Spring shackle Alignment Question

[Catfish-65]

I,m having the springs on my 65 Polara re-arched and would like an opinion on locating rear shackles, should they when under load just ahead of the shackle perch center, right below center or just behind center. this answer will help to achieve the center to center measurement on the bushing centers on the finished sping,,, Any input would be appreciated,, Thanks in advance.. Catfish 65,, (Dave)

 

[mr. fix it]

I may be wrong Catfish but shouldn't the rear shackle pin be slightly pivoting to the rear when it is on it's wheels with no load in the trunk or rear seat?

My were & still are nearly a vertical plumb point which gives the car a higher rear stance than stock.

The clip above is for the 65 Chrysler FSM.
Unfortunately the 65/66 Polara FSM doesn't show a picture.

 

[mr. fix it]

In any case be careful not to have them arched too much as they will be a bear to install and change the ride height quite a bit in the rear putting extra weight up front.

You may find that you need to increase the front ride height when all is said & done which in turn could mean its' alignment time.

 

[Davea Lux]

You want a slight pivot to the rear so that the shackle can move freely to the rear as the spring is compressed under load. That will improve ride quality and help keep the rear spring bushings from getting pounded out on rough roads.

Dave

 

[Catfish-65]

Thanks to all ,, just what I wanted Dave

 

[James Romano]

I bought new springs... But a good measurement if you want a little "*** up" for larger rear tires and the classic hot rod look is 1". Don't go over that. It's too high. 1" and use gas shocks... Never air shocks.

I got my rake with wheel size, spring arch and gas shocks. If this is that you want. If you want stock look. Don't bend over stock height.

A lot of guys use shackle extenders and air shocks. Very dangerous.