Sheared Leaf Spring Pins (1 Viewer)

[srgould41]

I am getting tired of sheared leaf spring center pins. Had one fail on the trail yesterday and the leaf pack fell apart.

Suggestions? Larger diameter bolts? One guy I was wheeling with said he welded stops on the upper spring on each side of the axle perch on his old truck. I would think that would destroy the spring temper.

Thanks

 

[jstncse]

Sounds like the Ubolts are not tight enough. I have only sheared one center pin before and that was the case with it.
Are you are racing or running pretty extreme trails with a heavy foot?

I wouldn't weld anything to the spring pack.

 

[srgould41]

I hate the idea of welding on the top spring too. That would be a last resort type of fix. I know I have sheared at least 4 pins in the past 4 years. Thinking back, it may have only been the front packs. Our local trails are tight, muddy, full of boulders and tree roots. The front tires take lots of heavy impacts. This was the first time the bolt actually departed the spring pack and let the castor shim fall out. As for u-bolt nut torque, if anything I over tighten them.

Sounds like the Ubolts are not tight enough. I have only sheared one center pin before and that was the case with it.
Are you are racing or running pretty extreme trails with a heavy foot?

I wouldn't weld anything to the spring pack.

 

[jstncse]

Caster shims are the cause. Long term solution would be a cut and turn, but welding the shims to the axle may help.

 

[JackA]

Back when my buggy had leaf springs up front, I had issues with breaking center pins. I upgraded them to an ARP bolts and never busted one again.

 

[srgould41]

I may look at ARP's or drill for larger diameter center bolts. I think jstncse has it right on the shims being part of the problem. Since they angle back when ever I hit an obstacle the tire will push rearwards which would want to push the axle away from the shim helping it loosen up. I am happy with my current springs so maybe re-welding the perches at the current castor angle might be a long term solution.

Back when my buggy had leaf springs up front, I had issues with breaking center pins. I upgraded them to an ARP bolts and never busted one again.

 

[jstncse]

I may look at ARP's or drill for larger diameter center bolts. I think jstncse has it right on the shims being part of the problem. Since they angle back when ever I hit an obstacle the tire will push rearwards which would want to push the axle away from the shim helping it loosen up. I am happy with my current springs so maybe re-welding the perches at the current castor angle might be a long term solution.

You are correct. The shims only have to move very little before the ubolts are loose. If you can change your perches then that would be ideal.

 

[Tapage]

any link to those ARP center pins .?

 

[GLTHFJ60]

@srgould41, are you using aluminum or steel shims? If the shims are long enough for the whole perch, and are steel, you should never have them loosen up, assuming you are using the correct center pin (deep enough head). This is also assuming that the correct initial u-bolt torque was set and the u-bolts were re-torqued after a week or so of road driving, or one wheeling trip.

No need for fancy ARP center pins. Get some grade 3/8" hex cap bolts and run them through the springs with nylock nuts. They'll never come loose and you can replace them at any decent hardware store if need be.

If your specific hex cap bolts have a head, or bolt, that's too big for the perch or u-bolt plate, drill it out a hair and never worry about them again.

 

[JackA]

They are not ARP center pins. They are just ARP bolts of the correct size to replace the center pins. They don't cost a whole lot either.

 

[Tapage]

part number .?

 

[srgould41]

The shims were steel. I have been using grade 8 bolts run up with nylon lock nuts on top of steel sleeves to make them long enough to go through the shim and axle plate. I will note that I have had the springs replaced/off/apart several times on the same u-bolts. I am going to replace the whole set plus keep a couple of the old ones for trail spares.

I have been reading the debate on grade 5 versus grade 8. 8 has a higher shear, but 5 is said to bend a little without shearing which is supposed to make for a better center pin. Makes for a good debate, but hard to verify.

I'm not sure what diameter the current pins are. I need to yank the good right side apart and check. There is a local spring shop where I can buy all the parts. I'll give them a call on Monday for prices. I hope their shims are mild steel and not cast so I can weld them to the axles. I might use some true center pins if they have them with long enough heads and keep some spares for the trail.

@srgould41, are you using aluminum or steel shims? If the shims are long enough for the whole perch, and are steel, you should never have them loosen up, assuming you are using the correct center pin (deep enough head). This is also assuming that the correct initial u-bolt torque was set and the u-bolts were re-torqued after a week or so of road driving, or one wheeling trip.

No need for fancy ARP center pins. Get some grade 3/8" hex cap bolts and run them through the springs with nylock nuts. They'll never come loose and you can replace them at any decent hardware store if need be.

If your specific hex cap bolts have a head, or bolt, that's too big for the perch or u-bolt plate, drill it out a hair and never worry about them again.

 

[srgould41]

Picked up parts from a spring shop. New u-bolts, machined steel shims and 3/8" center pins. I welded the shims to the axle perches. Before welding I opened the holes to accept a 3/8" pin with steel sleeves. It's a tight fit so no movement from slop. Should help, especially since I am in straight shear now with the shims being welded. After talking to the owner of the spring shop I'm not sure I'll use the center pins. He said they are not graded steel. I don't want to go back in with soft steel and shear the bolts again. Found some grade 5's the right length, but can't seem to find grade 8's in the correct length at the local hardware stores. Figures.

Lots of debates on the Internet between using grade 5 and grade 8 with 5 being preferred because it will bend a little before shearing. However, I suspect that is mostly conjecture. Going with the grade 5's for now with trail spares. If I shear one I'll hunt down the grade 8's.

5/16" grade 8 shear is 6980 (what I was using before)
3/8" grade 5 shear is 8250
3/8" grade 8 shear is 10050
3/8" ARP shear is 10490

Not enough strength increase to warrant the expensive ARP's.

P.S. the spring pin holes in my OME Dakars was just a hair under 3/8". Piece of cake to open them up using a cobalt drill bit, oil and a drill press on slow speed.

The shims were steel. I have been using grade 8 bolts run up with nylon lock nuts on top of steel sleeves to make them long enough to go through the shim and axle plate. I will note that I have had the springs replaced/off/apart several times on the same u-bolts. I am going to replace the whole set plus keep a couple of the old ones for trail spares.

I have been reading the debate on grade 5 versus grade 8. 8 has a higher shear, but 5 is said to bend a little without shearing which is supposed to make for a better center pin. Makes for a good debate, but hard to verify.

I'm not sure what diameter the current pins are. I need to yank the good right side apart and check. There is a local spring shop where I can buy all the parts. I'll give them a call on Monday for prices. I hope their shims are mild steel and not cast so I can weld them to the axles. I might use some true center pins if they have them with long enough heads and keep some spares for the trail.