Freak Ride IFS System

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 Red Devil wrote:

 White70JavelinSST wrote:

 Red Devil wrote:

Dennis: What keeps the lower arm from twisting with that arrangement?  Just the bushing at the arm pivot at the crossmember, or is the line-of-action of your strut rod coincident with the centre of rotation of the lower ball joint .. or close enough not to cause issues?

Thanks,RD
P.S. The stock strut rod also works.

RD, 

I'm looking for a replacement idea that does what you described and also doesn't shorten the moment arm of the strut rod and doesn't flex the heck out of the stock strut rod or the hugely stiffer bushings that appear to be the only choice available these days, unless the super soft ones are used and they turn to crap in a short time. I've had a strut rod break from too much flex and from then on I had to make sure the front doesn't droop too far. or compress too far. I have to limit the droop when I raise the car off the ground. Currently I'm using urethane but have a couple sets of more traditional bushings but still not factory hardness.

Stock strut rods typically fail due to a high-load or corrosion starting a crack that eventually fatigues and fails.  Unless you have particularly rough roads and excessive suspension travel, doubt the bushings themselves will cause a crack ... but stiffer ones may cause a fatigue failure much quicker.

Some stock cars use strut-rod type lower arms.  The arm and strut rod have spherical joints at the chassis pivots and the strut rod is fixed to the arm with a heavy clevis aligned with the arm axis so it allows easy adjustment, but doesn't add another degree of freedom (unlike Dennis' arrangement which relies on the straight bushing at the arm pivot and small strut rod offset to the ball joint for stability).

If the Open Tracker Racing arrangement works, could be a good option for a stock-type strut rod.
Open Tracker Racing strut rod spherical joint

One thing that also helps with the stock arrangement is to leave the strut-rod bolts to the arm snug when adjusting and torque after final adjustment to reduce induced preload.  Slot the holes in the arm if you need more adjustment than stock.

Hope this helps,RD

To add... My simple fix to the fatigue weakness of the rod, is to use a cut section of the factory rubber bushing's steel sleeve and wedge or weld in in place between the locating nut and the taper of the rod. By using such a reinforcement, the weak narrow and threaded rod will become stiff and apply forces against the nut to travel into the thick steel washer.

I also have utilised a centering pivot ball within the assembly. So hardly any negative force under travel will be added. Only the tightness of construction places about 10 lbs force to move the strut rod full up and full down. Unlike most bushed setups.

I think the biggest issue that is over looked to cause fatigue other than twisting from lower arm movement is, the stock sway bar. Since its arm length is short and is placed on the lower arm, the sway bar will pull the lower arm forward in upward travel, while the strut rod wants to pull toward the rear. The two opposing forces along with forces under suspension action is not the best for any setup. There would be less binding and twisting without the sway bar than without. Unfortuantely mostvwant their sway bar.

Though dennis' change up puts most all the bind and twisting from the sway bar forces, up against the natural pivot of the strut rod, where it is strong.

The issue is not cured with any strut rod setup, just better implemented as to resolve most of the symptoms with bushing pivots, all are better than stock for durability and longevity. If auto crossing, some consideration must be taken with how your strut rod, is strengthened or is changed out.