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If your truck is 4WD why do you want to lower the rear? If not then no, nothing has to replace that block, just take it out make sure the rear leaf spring pin fits into the top of the base plate on the axle, re-tighten the u-bolts are you are done, that is my take on it. Not sure what you are trying to accomplish though. Edited by: GMC2500HD
 

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Discussion Starter #3
Yup a 4x4. Gonna drop it 6", get some pink neon lights and airbags! Coooool.


Hope you don't mind me giving you a hard time
. And thanks for responding. It's a daily driver, usually empty.


I'm experimenting a bit actually. I'm looking to use a zero rate airbag to unload the rear springs about 2", yet retain stock height in the end. Why? Lower leafspring rate when unloaded=less harshness with most of the empty weight on sleeved airbags (not super duty type). That's the THEORY anyway. The compliance between the front and back of a stock truck seems to be a bit mismatched. Looking for a better handling, less harsh ride by firming the front, easing the rear, and still be able to carry a load effectively when it's time, through the use of ride quality air suspension in parallel with the leafs.


Edited by: masterp2
 

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No rear blocks on a 2500HD/3500 series trucks.....only on 1500's.


8.1
 

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A longer shackle will tilt your pinion angle up some which can cause some vibrations. I have read about some guys removing the bottom overload and using the air bags for heavy loads which resulted in a smoother less choppy ride.
 

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That be a spring pad that is needed and is welded to the axle. I had a set of Belltech 3" lowering shackles. They lowered the rear 1.5". That is not enough to cause a vibration without the shim even though Belltech recommended them. The shackles are easy to install. The shims are another matter. Later! Frank
 

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Discussion Starter #9
I looked at the belltech. Don't 3" lowering shackles lower the truck 3"? Looks like options available for 1", 2" and 3".


Perhaps yours were the 1"??????


Shim? Pinion angle? Please educate me.





Michael
 

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Actually, on a tension shackle, a longer shackle will turn the pinion to the ground.


As for associated problems, drive shafts require proper phasing of the u-joints so that they cancel out accel/decel behaviors inherent in the design. For a dual u-joint shaft, this means that both joints must be at the same angle, so that the stub sides are effectively parallel, and the yokes need to be in phase (turned the same way) too. For a CV shaft, you want the pinion pointed at the output, effectively straight through (no angle) on the lower u-joint. There is some leeway, but in general, you want it as close as possible. However, as usual, there is a compromise on leaf sprung axles. Under load, the axle will twist a bit, pointing the pinion up. Phase problems are most evident under load, so it is common to have the pinion slightly down “at rest” so that when the pinion rises the shaft is closer to "in phase".


Hope that helps.
 

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masterp,.....what Frank said...sorry for the confusion....on your part!!! LOL!!!



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masterp2, the three inch shackle only goes on the back of the spring. If there were shackles on both ends it would lower a full three inches.


Good post BadDog and you are right on the money but the change with 1.5" inch is very little compared to some of the lifted trucks I have seen. This truck has less angle than any I have seen. I actually installed the recommended 2 degree shims. I had to take the spring pack apart to install them between the first main leaf and the overload. What a job. When I got done I couldn't measure the difference. One final note: I absolutely could not keep them tight. Later! Frank Edited by: Frank Blum
 

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You do have to drop the back of the hitch down to get the bolts out. Later! Frank
 
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