The Positioning the Rack n Pinion page details how I determined the width of the rack by measuring and graphing the toe-in play while putting the front suspension through its travel. I guess the question that many people might wonder is how did I know that an 86 Buick Park Avenue rack would work?
I used Federal Mogul's "Steering & Suspension Parts from TRW Catalog X-4000" as a reference. It's main purpose at auto parts suppliers is to look up suspension parts based on the year/model/make of a vehicle. What it also supplies is the dimensions of inner tie rod assemblies, outer tie rod ends, sway bar links and rack n pinion units. Plus it provides a cross reference that lists which vehicles use which parts by part number. It is a great resource but you still have to do a lot of page turning to find the part that will work.
Once I had determined that the rack needed to be an end steer rack and was close to 20-24" in length from inner tie rod end to inner tie rod end. I looked up the Rack and Pinion Specification table. The racks are in ascending order based on the overall length.
Important rack and pinion specs
The overall length is measured from the end of one tie rod to the end of the other tie rod. The tie rods can be shortened and rethreaded if needed. The Inner to inner tie rod center to center length is the important measurement. It is dependant on the rack and cannot be modified. The outer tie rod end thread determines which outer tie rod can be threaded on to the rack.
The Rack and Pinion Specification table is divided into two parts: manual and power racks. Both tables are otherwise identical in format and the column headings are as follows:
The closest GM racks to what I needed from my testing was 1985-91 Cadillac, Olds and Buick fullsize cars with FWD. Racks are available in center to center lengths from 13.90" to 33" and overall length up to 50". Next I had to find a steering arm that would fit.
The steering arm was really hit and miss. There are so many variables involved that it is really trial and error. I went to the wreckers and basically pulled off every bolted on steering arm that I could find. I tried measuring them on the vehicles but it didn't work. I actually had to compare them to the ones that I had. I used the 67 Chevelle's as a starting point as it was the closest to what I wanted. I used a large piece of white cardboard and drew the steering arms mounting holes and their tie rod end centers on it. Even then it didn't tell the complete picture as the tie rod end center was in 3 dimensions in relationship to the mounting holes where the paper only showed 2 dimensions.
Steering arms starting at the bottom: 70 Nova, 63 Biscayne, 70 Ford van, 69 Ford 1/2 ton, 69 Impala, 63 GMC 1/2 ton, 67 Chevelle.
The other problem was the distance between the two mounting holes and the path of the steering arm between them. There had to be enough clearance for the lower balljoint and the lower control arm. The 70 Ford Van had ample clearance for the ball joint but had major interference with the lower control arm when the wheel was turned.
The 63 Biscayne had major clearance problems with the lower ball joint and was an inch too long. The 70 Nova's tie rod hole was 3" too low and so. The steering arms are the most difficult to find and to fit.
The 73 Ford Courier's steering arms worked the best and with some 1 7/8" standoffs made of 1" dia thick wall tubing were the closest to ideal. Next was finding an outer tie rod end that would mate the steering arm to the rack.
The criteria for the outer tie rod ends are: length, steering arm taper, small diameter, large diameter, type, thread and availability. The TRW book lists the specs for outer tie rod ends by length in ascending order.
VW outer tie rod end in black connected to Courier steering arm in silver.
Outer tie rod ends are available in lengths from 2.283" to 23.45" in roughly 0.050" increments so there are a lot choices that can be made. There is typically about 2" of thread on an outer tie rod with up to 1" of adjustment. The best choice for my application was a VW outer tie rod end. It was used on almost every VW Jetta, Passat and Golf for the past 20 years. It was plentiful and inexpensive. I did have to trim down the racks tie rods about 1 1/2" on each side and thread another 3/4" to make them work but what the heck? I also liked the use of a locking nylon nut instead of using a cotter pin. It makes the width of the steering arm not so critical.
If you were stuck and needed longer tie rods, you can change the inner tie rod assembly. There is a table that lists the inner tie rod assembly by ascending length.
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