AHC Sensor Adjustment for Lift

Joined
Mar 8, 2017
Messages
881
Location
NH
Considering either this or the OME lift. Only concern is will a loaded truck (bumpers, roofrack, 2,000 LB trailer) cause droop with the AHC? I know stock the AHC will adjust for trailers but I dont know if it still adjusts after this modification
 
Joined
Aug 14, 2018
Messages
522
Location
Morrison, CO
It will adjust until it reaches pressure limits and then it will failsafe to N or even L. You can add airbags to compensate for the added load and not have to worry about any failsafes, at least on the rear.
 
Joined
Mar 8, 2017
Messages
881
Location
NH
It will adjust until it reaches pressure limits and then it will failsafe to N or even L. You can add airbags to compensate for the added load and not have to worry about any failsafes, at least on the rear.
thanks!
 
Joined
Dec 17, 2019
Messages
28
Location
Los Angeles
Going to try this. Front end is about 1.25 inches lower than the rear, and I'm getting some tire rub on the windshield washer tank. Pressures are borderline normal on techstream so will plan on raising the front end about 0.5 inch and adjust torsion bars as necessary. Anyone else experience a sagging front end with AHC? 180k miles.
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,743
Location
Colorado
 
Going to try this. Front end is about 1.25 inches lower than the rear, and I'm getting some tire rub on the windshield washer tank. Pressures are borderline normal on techstream so will plan on raising the front end about 0.5 inch and adjust torsion bars as necessary. Anyone else experience a sagging front end with AHC? 180k miles.
What heights are you at front and rear? Some rake is intentional. 1.25 inches is not too far from factory settings.
 
Joined
Dec 17, 2019
Messages
28
Location
Los Angeles
Height up front is about 19.25 and 20.5 in the rear, however the left was maybe .25 inches lower after I looked a little closer, and techstream had the FL at -0.3 and FR at 0 in N. I adjusted the torsion bars (13 turns L, 3 R) and got them both at 0, with the front pressure at 6.8, now the right side is lower!

I do remember reading that left/right discrepancies should be adjusted with torsion bars and checked by physical measurement and not techstream height, which is what I plan to do after I crank the right a bit and back off on the left.

Does this mean the height sensor is inaccurate and needs adjustment? F5 wheels on 285/75 btw. Thanks for the help!
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,743
Location
Colorado
 
Height up front is about 19.25 and 20.5 in the rear, however the left was maybe .25 inches lower after I looked a little closer, and techstream had the FL at -0.3 and FR at 0 in N. I adjusted the torsion bars (13 turns L, 3 R) and got them both at 0, with the front pressure at 6.8, now the right side is lower!

I do remember reading that left/right discrepancies should be adjusted with torsion bars and checked by physical measurement and not techstream height, which is what I plan to do after I crank the right a bit and back off on the left.

Does this mean the height sensor is inaccurate and needs adjustment? F5 wheels on 285/75 btw. Thanks for the help!
I was just reading up on this last night. Here's my semi-educated take.

The techstream sensor height readings are somewhat independent of the actual height of the vehicle in terms of left/right.

Step 1 is to set the left/right balance. Turn one side up while you turn the other DOWN (yes, even if the front overall is lower than you want). You should get within 10mm side to side. Don't bother trying to get better than that. For simplicity, that's roughly 1/2".

Step 2 is to adjust the height of the position sensors of the car via techstream. This is done with the slotted tabs that the height sensors attach to. Your target is +/- 5mm (0.2inches) in techstream. The height measurements are from rear of lower A-arm bolt center to wheel center (spindle) and spec is 82.7mm front. Rear is 71.2mm from spindle center to lower control arm front bolt center. Alternatively, you can use the wheel center to fender. I would aim to get the sensors to reflect your measurements (if the left measures .25" (6mm) low, try to get techstream to reflect that. This will not necessarily raise or lower the entire vehicle, just adjusts what the car considers to be level and zero.

Step 3 is to adjust the actual height of the vehicle by adjusting the link stud length itself. You loosen the two nuts on the link, spin the threaded shaft with the center nut to lengthen/shorten and then tighten the nuts and test your height. Make all these height adjustments with the car off so it doesn't move around on you and your head.

Step 4 would be to dial in your pressures on the torsion bars at your newly set N height. You may have to do this before step 3 if you're attempting to adjust the car higher than it can push itself currently (pressures limits will stop the system from working itself to death). Target pressure is 6-7 Mpa after a N-L-N cycle.

Hopefully that helps and hopefully I got that all correct. The AHC thread on here is full of gold. @PADDO and @uHu have provided lots of great tips and instructions.
 
Joined
Dec 17, 2019
Messages
28
Location
Los Angeles
That's very helpful thank you! I'll have to get around to this eventually. I read that entire thread but there's so much information I'll have to read it again.

This morning I made some torsion bar adjustments and got my front height and left/right height to where I want it. It's just over 19.5 up front and pressures are within spec.

I'll have to make those adjustments you mentioned at some point in the future, still have a bunch of maintenance stuff to do. Thanks for your help, this forum is great!
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,743
Location
Colorado
 
That's very helpful thank you! I'll have to get around to this eventually. I read that entire thread but there's so much information I'll have to read it again.

This morning I made some torsion bar adjustments and got my front height and left/right height to where I want it. It's just over 19.5 up front and pressures are within spec.

I'll have to make those adjustments you mentioned at some point in the future, still have a bunch of maintenance stuff to do. Thanks for your help, this forum is great!
You're welcome! Good timing as I was just reading through all that.

Getting your heights close to correct and pressures in spec is most important. Dialing it in from there is all icing on the cake.
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,743
Location
Colorado
 
I lost my threaded rod, (does anyone know the part number? Easiest place to order from? Thank you in advance.
Looks like the parts diagrams only show the entire sensor arm with the rod. I'm guessing it's an M6 rod threaded opposite directions. Might be able to find a generic one and cut to size.
 
Joined
Jun 18, 2009
Messages
20
Location
Australia
Question for the gurus here. This is such a cool discussion

I live in Australia and I have the 2006 4.2l turbo diesel engine lc100 sahara (which has ahc). The turbo diesel torsion bars are heavier rated than the V8 TBs as diesel engine is heavier.

In Australia we also had a non ahc 4.2l turbo diesel model ( called the GXL) This has slighly stiffer torsion bars than a ahc diesel model

I have an ARB deluxe bullbar and just fitted a warn m12000 (thankfully cnverted to synthetic rope) and arb steel roof rack. Ialso have a arn twin compressor in engine bay. I have fitted rear helper airbags which are billiant when the rear is loaded up - running 15-20psi

My vehicle has stock ahc suspension - tbs and springs

The M12000 has just been fitted - a week ago and the front end seems to have dropped a little. I dont even know what is going on with the spheres but its safe to say that they are probably out of range judging by the comments here. The vehicle indciates H when selcted but it doesnt seem as hi as usual (basic obs)

My cruiser like most is (apart from parts mentioned above) 99% unloaded, except when we do annual camping trip and it's really loaded up

So do I:

1. Get toyota to crank the tbs so the ahc spheres get back to spec? OR

2. Fit the torsion bars from the GXL model installed (which are slighlty stiffer) and get toyota to check the spheres and make sure (with all the weight in the front of my cruiser) that the pressures are correct?
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,743
Location
Colorado
 
Question for the gurus here. This is such a cool discussion

I live in Australia and I have the 2006 4.2l turbo diesel engine lc100 sahara (which has ahc). The turbo diesel torsion bars are heavier rated than the V8 TBs as diesel engine is heavier.

In Australia we also had a non ahc 4.2l turbo diesel model ( called the GXL) This has slighly stiffer torsion bars than a ahc diesel model

I have an ARB deluxe bullbar and just fitted a warn m12000 (thankfully cnverted to synthetic rope) and arb steel roof rack. Ialso have a arn twin compressor in engine bay. I have fitted rear helper airbags which are billiant when the rear is loaded up - running 15-20psi

My vehicle has stock ahc suspension - tbs and springs

The M12000 has just been fitted - a week ago and the front end seems to have dropped a little. I dont even know what is going on with the spheres but its safe to say that they are probably out of range judging by the comments here. The vehicle indciates H when selcted but it doesnt seem as hi as usual (basic obs)

My cruiser like most is (apart from parts mentioned above) 99% unloaded, except when we do annual camping trip and it's really loaded up

So do I:

1. Get toyota to crank the tbs so the ahc spheres get back to spec? OR

2. Fit the torsion bars from the GXL model installed (which are slighlty stiffer) and get toyota to check the spheres and make sure (with all the weight in the front of my cruiser) that the pressures are correct?
Check pressures first and adjust torsion bars you already have.

I'd adjust it with a pretty full rig. If you adjust to a full rig you'll better avoid the ultimate ahc fear - failure on a trail.
 
Joined
Jun 18, 2009
Messages
20
Location
Australia
Check pressures first and adjust torsion bars you already have.

I'd adjust it with a pretty full rig. If you adjust to a full rig you'll better avoid the ultimate ahc fear - failure on a trail.

Thanks mate

Can you guys advise approximately how long does an 'adjust torsion bar - check pressure' take at a genuine toyota dealer who has the special ahc gauge?

Do you think with an ARB deluxe bullbar + Warn M12000 with synthetic rope, 2 baja designs soletk HID lights, arb twin comppressor and ARB steel roof rack, I'll be able to get enough adjustment out of the factory TBs to get the AHC pressures back down?

I've been quoted 2 hours.

Would 2 hours also be enough time to flush the ahc fluid? (Im not sure on ahc fluid intervals but my vehicle is coming up to 200,000km)

Really appreciate the knowledge in here on this issue
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,743
Location
Colorado
 
Thanks mate

Can you guys advise approximately how long does an 'adjust torsion bar - check pressure' take at a genuine toyota dealer who has the special ahc gauge?

Do you think with an ARB deluxe bullbar + Warn M12000 with synthetic rope, 2 baja designs soletk HID lights, arb twin comppressor and ARB steel roof rack, I'll be able to get enough adjustment out of the factory TBs to get the AHC pressures back down?

I've been quoted 2 hours.

Would 2 hours also be enough time to flush the ahc fluid? (Im not sure on ahc fluid intervals but my vehicle is coming up to 200,000km)

Really appreciate the knowledge in here on this issue
I think the factory bars can do it, but they may need to re-index them (uninstall them, twist an extra tooth, reinstall). Spring rates might be a little weird, but you'll have to try and see!

No idea on flush time. I think the factory method is more time intensive than alternative methods, but I'm no expert on flushes, yet!

2 hours should cover at the very least, measurement of system and adjustment of T bars.
 
Joined
Mar 31, 2019
Messages
260
Location
Charleston, SC
Going to try this. Front end is about 1.25 inches lower than the rear, and I'm getting some tire rub on the windshield washer tank. Pressures are borderline normal on techstream so will plan on raising the front end about 0.5 inch and adjust torsion bars as necessary. Anyone else experience a sagging front end with AHC? 180k miles.
Did you end up doing this? Im gonna try it tomorrow and I just want an extra inch out of the front end
 
Joined
Dec 17, 2019
Messages
28
Location
Los Angeles
No I haven't had a chance yet. I normalized the pressures, but never got around to the sensor lift unfortunately, maybe one of these days. Let me know how it goes!
 
Joined
May 15, 2019
Messages
8
Location
East Tennessee
I’m attempting to lift my ride a 1.5” sensor lift all the way around. I installed 30mm coil spring spacers and then slide all the sensors up to their highest adjustments. I haven’t adjusted the threaded part of the front sensors yet. This yielded me about .75” lift in the front and my AHC front pressure is 6.9 and rear is 6.8. Both front hub to fender measurements are equal at 20.25”. My passenger rear measurement is highest at 21.25” and driver rear is 20.75”. How do I level out the back end?
Also, if I adjust the threaded part of the sensors to gain more lift I understand my front pressure will go out of spec and need brought down with torsion bar adjustment. But won’t that also bring my rear pressures further out of spec? Any help is greatly appreciated. Thanks!
 
Top Bottom