How Tight Should Shackle Link Nuts Be On Trailer Suspension

Published 08/20/2021

Question:

I disagree with the experts answer. A knurled nut is designed to be seated one would think. Otherwise why the knurl? If the bolt spins, you will be wearing out the hangar as well as the links. If you try to tighten the hangar bolt with the nut, you stand a good chance of ruining the nut. The nut only has maybe 4 active threads. I use a press to seat the hangar bolts, and install them as a unit 2 bolts pre-pressed in links. Seating the hangar bolts is more of a challenge. Other than getting a 300# mechanic to hold a 20inch sledge hammer as back up to the bracket, while pounding on the bolt head with a 5 pound hammer. Someone has probably figured out how to press this bolt too. Any ideas?

asked by: William K

Expert Reply:

In regards to trailer suspension kits like the Suspension Kit for Tandem-Axle Trailers part # AP233, the shackle bolt heads are indeed seating into the hangers via the knurling on the bolt. If you hold a wrench on the bolt head and tighten the nut, this will seat the knurling. The bolt does not pivot on the outer shackle links but rather the spring/equalizer pivots on the bolt. There is no torque spec for this bolt/nut, you'll stop tightening when the spring/equalizer does not have any side to side play within the shackle links. Snug the fastener and then back it off a 1/4 turn to prevent binding. The locknuts used will prevent the nuts from backing all the way off.

expert reply by: Conner L