i meant i took the shims off the other ones and am trying to put them on the new springs.
the ones that are on the new BDS are not long enough to go through the shim,
would i put a nut on both sides of the bolt? bc at the bottom of the spring there is a nut, and above the spring the round part is bigger. so how would i keep the bolt tight?
Call around to the auto parts and ask for a 4" or 6" center bolt for your leaf springs. The BDS springs come with 5/16 center bolts. Now would be a great time to upgrade them. I drilled mine out to 3/8" but I have broke one already. I would go ahead and upgrade to 7/16" bolts. Drilling them out takes some time, but well worth the insurance. The new center bolts will be too long, so put them together and cut them off. Hope this helps.
just buy a grade 8 bolt of whatever lenth you need and make the head round with your grinder so it'll fit into the spring perch. no sense in making it harder than it has to be.
Like Erik said, go with a bolt. Center pins are made out of cheap metal... I don't know how many of them I've broken some way or another. Once you get your spring plate and u-bolts tightened down, it really doesn't matter.. but if you don't want it snapping when you're trying to do any other work to your springs, just go with a bolt.