get the job finished to wait for the correct cap to be sent out!)

4.2 Excess length on the intermediate shaft

When the steering column was first installed and connected to the rack, I found the upper universal joint was binding on the intermediate shaft. The intermediate shaft was too long and was protruding right through joint, interfering with its free rotational action, and making it bind at certain positions.  The solution was obvious. I removed the column, and cut approx 20 mm off the end of the intermediate shaft to shorten it, then reinstalled the column. Problem solved. Every car is a little different. 

4.3 Camber Adjustment

The stock camber adjustment system on later cars uses an eccentric bolt arrangement to adjust for camber, by moving the position of the bottom arm inner suspension mounting in and out. Under heavy loadings these can eccentric bolts can slip, so the TCP kit replaces them with solid steel adjustment plates, with three possible initial settings.

Standard eccentric bolt set up, with the TCP solid plate replacement. (Click to enlarge)

When I first installed the rack I had to choose one of these three positions, to set the suspension camber. I chose the innermost setting and the result was a slight positive camber. I then reset the mountings to use the centre setting, and the result was way to much negative camber. What to do? 

On consulting TCP, they advised me to use the mid setting, and then install standard adjustment shims on the upper arm mounts (as used on the 65/66 models) to pack the upper mounts out slightly till the camber was perfect. In fact I lowered the upper arms 1 inch, (see separate article) which meant that I actually used the outer setting, and about 9 mm of shims.

4.4 Bump-steer Adjustment  

The TCP standard position to mount the rod ends to the rack is onto the inner of the two set of holes provided on the centre link, as shown in the picture at install step 3.5. During the the final wheel alignment it was found that this position was displaced too far in-board of the bottom suspension arm, and this caused severe bump-steer when the suspension was depressed. (The toe in changed significantly as the suspension was depressed). The solution was simple. Move the inner tie rod ends to the outer of the two holes in the centre link. This requires each tie rod to be shortened by about 45 mm (1+3/4 inch). The available adjustment on the sleeve in the middle of each tie rod in my case was just adequate to shorten each rod the required amount, with about 1 full turn left before the two rod ends butted together inside the sleeve. (If it had proved to be too tight, I would have ground a few mm off each end.). The resulting improvement in bump-steer was dramatic as each tie rod now pivots inline with the bottom suspension arm inner pivot bolt.

4.5 Leaks:

The first rack that TCP sent leaked fluid very badly after just 100km of running. This unit was replaced by TCP without question..it was one of a batch of bad ones apparently. The second rack was a huge inprovement, but as the miles clocked up it did still seep a small amount of fluid and was never totally oil tight.

4.6 End Cap Abrasion

The end cap on the rack was prone to being struck by the adjacent tie rod on full right lock. I cured the problem by grinding a chunk of metal off the corner of the cap to provide more clearance.

5. Driving Impressions

The difference from the old heavy and worn manual steering system, to the new rack and pinion system was dramatic. Heavy was replaced with fingertip light, slop and vagueness replaced with pin sharp and accurate, and dead was replaced with good road feel. 

Manuovering in car parks, which previously was a real chore, became a delight. The car now steered like any modern car with powered rack and pinion steering system; light, sharp, direct. Turns lock to lock dropped from 4.5 to 3.5, which makes driving the car on twisty roads much less of an handful.

Less impressive was a "judder" when turning lock to lock at low speed. This was caused by the stock Ford pump being unable to pump enough fluid to smoothly power the rack. Easily cured by fitting the higher capacity pump TCP recommend

Ive now done enough miles with the system installed, and in different conditions to form final opinions. Yes its real nice to have power steering after the heavy manual system, but actually any powered system will do around town. 

Ultimately the biggest gain is when the car is travelling at high speed. In New Zealand we have relatively tight and twisty roads c/w most of the US. Its important therefore to be able to position the car accurately on the road. For example when you are sharing a narrow two-lane bridge with a Kenworth truck travelling in the opposite direction, you are both at 60 mph + and there's less than 2 ft of spare airgap....! Previously I would have been praying that I got the car in about the right spot, now I can place the car confidently exactly where I want it all the time, with no wander or drift. For me that has been the most significant gain in the conversion.

Ive noted that there is hydraulic "pumping noise" (hissing) coming up the steering column during turning. This noise originates from the stock power steering pump, which I was warned would be hydraulically noisy. The solution (when I am ready) is to fit a urethane column isolator, or better still, fit the adjustable output pressure  pump recommended by TCP. Changing the steel reinforced HP hose for a synthetic reinforced hose is another option I could try also.

In summary, before conversion driving the car was not really the pleasant experience I wanted. Now it is a pleasure.... and having pleasure driving the car is what Mustang ownership should be all about!