AHC Hydraulic Pistons

[HeebyJeebson]

I took my 2001 LX470 to the stealership for a full inspection, I'm new to this and feel comfortable in fixing what I can. They recommend typical things like replacing worn ball joints and a cv axle with torn/leaking boot. One of the things they said was to replace all 4 shocks. From what I've read they usually don't need to be replaced, and that "weeping" is fine for the AHC 'shocks' but one of them is full on leaking with fluid all over the control arm. Is that a salvageable part or should that be replaced? The others seem fine, if a little wet, and can be ignored?

Videos I've seen only remove the AHC entirely rather than replace the hydraulic.

Any advice is welcome!

 

[tbisaacs]

Replace it. They are super cheap.

 

[Coin]

AHC is pretty simple, and super reliable. So reliable, almost no dealerships know what they are working on. If you are serious about fixing what you can, read this:

Thread 'The ABCs of AHC - How to Measure, Flush, and Adjust all in one place'

May 29, 2020

I initially put this in the Definitive list of AHC maintenance items thread, but at almost 800 posts long and growing, it's going to get buried and the thread itself is very unwieldy.

In an attempt to make as focused a summary as possible, I present "The ABCs of AHC." It's intended as a comprehensive, linear checklist for anyone who needs to get their AHC back into factory tune. Information gathered from as many sources as I could find on this forum; I take no credit for developing any of this, just bringing it all together as much as possible. Special shout outs to...

• LndXrsr
• ahc
• Replies: 491
• Forum: 100-Series Cruisers

• 
• 
• 

It will arm you with The knowledge to keep your AHC happy for decades to come, and save you THOUSANDS of wasted dollars.

Seriously, read it.

 

[BullElk]

Replace it. They are super cheap.

Say huh? $240 per copy at the dealer cheap to you?

 

[Zuberg]

As others mentioned above, Dealerships don't necessarily know much about the AHC systems.

Given the amount of rust shown in your picture, you may want to have a shop or someone with decent AHC knowledge inspect the entire AHC system (all the lines) and see their condition. Rust is about the only thing that can kill these rigs and the AHC has a lot of lines and components that the rust can take out.

All/most the AHC bits and bobs are still available new, but once the rust starts taking pieces out it can get expensive quickly if you aren't replacing the components yourself.

 

[tbisaacs]

Say huh? $240 per copy at the dealer cheap to you?

Yea that’s what shocks cost. The alternative is drive around and keep nursing it or dump the whole thing for conventional suspensions which is much more expensive.

 

[BullElk]

Yea that’s what shocks cost. The alternative is drive around and keep nursing it or dump the whole thing for conventional suspensions which is much more expensive.

Perhaps.... but "super cheap" ? An actual failed AHC piston is very uncommon but the weeping is not uncommon and a very manageable option that costs pretty much $0 ....which is super cheap.

 

[Coin]

Yea that’s what shocks cost. The alternative is drive around and keep nursing it or dump the whole thing for conventional suspensions which is much more expensive.

Read the thread I posted. Most likely, all you have to do to stop the weep/leak is adjust your torsion bars.

 

[IndroCruise]

I took my 2001 LX470 to the stealership for a full inspection, I'm new to this and feel comfortable in fixing what I can. They recommend typical things like replacing worn ball joints and a cv axle with torn/leaking boot. One of the things they said was to replace all 4 shocks. From what I've read they usually don't need to be replaced, and that "weeping" is fine for the AHC 'shocks' but one of them is full on leaking with fluid all over the control arm. Is that a salvageable part or should that be replaced? The others seem fine, if a little wet, and can be ignored?

Videos I've seen only remove the AHC entirely rather than replace the hydraulic.

Any advice is welcome!

View attachment 3959248

It has all been said above already .....

Way back in 2016, as an AHC beginner before I was MUD-trained by @uHu and others, I allowed a Dealer's Mechanic to pursuade me to change the Front 'shocks' (which as I learned later, are not conventional 'shock absorbers' -- no gas -- but simple hydraulic struts -- actual damping is done by the Damping Force Control Actuators to which the 'globes' are attached).

The change-out was completely unnecessary.

The weep was caused by failure to monitor AHC pressures over time PLUS having ARB fit an ARB Deluxe Bullbar (adding around 80kg or about 170 pounds) WITHOUT correcting Front AHC pressures by simple adjustment at the Front torsion bar adjusters, then hitting a few 'interesting' trails with Front AHC over-loaded!!

So step #1 is to use the Torsion Bar Adjusters to transfer load OFF the Front AHC system and ON to the Torsion Bars. This could take as much as 15 minutes per side! The correction may elliminate the leak unless there really has been damage to the internal seals at the pistons ....

If you decide to go ahead with change-outs of AHC 'Shock Absorbers', then the following link gives some good descriptions and pictures:

Thread 'Front AHC shock bushing and cushion replacement'

Aug 9, 2020

I tackled this job yesterday, figured the shocks/rams were not leaking so why not refresh them? Maybe they'll last another 300k Rears are not as bad and I'll wait a little bit, lower ball joints are next.

New VS Old

Painted up

• Travis Bickle

• 

In my case Toyota/Lexus Part Number 48510-60081 was used for both RH and LH Front 'Shock Absorbers' -- there are some differences in Part Numbers for different Model Years (particularly relating to the details of the hollow tube at the top of the 'shock absorber' and the Upper Bush/Cushion) -- so it is best to check using the VIN for your vehicle.