Leveling and aligning truck with AHC after front end overhaul (1 Viewer)

[katit]

Anyone has any inputs on this? There is a few variables in play and I am not sure of a proper sequence.
I can deal with AHC sensors pressures but I can't do alignment.

I will do TOE adjustment approx by number of threads on tie rods. But camber/caster I lost (didn't remember how those were set)

What about torsion bars? How do you equalize those? Ok, I can go by height, but is this correct or precise enough? I assume it's OK if AHC not bled or sensors not adjusted, right? I am talking strictly L/R hights relative.

So, my plan is:
1. Get torsion bars to level truck somehow (not very important what height) I guess I need to set it to 19.75 at front
2. Get AHC bled and check sensors and pressure. First, get sensors equal L/R and show correct N value matching actual height. Second, get AHC pressure to correct value by adjusting bars equaly on both sides.

Will camber/caster alignment at shop later screw with my torsion setup and sensors?

So, any advice on correct steps to get whole thing correct appreciated.

 

[94SRUNNER]

I could be wrong, but it shouldn't matter which order you do these in. May as well have them align it first. They should not mess with the AHC system or torsion bars while adjusting the alignment. Once the alignment is completed, then I would focus on the AHC system. Do you have techstream?

How far, left to right, out of level is the front end of your truck?

 

[katit]

I could be wrong, but it shouldn't matter which order you do these in. May as well have them align it first. They should not mess with the AHC system or torsion bars while adjusting the alignment. Once the alignment is completed, then I would focus on the AHC system. Do you have techstream?

How far, left to right, out of level is the front end of your truck?

My truck doesn't have front end right now

I think it matters because for alignment I need to at least bring leveled truck with correct height at N to them.
I do have Techstream.

 

[94SRUNNER]

My truck doesn't have front end right now

I think it matters because for alignment I need to at least bring leveled truck with correct height at N to them.
I do have Techstream.

Well...you have bigger things to focus on now!

Then I say, once your front end is re-attached, then get your AHC system sorted. With the threads on Mud and the FSM, you should be able to get the AHC dialed it and you may be able to do a baseline alignment. I have read of guys on the forum here doing it in themselves, then having a shop fine-tune the alignment on a rack (maybe that is your plan?)

 

[katit]

Well...you have bigger things to focus on now!

Then I say, once your front end is re-attached, then get your AHC system sorted. With the threads on Mud and the FSM, you should be able to get the AHC dialed it and you may be able to do a baseline alignment. I have read of guys on the forum here doing it in themselves, then having a shop fine-tune the alignment on a rack (maybe that is your plan?)

I am trying to come up with a correct plan. Hence asking for advice. My guess is that first I need to get torsion bars setup (before even bleeding AHC or doing sensors adjustments). And first question - is there precise way to tension those bars other than crank both until L and R height is good and equal?

 

[94SRUNNER]

I am trying to come up with a correct plan. Hence asking for advice. My guess is that first I need to get torsion bars setup (before even bleeding AHC or doing sensors adjustments). And first question - is there precise way to tension those bars other than crank both until L and R height is good and equal?

The torsion bars have to be indexed correctly. The process is laid out in the FSM. Page SA-67 in the 2004 LC FSM. I dont have the specs on the AHC torsion bars, but it should be here on the forum.

 

[katit]

The torsion bars have to be indexed correctly. The process is laid out in the FSM.

Ahh. Thats right, I forgot about FSM I won't lose indexing because I placed marks but tensioning them is a question.

So, what is a correct sequence then? Torsion bars or AHC bleed?

 

[94SRUNNER]

Ahh. Thats right, I forgot about FSM I won't lose indexing because I placed marks but tensioning them is a question.

So, what is a correct sequence then? Torsion bars or AHC bleed?

I added the 2004 FSM pages, just as reference. You should search to find the AHC specific, but my guess it the process is very similar.

Get the torsion bars in and set per FSM, then bleed and tune the AHC system.

 

[Red Beard]

I just did my front end not too long ago. Control arms, bearings, swaybar bushings. I adjusted the torsion bars until I was in spec and then drove it up to the alignment shop. They saw the ride height was a tiny bit off so they adjusted it a bit more then did the alignment. I'm assuming the suspension settled a little more after I drove it up. After alignment, it drives perfectly straight.

Based on my limited experience, I think alignment should be dead last thing you do.

 

[katit]

I just did my front end not too long ago. Control arms, bearings, swaybar bushings. I adjusted the torsion bars until I was in spec and then drove it up to the alignment shop. They saw the ride height was a tiny bit off so they adjusted it a bit more then did the alignment. I'm assuming the suspension settled a little more after I drove it up. After alignment, it drives perfectly straight.

Based on my limited experience, I think alignment should be dead last thing you do.

I wish this will be the case.. I have very little confidence in alignment place. Any suggestions for shop in St Louis who know what they do?

 

[94SRUNNER]

I wish this will be the case.. I have very little confidence in alignment place. Any suggestions for shop in St Louis who know what they do?

Have you posted up in the St. Louis Clubhouse forum - MO- Gateway Cruisers - https://forum.ih8mud.com/forums/mo-gateway-cruisers.138/

I am sure a local member can offer recommendations.

Additionally, if you are on Facebook, there are 100 Series groups that can offer suggestions, not to mention other Land Cruiser groups.

 

[Red Beard]

I wish this will be the case.. I have very little confidence in alignment place. Any suggestions for shop in St Louis who know what they do?

Everything I saw before getting my alignment was ensuring they do a 0 camber alignment. You should see what they say if you ask about that.

The shop I brought it to kinda blew me off when I asked for it and said they were going to do whatever the system said. But, when they called back they said the system they use for alignments had the near 0 camber alignment for the Land Cruiser so they confirmed what I was asking for. So I bet as long as they're using a centralized system, they'll probably see the values for the 0 camber in the system.

I definitely recommend checking your local clubhouse for a known shop!

If it helps. this is what I got back from my shop.

 

[katit]

From IH8MUD member @2001LC I have in my notes to ask for 2.8-3 degree of caster.
Yes, I will be asking around for a good shop. Is 200 series same in terms of adjustments on top control arms? If thats a case I may have good luck with a dealer

 

[IndroCruise]

From IH8MUD member @2001LC I have in my notes to ask for 2.8-3 degree of caster.
Yes, I will be asking around for a good shop. Is 200 series same in terms of adjustments on top control arms? If thats a case I may have good luck with a dealer

Suggest use the practical advice from @2001LC and other IH8MUD Members.

Here are some more details which may help:

Before doing anything concerning AHC adjustments on an AHC vehicle, the first step always is to check and if necessary adjust the front “cross-level” of the vehicle.

The check is done at both Front wheels by measuring with a tape-measure the distance from the centre of the hub to fender lip immediately above, with the vehicle on level ground, and height at “N” setting.

The actual measurement number is not important at this stage. It IS important that the measurements at Right Front and Left Front be equal +/- 10 millimetres – see attachment.

The cross-level adjustment is done only with the torsion bar adjusters, never with the Height Control Sensor adjusters.

The cross-level check and adjustment is done with the engine OFF, for three reasons:

• for safety,
• to avoid any interference or self-levelling by the AHC system during the check and adjustment,
• to comply with stated FSM requirements.

There are two purposes of “cross-levelling”:

• Ensure that each torsion bar is carrying an equal share of the weight of the vehicle – otherwise the vehicle will feel strange on the road and there will be a difference when turning right and left,
• Avoid the vehicle leaning to one side – if the vehicle leans excessively to one side it will be impossible to adjust the Height Control Sensors correctly. Wrongly adjusted Sensors will cause the AHC Electronic Control Unit (ECU) to receive conflicting signals from these Sensors. In turn, conflicting signals will cause other problems, such as the ECU putting the AHC system into ‘fail safe’ mode.

It should be noted that the torsion bar adjusters on an AHC vehicle have only two purposes:

• cross-levelling of the front of the vehicle, and,
• adjusting Front AHC pressures by adjusting torsion bar loads.

Different to a non-AHC vehicle, the torsion bar adjusters are not used to adjust the front height of the vehicle. This would be impossible because any attempt to change heights using the torsion bar adjusters will be corrected as soon as AHC system begins operation. It will then self-adjust the vehicle to the heights determined by the Height Control Sensors. The front height of the vehicle is adjusted only by moving the Height Control Sensor adjusters.

Note: The AHC system is a two-channel system that deals with Front and Rear levels only. It is not a four-channel system. It is not capable of raising or lowering each of the four corners of the vehicle individually. In addition, when the vehicle is stationary such as when testing or adjusting AHC components, Right Front and Left Front are hydraulically connected -- the Front Gate Valve in the Control Valve Assembly is open. This means the AHC Right Front and AHC Left Front are at the same pressure and the vehicle will raise evenly at the Front. It is the same at the Rear.

The following reference leads to a five-page document giving the relevant Factory Service Manual (FSM) specifications for the front end geometry of various LC100 models, including models with AHC. The specifications are slightly different for LC100 models with AHC and for LC100 models without AHC. The front end geometry specifications for LX470 models is the same as the LC100 models with AHC.

In my part of the world, and maybe in USA, it can happen that a workshop looks up the wrong specification of front end geometry in their computer files and applies the wrong settings to a vehicle equipped with AHC. If there is any doubt, suggest print the extract at thefollowing link, take it with you to the workshop and explain the requirements.

https://lc100e.github.io/manual/
At the Index Panel on the left hand side of the opening page, follow the following tabs:
Repair Manual > SUSPENSION AND AXLE > FRONT WHEEL ALIGNMENT (Independent Front Axle> INSPECTION

On the question about whether to do AHC adjustments or wheel alignment and geometry first, the FSM guidance states:

“Before inspecting the wheel alignment, adjust the vehicle height to the specification”.

This is because large departures from the specified vehicle heights, Front or Rear, can affect the front end geometry.

So the sequence is:

• Check and adjust ‘cross-level’, then,
• Check and adjust vehicle 'operating height', then,
• Check and adjust wheel alignment and front end geometry.

At the the first page of the reference at the above link, the FSM gives detailed specifications and measurements for vehicle heights. These are difficult to use and the following approximations are described in IH8MUD threads and elsewhere. These approximations are widely used instead of the FSM details and have been found to be reliable. These are called the ‘operating heights’ or ‘ride heights’, measured with a tape-measure from hub-centre to fender-lip, with the engine ON and AHC operating after the suspension has settled, and with “N” height selected on the centre console. These hub-to-fender distances for a vehicle in stock condition (not lifted or lowered) are:
FRONT: 19.75 inches; REAR: 20.50 inches

Do you need some explanation about the steps to adjust vehicle height, and separately, to adjust the Height Control Sensors to the correct reading at the adjusted vehicle height?

 

[katit]

Do you need some explanation about the steps to adjust vehicle height, and separately, to adjust the Height Control Sensors to the correct reading at the adjusted vehicle height?

Thanks a lot for such detailed response. I think I am good. I didn't read FSM before disassembly so I didn't take measurements from torsion arms before loosening.
After reading all my plan is:

0. Don't tighten control arm bolts (not to twist bushes)
1. Get torsion bars into position (gap per FSM) just approximately while truck is on a lift.
2. Get sensors into middle position, or review photos and set them approx where they were.
3. Set truck on a ground and bleed AHC so it starts going into positions. Right now shocks out and after install there will be no pressure.
4. Read pressures and AHC position readings. Adjust sensors, adjust torsion bars to get truck leveled to specific height.
5. Torque control arms in N position when truck sitting on a ground.

Does it sound right?