Shackled in Confusion
I have read and absorbed all I can about shackles. And interestingly enough I have come to the firm conclusion that not
only is there a lot of misinformation floating on the web about how to install them, (not surprising,) but there are many
product manufacturers that don’t have a clue as to what they are building and what they are selling.
This I did find surprising. Let me explain.
Nomenclature: (To avoid confusion)
Sleeve- A hollow metal tube that goes inside the bushing.
Bushing- A rubber/polyurethane bushing that goes inside the spring eye.
Bolt- Well…ur..a bolt.
Shackle torque. I have heard it all, from finger tight to 100 ft. lbs. If you think about what the main purpose of this joint is,
which is to pivot, then of course there needs to be a friction point. And that friction point is between the sleeve and the bushing,
not between the bolt and the sleeve! This is evident by the fact that the torque of the bolt, being somewhere from 40 to 80 ft. lbs.
will capture the sleeve between the shackles very tight. This torque should keep the sleeve from rotating around the bolt and also
the sleeve should not rotate in relation to the shackle. It should all be as one piece with this amount of torque.. When it is all as
one piece with the proper torque it will also prevent the shackles from tilting sideways in the famous parallelogram shape. Now,
when you have this torque applied, if the poly bushings are being distorted, (to tight) or the shackle has side play, (too loose)
then your sleeve is the wrong length, either too long or too short.
Now this presents another issue. I have looked a several “Greaseable” shackle bolt kits. Most of these are a joke. Many are
made all wrong. If you get a kit that has a drilled bolt for the grease to go through you have gained nothing but a lighter wallet.
Remember, the friction surface is between the sleeve and the plastic bushing. It does no good to put grease between the bolt
and the sleeve as there is no relative motion between the 2 when properly torqued. Here are some examples of worthless kits.
However these guys have their act together. Notice on the good kits that the sleeves also have been drilled to allow the
grease to get between the sleeve and the plastic bushing, where it is actually needed.
I have also seen greaseable kits where the shackle bolt rides directly on the bushing. This is more junk as the bolts
cannot be torqued tight without crushing the bushings. You have to have sleeves and they have to be tight. If this
tightness causes a bind you have the wrong sleeves, or you just may need to add a washer the same ID and OD of
the sleeve to relieve the clamp-up on the bushings.
Is all this true? I don’t know. I just made it all up. But after studying the situation for a week it is an understanding
that makes sense to me and the approach I will use to set up my shackles so they are torqued dead TIGHT yet will
pivot without binding, distortion, or any looseness.
If anyone can shed more light or understanding please advise.