Pivot shaft problems

-
Demonic said:
The aftermarket pivot shaft nuts are sometimes locknuts - either nylon insert of slightly deformed on the end.
Click to expand...

I don't have aftermarket pivot shafts, just 2 sets of stock pivot shafts with stock nuts.

@72bluNblu I've seen your posts about tightening them without them being loaded by suspension and have actually tightened most of the suspension components except for the LCA's (due to this problem). You said you use an impact- do you use an air or electric impact? I have both but the strength of them is totally different, or does it not matter.
 
Oldmanmopar said:
This is what I have been telling all of you about the poly bushings being junk. Look at the picture and swallow your words. " no They can't move back the struts hold them in" LMFAO Lube it up a little more with a pin with a grease fitting. It may walk front and back a little easier and not squeak.
Click to expand...

Swallow my words?... I don't think I clamined 1 is better than the other. I got what I got, what had good reviews/was recommended. I also had stock bushings but those look to be a pain in the *** to replace from reading old threads lol.

Maybe I'll have to add greasable pivot shafts and adj strut rods to the never ending list of more parts I should get haha!
 
DentalDart said:
I don't have aftermarket pivot shafts, just 2 sets of stock pivot shafts with stock nuts.

@72bluNblu I've seen your posts about tightening them without them being loaded by suspension and have actually tightened most of the suspension components except for the LCA's (due to this problem). You said you use an impact- do you use an air or electric impact? I have both but the strength of them is totally different, or does it not matter.
Click to expand...

I always use greaseable pivot shafts, but I have not used the polygraphite bushings that PST sells, just regular poly. I know that the polygraphite is supposed to be self lubricating, so in theory it should not require greaseable pivots. But as I haven’t personally used them myself, I don’t know if they’re truly 100% self lubricating in actual practice, and if that holds up for their entire life.

I use an electric impact, and it’s a 3/8” drive not a 1/2” so it isn’t a massive amount of torque. I don’t use it to final torque the pivots, I use it to spin the pivot nuts fast enough that they grab and exert pressure on the pivot before the pivot spins. Here’s the other thing, you don’t have to be that careful with the torque. The greaseable pivots I use spec a 100 ft-lb final torque on pivot nuts. That’s A LOT. I forget that exact spec in for the stock pivots, but it’s 75 or 90 ft lbs. As in, you need a long handled 1/2” drive torque wrench and some muscle to get to that. It’s not easy. So I wouldn’t worry about using the impact, you’re very unlikely to over torque those pivot nuts.

Also, as pointed out already those nuts are usually lock nuts of some kind. The factory version are usually the type that have an eccentric lock thread, so they don’t thread on smoothly. Once you get more than a few threads on you’ll hit the “lock” threads and it will take effort. Which will spin the pivots if you have poly bushings. Hence the impact to spin the nut fast enough to override the tendency of the pivot to spin.

The factory procedure of torquing them at ride height is for the factory style rubber bushings. The factory rubber bushings are friction fit to the inner and outer shells, meaning, nothing spins. So the entire suspension travel comes out of the flex in the rubber bushings. So they have to be torqued in the middle of the range of travel of the suspension, half the travel is flex up, half the travel is flex down. The rubber doesn’t have enough flex to cover the whole travel. Which means if you tighten the pivots with the suspension hanging, the rubber tears after it gets a bit more than halfway through the travel. It will usually flex enough to sit down to ride height, but the next big suspension compression tears the bushings.

With poly bushings the bushing can spin in the outer shell or on the pivot. The travel is not dependent on the poly flexing, because it doesn’t flex much at all. So instead the suspension travel spins the LCA on the bushing or the bushing on the pivot. That’s why lubrication is important for poly bushings, and also why it doesn’t matter where you torque them. If the poly bushing isn’t lubricated, heat builds up from the friction of the bushing spinning on the pivot or in the shell. That’s why they squeak and deteriorate if not lubricated. Nothing spins in the OE rubber bushings, which is why those don’t need to be lubricated. So if your poly bushing starts squeaking, it means it needs more lubricant.

Which is why the people that complain about their poly bushings squeaking are also the same people that complain about them failing. All it means is they don’t know how to properly maintain a poly bushing. If someone told you a certain brand of oil turns to sludge after 20k miles you’d blame them for not changing their oil, not the oil for turning to sludge right? Same deal with poly bushings. They aren’t rubber, they don’t get maintained the same way.
 
72bluNblu said:
I always use greaseable pivot shafts, but I have not used the polygraphite bushings that PST sells, just regular poly. I know that the polygraphite is supposed to be self lubricating, so in theory it should not require greaseable pivots. But as I haven’t personally used them myself, I don’t know if they’re truly 100% self lubricating in actual practice, and if that holds up for their entire life.

I use an electric impact, and it’s a 3/8” drive not a 1/2” so it isn’t a massive amount of torque. I don’t use it to final torque the pivots, I use it to spin the pivot nuts fast enough that they grab and exert pressure on the pivot before the pivot spins. Here’s the other thing, you don’t have to be that careful with the torque. The greaseable pivots I use spec a 100 ft-lb final torque on pivot nuts. That’s A LOT. I forget that exact spec in for the stock pivots, but it’s 75 or 90 ft lbs. As in, you need a long handled 1/2” drive torque wrench and some muscle to get to that. It’s not easy. So I wouldn’t worry about using the impact, you’re very unlikely to over torque those pivot nuts.

Also, as pointed out already those nuts are usually lock nuts of some kind. The factory version are usually the type that have an eccentric lock thread, so they don’t thread on smoothly. Once you get more than a few threads on you’ll hit the “lock” threads and it will take effort. Which will spin the pivots if you have poly bushings. Hence the impact to spin the nut fast enough to override the tendency of the pivot to spin.

The factory procedure of torquing them at ride height is for the factory style rubber bushings. The factory rubber bushings are friction fit to the inner and outer shells, meaning, nothing spins. So the entire suspension travel comes out of the flex in the rubber bushings. So they have to be torqued in the middle of the range of travel of the suspension, half the travel is flex up, half the travel is flex down. The rubber doesn’t have enough flex to cover the whole travel. Which means if you tighten the pivots with the suspension hanging, the rubber tears after it gets a bit more than halfway through the travel. It will usually flex enough to sit down to ride height, but the next big suspension compression tears the bushings.

With poly bushings the bushing can spin in the outer shell or on the pivot. The travel is not dependent on the poly flexing, because it doesn’t flex much at all. So instead the suspension travel spins the LCA on the bushing or the bushing on the pivot. That’s why lubrication is important for poly bushings, and also why it doesn’t matter where you torque them. If the poly bushing isn’t lubricated, heat builds up from the friction of the bushing spinning on the pivot or in the shell. That’s why they squeak and deteriorate if not lubricated. Nothing spins in the OE rubber bushings, which is why those don’t need to be lubricated. So if your poly bushing starts squeaking, it means it needs more lubricant.

Which is why the people that complain about their poly bushings squeaking are also the same people that complain about them failing. All it means is they don’t know how to properly maintain a poly bushing. If someone told you a certain brand of oil turns to sludge after 20k miles you’d blame them for not changing their oil, not the oil for turning to sludge right? Same deal with poly bushings. They aren’t rubber, they don’t get maintained the same way.
Click to expand...

Has anyone ever told you that you are like a walking talking mopar suspension, brake, engine etc etc encyclopedia. You're like the FSM in human form!

Here we are currently. Nut off, torsion bar installed, strut rod installed, pivot shaft pressed into bushing and as far into the lca as I can get it by hand (had to use hold down straps and ratchet it as much as I could to get it to slide into the lca).

The picture shows the nut on the pivot shaft because i wanted to show as far as i could tighten it by hand.

Second pivot shaft picture with nut on it shows how far the impact gun was able to tighten it before it started spinning the shaft in the bushing, hooked the tie down back up, but cant get it any tighter than the 3rd picture of the nut at the moment.

I cleaned the inside of the nut with brake cleaner and a wire brush before trying to install it again.

My torsion bar adjuster is all the way out, should I put some load on the torsion bar and see if that helps lock the pivot shaft from moving a little and maybe it would be able to tighten on a little more?

20200214_172517.jpg


20200214_172614.jpg


20200214_174543.jpg


20200214_174551.jpg
 
I also redid my front suspension this winter...all with PST goodies including the greasable pivot shaft and poly bushings. I didn't install my torsion bars until after my pivot shaft nuts were tight and strut rods were in. 72blu was my go to on all install info from here.
Once my pivot nut started to get tight on the k frame the pivot pin pulled in tight to the pin housing and stopped spinning. I torqued it from there.
 
That's a self prevailing lock nut. It's "squished" on that outside to make the nut a "force fit" on the control arm pin so that it will not back off. That's what's causing the pin to spin and the nut not to tighten up, just like @mopowers up there ^^^^^ described. You must over come that by turning the nut faster than the pin and the only way to do that is with an impact gun. I much prefer air.

And yeah, I already told you about that @72bluNblu dork. He's a legend genius for sure. Great asset to the site.
 
those dots on the nuts show they're lock nuts

edit: i should refresh the page before i post :eek:
 
Yes I know they are lock nuts but I didnt have this problem with the last one :( I will try my air impact gun tomorrow, everything else is is on. Then just have to bleed some brakes, although I might try and install the prop valve slightly different.

20200214_184457.jpg


20200214_184514.jpg
 
Pain in the ***.

This nut is tight against the body but it's just keeps spinning the damn bushing out.

I got it all the way seated!

20200215_103907.jpg


20200215_103835.jpg
 
Hmmm.

You may have run out of threads. There should be a large, heavy duty washer on that pivot. Like, a washer that's almost a 1/8" thick. So it you may have bottomed out the nut on the threads before you put enough clamp force on the pivot to keep it from spinning. Which is bad for several reasons, but you won't be able to torque that to spec because you won't be able to stop the pivot from spinning like that. Sorry I didn't see that before, I don't think the washer that's on there is original now that I'm looking at it more closely.

The other thing you can try is using a heavy duty lock washer as well. Not for it's locking capabilities, but because as soon as you start compressing the lock washer it will put a longitudinal force on the pivot pin. Basically it will start pulling on the pivot which will help to keep it from spinning. The other thing is that those lock nuts are really only intended to be tightened a couple of times. So you may need another lock nut, the threads may be trashed at this point.

The ones that come with the Firm Feel greaseable pivot shafts are just nylock nuts. Again, these get torqued to a very high number, which makes the locking action of the nut an extra safety feature. Torqued to spec should be more than enough to keep even a regular nut from backing off.

Here's a picture of the washer and nut that comes with the QA1 LCA's. The stock one's aren't this thick, but you get the idea.
img_3921-jpg.jpg


Here's a shot of my car, you can see the nylock nut that's on there. But not the HD washer really. It's there, I promise.
img_4373-jpg.jpg


And thank you guys for the kind words. I still learn stuff about these cars all the time, but suspension and setting cars up for handling has always been one of my interests all the way back to when I was 16 and started driving my '56 Austin Healey that had been prepped for vintage racing. I definitely don't know everything and suspension tuning is one of those things that even very experienced people have different opinions about.
 
The large washer is on there, the same size one as the passenger side. I dont think this nut is coming off anytime soon!

I started picking up the garage, and I will bleed the brakes in a bit and see how she does, hopefully nothing blows up or falls off :rofl:
 
DentalDart said:
The large washer is on there, the same size one as the passenger side. I dont think this nut is coming off anytime soon!

I started picking up the garage, and I will bleed the brakes in a bit and see how she does, hopefully nothing blows up or falls off :rofl:
Click to expand...

Don't run that car on the street like that. Seriously, do not.

If the pivot is still spinning you haven't torqued it properly. The pivot SHOULD NOT SPIN during normal operations. If it does, it means the LCA can move around, and that is NOT what you want. You need to remove that nut and figure out what's going on.

If you want to know about the consequences, you can ask Oldmanmopar as he should know that one all too well. His car was totaled because he used UCA eccentrics that didn't have the flat cut far enough down the bolt. The washer bottomed on the flat without putting pressure on the UCA, which meant the UCA could move around. His car ended up wrapped around a pole at the drag strip because of it.

It's critical that your suspension functions as it was intended. The pivot has to be torqued that high for a reason, the factory did not want that pin moving around. If it does, not only will it mess with your alignment, but eventually it will hammer the pivot tube out of the K member.
 
72bluNblu said:
Don't run that car on the street like that. Seriously, do not.

If the pivot is still spinning you haven't torqued it properly. The pivot SHOULD NOT SPIN during normal operations. If it does, it means the LCA can move around, and that is NOT what you want. You need to remove that nut and figure out what's going on.

If you want to know about the consequences, you can ask Oldmanmopar as he should know that one all too well. His car was totaled because he used UCA eccentrics that didn't have the flat cut far enough down the bolt. The washer bottomed on the flat without putting pressure on the UCA, which meant the UCA could move around. His car ended up wrapped around a pole at the drag strip because of it.

It's critical that your suspension functions as it was intended. The pivot has to be torqued that high for a reason, the factory did not want that pin moving around. If it does, not only will it mess with your alignment, but eventually it will hammer the pivot tube out of the K member.
Click to expand...

It's not spinning anymore. I edited my first post from today and said I got it seated all the way.

The dang thing kept spinning, I had the strap attached then raised the lca a little with the jack and tapped the bushing/pin back into the lca and got it to tighten a little more with the air impact gun.
 
You must log in or register to reply here.
-

Back
Top