IRS TR Front Suspension Rebuild

(January 2003, Raymond L. Hatfield)

These instructions were compiled during the restoration of a TR4A front end. Parts replaced included the rubber bushings, the brake system (brake calipers, brake pads, hydraulic pipes and hoses), springs, shock absorbers, upper ball joints, tie rod ends, steering rack boots, trunnions, wheel bearings and all hardware. Before any disassembly is attempted, it is wise to have ready access to a few simple items. These include a notebook, both large and small zip lock bags, small paper tags to use as labels in the bags, a parts catalog with clear diagrams and a shop manual (or several). The following work was completed using The Roadster Factory's rubber bushings, because they came with the car when I purchased it. The process for polyurethane bushings is similar but will differ in several important ways, and may be covered in a separate article at a later date. This is a rough draft, comments and corrections are welcome.

Assembly

• 1) Lubricate inner ball joint and install new boots to steering rack (this task is more difficult than you might imagine; cut a 2 x 5 inch strip from a 1 gallon plastic jug and use this as a funnel to slide the boot over the large diameters encountered while sliding the boot into position).
• 2) If you removed the fulcrum mounting brackets, loosely bolt them to the forward most holes on the frame mounts ensuring that the wishbone mounting hole is towards the top of the bracket; replace shims as noted during disassembly (you did remember to write this down, right?).
• 3) Use anti-seize compound to lubricate the shafts on the fulcrum pins then slide the stainless steel sleeves over these shafts; lubricate the outer surface of the sleeves (lubrication of all sleeves and bushings is done with anti-seize compound)
• 4) Lubricate the 2 halves of both upper wishbone bushings and slide 1 half of each onto each end of the fulcrum pin
• 5) Install the upper arms onto the fulcrum pin and use a soft mallet to tap them over the bushing placed in the previous step (note that the upper wishbones can be used on either side of the car, however, the wishbone with the greatest curve is positioned to the front while the wishbone with the lesser curve is positioned to the back)
• 6) Place the other half of the bushings onto the shaft and work/tap them into the wishbone; when you see enough thread, place a washer and castle nut on the shaft, tighten the nut to push the bushing home; back the nut off and leave the wishbone arms very loose for the next step
• 7) Install the new upper ball joint between the upper wishbone arms (the outer most bolt is inserted rear to front while the inner most bolt is inserted front to rear); secure using nyloc nuts and torque to 30 ft lbs
• 8) Torque the fulcrum pin castle nuts to 35 ft lbs, insert the cotter pin and bend it to secure the nut
• 9) Thoroughly lubricate the bushings for the lower wishbones, tap them into the wishbone arms and insert a well lubricated sleeve into each bushing (note that the driver side rear wishbone is the same part as the passenger side front wishbone and the driver side front wishbone is the same part as the passenger side rear wishbone)
• 10) Insert the lower wishbone arms into the fulcrum brackets, slide bolts into brackets from outermost towards shock tower and loosely fit the nyloc nuts
• 11) Fill a new trunnion about 1/4 full of 90 weight gear oil, slide a new seal over the threads on the vertical link, screw the trunnion onto the vertical link until it stops, back off until trunnion rotates through its necessary rotation, and fit the stop to the trunnion with a lock washer and bolt
• 12) Loosely fasten vertical link to stud on ball joint using washer and nyloc nut
• 13) Insert new bolt (from rear to front on left hand side/ from front to rear on right hand side) through lower wishbone bushings, through trunnion and through other lower wishbone bushings on the other side (note that you will use 4 washers per side as follows: one under head of bolt, one on either side of the trunnion and one under the castle nut), install castle nut but do not tighten
• 14) Tighten nut holding vertical link to the ball joint to 45 ft lbs. The stud on the ball joint will sometimes turn with the nyloc not as you attempt to tighten the nut. If this happens, place a block of wood between the upper wishbone and the top of the wheel well. Position a padded jack under the trunnion and gently raise the jack until the stud is pressed firmly into the vertical link. Tighten the nyloc nut and remove the jack.
• 15) Install brake caliper mounting bracket and tie rod lever to vertical link taking note of 4 different length bolts. The longest bolt is installed in the top hole closest to the tie rod ball joint. It passes through the brake caliper mounting bracket, through the vertical link, through a spacer piece, through the tie rod lever and is fastened with a nyloc nut. The next longest goes through the top rear most hole. It passes through a locking plate*, the brake caliper mounting bracket, the vertical link, the tie rod lever, and is also fastened with a nyloc nut. The third longest bolt passes through the lower front most hole in the brake caliper mounting bracket and is threaded into the vertical link. It protrudes from the rear of the vertical link by about 1/2 inch to allow the mounting of the brake plate. The shortest bolt passes through the remaining hole in the locking plate, the lower rear most hole in the brake caliper mounting bracket and is threaded into the vertical link. All 4 bolts are then torqued to 30 ft lbs. The ears on the locking plate are then bent up against the flat of the bolt heads for security. (* Note- the locking plate must be bent into a gentle arch so that when the ends of the plate are touching a flat surface, the center of the plate is about 1/4" in the air. If you do not bend the locking plate, it will appear to be too long when placing the bolts).
• 16) Insert the locking nut and outer tie rod end onto the steering rack, position them according to previously recorded measurement, and tighten the lock nut.
• 17) Insert tie rod ball joint stud into the hole on the tie rod lever, fit washer and nyloc nut and tighten nut to 35 ft lbs. If stud spins while tightening nut, use procedure in step 14 above.
• 18) Press one spring pad into the seat of the shock tower and another into the spring pan. Insert the spring compressor into the shock tower, slide spring and spring pan onto the lower end of the compressor's threaded rod.
• 19) Tighten the compressor until the spring pan just touches the lower wishbones. Align the studs in the wishbones with the corresponding holes in the spring pan and continue compressing until the spring pan is flush with the lower wishbones. Insert 4 bolts (bottom toward top), fit 6 washers, 6 nyloc nuts and torque to 30 ft lbs.
• 20) Now, go back and torque the following fasteners in this order:
  A) The bolt through the trunnion to 55 ft lbs; insert and flair cotter pin
  B) The nuts on the mounting brackets to frame to 25 ft lbs
  C) The lower wishbone to mounting bracket bolts to 40 ft lbs (Note - it is important that steps B and C are not reversed as the stainless steel sleeves need to be able to pivot slightly on the bolt to ensure they remain in line with one another.)
• 21) Install the fulcrum brackets to the hole in the bottom of the shock absorber and tighten the nyloc nut to about 10 ft lbs; fit the top of the shock into the hole in the shock tower and tap the fulcrum brackets over the studs on the bottom of the lower spring pan; fit lock washers and nuts to these studs and tighten to 30 ft lbs; tighten the nut on the top of the shock until the rubber bushing is the same diameter as the washers and run another nut down the stud to lock it in place.
• 22) Replace the brake caliper dust cover assembly using the bolt protruding through the vertical link and a nyloc nut.
• 23) Lube the stub axle, front hub assembly bearing and race with wheel bearing grease.
• 24) Slide hub assembly on to stub axle; fit D washer, castle nut and tighten nut slowly until the hub begins to resist turning; back nut off by 1 flat on nut, install and flair cotter pin.
• 25) Apply wheel bearing grease to nut and cotter pin; fill dust cap 1/4 full of grease; tap dust cap home using a hammer and a block of to avoid marring the cap.
• 26) Replace body to frame mounting bolt.
• 27) Install road wheels and test drive.