Changing out the AHC suspension fluid?

[uHu]

Easier to lower and rise with the "active test" (that's what it's called in the manual), where you run the pump and valves manually. Just did it, but couldn't get it down to the bump stops at the rear, about 10 mm to go. Also, the rear shocks where difficult to get to w/o a lift or similar, so I measured the travel between bumpstop & axle.
Front was OK tho'. Measured from under the top bracket to center of lower bolt.

The numbers:
Front: compressed 355 mm, extended 455 cm (= 100mm travel)
Travel measured at the wheel is 168 mm

Rear: Got a travel of 220 mm (210 mm top, plus 10 mm from bottoming when compressed)

Can you use this Hoser?
What's your aim? Something exciting?

 

[hoser]

Thanks guys. Just thinking how I can improve my suspension. These are some rough numbers, the rear suspension has 10" of travel. At stock ride height, it is about 4" of up travel and 6" of down travel... so the ratio is about 40/60. When lifting 3", the ratio changes to 70/30... or 3" of down travel. I'm thinking if I put a 2-3" shock extension bracket, lower bump stops and longer springs, I can get back closer to the 40/60 ratio. No gain in travel since I'm still using the same AHC shock, just better down travel. Thoughts? Waste of time?

 

[uHu]

I foresee problems w ball joints & poss CV joints up front. Dont think they can take another 3" down. But maybe I'm wrong. Ref thread re IFS travel gain.
Otherwise it sounds good for wheeling, as you would improve when flexing.
Why not find longer shocks? Is it impossible?

 

[hoser]

When I said, 2-3" down, I was talking about the rear suspension. I think 1-2" down might be possible on the front with new UCA's and ball joints.

Yes, the other option would be to go with aftermarket shocks but then I would lose all the nice features of the AHC system. Please, somebody show me custom made replacement AHC shocks.

 

[Tinkerer]

Tinkerer, by any chance can you measure the length of the front and rear AHC shocks at full suspension compression? When you bleed the actuators, your suspension will lower completely to the bumpstops.

I'm also looking for the measured length of the AHC shocks compressed and extended. Anybody have a uninstalled AHC shocks?

OK, measured shocks at full-compress to bump stops:

Front ~14" (agrees with uHu 355mm)
Rear ~ 18-1/4"

Both measured from CL of lower bolt to underside of top shock mount bracket (shock side).

 

[hoser]

Thank you Tinkerer!

 

[tabraha]

hoser, I'm getting ready to change my AHC fluid. To bleed the damping force actuator, what screw is the bleed screw? I don't see it denoted on the illustration, got any pics of said bleeder plug?

 

[Jim_Chow]

hoser, I'm getting ready to change my AHC fluid. To bleed the damping force actuator, what screw is the bleed screw? I don't see it denoted on the illustration, got any pics of said bleeder plug?

There's another page in the FSM that shows the bleeder. Anyways, if you peek underneath, it'll be obvious.

 

[tabraha]

Hmm.... here's my stab at it then.

 

[hoser]

Yup! Use a clear hose so you can see what's going on.

 

[Tinkerer]

tabraha, is that mud I see dried on there?

FWIW, I removed the dust cap completely from the bleeder screw, to get the hose better seated on the barb when bleeding. Then put the cap back on when done.

FWIW # 2: If this AHC Fluid is anything like brake fluid (and it seems to be similar), watch out and keep it away from the painted body surfaces! (Or clean immediately if some gets on painted surface.)

FWIW # 3: I had to use 2 cans of AHC Fluid. Someone else posted that 1 can would be plenty, but that was not the case for me. Trying it with only 1 can left me with a dry reservoir at N height, and possibly air in the system at the pump, so I had to get another can and re-bleed all 4 from L setting to minimize each bleed volume. (And even 2 cans did not allow bleeding the Accumulator...may get a few more cans and redo AGAIN, to fully bleed including Accumulator...)

 

[tabraha]

Thanks for the help guys. Tinkerer, I try my best to keep only the freshest premium mud underneath my Lexus.

 

[tabraha]

Bump... Just wanted to say thanks to hoser and Ben. I was surprised how easy it was to service the AHC system. I've got pics of the old fluid vs. new. Long story short, new fluid was crystal clear, old fluid was so dirty you couldn't even see through a beer mug full of it. I only got drenched by one corner. The others played nicely.

 

[hkeller]

uhu: Can you post the instructions from the FSM regarding replacement of the rear spheres. I am getting ready to do this soon. Do I need to bleed the system after replacement? Thanks!

H.

 

[UTE BACK 100]

I have these parts if anyone needs let me know offline alanpodvin@comcast.net 2 trucks worth-

 

[1loudLX]

yeah....because you chopped the crap out of two LX470s....lol

 

[uHu]

hkeller:

The FSM says:
1 Let out pressure (bleeding).
2 Unscrew sphere.
3 Coat o-ring of new sphere with AHC fluid and install the new sphere.
4 Bleed, while keeping the reservoar filled above minimum.
5 Check for leaks.
The FSM advises to keep an eye on the back-up ring and the o-ring, in order to get them installed in the right order/place.
The FSM specifies the use of an SST (09922-10010) as a spanner, to which you can attach a torque wrench.
Otherwise use a 36 mm cheap spanner with max 8 mm thickness. (I used a bench grinder to get it thin enough)
good luck

 

[Jim_Chow]

Like this? http://shoptoolsshoptools.com/shopexd.asp?id=2040

 

[hkeller]

Thanks uHu.

Could you elaborate on number 4, bleeding while keeping the resevoir full. Once you've let the pressure off to install the new sphere, would there be any more bleeding to do?

Also, do I need to order the back up ring and o-rings separately? Any chance you have part numbers?

Thanks!

 

[hkeller]

By the way, our LX passes the graduations on the resevoir test. It gets more than 12 from low to high. However, I am all but certain the rear spheres are gone, as the rear rides just like the front when the front spheres went.