Adjusting Torsion Bar with AHC questions.

[1meancruiser]

I got around to adjusting the torsion bar on my 2006 LC with AHC. The drivers side TB was very difficult to torque, requiring all my strenght and 1/4 turns, for a total of 3 turns. The right side TB was very easy to torque and i turned 6 turns without stopping. It took 6 turns to get the tightness somewhere close to where the left side was. Is this difference in tightness normal? Also, the height of the LC is pretty even on both sides, and the rake is fine so i have no intentions on adjusting the height sensors.

I mainly did the TB adjustment because i'm sure the prior owner had not adjusted the TB yet and I wanted to take some of the pressure off of the AHC, i was just surprised at how loose the right side was. Any feedback is appreciated...

 

[PADDO]

I'm more comfortable with proportional adjustment of both sides to a target pressure. Cranking one side 3 turns and the other 6 to achieve similar effort on the adjusters is a different approach. In the absence of techstream i'd think, say, 2.5 turns each side from your baseline would get you closer to nominal pressure. That said, when I last adjusted mine there was a significant difference in the effort required between either side, but I still followed the FSM procedure to adjust both sides equally.

 

[tibo123]

I spent 2 days last week adjusting the pressure within the system (using techstream).
I adjusted both sides equally and I also noticed the right side was easier to tighten than the other one.

 

[1meancruiser]

I'm more comfortable with proportional adjustment of both sides to a target pressure. Cranking one side 3 turns and the other 6 to achieve similar effort on the adjusters is a different approach. In the absence of techstream i'd think, say, 2.5 turns each side from your baseline would get you closer to nominal pressure. That said, when I last adjusted mine there was a significant difference in the effort required between either side, but I still followed the FSM procedure to adjust both sides equally.

Got it, i'll back off the right side a bit. I just figured, torque pressure equals torsion strength...apparently not correct.

 

[tmils470]

Can you over tighten the front bars?

Tightend mine 3 turns last night, PO did not do any adjusting on my'02 with 63k miles.
My question is can you do any harm, or is there any problem with over tightening the front bars?
This unloads the AHC and I would think it would work less and last longer.
Will it get "confused" if it can not lower the front enough if L is selected?

The truck looks level and drives better too.

 

[PADDO]

Tightend mine 3 turns last night, PO did not do any adjusting on my'02 with 63k miles.
My question is can you do any harm, or is there any problem with over tightening the front bars?
This unloads the AHC and I would think it would work less and last longer.
Will it get "confused" if it can not lower the front enough if L is selected?

The truck looks level and drives better too.

3 turns each side probably puts you back in the spec ballpark and that's good. Adjusting to known neutral pressures is the best way to go and the cheapo Chinese techstream/miniVCI does the trick nicely. Someone recently posted up how to get it to run in Win7 as opposed to XP which most of us have to use if that's holding you back from purchasing it. I can't see anyway of breaking the system by over cranking, within reason, but if you really unload the hydraulics by transferring that load to the torsion bars you'll reach a point where the damping system can't function properly and ride quality will really suffer due to all tire + spring with no compression/rebound damping. I couldn't guess if it would last longer if tuned to run at a lower neutral pressure, but I've experimented with running at max and min neutral pressure for the same all up vehicle weight and it does make a noticeable difference in the compression/rebound feel.

 

[tmils470]

Thanks for the info.
I think it is damping well so I will leave it as is until I can find something to read the pressures.
I read the work around for the windows and it seemed to difficult for my computer skills.
I would like to find an Indepentdent shop that can do this for me and not charge a crazy amount of money.
Any suggestions for the SF east bay area?

 

[Wilsil]

Isn't a Mud member close to you who has a mini-VCI?

 

[dfrelich]

I was comparing notes with what was found on this site and the FSM. One thing I'm not quite understanding why some says just to do 2 or 3 full turn with the bolts whereas the FSM says to be sure that the bolt are in with the spec.

Can anyone of you chime in with your thoughts?

What I found with mine was "very loose". Outside the spec. I cranked good numbers of turn. I think around 10 full turns for LH and 11 for RH before I finally got within the spec, then I cranked past 2 mm the minimum. 10mm for the LH and 4mm for the RH. I'm thinking of going back and 4 or 5 more mm.

FYI -- as I got near the spec, the turns becomes harder. Both sides were met with even resistance when turning.

Below is a snapshot of the spec for your reference.

 

[PADDO]

Adjusting the TBs several turns relates to lowering the AHC's front neutral pressures, 2 to 3 turns will lower pressure somewhere in the range of 0.4 to 0.6 MPa. The diagram you are referencing appears to be related to a remove/reinstall TB procedure and that's not the same as tweaking in neutral pressures for AHC vehicles. HTH.


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[dfrelich]

Definitely pressure has decreased. The fluid tank has gone up an inch or two.

So I guess I should get the pressure tested before I do alignment.

 

[PADDO]

Definitely pressure has decreased. The fluid tank has gone up an inch or two.

So I guess I should get the pressure tested before I do alignment.

Sounds like you've unloaded the AHC and the TBs are now carrying all of the front vehicle weight. You might look at undoing what you did and use the FSM procedure to adjust AHC vehicle height and neutral pressures, they were posted in PDF about a week ago.


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[dfrelich]

Do you think I should undo what I did? Especially when I found that the TBs were not within spec to begin with.

What PDF were circulated? I must have missed that.

 

[PADDO]

It's hard to say exactly where your system is at present, I posted two relevant FSM procedures on checking/adjusting neutral pressure and vehicle height on 6/24. Check them out in conjunction with the procedure you used to crank up the TBs and I guess you can then determine the best way ahead that gets everything in spec. Maybe both your TB bolts had backed way out and neutral pressure was off the charts high and now its ok? Without pressure readings it's all speculation.


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[dfrelich]

All right. I came back from the toyota service shop. I had wanted them to check the alignment. No alignment adjustments were needed. I've asked them to check out pressures via tech stream. Not quite sure if they ran the test but they said everything checks out ok. I'll just order MINI VCI and related. Just to be on the safe side.

Everything felt normal. Just a tad bit improvement to steering response. Which I like though.

Happy 4th!

 

[LXstatic]

Quick question, do I need to adjust TBs while on jack stands or can I do it with tires on the ground?

 

[flintknapper]

Quick question, do I need to adjust TBs while on jack stands or can I do it with tires on the ground?

You can do it while on the ground BUT....it will be much more difficult to turn the adjusting bolt as all the weight of the vehicle is against the torsion bars. Better to lift the vehicle, make the adjustments (if more than a couple of turns are needed) then lower back down. Drive a short distance to settle the new adjustment and remeasure.

 

[menancyandsam]

If you put the AHC in high it makes real easy to adjust the TB's.