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Discussion Starter #1
just had my brand new (600 mi) sierra rcsb dropped at a shop in Austin (4/7 belltech). it looks killer but has a nasty vibration when accelerating and decelerating (0-50 mph). Upon my investigation (10 min ago) the rear is 1 inch off (measured the leafs to the bottom plate (flip kit)). I can say im not taking it back and will fix this on my own or have a pro do it. I have a pinion angle tool and have the tools to fix it in my driveway. The questions I have are: it is as simple as loosening the u bolts and hitting it with a hammer while on stands? it looks like both axle perch are bolted to the leafs? do I need to lift the truck and drop the rear mounts to relocate the axle perch so that they are square? is it ok to jack the truck up by the rear diff and then set the frame on stands to unload the springs to relocate the perch? any other tips?

Last question any shops out there that specialize in this in the central texas area (Ft Hood, Austin) that could fix it in a few hours for a reasonable price?

thanks guys, matt
 

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a pic would help in figuring out whats wrong but one of the perches could be installed backwards? there is a bolt through the spring pack that locates the axle perch. the hole in the bottom of the axle perch is offset

Jack the rear of the truck up, put jack stands under it, loosen the u bolts and use jack to lift, reposition the axle, no hammer need.
If you don't have the instructions for the flip kit they are on belltechs website.
 

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Discussion Starter #3
thanks, yes the bolt/nut combo locates the perch. they are symmetrical, so ishould be less concerned about the "rough" measurements. I still have the rumble strip feel when accel/decelerating. it has the transmission spacer. I have a pinion tool but am curious if any of the other rcsb guys have the same feel after the drop. Also to note when stabbing the throttle off the line its smooth and no rumble (vibration). Does anyone have any clue/insight/advice? thanks, matt
 

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Discussion Starter #4
new update. after filling up the truck it does seem to ride better. I will try and load the rear suspension and see if that improves the ride. question: loading the suspension would effectively be DECREASING the pinion angle?? as the rear is lowered the differential is being brought more 'in line' with the transmission output. no? thanks matt
 

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CHIMICHANGA
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I'm sorry I cannot answer any of the questions but where did you get the drop installed?
 

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The Lowering Experts
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The Regular Cabs need 2* shims, do not use the transmission spacer. Call the tech department over at Belltech, they will take care of you on the shims.
 

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Discussion Starter #7
DOH!!!!!!!!!!!!!!!!!! that's a key piece of info!!!!!!!!!!!!!!!!!!!!! are the shims for the rear or the front of the perch??
thanks. the shop installed everything properly and it looks good.
 
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