Need some AHC Help

[dr335i]

Recently bought a 2001 LX470 with 260k miles. The thing is in really amazing condition. Super clean interior and exterior and I have a service history dating back to new! It isn't perfect, it's due for another timing belt/water pump change, one of the heater T's hasn't been replaced (at least at the same time the other one was), has a few slight oil leaks. Overall though, I'm very happy with it!

My suspension isn't crazy bouncy or anything but it does have a little bounce to it and it's definetly not as smooth as it should be. You definitely know you're not riding on a cloud but it goes into high and low as it should. Every now and then after I start it I feel it adjust but I can never tell if it's low after its been sitting or not. If it does drop it's definitely not a lot. Anyway, I ran across that "definitive AHC maintenance list" thread. Decided to go outside and check mine.

First warning sign was that the fluid was well above the "max" line. So I put the vehicle in low. Fluid was dead even with the halfway point of the reservoir (where the tick marks stop). Put it in high and the fluid went down *maybe* four ticks. Like I said, the car isn't riding horrible at all or anything but it's not at its peak performance. At this point I'm wondering if it would even be worth it to flush the system and maybe get my fluid level back to where it should be and see what happens. If my globes are shot, I'm not opposed to buying the Pleiades globes if that's all I need but I don't really know what all the other weak points of the suspension are (changing struts, springs, etc)

I know the easiest thing to do will be to swap to the LC Suspension but I just really like that ultra smooth "Lexus" gliding feel that only hydraulic and air suspension can get you. Plus I think the AHC is actually a pretty cool little system and it's already come in handy a few times. Any advice?

 

[thibaut]

If the spheres are original, they are most likely dead by now. If you are keen on AHC, then I would suggest 3 things:
- purchase 4 new spheres (pleiade or the guy in the UK that sells some on ebay)
- purchase new set of springs for the back. They sag over time and put too much pressure on rear. There are aftermarket you can buy for very reasonnable price but make sure they are the one for AHC. If u use toyota part number they come up (german made)
- replace the spheres, spring and fluid and then do a proper suspension height set up adjusting torsion bars in the front and checking with computer the pressures in the AHC system

 

[JPS]

If the spheres are original, they are most likely dead by now. If you are keen on AHC, then I would suggest 3 things:
- purchase 4 new spheres (pleiade or the guy in the UK that sells some on ebay)
- purchase new set of springs for the back. They sag over time and put too much pressure on rear. There are aftermarket you can buy for very reasonnable price but make sure they are the one for AHC. If u use toyota part number they come up (german made)
- replace the spheres, spring and fluid and then do a proper suspension height set up adjusting torsion bars in the front and checking with computer the pressures in the AHC system

Where are people getting LX springs for the rear?

 

[dr335i]

If the spheres are original, they are most likely dead by now. If you are keen on AHC, then I would suggest 3 things:
- purchase 4 new spheres (pleiade or the guy in the UK that sells some on ebay)
- purchase new set of springs for the back. They sag over time and put too much pressure on rear. There are aftermarket you can buy for very reasonnable price but make sure they are the one for AHC. If u use toyota part number they come up (german made)
- replace the spheres, spring and fluid and then do a proper suspension height set up adjusting torsion bars in the front and checking with computer the pressures in the AHC system

About what I expected to hear. I might go and test drive a Land Cruiser and see how the suspension feels to me. All the sensible parts of me are telling me not to dump that much into a 17 year old and truck just because it might ride marginally better especially being a third vehicle.

 

[PADDO]

First warning sign was that the fluid was well above the "max" line. So I put the vehicle in low. Fluid was dead even with the halfway point of the reservoir (where the tick marks stop). Put it in high and the fluid went down *maybe* four ticks. Like I said, the car isn't riding horrible at all or anything but it's not at its peak performance. At this point I'm wondering if it would even be worth it to flush the system and maybe get my fluid level back to where it should be and see what happens. If my globes are shot, I'm not opposed to buying the Pleiades globes if that's all I need but I don't really know what all the other weak points of the suspension are (changing struts, springs, etc)

I know the easiest thing to do will be to swap to the LC Suspension but I just really like that ultra smooth "Lexus" gliding feel that only hydraulic and air suspension can get you. Plus I think the AHC is actually a pretty cool little system and it's already come in handy a few times. Any advice?

What’s the service history say about AHC fluid changes? A higher then max fluid level has no bearing on damping or the graduation test as such, but with the fluid level well above high I’d want to ensure that nothing other than AHC hydraulic fluid was added to the reservoir. If you search the term “water reaction test” by me you’ll see images of what AHC fluid + brake fluid contamination looks like in a test jar, you’ll also see how AHC fluid and just water don’t mix. What’s probably happened is your reservoir level has lowered as your globes have expired (proportionally more fluid fills the globes as the nitrogen charges diminish) and its been topped off. Fingers crossed it was with AHC fluid, or at a minimum a hydraulic fluid or ATF which isn’t catastrophic at all, and not touched by a quickie lube place that wouldn’t know AHC fluid even existed. In the expectation your current fluid doesn’t show signs of contamination then you could go ahead with a fluid changeout, new aftermarket globes and neutral pressure corrections for <$900, parts only. If there’s any doubt about the old fluids integrity then the sensible approach would be a full internal cleanout including removing and flushing the shock actuators prior to fitting new globes. Or consider replacing the system with conventional. All comes down to the repair v replace conundrum and what your expectations and budget allow.

 

[sailor95]

Sorry to thread hijack but @PADDO , Im thinking of doing some AHC maintenance myself due to the fact that there is no fluid in my reservoir and I have noticed a bit more shakes and rattles to my ride in the past years. I am weary to even mess with the system though because i dont want it to fail with any minor changes because it is so old and used, 2000 model with 343K. It's used more like a truck than most truck owners use they're trucks, pulling scrap trailers, mudding in highschool, and cross country with 5 other friends. Last year i experienced my first ride in low due to 5 other people and luggage going from GA to CO and back. Anyways, just worried if i tinker with it, it will realize its age and fail, suggestions on where to start?

 

[thibaut]

For the AHC springs, german company Suplex makes some. Make sure you buy the right type as they also make much beefer onces for LC which have been converted to non-AHC

I bought from these guys (I am in the uk)
Suplex Standard Rear Coil Springs with AHC - Purple Band

 

[PADDO]

Sorry to thread hijack but @PADDO , Im thinking of doing some AHC maintenance myself due to the fact that there is no fluid in my reservoir and I have noticed a bit more shakes and rattles to my ride in the past years. I am weary to even mess with the system though because i dont want it to fail with any minor changes because it is so old and used, 2000 model with 343K. It's used more like a truck than most truck owners use they're trucks, pulling scrap trailers, mudding in highschool, and cross country with 5 other friends. Last year i experienced my first ride in low due to 5 other people and luggage going from GA to CO and back. Anyways, just worried if i tinker with it, it will realize its age and fail, suggestions on where to start?

I’m guessing you must have some fluid in the reservoir, maybe just the absolute minimum covering the pump intake or you just can’t see the actual level. If you’re serious about working on the system you’ll need to ensure you’ve got sufficient fluid for normal L-N-H cycling to start with. At 343k it’s served you well but sounds like it’s ready for some TLC.

 

[PADDO]

For the AHC springs, german company Suplex makes some. Make sure you buy the right type as they also make much beefer onces for LC which have been converted to non-AHC

I bought from these guys (I am in the uk)
Suplex Standard Rear Coil Springs with AHC - Purple Band

Purple, Pink, Yellow, Green, Brown paint spots, differing free lengths and spring rates across different markets can all get a bit confusing. Then you add in the very useful uprated King KTRS 79s. Definitely not a case of “one coil set fits all”.

 

[tacoduck]

I’d start w a fluid swap. Go to a Toyota dealership and by the ahc fluid and do the swap. Easy job.

 

[sailor95]

Anything you would suggest getting my eyes on first before I attempt a fluid swap with your method? As much as i would love to throw in the slee medium 1.5'', my bank account would not, just scared of something breaking when correct pressures are restored if that is even possible. Just guessing my pressures are out of whack due to ride and inability to hold considerable weight anymore.

 

[tacoduck]

swap fresh fluid... It can't hurt, and might fix the problem. for 50 bucks in fluid, thats where I would start.