AHC Height question

[loop737]

Hello All,
First, let me state I have read the "Definitive" thread and don't remember this specific problem. I just swapped the rear springs on my 06 LX 470, measurements prior to the swap.
LF= 19.50
RF= 19.75
LR=20.0
RR=20.5
After swap
LF=18.75
RF=19.0
LR=20.5
RR=20.5
As you can see the rears are now perfect, but why the lowered front? I used stock LX springs, going to fix the 1/4 inch difference up front with the torsion bars but don't want to start messing with the front sensors until i get some advice here. Thanks. Dont have techstream yet but plan on ordering it today.

 

[winegamd]

The LC100 rear springs are higher rate than the AHC rears. You have essentially shifted your weight bias forward with the higher rate springs.

 

[soreneagle]

No weight transfer when the height at the rr remains unchanged but lifting the lr would shift load onto the front. It is odd to lift one side of the rear 1/2" and end up with a consistent 3/4" droop a cross the front. On my LX one of the front linkages had moved in the sloted bracket on the USA. Got to get the Techstream! I have it on order too.

 

[loop737]

The LC100 rear springs are higher rate than the AHC rears. You have essentially shifted your weight bias forward with the higher rate springs.

Actually used OEM Lexus AHC springs, no change there, just new

 

[LBridges]

If you have the AHC system still in place then the height sensors got pushed out of position or the system just hasn't cycled so it's back to your "normal" height. What I'm getting at here is the rear side to side values can be off by weakened springs, and the front side to side difference by TBs out of adjustment. I don't think 1/4" on the drivers side front seems excessive due to the usual factors. I would try to suggest how to fix this but I'd probably screw it up, so I suggest a search for AHC post by Paddo and skim through to find his adjustment procedures. Pretty much requires Techstream.

 

[uHu]

That's not much of a difference, before and after. Not more than approx what the ahc allows. The method to get consistent readings is to always put it in low first, let it stabilize there, and then press N and wait antil 30 sec after the N light is steady. (And getting in and out of the car will alter the height as well.) If you then get differing height readings, you might have a loose sensor link, or a faulty sensor. The springs (TB & coil) have no influence on the height (other than L/R lean), as long as they help lifting enough.
L/R lean is handled by the TBs alone.

 

[loop737]

That's not much of a difference, before and after. Not more than approx what the ahc allows. The method to get consistent readings is to always put it in low first, let it stabilize there, and then press N and wait antil 30 sec after the N light is steady. (And getting in and out of the car will alter the height as well.) If you then get differing height readings, you might have a loose sensor link, or a faulty sensor. The springs (TB & coil) have no influence on the height (other than L/R lean), as long as they help lifting enough.
L/R lean is handled by the TBs alone.

Drove the truck, cycled between L to H to N, then measured again, this time 19.75 on the RF and 19.5 on the LF, exactly as before the swap. So I'm happy, just have to adjust the torsion bars and should be good to go, thanks for the help.