Outer Control Arm Poly Bushing Too Wide?

[GV Z Car]

Installing Poly Bushings on a 71 Z. Rear Control Arm Outer Bushing seems really too wide. Looking for tips of how to get the control arm and  Stub/Strut Axle assembly together. Should I sand down the bushing equally on both sides (frankly not leaving much of the bushing to remain.

 

Any Thoughts?

 

[zKars]

The most recent couple of these I installed had much thinner inner faces that these. The fit was 'snug', but this looks impossible. I guess I'd take them out and sand them thinner. What brand are they and when were they purchaced.  Tough to use anything sharp other than on a lathe.

[GV Z Car]

zKars

Thanks for the quick reply. Kit was purchased summer 2015. Energy Suspension brand - Hyper-Flex Master kit.

[zKars]

Hmmmm... Maybe these are not the right inner bushings? Kit incorrect? Maybe some of the other bushings just happen to fit that ID? Look at the others for the ones with the really skinny flange... just grasping at straws here

[zKars]

DIdn't think I had one, but I do. Here is how the "right" one looks. The flange is 0.125 thick. 

[GV Z Car]

That's a different bushing than what I have ...there is no difference in the flange on either side. Based on what you are telling me I suspect I have a couple of incorrect bushings for the inner side.

Thanks Kcars.

[Zed Head]

Some of the bushings that companies sell are only being sold becuase they can be sold.  Is there an advantage to putting hard urethane in the bushing closest to the road?  A harder material in a big bushing can stop a lot of deflection but how much does that narrow bushing really buy?  Probably transmits a lot of road noise.

Just a thought.  Nothing wrong with mixing materials.

[GV Z Car]

Food for thought Zed Head.

Thank you for responding...

Not sure what to do yet.

[Zed Head]

The thing about those outer bushings is that they designed those two thin flanges of urethane to take side loads, apparently.  Not huge, but still not the best way to do it.  In the stock configuration, the rubber bonded to two tubes of metal controls the centering of the arm.  It's more than just a material change, the way they work changes also. You could probably cut that outer material completely away and stick a couple of thin washers in there, in its place.  You could just look at how it's supposed to work and make it work the way you want it to.

[GV Z Car]

So what your saying is the upper (or inner bushings that connect the control arm to the frame) along with the strut itself control the vertical articulation. The outer (closer to the wheel) bushing actually controls more lateral motion..therefore as you suggest, I could either go back to a stock bushing or modify the urethane bushings with a thin washer?

[Zed Head]

I'm only pondering the outer bushing.  Actually, you may not even need or want a washer. If you look at how the stock bushing works, the hub casting must rub on the control arm surfaces occasionally,like when you hit the brakes or accelerate.  So those two gaps are actually pretty precisely fitted, I would think.  Metal on metal, a bearing surface, whenever a forward or backward force is applied.  The casting rubs on the arm.  Otherwise the rubber centers it.  Nissan didn't put anything between the two.  Not sure why the aftermarket guys did, except that their design allows sliding back and forth.

[Captain Obvious]

I'm no suspension expert, but I got a couple comments.

There should never be moving metal to metal contact with the stock bushings. The inner sleeve is longer than the outer sleeve, and that keeps the bottom of the knuckle centered between the two outboard prongs of the control arm. The only points of contact are supposed to be the outer sleeves pressed immovably into the control arm, and the inner sleeves pinched immovably tight to the bottom of the knuckle by the spindle pin and nut.

You could, in theory, strain the rubber so much with enough force that you actually move the knuckle fore or aft to the point where the outer sleeve would make contact with the knuckle casting (metal to metal), but in actual operation that's not supposed to happen.

The urethane is a whole different animal... There NEEDS to be urethane compressed between the knuckle and the arm in order to keep the arm centered between the two prongs. If you simply can't get those bushings squeezed into place, you could probably remove some material from them, but keep in mind that it's supposed to be a tight fit. Question is "how tight?" and I don't have that answer.

Maybe they're just TOO thick in that location, but keep in mind that there needs to be plastic to metal compression sliding contact in that location, as well as the tube through the center of the urethane. And yes... That sliding is why they can squeak.

The urethane and stock bushings operate on different principals. The stock bushings torsion, the urethane bushings slide.