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Was looking over the tech section on opening up the front of the rear wheelwell to provide more tire clearance, as I would like to increase the rear tire size to >28". Problem is my 69 GTS has the wheelwell molding and I want to keep them.

One mopar guy suggested redrilling the shock plate and moving the rearend back about 1.5" on the springs.

How will this affect the spring rate and what would it do to the launch 60' times?
Open for discussion.

Thanks,
Greg

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I did it on my 69.
I drilled the locating hole on the spring mount and the shock plate to about 1".
I gained about 1/2" more room. Im running a 28.5 tall drag radial thats right at about 9"
tread width. Works Great. 0/
Rick
 

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moving the rearend back 1 inch will allow a gain of 1 inch of clearence, equating to 2 inches of tire dia. as only 1/2 of the tire is between the housing and the panels edge.
 

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Just make a 1" thick aluminum spacer and install it between the front spring hanger and frame.
Simply knock out the hanger bracket studs use the hanger for a hole template and drill the spacer out, install suitable length new bolts and tig the heads to the hanger bracket....BINGO BANGO BOINGO !
 

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AAOUTLAW said:
Just make a 1" thick aluminum spacer and install it between the front spring hanger and frame.
Simply knock out the hanger bracket studs use the hanger for a hole template and drill the spacer out, install suitable length new bolts and tig the heads to the hanger bracket....BINGO BANGO BOINGO !
how does that effect the shackle angle?

Brian
 

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it increases the angle on the shackles...but it's to "the good " moving the shackles forward is a bad thing, if they "overcenter " they will tie up the spring. But the math escapes me right now. I think the shackles have around a 4" bolt center...i dunno...i would never use a suspension designed by Abe Lincoln for his lumber wagon..anyways...with a 4" bolt center the angle change would be somewhere's around about 15-20 degrees and there is enough room for that, i have done this before.
The rear shackles are similar to an idler arm on a steering linkage, they allow movement but just basically just sit there and pivot. The front spring eye bears most of the load.
 

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AAOUTLAW said:
it increases the angle on the shackles...but it's to "the good "  moving the shackles forward is a bad thing, if they "overcenter " they will tie up the spring.  But the math escapes me right now. I think the shackles have around a 4" bolt center...i dunno...i would never use a suspension designed by Abe Lincoln for his lumber wagon..anyways...with a 4" bolt center the angle change would be somewhere's around about 15-20 degrees and there is enough room for that, i have done this before.
The rear shackles are similar to an idler arm on a steering linkage, they allow movement but just basically just sit there and pivot. The front spring eye bears most of the load.
Cool, I was just curious how much angle it would put into the shackle. Thanks

Brian
 
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