AHC TB Reindexing in Case of Failure... But What About Droop? (1 Viewer)

[GTV]

In the two years I've owned my 100 series I've come around to really appreciate AHC but being a comparatively complicated system it does come with risk. @FxFormat's recent post illustrates exactly what I'm talking about.

If this were to happen in a remote location it could be a real problem. I'm looking to mitigate that risk.

Simply put, I'd like to reindex my torsion bars to leave as much thread on the adjusting bolts as possible. In case of failure I could just wind them in, raising the front enough to get me out of a pickle. Now, maybe I've missed it but I haven't found any information on droop vs the lighter weight AHC torsion bars... Is droop as critical on an AHC suspension as it is with the standard static suspension? Is there anything else I'm missing here or is there an alternative solution I've missed?

 

[ktmracer01]

Sorry to see that you have an AHC leak. Hopefully, it's just the shock and not one of the lines. They can be tricky to replace.

To answer your question, the 'droop' as I understand it is the amount of wheel travel you have. Re-indexing the torsion bars will not affect wheel travel. What it will affect it the amount of pressure on the system and the ability of the shocks to mitigate rebound and compression when the TB is adjusted to maximum torsion.

I installed Sway away torsion bars on my rig after installing a front bumper as a preventative measure for what you're experiencing. It's a little stiffer in the front than before, but I'm not worried about it. Others have installed Old Man Emu, and I've heard positive results.

 

[GTV]

Sorry to see that you have an AHC leak. Hopefully, it's just the shock and not one of the lines. They can be tricky to replace.

To answer your question, the 'droop' as I understand it is the amount of wheel travel you have. Re-indexing the torsion bars will not affect wheel travel. What it will affect it the amount of pressure on the system and the ability of the shocks to mitigate rebound and compression when the TB is adjusted to maximum torsion.

I installed Sway away torsion bars on my rig after installing a front bumper as a preventative measure for what you're experiencing. It's a little stiffer in the front than before, but I'm not worried about it. Others have installed Old Man Emu, and I've heard positive results.

To be clear I personally am not currently experiencing any AHC issues, the picture is not mine just an example of what can happen.

For my ‘07 LC I’m keeping a very mindful eye on weight (especially over the front axle) so the standard lightweight AHC bars should suit my needs just fine.

 

[FxFormat]

I found out that the shock itself has sprung a leak, looks to be from the valving/piston. I suspect the broken sway bar link might've attributed to the excess wheel travel and when i hit a bump it ruptured the shock. I don't have evidence but the same corner that the link broke, was the same corner the shock leaked, just days after the broken link. It's a good idea to have room in your TB to hoist the truck in case of a fail like mine, you'll still bounce around like a pogo stick but your wheel isn't gonna hit the fender like mine did.

If anyone has connections to some AHC shocks please let me know, i need one before saturday, i bought some aftermarket ones on amazon but will return that if i can't find an OEM ahc shock.

 

[uHu]

...Simply put, I'd like to reindex my torsion bars to leave as much thread on the adjusting bolts as possible. In case of failure I could just wind them in, raising the front enough to get me out of a pickle. Now, maybe I've missed it but I haven't found any information on droop vs the lighter weight AHC torsion bars... Is droop as critical on an AHC suspension as it is with the standard static suspension? Is there anything else I'm missing here or is there an alternative solution I've missed?

The position of the adjustment arms will not in any way affect the droop or any other parameter, as the TB will still be in the exact same position.
That's a very good idea though - I wonder how much the full travel of the adjuster will manage to lift the front off the bump stops, if at all. In any case, it will behave better with more torsion bar tension, in an emergency, if the ahc fails.

... i bought some aftermarket ones on amazon but will return that if i can't find an OEM ahc shock.

Aftermarket AHC shocks? I searched Amazon - found "gas shocks" that supposedly fit LX470. Gas shock doesn't match the AHC system, and it doesn't mention AHC anywhere.

 

[ClassyJalopy]

I found out that the shock itself has sprung a leak, looks to be from the valving/piston. I suspect the broken sway bar link might've attributed to the excess wheel travel and when i hit a bump it ruptured the shock. I don't have evidence but the same corner that the link broke, was the same corner the shock leaked, just days after the broken link. It's a good idea to have room in your TB to hoist the truck in case of a fail like mine, you'll still bounce around like a pogo stick but your wheel isn't gonna hit the fender like mine did.

If anyone has connections to some AHC shocks please let me know, i need one before saturday, i bought some aftermarket ones on amazon but will return that if i can't find an OEM ahc shock.

@Lexus Cruiser recently removed his AHC stuff!

 

[GTV]

The position of the adjustment arms will not in any way affect the droop or any other parameter, as the TB will still be in the exact same position.
That's a very good idea though - I wonder how much the full travel of the adjuster will manage to lift the front off the bump stops, if at all. In any case, it will behave better with more torsion bar tension, in an emergency, if the ahc fails.

Thank you @uHu! It will likely take a bit of trial and error to get them maxed out (along with pressures and height) but I figured it can only be of benefit, especially in an emergency. Glad I had a good idea, at last!

 

[medtro]

I installed Sway away torsion bars on my rig after installing a front bumper as a preventative measure for what you're experiencing. It's a little stiffer in the front than before, but I'm not worried about it. Others have installed Old Man Emu, and I've heard positive results.

Have you done anything to the rear to avoid situation like this?

 

[medtro]

Thank you @uHu! It will likely take a bit of trial and error to get them maxed out (along with pressures and height) but I figured it can only be of benefit, especially in an emergency. Glad I had a good idea, at last!

How are you going to emulate the failure for this reindexing test?

 

[ktmracer01]

Have you done anything to the rear to avoid situation like this?

I didn't do anything specifically as a preventative measure for the rear AHC. I expect the rear springs can support factory load in the event of an AHC system failure. I did install King springs and spacers, though. They were installed for the future installation of a rear bumper and swing-out tire carrier. I also haul approx. 200-300lbs in the back of my rig when I'm on an adventure, and extra passengers.

 

[GTV]

How are you going to emulate the failure for this reindexing test?

I haven't yet thought of a simple way to test it out. If someone has an idea I'm all ears but I'm not all that worried about it. It can only help... right?

For the rear I plan to install airbags once I have onboard air. I also have King's + 35mm of spacers.

 

[medtro]

I haven't yet thought of a simple way to test it out. If someone has an idea I'm all ears but I'm not all that worried about it. It can only help... right?

For the rear I plan to install airbags once I have onboard air. I also have King's + 35mm of spacers.

I think it can only help too but is it enough help when you are in the middle of no where? Knowing that it is going to work would be better.

I am running LC100 TBs and LX570 rear springs. Hopefully we will never have to find out what works.

 

[J1000]

I found out that the shock itself has sprung a leak, looks to be from the valving/piston. I suspect the broken sway bar link might've attributed to the excess wheel travel and when i hit a bump it ruptured the shock. I don't have evidence but the same corner that the link broke, was the same corner the shock leaked, just days after the broken link. It's a good idea to have room in your TB to hoist the truck in case of a fail like mine, you'll still bounce around like a pogo stick but your wheel isn't gonna hit the fender like mine did.

If anyone has connections to some AHC shocks please let me know, i need one before saturday, i bought some aftermarket ones on amazon but will return that if i can't find an OEM ahc shock.

Are you really sure it's leaking? They have a relief valve at the top so if you bottom out it spurts a little fluid out the top but otherwise there is no damage. Take it to a car wash and clean off all the fluid and I bet it doesn't come back.

 

[Lexus Cruiser]

@Lexus Cruiser recently removed his AHC stuff!

I did, but I literally just sold it about 20 minutes ago.

 

[suprarx7nut]

I found out that the shock itself has sprung a leak, looks to be from the valving/piston. I suspect the broken sway bar link might've attributed to the excess wheel travel and when i hit a bump it ruptured the shock. I don't have evidence but the same corner that the link broke, was the same corner the shock leaked, just days after the broken link. It's a good idea to have room in your TB to hoist the truck in case of a fail like mine, you'll still bounce around like a pogo stick but your wheel isn't gonna hit the fender like mine did.

If anyone has connections to some AHC shocks please let me know, i need one before saturday, i bought some aftermarket ones on amazon but will return that if i can't find an OEM ahc shock.

I think we have some used shocks in the Air Down Gear Up shop. If you still need some next week I can take a closer look at what we have. I can't guarantee they're any good, but I don't know them to be bad.


@GTV why not just learn/document the reindexing process and keep the tools/process printout in your car? I wouldn't do it ahead of time, but I do think knowing how to do so in the field is smart. Prepare for failure, but don't plan your life assuming it's all going to go wrong, haha.

 

[medtro]

@GTV why not just learn/document the reindexing process and keep the tools/process printout in your car? I wouldn't do it ahead of time, but I do think knowing how to do so in the field is smart. Prepare for failure, but don't plan your life assuming it's all going to go wrong, haha.

I wouldn't want to deal with this on any trail.

Torsion bar adjustment bolt completely wrecked on a rust free vehicle.

This is only one side. I can’t remove the other even with penetrating oil and propane torch with shovel on breaker bar for leverage.

forum.ih8mud.com

 

[SuperExciteBike]

Probably about to trigger a potentially huge debate but when working properly, AHC is awesome and arguably superior to standard static suspension. AHC levels ride height when fully loaded with passengers and cargo. It adjusts pressures on the fly to improve handling. Too tall to fit in a garage? No problem switch to low mode. Want to do some light crawling? Switch to high mode for 2.5" lift. All of this with no hit to fuel economy vs a statically lifted rig. For most people who 95% highway and 5% off road over washboard/trail/dirt/forest/desert, hard to beat.

Compared to conventional spring/shock suspension, yes, AHC is a more complicated system but I still prefer it for the above reasons. Failures are rare but as with any system like brakes, A/C, powertrain, drivetrain, steering, they are always possible especially when there is a lack of maintenance.

The biggest factor is properly maintaining the AHC system as our rigs age. To give the AHC a general tune up, 1) flush the fluid with genuine Toyota AHC fluid and 2) follow these procedures:

For perspective, on my 2006 with 169k, I have done the following -

Replaced hydraulic fluid with genuine Toyota AHC fluid
Replaced all 4 AHC "shocks"
Replaced all 4 AHC "globes"
Adjusted front torsion bar back to OEM pressure range and cross leveled
Replaced stock rear AHC springs with King AHC springs to get rear pressure in spec due to increased load (roof rack, ARB drawers, and A LOT of camping gear)

As a result of doing the above my 06 LX now rides as I would expect it to off the lot. I've taken this thing all over the southwest and it is business class luxury every time I get in.

AHC is not for everyone but nice stuff requires upkeep. At the end of the day whatever you decide to do, I think we can all agree we're all in pursuit of the same thing. And that is to get on the road and be able to smile and think: this is what Land Cruising should feel like.

 

[Moridinbg]

If the AHC gives up you are on bump stops and that's it. The stock torsion bars would have to be reindexed to unsafe levels to be able to even slightly lift the vehicle above the bump stops, if possible at all. The rear springs are plain unable to.

 

[hoser]

The Strutmasters (AHC elimination) kit uses the stock AHC t-bars but specifies to re-clock them by 2 splines. I'm not recommending this kit, I'm just saying it can kinda support a stock weighted 100.

If somebody wanted to be ultra prepared, I'd say a 30mm socket and pre-installed Timbren or Wheeler Bumpstops front and rear would be part of the plan.

I think most common AHC failure is the AHC sensors. Three connectors with the "right" resistor that tricks the system into thinking all is fine and dandy would be cheap and helpful. I have not tested this theory though.

In my 20 yrs of ownership, I've had one AHC failure, 600 miles from home but I was able tinker with it and made it home without issue. It was an AHC sensor failure. When I got home, I disconnected the "bad" sensor and drove around town. Except for the blinking light, it was fine. The rear only has one sensor. So, if anything, a spare rear sensor would be most helpful.

I should perhaps test these theories further.... but maybe somebody else can!

 

[J1000]

AHC rules