Trailing Arm Bolt Factoid

[68/70Vette]

Removing and replacing your rear suspension trailing arms? You may find you want to replace the trailing arm bolts...corrosion damage most likely. The bolt actually functions as a pin. The trailing arm pivots on the bolt and all the acceleration produced by the rear wheels is imparted to the body/frame of the car through this diminutive bolt (pin). The repro trailing arm bolts are excessively threaded. Functioning as a pin, the part of the bolt near the head is a unthreaded shaft that contacts the frame mounting hole. However the other end of the repro bolt is threaded where it contacts the frame mounting hole. Lets say you've a 3300 pound Corvette and you launch with an brief shock acceleration of 1 G. Each bolt puts a 1650 pound momentary force on the frame. Since the bolt contacts the frame at the "head" end and the "tail" end, that's 825 pounds of shock load at each end. The repro bolts are threaded where the "tail" end contacts the frame . MY POINT..the repro bolt thread are going to eat into the frame opening hole with shock acceleration forces because they contract the frame with threads. eame .

Where to get an original rear suspension trailing arm bolt? EASY! You already have two that are probably in good shape. They are the bolts that attach the differential torque arm bracket to the differential! You can remove one, or both, and replace them with normal bolts (with nylon locking nuts)/

 

[Twin_Turbo]

80-82 doesn't have the pinion snubber bracket bolts. Are you 100% certain they are the exact same length? From what I remember they were not the same on the 63 and 69 I did. In fact, I think the brackets were not eve the same on all cast iron diffs. i don't remember exactly what it was but something was different.

 

[68/70Vette]

On my 68 and 70, the diff bracket bolts appear to be the correct lenght. The transition from unthreaded shank to threads occurs exactly where the bolt end exits the frame. The differential bracket I'm using now was bought on ebay. I have a second bracket that I also bought, and yes....you are correct.. the second one is different. I had to look at the 68 to decide which one to use.