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Old 03-18-2010, 12:42 AM   #78
OYMC
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Join Date: Jun 2009
Posts: 269
Custom 1987 GMC Crew Cab Short Bed

The remedy...

After taking a number of measurements I discovered that the rear axle center line was between 5 3/4" - 6" to far forward, and needed to be brought back.

After unbolting the rear leaf spring shackle hanger I found that the difference in measure between the two vertical sets of mounting holes was very close to the distance I needed to move the axle back. In order to insure that the suspension would remain square to the chassis I decided to reuse the two rear mounting holes on the chassis to the two front mounting holes on the shackle hanger.

As for the front leaf spring hangers I discovered that the distance between the two lower chassis mount holes where 6 1/4" apart. I thought to myself how much I would be able to tell having the axle center line back 1/4" from exact wheel well center? After determining that I more than likely will not notice any real difference in 1/4" I went for it.

I scribed a line over the top of the two lower chassis mounting holes for the front leaf spring hanger all the way back until I ran the scribe off the end of the chassis. Once I reattached the front lower leaf spring hanger mounting hole to the rear mounting hole on the chassis, I adjusted the angle of the hanger until the top of the lower rear hanger mounting hole was in line with my scribe line. At that point I tightened the bolt down so the hanger would not move out of adjustment. I drilled out the two top chassis mounting holes through the existing hanger mounting holes, and then drilled a new mounting hole through both hanger and chassis about 3" above the existing rear lower hanger mounting hole. *Note the two bottom holes on the hanger bolt to a separate bracket, and not the chassis.

The lower bracket required a little fabrication to be reused. After I had fully assembled the front leaf spring hangers to the chassis, I attached the lower bracket to the hanger.

Because I moved the hangers back 6 1/4" the angle of the chassis has changed (Chassis kickup), and the lower bracket no longer fits the way it should.

While the lower bracket was attached to the hanger I could build a wedge into the bracket that would fill the gap between the chassis and bracket. I used construction paper to make my templates, and then cut out the final pieces from 1/4" flat stock. After welding everything up, I test fit my new bracket(s), and everything looked, and should work great!

Other parts I moved: Shock mounts, brake line bracket, bump stops (Yet to be installed), and the parking brake cable guide bracket.

All in all I am very happy with the way it all turned out.

Tomorrow I will be installing the gas tanks, and bump stops. If I have time I will refit the bed to see how it all looks.

Oh yeah...I didn't paint the brake shoe backing plates because I have plans to convert to discs.
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