Tuesday, February 18, 2020

New Rear Leaf Springs

In February of 2015, I installed a set of Grab-A-Trak leaf springs on the Mustang.  They are 4.5 leaf springs with a mid-eye which are advertised by Grab-A-Trak to be between 1 and 1.25".  I neglected to measure before installing the springs originally but the installed ride height was 25" afterwards.

My guess at the time was that the rear of the car dropped between .75" and 1" from installing the springs.  I expected less as I thought the stock rear springs were already sagging considerably.  It was only after installing the springs that I began to experience problems with the tires rubbing the quarter panel.

In March of 2015, I installed a set of Scott Drake extended shackles.  My understanding was they would increase the height some and I thought it could stop the rubbing.  These raised the height of the rear about 3/4" which settled out to a final ride height after driving around a while to 25 5/8".  However, it did not stop the rubbing on the tires on the quarter panel. 

I just ordered a set of 4.5 leaf, standard eye Grab-A-Track leaf springs in January.  They have been on back order so I called to find they did not expect to get any in for a few months!  They offered me the 5 leaf, standard eye spring as they had them in stock so I had them sent out.  I'm a little worried about the 5 leaf being too stiff (195 lbs vs 175 lbs) but I'll give them a try.  

If I installed the new standard height springs with the extended shackle, I imagine it would raise everything about 1" or so to 26 5/8".  However, I plan to go back to the standard height shackle which should drop the rear 5.8" and put me at 26".  This is essentially a 1/2" increase in rear ride height.  If this works, I think it would be about perfect.

The plan afterwards is to buy new springs for the front to match the ride height of the rear.  I'll buy another set of 428 lb coil springs and but a little off to perfect the height.  I just want to get the rear height right first and then I will work on the front. 

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