AHC Adventures "Schock" replacement

[IceStorm]

Hare is a phone pic oft he screen. This car has all new jacks installed by Toyota and probably a new height sensor in the back. When I got it it's rear end was way to high so I adjusted the height by adjusting the slide on the sensor in the rear, getting the back down to about 53 or 54cm. Since this is the way it came back from Toyota I doubt they did any adjusting of the AHC.
Very best the form Iceland, 8°c and raining right now.

 

[PADDO]

Hare is a phone pic oft he screen. This car has all new jacks installed by Toyota and probably a new height sensor in the back. When I got it it's rear end was way to high so I adjusted the height by adjusting the slide on the sensor in the rear, getting the back down to about 53 or 54cm. Since this is the way it came back from Toyota I doubt they did any adjusting of the AHC.
Very best the form Iceland, 8°c and raining right now.

View attachment 1728405

Have you got accurate height measurements for each corner? These determine if you need to adjust out front side to side lean. Stock height is 500mm front and 520 rear so you’ll not get your rear back into design pressure range if you’re at 530-540mm without some intervention. Front pressure at 9.2 is quite high and would need something like 10-12 net turns to get it to where it needs to be - but this all depends on actual measured heights. Your height accumulator pressure will hopefully lower a fraction when your neutral pressures are corrected, as will your rear pressure change on adjusting the torsion bars.

 

[IceStorm]

Have you got accurate height measurements for each corner? These determine if you need to adjust out front side to side lean. Stock height is 500mm front and 520 rear so you’ll not get your rear back into design pressure range if you’re at 530-540mm without some intervention. Front pressure at 9.2 is quite high and would need something like 10-12 net turns to get it to where it needs to be - but this all depends on actual measured heights. Your height accumulator pressure will hopefully lower a fraction when your neutral pressures are corrected, as will your rear pressure change on adjusting the torsion bars.

I will get all 4 coroners measured and port it back here tomorrow . I would not be surprised is if was a tad high in the front as well.

 

[IceStorm]

I will get all 4 coroners measured and port it back here tomorrow . I would not be surprised is if was a tad high in the front as well.

whent out today and measured hight. Rear is 52.5 front left is 51.5 and front right is 50.8 (best measurement i can get from ceter ub to top of wheel arch)
I also took a screen dump this time of the Data

Very best regards

 

[IceStorm]

@PADDO It's A diesel so a bit heavier in the front. Yet the number seem a bit high on the front pressure

 

[IceStorm]

@PADDO Have the car on the lift replacing the rear diff lock. Had a look at the front tensions bars, and they look look the right one is tight and the left one is loose. Is it possible this is correct? I will check if the left one has been replaced at any time.

 

[mallard75]

Sure, since you asked so nicely Take some hub center to fender bottom height measurements at each corner when parked on flat level ground, no junk in the rear (or if you’ve got extra weight permanently fitted give a rough outline of what is where) and do a L to N raise. Post a screen shot of the AHC data list page going from L to N with your actual measured heights and we will go from there.

What should the measurements be from hub center to fender in the neutral position? I am about to embark on an AHC adventure of my own. My 2007 now has a TJM front bumper and it looks like the weight is causing problems with my ahc. I am planning on adjusting the torsion bars to correct the height.

Currently the ahc is in N position. It will move to H or L but as soon as I start driving it returns to N

Am I on the right thought path?

 

[PADDO]

@PADDO Have the car on the lift replacing the rear diff lock. Had a look at the front tensions bars, and they look look the right one is tight and the left one is loose. Is it possible this is correct? I will check if the left one has been replaced at any time.

View attachment 1745710

View attachment 1745711

Yes it’s normal to not have the same number of threads or apparent tension at the bolts. The objective is to have equal front vehicle heights both sides, ie no side to side lean, and the desired neutral pressure at your N height - if you can achieve that within the bounds of the available torsion bar bolt adjustment ranges then you’re good. There’s FSM procedures for setting up the TBs if they’ve been removed and it details differing bolt head heights, however with AHC the final step is to adjust individual TBs to eliminate any lean and to achieve the correct normal height preload pressure of 6.9MPa on Techstream or 5.7MPa at the damper assemblies via pressure gauge. Have you got your pressures sorted out? Shoot me a pm if you like.

 

[PADDO]

What should the measurements be

My 2007 now has a TJM front bumper and it looks like the weight is causing problems with my ahc. I am planning on adjusting the torsion bars to correct the height.

Currently the ahc is in N position. It will move to H or L but as soon as I start driving it returns to N

Am I on the right thought path?

No you’re on the wrong thought path

Factory heights are ~19.5 inch front and ~20.5 rear.
Vehicle heights are changed with height sensor adjustments; pressures and front leans are corrected with torsion bar adjustments.
The vehicle AHC/AVS is designed to return to N when driven.
These points have been covered once or twice in a thread or two

 

[mallard75]

Thanks. Yes I been reading. Was a little confused between adjusting sensors vs TB to offset bumper weight. There seems to be some conflicting views. I trust you though.

Also I guess I have a little to learn about the AHC and it’s purpose. Seems like an elaborate system for such limited purpose. My 99 did not have it. Can’t say that I’m glad to have it on the 07 yet. Will have to learn the benefits.

 

[IceStorm]

Yes it’s normal to not have the same number of threads or apparent tension at the bolts. The objective is to have equal front vehicle heights both sides, ie no side to side lean, and the desired neutral pressure at your N height - if you can achieve that within the bounds of the available torsion bar bolt adjustment ranges then you’re good. There’s FSM procedures for setting up the TBs if they’ve been removed and it details differing bolt head heights, however with AHC the final step is to adjust individual TBs to eliminate any lean and to achieve the correct normal height preload pressure of 6.9MPa on Techstream or 5.7MPa at the damper assemblies via pressure gauge. Have you got your pressures sorted out? Shoot me a pm if you like.

Thanks @PADDO will do. I had it on the lift doing work on the rear diff lock. So I turned the left TB 5 turns, just to see what the TS would say. A bit surprisingly it the pressure dropped in the front from 9.2 to 7.6 and the back from 7.3 to 6.8. I will pop under it again and turn the other TB 5 turns as well, now that I know it is normal to see the difference I will send you a PM once I have the data. Thanks again Paddo