No, I've had both stock and RT upper control arms with the same 4.1" set-up - no changes -

 

Just ordered my front setup fro John DB Rods. He recommended 3.6 shock
850# spring. This is for a 2006 rcsb Sierra with a iron block 370ci motor. I have 2" mcgaughys spindles and 3" spring with a 1" spacer (total drop approx 4.25") and want to be around 3.75"-4" total drop as I'm rubbing now with 22", +22 offset wheels. Can't wait to get them.

 

What are your measurements from ground to fender or center of hub to fender front and rear?

 

Unfortunately I don't remember the specifics, I think it was somewhere around 29"- 30" ground to fender.

 

Ok cool thanks. With the combo i described above, does it look like I should be able to achieve the hieght I need. Does that combo sound right for my truck? Sorry for all the questions but after reading most of this thread you seem very knowledgeable on the subject.

 

No, I think that would be too low of a set-up, quick math would put desired ride hight from LCA to shock tower at 11.53" (remember we want to keep the shock as close to the center of its overall travel for the best ride), and you would have a total of 1.8" of travel before the shock bottomed out.

My first set-up was a 4.1 shock where my ride hight was 12.48" (iirc I was actually at 13" so cranked up on the coils a bit which is ok to do), and that netted me a overall ride hight (including drop spindles) of a 5" drop.

So for what you want to achieve I think the 5.2's (with a 12" spring at 750-800#) would be ideal, this would put the shocks at the optimal sweet spot in their travel at 14.13" this should be about a 4" drop (including spindles) with a lot more room to play with to dial it in than the 3.1's

Best bet would be to try and measure your truck at its current hight from the lower shock mount to the upper shock mount (full weight on the suspension), this should give you a solid base line of your truck that you can better work with.

 

Ok I'll try and get a measurement. My coilovers will be here next week so I guess I'll have to try them.

 

So would I be better off with stock spindles with the 3.1 shock, to get to 3.75-4" drop? Haven't had a chance to measure where I'm at now yet.

 

No matter what the 3.1's won't ride good at all, they don't have enough travel (at their sweet spot they only have 1.8" of travel) and you would need a super stiff spring rate to keep them from bottoming out.

I don't recommend them, and sure you could go back to stock spindles, but you still run into the same travel limits on such a short shock.

 

Hmm...I wonder why he recommends that combo. He said a lot of those combo get ordered and work good. I'll try and get a measurement tomorrow