Feeling every crack with my AHC

[128keaton]

I live in a city with awful roads, so I thought I was doing myself a favor buying a LX with AHC.

Wrong.

About 3 weeks after purchase, I noticed how truly terrible the ride had become.
I performed the graduation test and received ~7 graduations on the unit. I just fully flushed with new AHC fluid from Toyota, and the ride felt better, but now it is back to garbage. On a cracked road surface, I can feel the vibrations, and the cabin vibrates with it. Loud, annoying. Speed bumps and potholes just suck the truck in and it feels awful. Expansion joints are worse.

I put the truck in the "diagnostic mode" to check for rebound. Felt very soft, and it firmed up pretty well as I pushed the brake pedal.

I'm thinking accumulators at this point, but I hope to god not, I can't afford $800 worth of parts.

Anything else I am missing? Comfort to sport does firm it up around corners and the rebound of the shocks. The switch works as per TIS.

 

[thetoyotaman]

Have you checked your pressures? It may be on the high side with age and springs settled.

 

[128keaton]

Have you checked your pressures? It may be on the high side with age and springs settled.

Yes. I adjusted the T-Bars to be 6.7 in the front. The rear is 7.1. Not too far off on the rear.

 

[PADDO]

At 7 graduations your damper globes are effectively finished, flat, worn out - like most things they have finite functionality.

 

[128keaton]

At 7 graduations your damper globes are effectively finished, flat, worn out - like most things they have finite functionality.

That is what I feared.
Maybe I can find someone to trade for a Land Cruiser without AHC.

 

[jLB]

I live in a city with awful roads, so I thought I was doing myself a favor buying a LX with AHC.

Wrong.

About 3 weeks after purchase, I noticed how truly terrible the ride had become.
I performed the graduation test and received ~7 graduations on the unit. I just fully flushed with new AHC fluid from Toyota, and the ride felt better, but now it is back to garbage. On a cracked road surface, I can feel the vibrations, and the cabin vibrates with it. Loud, annoying. Speed bumps and potholes just suck the truck in and it feels awful. Expansion joints are worse.

I put the truck in the "diagnostic mode" to check for rebound. Felt very soft, and it firmed up pretty well as I pushed the brake pedal.

I'm thinking accumulators at this point, but I hope to god not, I can't afford $800 worth of parts.

Anything else I am missing? Comfort to sport does firm it up around corners and the rebound of the shocks. The switch works as per TIS.

In another post, you mention that you have "33s". I suspect you've got "Light Truck" E load range tires. I know that the the ride on my LX w/ AHC became much less "Lexus like", after my LT tires.

 

[128keaton]

In another post, you mention that you have "33s". I suspect you've got "Light Truck" E load range tires. I know that the the ride on my LX w/ AHC became much less "Lexus like", after my LT tires.

That would be my 4Runner post. I have stock Michelins on this LX.

 

[128keaton]

I will double check tire pressures in the morning. They were around mid-30s when I bought the truck, but maybe Firestone filled them up too much. Pretty much SOL on ride quality if not.

 

[95Fantasma80]

At 7 graduations your damper globes are effectively finished, flat, worn out - like most things they have finite functionality.

@PADDO

Apologies to thread hijack slightly as i am dealing with same issue as OP, my 2001 with 192k hates the small cracks on floor which vibrate through cabin as well. I know I have bushings, and new accumalators in future as well as rear springs.

My question for you sir is if the springs in front of car need replacing as well? I adjusted my torsion bars to get front specs correct, but I'm wondering if a new pair of springs would have accomplished the same and give better AHC performance conpared to just adjusting torsions bars, i know replacing rear springs to get AHC back to spec but why not the same process for front?

Edit: I'm such a noob! sorry guys haha.

 

[Qtonic]

The spring force in front is provided by the torsion bars. There are no front springs.

 

[PADDO]

Looks like we need to start referring to our torsion bars as our torsion springs

 

[68W65D]

I've had a similar complaint for a while. And every once in a while, a thread like this pops up and there is never a real definitive answer.
Like you, I have flushed the AHC fluid, checked pressures in TechStream, played with tire pressure, etc.

Here is my plan so far:
1) New globes (mine are also at 7 so I figure it is time)
2) New sway bar bushings, front and back

Hopefully that will fix it.

Some have suggested the harsh ride feel can come from the road force being transmitted through the UCA or LCA and they recommend getting new bushing and ball joints for these. The bushings for the front LCAs are apparently very difficult to replace.
If you want to make changes to the UCA, it has been suggested you can buy an aftermarket UCA set up that will come with new bushings, new ball joints, and allow for more adjustment. This gets spendy.

If I remember correctly, one said just by swapping the ball joints, his problem went away.

I wish you luck. I'll post my results when I do my swaps, but it'll be a few months.

 

[128keaton]

I've had a similar complaint for a while. And every once in a while, a thread like this pops up and there is never a real definitive answer.
Like you, I have flushed the AHC fluid, checked pressures in TechStream, played with tire pressure, etc.

Here is my plan so far:
1) New globes (mine are also at 7 so I figure it is time)
2) New sway bar bushings, front and back

Hopefully that will fix it.

Some have suggested the harsh ride feel can come from the road force being transmitted through the UCA or LCA and they recommend getting new bushing and ball joints for these. The bushings for the front LCAs are apparently very difficult to replace.
If you want to make changes to the UCA, it has been suggested you can buy an aftermarket UCA set up that will come with new bushings, new ball joints, and allow for more adjustment. This gets spendy.

If I remember correctly, one said just by swapping the ball joints, his problem went away.

I wish you luck. I'll post my results when I do my swaps, but it'll be a few months.

Every single 150k Toyota I've had needed new LCA and UCA bushings around that point. Pretty sure this truck will need it at some point.

Still working on sourcing some better or new globes, and then next is new swaybar bushings. Thank you for your help. Will double check ball joints as well.

 

[thetoyotaman]

Does the 7 or 10 graduation change depend on adjustments or setup at all? Seems like I read something about that. Does Toyota have an inspection method for the globes?

 

[128keaton]

Does the 7 or 10 graduation change depend on adjustments or setup at all? Seems like I read something about that. Does Toyota have an inspection method for the globes?

I think few mentioned they got more graduations with a flush, but I don't see how that is possible if you're dealing with a ruptured or flat globe. I certainly didn't get any.

Maybe torsion bar adjustment? But I doubt it figuring how the system works.

I guess I also mis-understood the diagnostic mode test, with the system getting stiffer, meaning that the globes were working.

 

[thetoyotaman]

How do you perform the diagnostic test mode for the AHC?

 

[bamabrock]

How do you perform the diagnostic test mode for the AHC?

everything AHC is here:
Definitive list of AHC maintenance items

 

[68W65D]

I am curious if this is even an AHC issue.

Are non-AHC vehicles experiencing this issue? Or is it just the LXs?

 

[TXLX100]

AHC Globes are clapped out. Best ride you will get is on brand new globes, new rear coils, properly adjusted torsion bars, and a street-ish tire. Next best thing is swapping in a conventional land cruiser OEM suspension

 

[ClassyJalopy]

I had very harsh ride and a lazy AHC that was holding the truck up fine but was slow in raising and lowering it. Flushing the fluid and cranking the torsion bars helped with the raising and lowering but ride remained harsh. Since I noticed some rust on the AHC lines (nothing was leaking anywhere) and since I had only 5 graduations from low to high, I decided to strip off AHC and put used LC torsion bars, OME rear springs and brand new Toyota shocks ($200 for all 4 shocks!). The shocks cushions (on the top of the shock) and bushings (in the 'eye' of the shocks) were still in once piece but were rock hard. This also gave me about 1.75" lift (almost like riding in High setting with AHC)

After all that my truck started soaking large bumps very well, but the small cracks, bridge joints etc would still not be absorbed. I replaced all 4 front ball joints this week and that ended up making the ride much better. My truck is 20 years old and by all accounts the ball joints were factory original. Once out, the play in the ball joints was scary!

I still feel some imperfections in the road but they don't make the change in my cup holder jingle and don't wake up my babies in the back seat!