I've been collecting parts for the last 6 months to rebuild the AHC on my 1999 LX470. I have a full set of new OEM globes, 4 new shocks and rear springs. Both front shocks are leaking fluid along with one in the rear. So, what's the difficulty (Banana) rating for a home garage mechanic? I've bled the system before with no trouble, but I'm a little concern about the R&R of the globes and shocks. Looks like a really thin open end wrench is needed for the globes and the clearance at the top of the rear shocks looks tight! Anyone have advice they can share? Also, how do I use TechStream data (attached) to set-up AHC? Thanks
Ready for AHC Rebuild on 1999 LX470; Looking for Banana Rating
- Thread starter Agent T
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You need to take your pressure readings when you raise from low to normal height, your reading at High in the image isn't useful for anything much.
So, adjust cross level at the torsion bars then front and rear heights if necessary. Then knowing accurate (low to normal) pressures you'll likely need to install the new coils to get the rear pressure down and you'll also need to adjust your torsion bars for the front pressures. Adjusting pressures is an iterative process to get things dialed in accurately. A ford fan clutch 36 mm wrench is what you need for the damper accumulators. Lift the front or rear as you change the accumulators to minimize fluid loss. Don't forget the system is under pressure and the vehicle will drop when you crack a bleeder. You'll need a can of fluid to top off and bleed the system after installing your new globes. It's very likely your shock actuators are leaking due to high neutral pressures as they rarely fail. So unless they are damaged or rusted out I suspect you'll find that the leaking will self correct when your pressures are normalized. If you really want to replace them then install new O rings. Search "AHC fsm" for guidance .pdfs that I've posted previously on setting heights and pressures. I'd really recommend setting the system up properly (heights and pressures) before you start changing components.
So, adjust cross level at the torsion bars then front and rear heights if necessary. Then knowing accurate (low to normal) pressures you'll likely need to install the new coils to get the rear pressure down and you'll also need to adjust your torsion bars for the front pressures. Adjusting pressures is an iterative process to get things dialed in accurately. A ford fan clutch 36 mm wrench is what you need for the damper accumulators. Lift the front or rear as you change the accumulators to minimize fluid loss. Don't forget the system is under pressure and the vehicle will drop when you crack a bleeder. You'll need a can of fluid to top off and bleed the system after installing your new globes. It's very likely your shock actuators are leaking due to high neutral pressures as they rarely fail. So unless they are damaged or rusted out I suspect you'll find that the leaking will self correct when your pressures are normalized. If you really want to replace them then install new O rings. Search "AHC fsm" for guidance .pdfs that I've posted previously on setting heights and pressures. I'd really recommend setting the system up properly (heights and pressures) before you start changing components.
- Thread starter
- #3
Hey Paddo, thanks for the prompt reply and information. So, just to be clear. You recommend setting the heights and pressures as close to stock as possible BEFORE replacing any parts?
My plan is the replace the damper accumulators (globes), shock actuators (shocks) and rear springs at the same time. Do you recommend splitting the installation of any of these components up? (Example: R&R the globes, confirm settings. R&R springs, confirm settings, R&R rear shocks, confirm settings, R&R front shocks, confirm settings)
Also, I have new front upper control arms, lower control arm bushings, lower ball joints, tie rod ends and all new sway bar bushings and links to replace. I was planning on completing the AHC system overhaul first, then have a shop complete install the UCA, LCA bushings, joints, etc...then have them align the steering.
What do you think?
My plan is the replace the damper accumulators (globes), shock actuators (shocks) and rear springs at the same time. Do you recommend splitting the installation of any of these components up? (Example: R&R the globes, confirm settings. R&R springs, confirm settings, R&R rear shocks, confirm settings, R&R front shocks, confirm settings)
Also, I have new front upper control arms, lower control arm bushings, lower ball joints, tie rod ends and all new sway bar bushings and links to replace. I was planning on completing the AHC system overhaul first, then have a shop complete install the UCA, LCA bushings, joints, etc...then have them align the steering.
What do you think?
I was thinking along the lines of starting your R&R from a good known baseline, then if something isn't right after your work you can narrow down your fault finding effort. Just from a practice and educational perspective there might be something gained from knowing your before heights, pressures and reservoir graduations and then comparing to the afters, eg the interaction of rear coil spacers on front pressures etc or how a 1/4 inch height adjustment changes pressure. There certainly isn't anything prohibiting you from doing this in one fell swoop though.
- Thread starter
- #5
Okay, so I installed new upper control arms, lower control arm ball joints and bushing, new steering rack with new tie-rod ends (old bushings were mush and rack was leaking from both ends), all bushings and links for the front and rear sway bars, new Lexus rear coil springs, four new Toyota actuators (globes) and four new Lexus shocks.
At 205,000 miles the ride was harsh and I could feel every little bump in the road. At the same time, the rebound was soft and squishy...go over a speed bump and it would roll 2 or 3 times after the bump. After the rebuild, the soft and squishy feeling is gone and the steering feels nice and tight. Ride is still a more bumpy than I had hope for. I can't remember how she rode when I bought 16 years ago...its' been way too long. But, I do remember that the softest ride setting was too soft for me. Now I have it set at the lowest and I want to go lower. The ride adjustment setting works, but it doesn't seem to have as much range as it had before. Maybe she's fine and I'm getting a little worn out.
I decided to drive her a couple of weeks to let everything "settle". Tonight I plugged in my techstream and found that that I have an error in the AHC system; error code C1762 - Abnormal Oil Pressure for Pump. Also, I notice the oil temperature sensor reading is way up 118 compared to 60's before I started the project. Additionally, both front and rear pressures are on the high side of range with the rear being just out of specs. It could be that I ran this test in my garage and the floor slopes a little with the rear being lower. I did the work and previous testing on level ground. Anyway, I've attached techstream screen prints from the beginning low height setting and the end neutral height setting. Any advice is greatly appreciated. Thanks again.
At 205,000 miles the ride was harsh and I could feel every little bump in the road. At the same time, the rebound was soft and squishy...go over a speed bump and it would roll 2 or 3 times after the bump. After the rebuild, the soft and squishy feeling is gone and the steering feels nice and tight. Ride is still a more bumpy than I had hope for. I can't remember how she rode when I bought 16 years ago...its' been way too long. But, I do remember that the softest ride setting was too soft for me. Now I have it set at the lowest and I want to go lower. The ride adjustment setting works, but it doesn't seem to have as much range as it had before. Maybe she's fine and I'm getting a little worn out.
I decided to drive her a couple of weeks to let everything "settle". Tonight I plugged in my techstream and found that that I have an error in the AHC system; error code C1762 - Abnormal Oil Pressure for Pump. Also, I notice the oil temperature sensor reading is way up 118 compared to 60's before I started the project. Additionally, both front and rear pressures are on the high side of range with the rear being just out of specs. It could be that I ran this test in my garage and the floor slopes a little with the rear being lower. I did the work and previous testing on level ground. Anyway, I've attached techstream screen prints from the beginning low height setting and the end neutral height setting. Any advice is greatly appreciated. Thanks again.
Why don't you get it to level ground and adjust the front torsion bars to get pressures in spec. Can't answer about oil temp other than you might of operated it more to raise temps. With all that work you have just done I'm not surprised it pulled out a pressure fault code, just clear it and see if it returns after it is operating with in spec.