Outer Tie Rod End Taper
 

I replaced the steering arms on my '67 GTO during a brake upgrade and the holes where the tie rods attach are too small - can't get the castle nuts down far enough to make room for the cotter pins, so I need to ream them out. I see 7 and 10 degree reamers for sale.

Which one do I need?

TIA

The most common taper on ball joints, and tie rods, is 7 degrees.

The other reamers are known as repairman reamers, used to ream holes in parts such as structural steel to aid in getting the fasteners started through 2 thicknesses of steel when assembling them.

They also are used to ream the ends of pipe to remove the inner burr after using a pipe cutter.

Many years ago while fitting steering linkage from a later A body (1973) to my 69 Grand Prix stock car, I tried to use the repairman reamer in the spindle arms to accomadate the larger studs. I quickly found out that the tie rods and ball joint tapers were at a definitely different angle.

In stock cars, the shocks also have tie rod swivel ends and when securing them to the suspension, and frame, you need to make, or buy, tapered holes in a piece of 1/2 inch steel, so I also needed the correct reamer for tie rod ends for shock attachment points.

Of course if the hole is not the same taper as the stud, the stud only contacts a small portion of the hole, and is subject to breaking when put in a shear scenario so taper mismatch can cause failures.

I hope this information is helpful.

Yes, very helpful. thanks.