LX470 AHC Accumulators (Updated with pressures & comments) (1 Viewer)

[Rio Sunset]

2001 LX470

Front pressure- 8.6 MPA

Rear- 7.7 MPA

AHC works in all positions, damping settings appear to work to an extent.

Vehicle is somewhat bouncy when not on sport mode. A case could be made for getting 7 gradations between low and high, but it is likely closer to 5.

Seems that the dampening is somewhat lacking.

AHC has been flushed with OEM fluid.

Is it possible that the 'GLOBES' have not failed?

I am leaning towards four new "Toyota" accumulators.

Should I adjust neutral pressures and retest gradations? What effect would higher pressures have on the gradations test?

New springs and crank torsion bars?


Thanks!

 

[2001LC]

Globes.

 

[Rio Sunset]

$1150 shipped for OEM 'Toyota' globes reasonable?

 

[BullElk]

Just curious....when would it be shocks and not globes ?

 

[Rio Sunset]

I think there would be indications of fluid leakage at the shocks if they failed. Additionally, the vehicle would likely have difficulty maintaing height.

 

[Rio Sunset]

In this application the 'globes' are the dampers. Just curious to see if anyone has had a lack of damping attributable to other factors. My pressure are 2MPA higher than toyota spec, however I don't believe this would result in the bouncy ride.

 

[2001LC]

@PADDO is the expert here. You may want to see what he has to say before puchases. Sources for AHC Accumulator Globes

 

[2001LC]

Weak rear spring, T-bars not adjusted properly would give a bouncy ride. But 5 gradations after a proper flushing is good indication of weak globes.

 

[sorich]

You won’t know the condition of the globes without getting the system to the right pressure range. Adjust tbars to get the front pressures in line first, replace springs in rear to get rear pressures more in line (if replacing springs, install spring spacers at the same time), then do the graduation test and see where you are.

My understanding is that test is only useful if pressures are good.

 

[kingkonger708]

I have a full OEM AHC system for sale on a low miles Land Cruiser in perfect working condition if you are interested. I installed a lift and the existing suspension was in such good condition that I had it professionally removed.

 

[JPS]

$1150 shipped for OEM 'Toyota' globes reasonable?

5 graduations means the accumulators are shot. I just did a change this past weekend and paid just under $1150 myself. I think I found a little bit cheaper price somewhere, but went for the great reviews from the seller, US shipping, and supposedly 2017 OEM produced globes.

I also did an AHC fluid swap at 5 grads about 6 months ago, but after accumulator change I stopped counting at 12 or 13 grads. The ride is 100% fixed. My vehicle would lift rear then front before the globe/accumulator swap, but still functioned pretty quickly from L to H. Now it lifts evenly. I kept the AHC for now, but may switch out to shocks in the future. If you plan to offroad seriously, maybe go ahead and switch it out.??... all depends on your plans for the vehicle.

Next, I need to get some techstream software and adjust the torsion bars. Im also sure the rear coil springs need to be replaced, but have not found a source yet for Lexus made springs.

Where in South Florida are you located?

 

[JPS]

In this application the 'globes' are the dampers. Just curious to see if anyone has had a lack of damping attributable to other factors. My pressure are 2MPA higher than toyota spec, however I don't believe this would result in the bouncy ride.

You can slowly put a single tire up on a curb and roll off on each side. You will feel a big difference if one of the four doesn't bounce as bad or does..... not sure if this is recommended, but its what I did first.

Also, follow the bleeding swap procedures, making sure all the pressure is bled off, and take a globe off. If it is shot, u can stick a pencil inside the globe and there will be no resistance. A healthy globe will have resistance much sooner. I had one healthy globe after 175K, but I'm the type who changes all out when one goes bad.

 

[PADDO]

You can slowly put a single tire up on a curb and roll off on each side. You will feel a big difference if one of the four doesn't bounce as bad or does..... not sure if this is recommended, but its what I did first.

Also, follow the bleeding swap procedures, making sure all the pressure is bled off, and take a globe off. If it is shot, u can stick a pencil inside the globe and there will be no resistance. A healthy globe will have resistance much sooner. I had one healthy globe after 175K, but I'm the type who changes all out when one goes bad.

The “pencil test” demostates if the diaphragm has ruptured, rendering the accumulator unequivocally unserviceable scrap. This one is easy to diagnose. The other failure mode, normal gradual degradation through gaseous permeation - going flat over time - also renders the accumulator functionally unserviceable with unacceptable damping response yet the diaphragm still remains intact and can’t be depressed by hand with a blunt object like a pencil. Unfortunately it’s not as easy as saying the diaphragm is intact therefore the accumulator is healthy. In a vehicle with three of four OE accumulators ruptured there could be a bigger issue and the fourth is not likely to be healthy at all. With all things being equal, with correct neutral pressures and four new fully charged accumulators the system collectively expels 14 graduations of fluid back to the reservoir for the L to H test. Toyota deems the accumulators functionally unserviceable and undercharged when they collectively return only 7 graduations (US market) and personally I think anything less than 9 grads is a becoming a pretty harsh ride. The L to H test can’t isolate a single serviceable or unserviceable damper accumulator (or any combination of) but putting the system into test mode and doing the 16 step damper check does help to isolate a ruptured accumulator(s) and damper control problems.

 

[JPS]

In a vehicle with three of four OE accumulators ruptured there could be a bigger issue and the fourth is not likely to be healthy at all.

Hi Paddo,

On my vehicle, I was making the ASSumption that the globes having 175K miles were shot from age/usage. What could the bigger issues be, all things considering?

Thanks.

 

[PADDO]

Maybe I misunderstood your situation as I read it that you had three ruptured accumulators as per sticking a pencil in and it bottomed out and one that was not ruptured because the pencil stopped up hard against the diaphragm retainer? If that’s the case then three rupturing could be due to simple mechanical failure of undercharged diaphragms being worked too hard for too long; or it could be due to particulate contamination rubbing the diaphragms through; or could be chemical contamination, such as brake fluid, reacting with and destroying the diaphragm material. I don’t want to sound alarmist but three of four rupturing (if that’s the case) is a bit of an anomaly. But if they were all intact, yet you were only getting a few graduations on the reservoir and the damping was horrible then that sounds more like general, age related flatish accumulators.

 

[JPS]

Maybe I misunderstood your situation as I read it that you had three ruptured accumulators as per sticking a pencil in and it bottomed out and one that was not ruptured because the pencil stopped up hard against the diaphragm retainer? If that’s the case then three rupturing could be due to simple mechanical failure of undercharged diaphragms being worked too hard for too long; or it could be due to particulate contamination rubbing the diaphragms through; or could be chemical contamination, such as brake fluid, reacting with and destroying the diaphragm material. I don’t want to sound alarmist but three of four rupturing (if that’s the case) is a bit of an anomaly. But if they were all intact, yet you were only getting a few graduations on the reservoir and the damping was horrible then that sounds more like general, age related flatish accumulators.

Good to know, hopefully 2x flushing will get any contamination out if that was the case. I now have a HUGE label on my reservoir in case I get it serviced by someone else in the future.

I did notice one thing interesting, when I flushed 6 or more months ago I got some nasty AHC fluid out.... blackish. it looked on par to what I have seen in pics and video. I imagined it was original fluid, and bled until nice clean pinkish fluid. Strangely enough the vehicle rode immaculate for 2-3 days! At this time I had 6 graduations and the bleeding was more than likely a waste of time, but I went ahead anyway. Also, more than likely, all three Accumulators that were trashed, were trashed at that time.

I flushed again to change the globes and it came out tan/foamy this past weekend. I have also seen others get these results, but I was wondering if this was an air contamination on my first attempt? Or it could have been from the dissolved internals of the accumulator itself?

I have put 2 large AHC cans through at this time and then some. I might actually bleed it again just to be safe, but I am pretty confident that whatever, if any, contaminant that could have been in there is flushed out at this time.

Thanks!

 

[Rio Sunset]

I adjusted the pressures to spec, and now have a almost bounce free ride and 7 gradations. May put the ahc into test mode to see if the accumulators need attention.

 

[PADDO]

I adjusted the pressures to spec, and now have a almost bounce free ride and 7 gradations. May put the ahc into test mode to see if the accumulators need attention.

To get the most damping out of your tired accumulators you should try and relieve as much hydraulic preload on them as practical by getting the front pressure down around 6.7MPa and the rear below 6MPa. It makes a difference.

 

[ChuckB]

I've got a semi-related question for @PADDO. I'm still in the process of going through the same evolution. My most recent pressures were 6.6 front and 6.7 rear.
On the rear I have new AHC Springs and a 30mm spacer. I expected the pressure to be a little bit lower. I do believe it has come down from around 7.7, but think it should be lower. Is my next step to adjust the rear height sensor to reduce the height in the rear? I need to measure it again but I think its sitting a little bit high and know it should be about 520mm. Visually it looks high though.
Already flushed once, but going to do it again as well. Then start taking a look at the accumulators if necessary.

 

[JPS]

I've got a semi-related question for @PADDO. I'm still in the process of going through the same evolution. My most recent pressures were 6.6 front and 6.7 rear.
On the rear I have new AHC Springs and a 30mm spacer. I expected the pressure to be a little bit lower. I do believe it has come down from around 7.7, but think it should be lower. Is my next step to adjust the rear height sensor to reduce the height in the rear? I need to measure it again but I think its sitting a little bit high and know it should be about 520mm. Visually it looks high though.
Already flushed once, but going to do it again as well. Then start taking a look at the accumulators if necessary.

I cant answer as well as Paddo, but have u measured hub to fender and looked at torsion bar corrections?

Also, where did you get your AHC springs? I will be looking for some soon.