Aluminum vs Steel Lower Control Arms

[Hiram]

Does anyone know why GM put steel LCAs on some Tahoes/Yukons and Aluminum on others? I recently converted my Denali to the PPV suspension (shocks and springs) expecting a 2" drop in the front and rear. It only dropped it .5" in the front and I'm wondering if that has something to do with the aluminum LCAs that come on the PPV Tahoes. My measurements from the center of the wheel to the fender are 21" in front and 21.5" in the rear. From what I can tell from research online, the PPV measures to be 20.75" in rear and 19.75" in the front.

This has me stumped, I'm completely at a loss as to why I didn't get as much of a drop as I should have. I'm thinking it might be the aluminum lower control arm design. Does anyone have any ideas...?

 

[NORCAL SS]

gm used different springs on the 07 up trucks. My truck sat high were as others sat 1 inch lower. the springs you had in your truck were the lower rated springs. Thats nothing new. My truck was from ground to fenderlip 36.75 stock where as others were 35.75 from ground to fenderlip stock. The ppv ones also look lower due to the 265 60 17 tires 29.5 vs 32.1 on the 285 45 22. the tire alone will give a 1.3 drop about from ground to fenderlip vs a stock truck on 285 45 22

 

[CrashTestDummy]

Your PPV started out 2"-3" LOWER than a standard Tahoe. That is mostly from the springs. The 17" wheels are also a smaller diameter than a standard Tahoe. Most lowering kits describe their expected drop from a stock standard Tahoe, NOT a PPV.

I'm surprised you got an additional 1/2".

 

[NORCAL SS]

like i said depends on the springs gm put in his truck. On the trucks with the higher spring rates will lower more. If they used the lower springs rates wont drop it as much over stock.

Hiram question for you what size tires do you have on the truck now? also what does it measure from ground to fenderlip all around?

 

[Hiram]

Your PPV started out 2"-3" LOWER than a standard Tahoe. That is mostly from the springs. The 17" wheels are also a smaller diameter than a standard Tahoe. Most lowering kits describe their expected drop from a stock standard Tahoe, NOT a PPV.

I'm surprised you got an additional 1/2".

Sorry I might not have explained that very well...I don't have a PPV, I've got a Yukon Denali that I installed the PPV shocks and springs on. My stock ride height from the ground to fender lip was 37.75" rear and 36" in front. After I installed the PPV shocks and springs it is 36.25" rear and 35.75" in front.

I'm running the stock wheels and tires 275/55/20. I measured from the hub to fender lip originally to get a more accurate number regardless of tire size.

---------- Post added at 02:33 PM ---------- Previous post was at 02:24 PM ----------

like i said depends on the springs gm put in his truck. On the trucks with the higher spring rates will lower more. If they used the lower springs rates wont drop it as much over stock.

Hiram question for you what size tires do you have on the truck now? also what does it measure from ground to fenderlip all around?

275/55/20 are the tires I'm running. From my understanding, if you measure from the hub to fender lip it doesn't matter what the tire size is. The PPV Tahoes measure 20.75" in the rear and 19.75" in front measuring from the hub.

I installed the exact same PPV shocks and springs from GM, and somehow didn't get the drop. This is why I was wondering about the aluminum lower control arms. The hybrid models and the Z60 (street suspension) sierras all sit about 1" lower and use the aluminum lower control arms. The PPV comes with Aluminum LCAs as well...

Just wondering if anyone knows for sure about those LCA dimensions compared to the steel ones, or if there is something I'm missing as to why I didn't get the drop.