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Using 5/8 bolt in place of spindle pin


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On 3/4/2021 at 8:17 PM, gnosez said:

I have had a 5/8 bolt in the rear control arm/strut for over 16 years and 250 track days with no issues whatsoever.  I have not found one good reason to use the locking pin and I have several rear control arms from old SCCA EP cars that use either a through bolt or a spindle pin without the locking pin.

 

The idea behind the spindle locking pin is that it is an extra safety mechanism.  If you lose one or both nuts and washers on the spindle pin it can't slide out, assuming you have one that can actually be removed without the use of a large press.  I have used a bolt in mine an no pin or similar mechanism and have no plan to ever again.  That said I do regular bolt/nut checks on my car as part of their maintenance, which a large portion of the public think is either silly or a complete waste of time.  Probably the same people who shouldn't be driving an old car without all the modern nannies or insert version of onstar they need when they lock themselves out of their car because it doesn't need a key to start.

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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

The idea behind the spindle locking pin is that it is an extra safety mechanism.  If you lose one or both nuts and washers on the spindle pin it can't slide out, assuming you have one that can actuall

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5 hours ago, tube80z said:

 

The idea behind the spindle locking pin is that it is an extra safety mechanism.  If you lose one or both nuts and washers on the spindle pin it can't slide out, assuming you have one that can actually be removed without the use of a large press.  I have used a bolt in mine an no pin or similar mechanism and have no plan to ever again.  That said I do regular bolt/nut checks on my car as part of their maintenance, which a large portion of the public think is either silly or a complete waste of time.  Probably the same people who shouldn't be driving an old car without all the modern nannies or insert version of onstar they need when they lock themselves out of their car because it doesn't need a key to start.


ahh! You know, that does make some sense. I thought it was to keep it from rotating, but clearly it keeps it from moving down its centerline as well.

 

Wait... you don’t have Onstar? How do you live man! I ask them for a drink while I’m in traffic. Amazon delivers with the drone. Now that’s “hybrid”. 

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I'm well aware of the reasoning (over-thinking) regarding the locking pin and I reject their concern based on tens of thousands of miles on my street Z which is driven hard and tracked every once and awhile. Neither nut has ever loosened. Add to that the fact that 1 out of every 5,000 spindle pins come out by simply pulling on them.  

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Most of the discussion about the spindle pin and locking bolt is about why Nissan did things that way.  And, as often mentioned, just because something didn't fail doesn't mean it's better.  There are many areas on the Z where you could just use a cable or a chain or drill a hole and use a bolt.  In the end the car owner needs to know what they're trying accomplish and take responsibility.  The internet is full of all kinds of starting points to think about but it can't decide for you no matter how many posts are posted.

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43 minutes ago, NewZed said:

Most of the discussion about the spindle pin and locking bolt is about why Nissan did things that way.  And, as often mentioned, just because something didn't fail doesn't mean it's better.

I'm not sure anyone is trying to say a 5/8th bolt is better but it certainly works just as well, it's simpler, will always be easier to remove and for what it's worth less expensive.

As much as possible the threaded portion should be kept to a minimum with the shoulder of the bolt extending almost the entire length of the shaft hole.

Considering how soft the steel is of the OEM pin a grade 5 bolt should be fine.

@gnosez, what grade of bolts are you using?

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I was responding more to gnosez's comment about "over-thinking".  He has a tone of superiority, but really he's just a guy who decided to use a bolt, apparently because it's easier and cheaper.  Nothing really superior about that.  It's just a choice.

 

The whole point of these forums is to generate things to think about, but the value of those things is opinion.

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For a friends street car that used the toe-link design and rod ends on the strut side I used a special capture washer on the outer side so if the ball in the rod end is to pop out the control arm still stays attached.  On the inner strut side I used a rod end spacer that's similar to a conical design.  The bolt was torqued to 125 ft-lbs (grade-8 torque spec) and a Stover nut was used.  I used the same setup for a number of race cars but used a nylock instead of the Stover to make it easier to work on at the track.

 

One thing I should point out is that I used a properly long 5/8 fine-thread bolt.  Meaning the rod ends were all supported by the non-threaded section of the bolt.  I had to find some really long bolts and cut off the extra threaded section.  I see a lot of the kits sold with bolts that have rod ends on the threaded sections, which shouldn't be done.

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Threaded 5/8 or 16mm bolts have been used for decades by SCCA and non-SCCA racers and track folks. I just sold a set of RCAs from an ex-SCCA car that was raced in the late 70s and 80s that had bolts installed back then. I didn't invent the use of a bolt and the first one I used came with the T3 rear control arms some 12 or more years ago. Since then I have replaced the bolts a few times and I have yet to hear of anyone reporting an issue with the use of said bolts. Once again, I understand why Datsun thought the locking pin was necessary I'm just saying my anecdotal experience with stock spindle pin bolts that have not loosened  on any of my Zs nor have I found any on the dozen or so RCA arms I have collected over the years.

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4 minutes ago, gnosez said:

Threaded 5/8 or 16mm bolts have been used for decades by SCCA and non-SCCA racers and track folks. I just sold a set of RCAs from an ex-SCCA car that was raced in the late 70s and 80s that had bolts installed back then. I didn't invent the use of a bolt and the first one I used came with the T3 rear control arms some 12 or more years ago. Since then I have replaced the bolts a few times and I have yet to hear of anyone reporting an issue with the use of said bolts. Once again, I understand why Datsun thought the locking pin was necessary I'm just saying my anecdotal experience with stock spindle pin bolts that have not loosened  on any of my Zs nor have I found any on the dozen or so RCA arms I have collected over the years.

 

 

What did you use for a nut (nylock, lock washer, metal locking, double nut,etc), and what did you torque to?

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The bolt SHOULD NOT be pivoting. It should be stationary, with the bushings or bearings moving independently of the bolt. If the bolt is spinning in the housing, it's going to wear the bolt. If you're using poly bushings, refer to the video I posted earlier, which shows the sleeves being captured and the poly rotating around the sleeve. If you're using rod ends, the monoball is captured and the rod ends do the pivoting.

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The control arm will be moving in relation to the hub casting as the suspension moves.  The bolt and nut will be clamping the "ears" of the arms against the hub surfaces.  Regardless of whether the arm ears deflect enough to make the surfaces contact my point is that the bolt is an axle, or think of it as two separate axles, one on each end.  There is rotation around each of those axles.

 

Again, over-thinking, but that's part of the point of a forum.  To be clear though, I think that gnosez is talking about the simple act of replacing the spindle pin with a 5/8" bolt, no mono-balls or rod ends.  You might be talking about a different application.

 

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The spindle-pin bolt doesn't rotate.  If it does then you have bigger problems.  In a stock car the inner bushing tubes are all compressed by the spindle pin nut against the strut.  The rotation comes from the rubber actually winding like a torsion spring.  That's why it's typically stated in the manuals that you need to torque at ride height or off jack stands.  As Jon mentions with poly the inner bushing tube is locked in place and the poly slides around the inner bush tube.  A rod end setup works exactly the same.

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That is incorrect.

The bushing has an inner sleeve which slides over the spindle pin. When you tighten down the nut on the end of the pin, it locks the sleeve in place, and the rubber distorts to allow for the motion of the arm. This is why you should tighten all of your bolts and nuts with the weight of the car on the ground when using rubber. You want the bushing not to be deflected at ride height, so that it can move equally easily and equally far in either direction. If you were to tighten the nuts on the spindle pins with the car in the air, then the rubber would deflect quite a bit just to get to ride height, since the bushing and the sleeve does NOT rotate on the spindle pin. The arm is separated from the spindle by the bushing, that is its purpose.

As it happens I recently did battle (and lost) with probably my 10th set of spindle pins. This one broke my BIL's puller, it was a real bummer. Anyway, I still have the ends of the control arms that I hacked off with the rubber bushings in situ. You can see that the sleeve in the middle of the bushing protrudes out from the arm. When you tighten the spindle pin nuts, this locks the sleeve in the middle of the bushing in place against the strut housing.

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You guys are right about the stock parts.  Crushing the control arm ears would not happen.  With those parts it's just the simpel safety factor of breaking the bolt and having it slide out.

 

I'm still a fan of thinking things through to the extent that a person can.  It's more than just "throw out the spindle pin and slap a 5/8" bolt in there instead".  With the PU bushings that most people install when they remove their spindle pin the control arm ends slide forward and backward on the bushing.  Does the nut and bolt need a proper sized washer to support the bushing or control arm surface?  What size should it be?  Worth thinking about.  Most of the PU bushings are too thick to fit in the gap.  Should they be trimmed or should the control arms be spread to squeeze it in there?  Why didn't the PU guys get the PU part right, so that it fits?  Is the sleeve that they supply right?  

 

The first guy's post was about the InvincibleExtremes setup.  Might be far from the crusty old stock Nissan bonded rubber parts.  You'd really have to see the parts to know if the Nissan design is being followed.  There's an assumption that he does do but so far it doesn't look like anyone has actually got theirs together yet.

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