Hello, I'm working on a 1947 pontiac sled. I've been lowering it with blocks, but recently I removed the shackles which are about 5 inches long. In order to lower the car more I was thinking about making my own shackles at 3 inches long made of 3/8 inch spring steel. Does anyone know of negative impacts of shortening the shackles?
As long as you keep the shackle angle the same number of degrees from 90, it should work OK. You may loose a little spring travel, but I suspect you already lost that with the blocks. I'd really like to see pictures of the current shackle setup to be sure. The shackles were probably not spring steel, if they were one piece "C" shaped, they may be cast or forged. If they were two straps with a through bolt on both ends they were probably mild steel. Gene
Gene, It's a two piece shackle with a center bolt. The bend in one shackle tells me that it is a mild steel too.
I shorten the rear shackles on my AD by taking off the stock shackles and drilled new holes at one end of the shackles. I then removed the stock hole I didn't need with a cut-off wheel and reassembled the shackles.
this will probly work fine, but remember; removing 2 inches from the shackle will only lower the rear axle about 1 inch, but every inch helps.
True, very true. In addition to the modified shackles, I have 5 inch drop springs with 2 leafs removed and 1.5 inch O.G. cast iron lowering blocks. Imagine, all that just to get the rear to where I wanted it to be.
I know what you mean....I have 3" dropped springs, removed 2 leafs & added 1" blocks......any more & I may need a notch.
Skip fucking with the shackles the net gain is not worth the effort. Relocate the springs to the inside sides of the frame instead of the stock location for an additional 3inches. If the pontiace has the frame that's upside down"hat" with a plate spot welded to the bottom you will need to clearance the flange at that part of the frame. Near the perches . Been done a million times. You can cheat your pinion angle a little when you relocate the pads on the rear-end to compensate for the blocks as well
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