2000 LX470 AHC Suspension Question (1 Viewer)

[Michael Scarn]

Hello Everyone,

I know there are so many threads discussing AHC, and I have done quite a bit of research but couldn't find answer to my issue.

Thanks to so many informative threads, and the AHC maintenance video and cheat sheet by YotaMD, I replaced all four accumulator globes from IMPEX Japan, flush the lines with new AHC fluids that comes in the tin can. I cross leveled the vehicle (still not able to get it perfectly even, but at least within ~1/4" difference) and got the front pressure in spec by cranking the torsion bars. I still need to get a new pair of rear springs to lower the rear pressure. The ride quality is totally different now!

But here is the issue I've noticed, the issue was present before and after all the above works were done. Every time I drive over a moderately height speed bump, the driver side would ride much smoother than the right side. It feels like the passenger front side would bounce off the speed bump and then almost drop off the edge when getting over the bump, and make a louder/harsher thump noise compare to a softer thud like the rest of the tires. Also, when going over a pot hole, the passenger front seems to right rougher than the rest.

I have read again and again that the actual shocks on the AHC suspension generally is not a source of suspension issue. Could it be the torsion bar crank rate? I did have to crank the driver side way more than the passenger side when I tried to cross level. What else could be a possible issue?

I do have a torn CV axle boot on the passenger side. Could a worn CV axle cause this issue? Also, when I turn either left or right, I would occasionally hear this low pitch grinding noise with vibration from either or both wheels. Took it to a local mechanic who used to be a master mechanic for Toyota and works with a lot of cruisers, he replaced both bearings, steering rack, lower ball joints. He also checked the upper ball joints and found no issue. Could all theses be related to the CV axle/suspension?

I'm just at a loss at this point after all the repairs and work, and still can't diagnose or fix the issue.

Thank you all so much in advance!

 

[BullElk]

I have also noticed the same type harsh fall over a speed bump after I adjusted for a sensor lift. Perhaps your PS front lift bracket has moved.

 

[Jcreme]

The CV joint would not be a player in suspension action.

The first thing I would look at would be the condition of the shocks (even though they are really only hydraulic plungers, Toyota refers to them as "shock absorbers") maybe the right side is worn out and binding up.

At the same time, I would double check the ride height after driving around for a day or two. After everything has had a chance to move around and settle in. (FYI I had a hard time getting closer than 1/4 inch also). Maybe you do have a higher-than-intended preload on the right side.

Next I would check the condition of bushing and ball-joints, looking for something that is so bad-off it is binding. Usually worn out bushings cause a loose, worn-out feeling, but it will definitely feel different.

Lastly, I've noticed an exceptionally high degree of front-to-rear interactivity on this vehicle. Meaning, I see/feel/hear something in the front, but the problem is in the back or vice versa. So don't fixate on the front.

For example, you noted that your rear pressure is high and you need new rear springs. In addition to the adding more pressure on the hydraulic system, it will also put more weight on the front springs, magnifying any problems there, such as you have one spring too tight.

Lastly, don't discount that you might just be overly sensitive after working on the suspension and sensing a problem that is really in the realm of ok. I know that happens to me!

Good luck!

 

[suprarx7nut]

If you can manage to get the 16 step test to run, that would help you clear the shock and that corner's actuator (the valve that controls shock absorption). I tried running that test a few times and it didn't seem to run for me. I only gave it 5 minutes of my time, so I suspect a few more tries would have yielded something more interesting.