Outer Control Arm Poly Bushing Too Wide?

[sweatybetty]

i just replaced mine with the same kit, and had the same problem. it took some work, but i was able to force everything together without and modification. i ended up getting one side started, and then, using a putty knife as a lever, force it together with a BFH. if you need to take some off, do as little as possible

[sweatybetty]

i just replaced mine with the same kit, and had the same problem. it took some work, but i was able to force everything together without and modification. i ended up getting one side started, and then, using a putty knife as a lever, force it together with a BFH. if you need to take some off, do as little as possible

[Zed Head]

1 hour ago, Captain Obvious said:

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.

I believe that you're correct, in should never be.  But there must be something stopping the control arm from moving back and forth around the hub, or the hub moving inside the arm,because there's rubber there, and rubber compresses.  The other piece stopping movement is the locking pin in the hub.  Probably why it and the metal around it gets deformed.  The locking pin locks the spindle pin in place and the washers and nuts on the spindle pins compress the inner sleeves against the shoulder of the spindle pin.  You can draw a line of force through the washers, the sleeves, and the spindle pin, to the locking pin and hub.  Easier to imagine without the control arm in place.  There must be some metal to metal contact somewhere, at times, either at one of the two inner gaps, or at one of the two spindle pin washers on the outside against the outer edges of the control arm bushing holes.  In static conditions the hub and spindle pin become one solid assembly floating/isolated in two pieces of rubber.  But loads can compress and elongate the rubber in any direction.  Nissan designed a lot of their Z parts to be hanging in rubber space.

There are people on Hybridz replacing the spindle pin with 5/8" bolts.  I think that I went through this whole thought process before but forgot the details.  They get metal to metal contact for sure, easily, if they don't grind a locking slot in the bolt.  Then it's just a time-consuming way to make a spindle pin.

Anyway, there's just two examples of how to look at these aftermarket parts.  What are they supposed to be doing and what will they really do?

 

[LeonV]

I had to sand a chamfer in mine to get them to fit, also using the Energy Suspension kit.

[Darrel]

Take your car jack and spread the lower control arm about a 1/4" maybe a little less, it will spring back but it will give you enough room to install the bushings.

[Captain Obvious]

22 hours ago, Zed Head said:

I believe that you're correct, in should never be.  But there must be something stopping the control arm from moving back and forth around the hub, or the hub moving inside the arm,because there's rubber there, and rubber compresses.

Well when I say should never be, what I mean is "if there is ever metal to metal, it's not normal and there's a problem somewhere that needs investigating". Worn out soft bushings, something not tightened properly, bent/cracked parts somewhere.

I haven't analyzed the geometry to the depth that I could put numbers on it, but ballpark thinking about the geometry of the parts... Just imagine how much of an angle would be required on the rear wheel in order to compress that rubber to the point that you get metal to metal contact.

Three degrees of toe? Five? Ten? I don't know what the real value would be, but I suspect that if you're rear corner is ever being twisted that far, then you've got a serious problem somewhere. Even if it's a transient. Like I said, I'm not a suspension guy, but it just seems unlikely. Have you seen this with a good condition, properly installed stock setup? Clean rub marks where metal to metal contact has occurred?

I don't know what's going on with people using a 5/8 bolt instead of a real spindle pin, but I suspect (didn't measure it) the original spindle pin is 16mm diameter and a 5/8 bolt is a little smaller than that. If that's the case, then who knows what that extra slop inside the knuckle is doing. I think it's a bad idea.

[zKars]

 Let's get a couple of thing straight about the correct function of these bushings. 

In the stock bushings, the inner and outer steel shells are BONDED to the bushing rubber between them. When you assemble the strut to the control arm, you leave the pin loose until the car is at normal right height. THEN you torque everything down. This LOCKS the center sleeve of the bushings in the control arm to the strut and leaves the rubber in a neutral un-twisted position. 

From this point on, ANY suspension motion twists the rubber in the bushing, there is no rotation of the pin in the bushing or in the strut. 

Poly bushings are completely different as the bushing is not bonded to the control arm hole (you remove the stock bushing outer tube that WAS bonded to the control arm hole, that hole becomes the outer constraint) or to its center tube that the spindle pin passes through. They allow rotation of the center tube in the bushing. hence the need for that sticky lube so they don't squeak.  They are too stiff a material to use them like stock rubber bushings. The center bushing tube is still locked to the control arm when it's all torqued correctly. It matters little what sort of bolt you use to create this lock up condition, spindle pin or 5/8's bolt. Although the slightly smaller OD 5/8 bolt does allow for a tiny bit of slop in the strut hole. But if its all locked up correctly, there ain't no room for schnanigans..

[Captain Obvious]

Here's a couple pics I whipped up a while ago that explain how the stock bushings work.

Here's the rear outers:

And even though we are talking about rears, here's the front inners. Even though it's the front, the concept is identical:

[Zed Head]

We're all agreeing on the principles.  The rest is a matter of degree.

I don't remember what the eight possible contact surfaces looked like when I took mine apart.  The nature of the driving before disassembly would play a part also.  Might start searching images to see what's been captured unintentionally.  Maybe somebody has some parts apart right now?

[Captain Obvious]

9 hours ago, Zed Head said:

We're all agreeing on the principles.  The rest is a matter of degree.

Haha! I see what you did there. 

[GV Z Car]

So here's where I'm at. Trimed the bushing and then used the bfh method but it's really torn the inner sleeve bushing to the point that it's ripped. Beginning to wonder about this kit. Any thought?

[GV Z Car]

Yet another update. Brute force creates results...pounding the crap out of it and boom! One is on. Now for the next.