U Bolt Torque Thread (Rusty Calling You)

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How tight is that center pin set at Ed in ft/lbs and what size bolt is that? Give me an accurate reference.
 
thanks 67, thats the kind of stuff i was waiting to hear. I see the words like bind and clamp to describe the force of the u bolts on the leaves.
 
Good God Almighty. Ed, if nothin else, I give you credit for a hard head.

Read the Mopar suspension manual. IT'S IN THE BOOK. There IS movement between the spring plates. The front and rear segments MOVE INDEPENDENTALY of each other. That discounts the center bolt altogether in the argument. The book even talks about the DIFFERENT RATES that the front and rear segments move. Sorry if you caint get your head around it, Ed. The deck of cards is a PERFECT EXAMPLE. It matters not that the center bolt is there, since the front and rear segments flex AT DIFFERENT RATES. This is how all leaf spring suspensions work. You tighten the spring plates too much and it makes them bind. They have to be able to slip. I don't even understand why there's an argument. Since the front and rear segments move at different rates, it's almost the same as having NO center bolt at all. One more time. READ THE MOPAR SUSPENSION MANUAL. IT'S IN THE BOOK..

READ THE BOOK. READ THE BOOK. READ THE BOOK.
 
805moparkid said:
thanks 67, thats the kind of stuff i was waiting to hear. I see the words like bind and clamp to describe the force of the u bolts on the leaves.
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RIGHT! You want to hear the kinda stuff that agrees with your point, when YOU'RE WRONG.

I've done my best on this. It's like talkin to a brick wall X 10.
 
Bad Sport said:
According to my Mopar Performance 9th edition, it clearly states NOT to over tighten the U bolts. It can cause spring friction. Where does friction come from?

Hint: movement
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Yeah and it gets pretty specific about the different rates between front and rear segments.

I don't understand. I'm befuddled why there's still an argument.
 
805 you fooling around with thos S/S cars should know this stuff.take one of them to the track and just for ***** and giggles try a pass tightening them up up with the air wrench to god knows what..then make another pass tightened to species...and look at your 60 ft. times I think you will find it will take that rear end from dipping up and down like I seen on that one car I seen you all testing....I believe you will be having the wheels higher than they do....Artie=D>
 
RustyRatRod said:
Yeah and it gets pretty specific about the different rates between front and rear segments.

I don't understand. I'm befuddled why there's still an argument.
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We're not talking about movement IN FRONT or TO THE REAR of the U bolts, we are talking about movement WITHIN the U bolt clamping area. I am not quoting some kid who posted on twitter or facebook. I'm quoting companies that are in, and have been, in the business of building suspension parts in some cases longer than I've been alive

http://www.google.com/url?sa=t&rct=...L6D9o3QDHnUD-_gog&sig2=eNC1TmcauCtByKHgsrf1vg
 

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Then we are talking about two different things.

I was under the impression we were discussing how leaf spring U bolt torque effects leaf spring function. My apologies. I'll leave it to the experts.

67Dart273 said:
We're not talking about movement IN FRONT or TO THE REAR of the U bolts, we are talking about movement WITHIN the U bolt clamping area. I am not quoting some kid who posted on twitter or facebook. I'm quoting companies that are in, and have been, in the business of building suspension parts in some cases longer than I've been alive

http://www.google.com/url?sa=t&rct=...L6D9o3QDHnUD-_gog&sig2=eNC1TmcauCtByKHgsrf1vg
Click to expand...
 
PanGasket said:
with the U-bolts torqued down that much, it doesn't allow the leafs to move freely as much. That's pretty obvious stuff right there. When the leafs are at proper torque spec, it allows proper interleaf friction which creates a damping affect. By overtorquing, you are taking away the leafs abilities to slide around as much and create friction against each other to create a proper damping affect, you are now creating(more of) a completely different animal called stiction, or static friction/static cohesion. This is caused when two objects are pressed against each other, not sliding or traditional friction causes. This requires more force force parallel to the surface of contact in order to overcome static cohesion.
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I can't find the cohesion setting on my impact. :banghead: lol
 
So, if the leaf spring pack doesn't move within the area of the u-bolts, what does it matter if you over-torque the bolts? As long as the housing isn't crushed and the bolts don't over-stretch?

I don't get how over-torqueing the bolts would cause the leafs to bind. The ends are still free.
 
RustyRatRod said:
... One more time. READ THE MOPAR SUSPENSION MANUAL. IT'S IN THE BOOK..

READ THE BOOK. READ THE BOOK. READ THE BOOK.
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Have to agree on this one. Being an Engineer, a lot of thought, theoretical and practicle, goes into a torque value. What you are bolting together, what is in between, what deformation you get when the forces are applied. You want to disregard it, you are on your own. Good Luck. Maybe you are smarter than a group of Engineers, let alone the guys who could put a car together and wade through a sea of Chevys and come out on top. As Rob said, and what we always said "RTFM". Read the F'n Manual.
 
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