Spindle Pin Set Screw - Needed or not?

[calZ]

I'm working on installing a set of T3 rear uprights. The uprights don't include a hole for a spindle pin set screw like the OEM uprights do. With how the pins are clamped into the outer control arm bushings, this will result in the spindle pin rotating in its bore as the suspension travels. Surely this will cause wear and slop over time? 

 

The metal is plenty thick enough to drill and tap for a small bolt, so that's where I'm leaning. Anyone have an opinion on this? 

[evildky]

Pretty much anyone running adjustable LCA's or aftermarket upright just run a long bolt in place of the spindle pin with no center wedge pin.

[NewZed]

What's the bore size of the T3 parts?  With a tight tolerance and some grease it becomes more of a bushing type application.  I think the original pin is 16 mm.  5/8" is loose.

 

 5/8" = 0.625" = 15.87 mm

 

The lock pin allows the bushings to perfom their spring action with vibration damping, and also keeps the arm legs (?) connected if the nuts come off.  If you switch to the PU bushings there's rotation inside the bushing anyway. 

 

 If I was using a 5/8" bolt I'd probably just safety wire the nuts or create a flat and use a peenable nut.  Just for peace of mind.

 

Just some thoughts.  A bolt and some threadlocker and you'll probably never notice a difference.

[JMortensen]

The stock rubber bushings will impart a pretty significant twisting force on the pin. Rod ends or a similarly smooth pivoting mechanism don't need to worry about torque on the spindle pin (or bolt), so no need for a hold down. It's a 5/8" bolt, so torque it to 100 ft/lbs or similar and it's not going anywhere. If you're really worried could put witness marks on the pin and housing to make sure it doesn't rotate, but it ain't gonna rotate.

[NewZed]

Don't overlook the fore and aft movement.  The bushing sleeves and bolt length and nuts and washers all need to be considered.  There are no clear exploded views of how all of the parts there fit together.  You kind of have to mental it all together.

 

 

[calZ]

I'm using OEM spindle pins in OEM bushings and control arms. The T3 bores are tight enough that glue residue from the part tag on the spindle pins keeps the pins from sliding into the bores. If it were rod ends I agree that there wouldn't be an issue. 

 

There will be shims between the upright and control arm bushings to make the fore and aft movement essentially nothing, so I'm really only worried about the rotational force from the control arm bushings. 

 

I think I'll add in the lock screws. The time it will take me to drill and tap two holes is pretty minimal, and I'll stop worrying about it.