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Using 5/8 bolt in place of spindle pin

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I have researched replacing the spindle pin with a 5/8 bolt.  I know people have done this before.  I am putting in the Ford super 8.8 kit from InvincibleExtremes (Vlad) and it replaces the spindle pin with a 5/8 bolt.   I also had the (dis)pleasure of removing my factory spindle pins.

 

What I want to know is, when people have used a bolt, what do they tighten the nut torque to?  I have poly bushings, and when the nut is tightened, the metal sleeves of the bushings will tighten against the metal bore of the new upright in the kit. I was worried about the metal to metal contact in this area but this is the same as stock, right?  I was considering putting a thin Delrin washer (thrust washer?)between the bushing sleeves and the upright.  

 

I will be using a nylock nut, and probably another jam nut just to be safe.  But what torque should I tighten the nut to?  I believe factory torque spec is 65 ft-lbs.

 

Thanks

Edited by fusion

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I think the 5/8" bolt is a good alternative but it's main drawback is the shaft of the bolt rotating inside strut/hub housing so you really need to grind out that notch and install the anchor pin as you would with the stock pin.

As for the torque spec. I would check what the specs are for the 5/8" bolt you are using, you can get those bolts/nuts in grade 5 and 8.

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Thanks grannyknot.  I'm not really concerned if the bolt can take the torque, I'm more concerned about the fact that the spindle pin has shoulders on both ends which prevent the nuts from being tightened too far where the bolt has threads that would allow you to tighten the nut to the point where the upright would barely be able to turn because there would be so much friction between it and the control arm bushings.  

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Have you seen this thread?  It doesn't sound like binding has been a problem (yet) for anyone, but you could always slide an oversized "sleeve" over the bolt, between the two mounting eyes on the control arm...use simple steel tubing to make the sleeve.

 

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3 hours ago, fusion said:

Thanks grannyknot.  I'm not really concerned if the bolt can take the torque, I'm more concerned about the fact that the spindle pin has shoulders on both ends which prevent the nuts from being tightened too far where the bolt has threads that would allow you to tighten the nut to the point where the upright would barely be able to turn because there would be so much friction between it and the control arm bushings.  

 

This should be explained in the instructions with the kit, because it should have been addressed when the system was designed.  

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The main issue with the 5/8 bolt is that it is a couple thousandth's smaller than the pin, so it is loose in the spindle bore. If you torque the bolt down so that it doesn't move, I think you're OK to use the bolt with no huge issues.

Torquing the bolt shouldn't be a problem with poly bushings in theory, but probably is in practice. The idea with poly is that the sleeve should be tightly held by the bolt, or the nuts on the stock pin. The bushing is intended to rotate around the stationary sleeve. The problem is that the bushings are almost always way wider than the sleeve, so you have to torque the crap out of the bolt in order to hold the pin stationary, and I can tell you from personal experience that this makes the suspension REALLY hard to move. My guess is that most people don't actually tighten this all down correctly, they just tighten it "enough" and if that is the case,  then the bolt can actually pivot in the bore (wearing the bolt), and the bushings can also move around the sleeve. Whichever requires less force is more likely to happen. If you're going with a rod end style control arm, this is really not an issue at all. Torque it down tight enough and you're good.

The solution with poly is to sand the bushings down to reduce the bushing width, so that you don't have to torque the bolt to 100 ft/lbs to compress the bushing enough to lock the sleeve in place. In addition to cutting the length of the bushing down so that there isn't so much compression on the bushing, another thing to do would be to sand away a lot of the surface area on the outer ends so that the resistance to the bushing spinning is reduced. In combination these two things will still control toe change because the bushing extends into the control arm and you wouldn't be removing that part but it will reduce friction A LOT. 

After modding the bushings another thing to look at is adding zerk fittings to the outer ends of the LCA so that the bushings can be greased. Easy to do, works great. What doesn't work is zerks on the inner bushings; the bushing saddles aren't tight enough, so rather than going in between the bushing and sleeve, grease added just squishes out the corners of the bushing saddles.

If you're installing poly bushings, watch this video first and consider the above mods to improve their function. This video talks about a Miata poly bushing with a better design that has these features incorporated, along with cross hatching that allows lubrication to stay in the friction area between bushing and sleeve, which is far better than what Energy Suspension is making for Zs. Probably not enough market to justify doing this for a Z though...


 

Edited by JMortensen

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The one thing that hasn't yet been mentioned I'd like to point out is get a bolt long enough so only the shank is against the bushes.  If you buy a bolt that fits it will most likely have threads in one of the bush ends.  I don't think I'd recommend notching for the spindle pin as this will add a failure point and this system doesn't have the fail safe the stock system has.  If you do decide to notch the bolt make sure to paint of put some corrosion inhibitor on it.  

 

cary

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Since the 5/8" all thread is smaller than the original pin over time you will develop what is called fretting. The fretting is a type of wear and can create a rusty looking finish.  I personally would stay away from all thread and just spring for the pins. 

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15 hours ago, fusion said:

The kit I am using has a 5/8" bore on the upright/spindle specifically for the 5/8" bolt.  The control arm bushings are still very slightly bigger though

 

 

Oh that's different:) Carry on.

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