2003 LX AHC - Shock repair, replace, or wait (3 Viewers)

[Beehett]

Driver rear shock on my 2003 LX with 160k is weeping. System seems to work fine for now. I thought i read someplace that these can be rebuilt with new O-rings but didn't find anything on these forums. I am NOT planning on spending $5k to rebuild the whole system, but don't mind a few hundred to get many good years. A couple questions:
1) Can they be rebuilt
2) is it most people's experience that once the first fails, they all go quickly
3) Have people replaced just one or do most switch out to an OME kit at first sign of an issue

Any insight much appreciated.

 

[Mauser]

My front shocks were seeping like that. I checked the pressures and they were 8.1. I cranked the torsion bars some and got the pressures down. No seeping now.

 

[trdcorolla]

My front shocks were seeping like that. I checked the pressures and they were 8.1. I cranked the torsion bars some and got the pressures down. No seeping now.

Ditto

 

[Beehett]

Great. And how would I adjust the torsion bars?

 

[Ramathorn15]

Great. And how would I adjust the torsion bars?

If it's the rear, youll likely need new rear coils. You need to read your pressures first to really know what's going on.

 

[CanadianRockyCruiser]

With the giant bolts attached to the torsion bars, near the middle of the frame. You will need to buy the techstream ODB2 tool to measure your pressures, but a few turns of the torsion bars should help. Make sure you turn both evenly, to keep a balanced stance.

 

[Ramathorn15]

Here's what you should do:

1) research techstream and buy the cable. You should be able to get it on a laptop for around $30 including the cable.

2) take a reading of the front and rear shock pressures. Compare those to the factory specs (you'll have to search for these as I don't remember off the top of my head. Something close to 6.7mpa front and 6.4mpa rear)

3) crank the large 30mm torsion bar bolts under the truck. Mark the bolt so you can count how many turns. Each turn lowers the pressure about 0.2mpa. do the same number of turns left/right.

4) read pressure again and adjust until the front is in spec. If the rear is still really high, you'll need new coil springs or 30mm spacers to compensate for the old saggy ones.

You should quit weeping at that point.

 

[Mauser]

I added air bags to mine for pulling the trailer. If I keep 6.5 psi in them my pressures are at the bottom of spec. I dont remember what that number was though. When I tow my trailer I air up to 24 psi to keep the numbers close.

 

[BEG]

The good news is, it's unlikely you have to do anything to the shock actuators. They tend to seep fluid when the system pressure is too high. The even better news is that you get to delve into the wonderful world of AHC maintenance!

As @Ramathorn15 mentioned, you need a way to read the neutral pressures on the AHC system. Many people like Techstream. I don't. I prefer a handheld reader that's capable of reading AHC, ABS and all other Toyota proprietary codes. The one I use the iCarsoft TYT II.

Before making any adjustments, I think it's always a good idea to change out the old fluid, cross level the front end and then read the pressures. You can find details on how to perform these task in the "Definitive AHC Maintenance" thread.

Be aware that, while you can adjust the preload of the torsion bars in the front to get the pressures within spec, the rear will most likely require coil spacers, new springs, or both.

 

[Beehett]

Thanks guys. I've got the cable on order. I'm thinking adjust pressure and springs for current system, and then when globes go bad replace with OME lift (maybe 2" to 3"). For new rear springs, are there springs that will work with both the stock AHC and a 2" OME lifted suspension at some point in the future?

 

[CJ1117]

Thanks guys. I've got the cable on order. I'm thinking adjust pressure and springs for current system, and then when globes go bad replace with OME lift (maybe 2" to 3"). For new rear springs, are there springs that will work with both the stock AHC and a 2" OME lifted suspension at some point in the future?

Hi, new owner of 03 LX470 here (212k). I have the exact same seeping problem but on the passenger side rear shock. Did replacing rear springs help with the problem? did you replace one or both? I took my car to lexus dealer and they recommended replacing both Shocks. My AHC system still working normally, fluid level/ and movement seem normal. I haven't done AHC fluid flush. I'm also thinking about removing the entire AHC and replace with Land Cruiser's so i don't have to worry about it. I'm new to this and not very mechanically inclined. What would you do? Any recommendation would be greatly appreciated.

 

[BEG]

Hi, new owner of 03 LX470 here (212k). I have the exact same seeping problem but on the passenger side rear shock. Did replacing rear springs help with the problem? did you replace one or both? I took my car to lexus dealer and they recommended replacing both Shocks. My AHC system still working normally, fluid level/ and movement seem normal. I haven't done AHC fluid flush. I'm also thinking about removing the entire AHC and replace with Land Cruiser's so i don't have to worry about it. I'm new to this and not very mechanically inclined. What would you do? Any recommendation would be greatly appreciated.

AHC shock actuators go bad about as often as dealer techs correctly diagnose AHC issues, which is very rarely. They are, essentially, hydraulic rams with no gas charge and only function to transmit linear motion to the accumulator globes. My recommendation to anyone with any potential AHC issues is to flush the fluid, cross level the front suspension and read the pressures. Any AHC diagnostic processes outlined in the literature are intended to be done on a vehicle with all of these things done already, so that is always the first step. Nine times out of ten, this solves the issue. Seeping actuators are no different. Even with perfect pressures and new fluid, Toyota's own literature allows for a certain amount of AHC fluid to seep through the seals.

 

[suprarx7nut]

Hi, new owner of 03 LX470 here (212k). I have the exact same seeping problem but on the passenger side rear shock. Did replacing rear springs help with the problem? did you replace one or both? I took my car to lexus dealer and they recommended replacing both Shocks. My AHC system still working normally, fluid level/ and movement seem normal. I haven't done AHC fluid flush. I'm also thinking about removing the entire AHC and replace with Land Cruiser's so i don't have to worry about it. I'm new to this and not very mechanically inclined. What would you do? Any recommendation would be greatly appreciated.

Dealers are notoriously clueless on AHC. It's a problem.

Forget the shock replacement notion until you know neutral pressures. The dealers should have that figure recorded. If they do not, shame on them. I'd call them and ask for the recorded neutral pressure, as that's a very basic requirement for any AHC diagnostic work.

If neutral pressures are good, then the shock may be bad. That said, the service manual very clearly states some seepage is normal and expected. If it's enough to drip off the bottom, that's too much.

If neutral pressures are high, they must be adjusted. Adjusting the front is free and very easy. All you need is a 30mm wrench (and techstream or some other tool to watch the pressure readings). That's it. For the rear, you either replace the rear springs or add spacers. OEM springs will wear out over time so old ones need spacers or new springs.

IMO, AHC removal only makes sense if two scenarios:

1. You're building a rig to cross Africa, the outback of Australia, Pan-America highway or similar and will have hundred/thousand mile stretches of off-road travel with no access to help.
2. You have a seriously rusted rig with parts disintegrating. This is generally only a problem in the midwest or east coast of the US. Southern or western trucks are almost never rusty enough to warrant AHC removal.

In the past, AHC knowledge was a little less abundant and the dealer was a necessary evil. One that left many owners with limited options - pay the exorbitant and often erroneous dealer quotes for replacement of parts or convert the system to standard suspension. Today, thanks to communities like ih8mud, you have more options. There are a handful of experts on here that can help diagnose remotely better than the average dealer can with the car on their own lift. Given the abundance of understanding on the system as of 2020, it's generally very easy to identify the problem component and fix it more cheaply than you could properly convert a system. Additionally, AHC offers a combination of comfort and sportiness that you can't achieve with any other off-the-shelf system for the 100.

This video might offer some guidance.

AHC shock actuators go bad about as often as dealer techs correctly diagnose AHC issues, which is very rarely. They are, essentially, hydraulic rams with no gas charge and only function to transmit linear motion to the accumulator globes. My recommendation to anyone with any potential AHC issues is to flush the fluid, cross level the front suspension and read the pressures. Any AHC diagnostic processes outlined in the literature are intended to be done on a vehicle with all of these things done already, so that is always the first step. Nine times out of ten, this solves the issue. Seeping actuators are no different. Even with perfect pressures and new fluid, Toyota's own literature allows for a certain amount of AHC fluid to seep through the seals.

Bingo.