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Broken Leaf Spring Center Pins


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Was under the truck re-torquing my MT spring u-bolts, and reached up and could freely spin the center pins in each spring. Obviously the center pins are snapped inside. There has been no movement of the individual leafs; all are lined up are can not move up/down or left/right because the u-bolts hold them tight. No worries with the broken center pins, right?

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Good plan Alex. IIRC the existing pins are 5/16". Would like to replace them with larger pins, at least 3/8". How hard is it to drill through the individual spring steel leafs? Never did this before.........

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Unless you really want to spend your day with a drill, why not take the leaf packs to a machine shop? They probably wouldn't charge a whole lot and you would have more time to clean that filthy truck of yours. :bowdown:

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Appreciate the suggestion Remi.  :cheers:  But since I'm a very lazy bastid and like to do things the easy way whenever possible, it's makes sense to run it over to our small Chevy dealership in town after hours, use their body lift to drop the rear end, disco the ubolts, jack the axle up on stands and do the dirty deed with the leaf packs still connected. Might have to spring for a couple of cases of Miller HL though, but that's cool. 

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Appreciate the suggestion Remi.  :cheers:  But since I'm a very lazy bastid and like to do things the easy way whenever possible, it's makes sense to run it over to our small Chevy dealership in town after hours, use their body lift to drop the rear end, disco the ubolts, jack the axle up on stands and do the dirty deed with the leaf packs still connected. Might have to spring for a couple of cases of Miller HL though, but that's cool.

So that is your secret, you have access to a vehicle lift and a shop. :P
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So that is your secret, you have access to a vehicle lift and a shop. :P

So much for that idea. No more after hours working there - new insurance rules.  :cry: 

Are you sure your pins are 5/16"? XJs had 5/16" center pins. My recollection is that MJ factory springs used 3/8".

Almost positive Eagle. And my MT springs are aftermarket.

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I tried to drill thru 1 (one) new leaf spring.  I was told I needed a carbide tip bit...not.   Called a couple machine shops...no go.   

 

I got about half way thru  before the carbide tip was useless.

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Now that you mention it, I recall a few years ago discussing this with the owner of a commercial spring shop where my friend used to have his stock car springs made. They don't drill springs for the center pins -- they punch them.

 

The more I think about it, Don, the more I think you should just replace with whatever size is in there and keep the u-bolts torqued.

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Yep, the more I think about it the more I think that's the way to do it. That means dropping the rear spring perches, jacking up the axle, the disassembly of the leaf pack to get the pin holes lined up. Maybe I can loosely C-clamp the springs and drive a tapered drift pin up through the leafs to align the holes. Would be easier to just replace the packs, but my MT leaf packs are fine. I'll figure something out. What I'm curious about is why the dayem pins broke in the first place. :hmm:

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Go to Lowe's or Home Despot and buy a short length of 5/16" plain steel rod. The shortest they sell is probably 8" or 12". 8" might work, 12" I would cut in half.

 

Take it to your bench grinder (you DO have a bench grinder, right? If not, turn in your man card no later than Thursday at 1200 hours) and grind about a 60 degree taper on the end. Use that as your drive pin. A tapered punch will be too fat and will stop before all the holes are lined up. This thing-a-ma-bob will self-align the holes as the taper passes through, and the straight body enters the spring pack.

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It turns out they are not broken at all. The pins are turning because the nuts on the bottom have backed off and they are loose. Of course I can't get at the pin top to hold it w/o moving the axle up. I think if I loosen the ubolts one side at a time and let the springs expand a little it might create enough tension on the pins so I can tighten the nuts back up. If not I'll have to raise the axle up. Probably do that anyhow since I have to remove the 3* shims that I don't need there.

 

Note to myself: Next time you install new leaf springs TIGHTEN UP THE CENTER PINS BEFORE INSTALLING! Feel like a dumbazz..

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It turns out they are not broken at all. The pins are turning because the nuts on the bottom have backed off and they are loose. Of course I can't get at the pin top to hold it w/o moving the axle up. I think if I loosen the ubolts one side at a time and let the springs expand a little it might create enough tension on the pins so I can tighten the nuts back up. If not I'll have to raise the axle up. Probably do that anyhow since I have to remove the 3* shims that I don't need there.

 

Note to myself: Next time you install new leaf springs TIGHTEN UP THE CENTER PINS BEFORE INSTALLING! Feel like a dumbazz..

Doing one side at a time place a jack stand under the spring and rest the weight of the vehicle on it. Remove the tire on that side. Loosen the u-bolts and jack the axle up enough to get access to the pin head.

 

The other option is to use a 2x4 or 4x4 with a bottle jack on its side between the springs to press the them outwards to apply pressure on those pins.

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