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Old 01-11-2017, 09:01 PM   #1
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Join Date: Feb 2010
Member Number: 1612
Posts: 17
Default Rough Country rear spring shims

When y'all do an install using the Rough Country 4" springs, what do you do with the shims on the rear springs that are attached? I think my rear springs might be backwards because the fat end of the shims face the rear of my 78 traveler (SUA). Reading the Rough Country FAQ they say that the shim should be installed fat end facing the front of the truck in a SUA situation. I haven't noticed any vibrations or shaking so maybe I should just leave well enough alone? Wanted to see if y'all had any suggestions.
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Old 01-12-2017, 07:17 AM   #2
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Join Date: May 2012
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Location: Fremont
Posts: 446
Default Re: Rough Country rear spring shims

On the rear, there are no caster issues, so the thick part of the shims usually go in the front to tilt the differential yoke up towards the floor of the truck to reduce the drive shaft angle. The center pin is not centered on the rear springs, the long end goes to the rear. Measure from the center pin to the spring eyes.either the springs are installed backwards, or the shim is facing the wrong way on the springs. If the kit includes longer shackles, they will tilt the rear differential up, which can cause problems with a standard two u-joint driveshaft. In that case the shims are better left installed with the fat part to the rear, to tilt the differential yoke back down to where it was before the longer shackles were installed. You basically want to keep the angles of the transfer cases rear output shaft, and the differentials pinion shaft parallel within a degree or so. I speak from experience here.
1975 Scout II healthy 258, Wide T19 , 4:1 D300 3:54s,
1972 Real clean stock Scout II P/S, P/B, 345, T18, 3:73s
1969 Mach I. Balanced ported 351W, 650 double pumper, Super T10, Detroit locker with 4.11s. Lowered with racing springs, bars, Konis etc.
(Don't worry about getting arrested when I drive the Scouts).

Last edited by Hondo; 07-25-2017 at 10:39 AM..
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