1999 LX470 Very Bouncy Ride and Front Drops to Low Height Position (1 Viewer)

[ffl3883]

Hello

My truck has problem in Active Height Control. Couple weeks ago, I scanned the DTC it says faulty left front height sensor. It flashes OFF light when driving all the time. Couple days ago, I accidentally run over a small bump on highway and the OFF flashing is gone. There is only solid light on N for AHC. When I went home, I tried to change height. When I push H, the light at H flashes while light at N remains solid. Same goes for L. There is no change in Height. The next day, I realize my ride starts to get very bouncy when driving and I found out the front is at Low position while the back is at High position. What else went wrong this time ? Any thoughts are appreciated. Please see picture.

1999 LX470

• ffl3883
• May 17, 2017

Regards

Fliu

 

[camino70]

I would check height sensors, especially the front. Have you done anything to it recently?

This thread has a pic of broken linkage:
AHC help ... yeah another one.

 

[FxFormat]

My guess would be your accumulators are shot.

 

[geanes]

When was the system last flushed? Have you checked the fluid (light or dark in color)? Have you run the AHC test? The "bounciness" sounds like a blown shock to me (how old are they, ever been replaced?). The height problem could be a failed sensor or failed accumulator(s), or a combination.

 

[ffl3883]

Hello All,

I went to my mechanic today. They are a talented indie shop fixing BMW and Lexus cars. They suggested remove the AHC and turn into a land cruiser suspension since the suspension system is heavily rusted. They quoted for about $1000. I like the idea since I feel I will have less suspension problems down the road. Does the effort make sense ?

Thanks

FLiu

 

[camino70]

I would perform some simple checks before throwing money at it. Check the fluid level, check the color of the fluid and check the height sensors. I'm inclined to think its a height sensor issue, take some pictures. The pump is working and getting the rear off the ground. If it was just the accumulator, it would be at correct height with a terrible ride. I think the terrible ride is related to the height, hopefully not a bad accumulator too.

Look at the pic in the thread I posted above, turn the wheel and look foot away from the shock (sorry, improper term).

 

[davegonz]

$1000 parts and labor?

 

[ffl3883]

$1000 parts and labor?

Yes part and labor.

 

[ffl3883]

I would perform some simple checks before throwing money at it. Check the fluid level, check the color of the fluid and check the height sensors. I'm inclined to think its a height sensor issue, take some pictures. The pump is working and getting the rear off the ground. If it was just the accumulator, it would be at correct height with a terrible ride. I think the terrible ride is related to the height, hopefully not a bad accumulator too.

Look at the pic in the thread I posted above, turn the wheel and look foot away from the shock (sorry, improper term).

My left front sensor is bad according to DTC scan couple weeks ago at a Lexus shop. It seems to me that replacing height control sensor and accumulates would be more costly and my shocks are already in bad shape. What do you think?

 

[davegonz]

Did they specify what 100 series suspension bits they will use? An Ironman lift is right around $1k alone.

 

[ffl3883]

Did they specify what 100 series suspension bits they will use? An Ironman lift is right around $1k alone.

I will ask. Probably a budget one. What would you recommend for just normal driving. No off road.

 

[geanes]

You'll need more than just the shocks/springs for the conversion. Torsion bars will have to be replaced as the AHC torsion bars are not strong enough for non AHC running. If they can do a complete conversion to an Ironman or OME for $1k, I'd drive up myself and have mine done. Heck, OEM conversion for $1k seems awfully good pricing with labor.

 

[ffl3883]

You'll need more than just the shocks/springs for the conversion. Torsion bars will have to be replaced as the AHC torsion bars are not strong enough for non AHC running. If they can do a complete conversion to an Ironman or OME for $1k, I'd drive up myself and have mine done. Heck, OEM conversion for $1k seems awfully good pricing with labor.

The shop said they are not doing anything with front torsion bar. The quote includes the conversion kit and labor to install. Is that a Hugh problem not getting non AHC torsion bar ? What would you recommend for a budget Non AHC torsion bar ?

 

[geanes]

The shop said they are not doing anything with front torsion bar. The quote includes the conversion kit and labor to install. Is that a Hugh problem not getting non AHC torsion bar ? What would you recommend for a budget Non AHC torsion bar ?

Yes! The vehicle will NOT drive well at all with the AHC torsion bars on a conventional suspension. I defer to the AHC wizard Paddo who wrote the following on another AHC post currently running.....

"The question as to the adequacy of AHC (25.5mm) torsion bars being left in service after the AHC system has been gutted, instead of replacing them with the correctly rated bars (28.8mm) - or heavier if going aftermarket - often comes up. Here's some fun facts regarding the engineering behind torsion bars. All else being equal if you double the thickness of a torsion bar you increase its rate by 16 times so that extra 3+mm in diameter the conventional torsion bar has over the AHC bar provides significantly more effective torsional force - about 60% more actually. You can go to a site such as swayaway.com and in their Tech Room they have a cool TB rate calculator. Using conventional LC bars at 1.13in v AHC bars at 1.0inch (bar length and lever arm lengths are arbitrary as we're just looking at ratios) you'll see that the thicker bar provides approx. 60% more effective torsional rate at the front wheel. Working on the premise that Toyota's design engineers had big brains, plenty of time and billions of yen I'd like to believe they chose torsion bars appropriately rated for their respective applications. Accordingly anyone who seriously believes they can just reindex underrated AHC bars in a non AHC application and get away with it in the long term will ultimately be disappointed."

In short, absolutely replace the torsion bars if converting to non-AHC. If the shop doesn't believe you, show them the above. Paddo is the single most informed person on AHC....period.

 

[geanes]

Here is the other thread regarding AHC potential failure and diagnosis.....

First Bought a UZJ100: 1998 LX470, 198K mi. Failed AHC. Suspension Advice Needed.

It's a goldmine of info on testing and resolution.

 

[ffl3883]

Yes! The vehicle will NOT drive well at all with the AHC torsion bars on a conventional suspension. I defer to the AHC wizard Paddo who wrote the following on another AHC post currently running.....

"The question as to the adequacy of AHC (25.5mm) torsion bars being left in service after the AHC system has been gutted, instead of replacing them with the correctly rated bars (28.8mm) - or heavier if going aftermarket - often comes up. Here's some fun facts regarding the engineering behind torsion bars. All else being equal if you double the thickness of a torsion bar you increase its rate by 16 times so that extra 3+mm in diameter the conventional torsion bar has over the AHC bar provides significantly more effective torsional force - about 60% more actually. You can go to a site such as swayaway.com and in their Tech Room they have a cool TB rate calculator. Using conventional LC bars at 1.13in v AHC bars at 1.0inch (bar length and lever arm lengths are arbitrary as we're just looking at ratios) you'll see that the thicker bar provides approx. 60% more effective torsional rate at the front wheel. Working on the premise that Toyota's design engineers had big brains, plenty of time and billions of yen I'd like to believe they chose torsion bars appropriately rated for their respective applications. Accordingly anyone who seriously believes they can just reindex underrated AHC bars in a non AHC application and get away with it in the long term will ultimately be disappointed."

In short, absolutely replace the torsion bars if converting to non-AHC. If the shop doesn't believe you, show them the above. Paddo is the single most informed person on AHC....period.

Ok is that a safety issue or performance issue. If safety issue, I would replace for sure. My truck has rust problem on the frame. I don't plan to put in too much money. Anyways, what would you recommend for a budget non AHC torsion bar ? With part number would be great. Looks like the repair cost may increase to $2k. I am ok with the cost as long as it's necessary for safety.

 

[geanes]

I would think safety would definitely factor in as the torsion bar is a critical component of the suspension system on these rigs. OEM torsion bars not sure about price. The Tough Dogs from Trail Tailor seem to be a pretty popular option.

Tough Dog Torsion Bars

$320 for the pair

Slee Offroad offer a number of OME (Old Man Emu) kits from medium to heavy lifts for under $1200 that include new OME Torsion Bars. Labor would have to be factored in. But, there are a ton of writeups and how-to videos on here if you were inclined to tackle the project yourself and save the cash. Might even be a local mudder or two that would help out in exchange for some cold brews

Slee - Toyota 100 Series Land Cruiser Suspension Details

 

[geanes]

MetalTech has some good options as well....

Old Man Emu 100 Series Land Cruiser Medium Duty Suspension Kit

 

[ffl3883]

I would think safety would definitely factor in as the torsion bar is a critical component of the suspension system on these rigs. OEM torsion bars not sure about price. The Tough Dogs from Trail Tailor seem to be a pretty popular option.

Tough Dog Torsion Bars

$320 for the pair

Slee Offroad offer a number of OME (Old Man Emu) kits from medium to heavy lifts for under $1200 that include new OME Torsion Bars. Labor would have to be factored in. But, there are a ton of writeups and how-to videos on here if you were inclined to tackle the project yourself and save the cash. Might even be a local mudder or two that would help out in exchange for some cold brews

Slee - Toyota 100 Series Land Cruiser Suspension Details

Is this something that I can install after the conversion? The shop is quite reluctant to do it since it will cost too much labor hours for me.

 

[geanes]

Is this something that I can install after the conversion? The shop is quite reluctant to do it since it will cost too much labor hours for me.

Sure, but you will need an alignment post torsion bar swap. Remember too, if they do any type of lift, you'll probably need UCAs as well to compensate for the increased caster. If they just swap OEM or stock height, you wouldn't need UCAs unless they were worn out.