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Pneumatic Suspension


kevinfromseattle

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Ok, i am a total n00b, but I just got a 1999 lx 470, and when i try to lower or raise the suspension, it does so just fine, until i start going and the truck shifts into second gear. At that time the suspension automatically reverts ot the "N" setting in the middle. Is there a trick to making it stay at the desired hieght? or is my truck a lemon?

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oh. there isn't any way to lower the truck and keep it low for freeway speeds?

Yes and no. In stock mode, the LX will stay in "N" mode at 30km/hr or higher in 4wd high mode. If you overload the vehicle (over 1000 lbs incl. passengers), the AHC will revert to "L" mode. Otherwise, the only way to get the vehicle to drive in the height you want is to get one of those controllers sold in Japan. The simple ones (like the Banks) allow you to merely lock the AHC mode at any speed. The fancy ones allow you to adjust the front/rear height in 10mm increments while stopped or moving and have a few memory settings.

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I have the rx330 with the performance package that can go up and down and it lets me be on low for any speed, neutral for anyspeed, but when on high, it will go back to low at maybe 30 mph. Oh, and if i go past 60 or 65 mph, it will auto go to low mode for better milage.

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I have the rx330 with the performance package that can go up and down and it lets me be on low for any speed, neutral for anyspeed, but when on high, it will go back to low at maybe 30 mph. Oh, and if i go past 60 or 65 mph, it will auto go to low mode for better milage.

cool for you :huh: but i have a lx470

oh. there isn't any way to lower the truck and keep it low for freeway speeds?

Yes and no. In stock mode, the LX will stay in "N" mode at 30km/hr or higher in 4wd high mode. If you overload the vehicle (over 1000 lbs incl. passengers), the AHC will revert to "L" mode. Otherwise, the only way to get the vehicle to drive in the height you want is to get one of those controllers sold in Japan. The simple ones (like the Banks) allow you to merely lock the AHC mode at any speed. The fancy ones allow you to adjust the front/rear height in 10mm increments while stopped or moving and have a few memory settings.

thanks!

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The only other idea I can think of is to tweak with the height sensors. Some guys have forced their vehicles to stay permanently in the "high" mode by fabricating a longer AHC height sensor bracket at each wheel. I'm wondering if you could do the same in the other direction. You'd lose the "high" mode, though. If you want total (manual) control of the AHC at any speed, the little computer is the only way. The AHC is a clever idea in that you get the extra clearance when offroad, so you don't have to put up with driving a lifted vehicle that gets worse fuel economy, higher center of mass, etc. Yeah, it's too bad one couldn't drive on the freeway in either the low or normal modes. You'd probably get 2 mpg improvement in low mode.

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The only other idea I can think of is to tweak with the height sensors. Some guys have forced their vehicles to stay permanently in the "high" mode by fabricating a longer AHC height sensor bracket at each wheel. I'm wondering if you could do the same in the other direction. You'd lose the "high" mode, though. If you want total (manual) control of the AHC at any speed, the little computer is the only way. The AHC is a clever idea in that you get the extra clearance when offroad, so you don't have to put up with driving a lifted vehicle that gets worse fuel economy, higher center of mass, etc. Yeah, it's too bad one couldn't drive on the freeway in either the low or normal modes. You'd probably get 2 mpg improvement in low mode.

i've tried to find this controller on the internet and only have seen others talking about it. is it made by "JDM"? I want one tho, if you know more please tell

I would not want to permanently loose the high mode, I go surfing alot and have already actually 4byed my truck out at the coast. Center locking differentials are schweet!

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Here is the BBlanks part you are looking for.

http://bblanks.com/4wd/ahc/index.htm

Be advised that:

1) your alignment will be less than ideal (probably toe-out) unless you align it with the low setting with the intent to drive it in low all the time.

2) There is less "Up" suspension travel left when in low mode, maybe 2 inches? Hitting the bumpstops when on an off-ramp might not be so fun but you'll have to decide.

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I have a new LC 100 series TD fited with the adjustable suspension as has been fitted to the LX 470. It has been causing me some grief. In the first instance the ride height adjusted upwards erratically under its own control whilst driving. Unfortunately it has been erratic, and the Toyota dealer has been unable to find the fault. They blamed front and rear bars that were fitted. However it was doing it prior to the fitment of these items. I don't think they believed me. The vehicle stopped behaving erraticlly after a few thousand kms on gravel roads. However I have now discovered that the weight of these attachments (220kg) including a winch has meant that the maximum pay load has been reduced by 220kgs, as if I put more that 5 people or load equivalent the vehicle drops to the lower setting and sulks!. Is there a work around for this in terms of re springing the rear. There are issues with height settings and shock absorber pressures. I believe just placing heavier springs in the rear is likely to give the vehicle a mental breadown. Toyota have not a clue! Thus I am trying the Lexus circle for an answer.

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Yes, it is for that reason. Where we live (King Island) has a wallaby problem in terms of numbers. They are not quite as large as the kangaroo but will damage even a LC if they hit on the front of the vehicle. The front bar has a winch with a synthetic rope (to save weight). The vehicle is also fitted with a rear bar to get the spare wheel up from underneath, where it lays in anticipation of being dragged off. I am also interested in the device that was mentioned earlier that allows the vehicle's max speed in terms of height adjustment to be reset. It would be nice to be able to increase the vehicles max speed with increased ride height. 30km/h for extended periods over tracks that have a centre hump is a bit limiting. The change in centre of gravity from a 30mm ht increase will be minimal at 60 or 70 km/hr. It also assumes that there is no brains between the ears of the head behind the steering wheel.

So any thoughts?

Donald

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However I have now discovered that the weight of these attachments (220kg) including a winch has meant that the maximum pay load has been reduced by 220kgs, as if I put more that 5 people or load equivalent the vehicle drops to the lower setting and sulks!. Is there a work around for this in terms of re springing the rear. There are issues with height settings and shock absorber pressures. I believe just placing heavier springs in the rear is likely to give the vehicle a mental breadown.

Yes, you can change out the rear springs in your AHC equipped Land Cruiser. You might try using the standard (OEM) 80 series rear coils as they are a significantly stiffer (higher rate). Using OME coils might be too much if you aren't heavily loaded. With the AHC cruiser, part of the weight is suspended by the coils and part by the AHC shocks. The trick is that you have to adjust the AHC sensor(s) so that they work harmoniously with the new coils. As for your erratic height behavior, I do not know the answer.

There is good information on this site but you might want to visit www.IH8MUD.com where it is more off-road oriented. There are quite a few of your fellow Aussie's there as well.

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I will check that site out. As you said the trick is matching the AHC sensors/intelligence with the new coils. I am not chasing extra ht, just to reset the tare wt in terms of the AHC to leave me a little more pay load capacity. Thanks.

Any information on the ability to reset the speeds/height limits?

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You might also try talking to the guys at Slee Offroad. They modified a LX470 with a Sahara bar and custom rear bar/tire carrier. IIRC, they used OEM LC torsion bars and rear springs, then fiddled with the AHC sensors to make it so it was permanently in the high setting (I know this isn't what you want). I'm planning to fit sahara and kaymar bars on my LX470, but with no winch, I think I can get away with the stock springs. If the rear sags too much, I might try replacing them w/ stock LC springs (don't think it will, as the kaymar bar is only like 60kg w/o tire carrier).

These are the JDM AHC controllers I've seen so far. If I can interpret the text correctly, the ones on the far left and right allow one to lock it in high/low. The second from the left allows up/down adjustment, but says it has 2 settings for the lower side. The one in the middle (ASC100) allows for 10mm front/rear incremental adjustments, both up & down (+6 adjustments up, -6 adjustments down for 12 levels total; not sure if the front/rear adjust indepently, but I'm under the impression they do). There are also 3 memory settings. The fourth one from the left (ASE665) allows for +60mm to -70m adjustment while stopped, and +40-45mm when moving.

post-15198-1141444033_thumb.jpg

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Fraser, I know you aren't trying to raise the ride height but the ride height will be determined by which spring you choose. You might be able to get away with cutting your springs (to increase spring rate) and adding spring spacers but I wouldn't say that is the best way to do things.

As for using stock LC torsion bars, I'm not so sure you can. From what I've heard, the TD LC's use different length torsion bars. In any case, calling Christo Slee will surely be helpful.

Jim, 60kg in the rear will be nothing. It's just like having another lightweight person sitting back there. I wouldn't even change the springs.

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Jim

Thanks for your info. I note "the interpretation" required on the attachment. TJM have suggested coils that will give 10mm lift and 100kgs of extra wt. ARB have suggested 866 coils. I am unsure what their specifications are in terms of wts and lift. Any idea. I assume there is no easy method to check pressures other that rocking up to a Toyota dealer. There is not one here and it will involve a boat trip for the vehicle at a cost of a return trip of $A900. One would assume that as the front TB have been reset after the front bar was added then I don't need to think about new TB for it if the HT is correct. It is only the rear that needs attention.

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  • 4 months later...

I have a new LC 100 series TD fited with the adjustable suspension as has been fitted to the LX 470. It has been causing me some grief. In the first instance the ride height adjusted upwards erratically under its own control whilst driving. Unfortunately it has been erratic, and the Toyota dealer has been unable to find the fault. They blamed front and rear bars that were fitted. However it was doing it prior to the fitment of these items. I don't think they believed me. The vehicle stopped behaving erraticlly after a few thousand kms on gravel roads. However I have now discovered that the weight of these attachments (220kg) including a winch has meant that the maximum pay load has been reduced by 220kgs, as if I put more that 5 people or load equivalent the vehicle drops to the lower setting and sulks!. Is there a work around for this in terms of re springing the rear. There are issues with height settings and shock absorber pressures. I believe just placing heavier springs in the rear is likely to give the vehicle a mental breadown. Toyota have not a clue! Thus I am trying the Lexus circle for an answer.

The only way I know to increase the load carrying capacity before the height system goes into (can't take-it am now laying down on the job) is to retrofit stiffer springs to offset the 450# of weight you added.

The height control system has pressure limits such that when the vehical gets too heavy, the only way it can support it is to 'squat down'. Stiffer springs will definitely work.

BTW, be sure your accumulators are in good shape. I can modify them and recharge to a higher pressure so they will have full suspension travel range at the heavier weights you are carrying. Otherwise, suspension travel decreases with added weight (unless stiffer springs added).

Let your buddies on the LC forum know I can recharge their flat accumulators (all4 for what 1 costs at Dealer!)

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The only way I know to increase the load carrying capacity before the height system goes into (can't take-it am now laying down on the job) is to retrofit stiffer springs to offset the 450# of weight you added.

The height control system has pressure limits such that when the vehical gets too heavy, the only way it can support it is to 'squat down'. Stiffer springs will definitely work.

BTW, be sure your accumulators are in good shape. I can modify them and recharge to a higher pressure so they will have full suspension travel range at the heavier weights you are carrying. Otherwise, suspension travel decreases with added weight (unless stiffer springs added).

Let your buddies on the LC forum know I can recharge their flat accumulators (all4 for what 1 costs at Dealer!)

Thanks for your reply.

I have solved the problem. I replaced the rear coils with airbags. For normal conditions I have 18psi in them and for loaded cruising conditions I take the pressure to around 30psi. The vehicle does not lay down on me and raises and lowers as it should. It also rides as it should, which I suspect that the heavier springs would not allow in the unladen mode. I will keep your service in mind. although any issues here with the spheres should not be my problem for another 2 1/2 years when the warranty disappears.

Cheers

Donald (off the rock)

2005 4.2TD Sahara LC with AHC, Frnt & Rear ARB Bars 12000lb winch and Codan HF Radio

dinibili@kingisland.net.au

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Fraserbluff, just curious, are you running the two airbags with a T-connection or individually? I realize the shared T-connection would allow for better articulation but was wondering what benefits running them individually offered? Better on-road handling I'm guessing.

Edit: I just reread your post. You REPLACED the coils with airbags. The airbags I am familiar with are made by Airlift and are installed inside the coil as a "helper." Anyway, how are those working out for you? I have had my suspension overloaded and revert to low mode as well on a few occasions. Fortunately, with a Hi-lift jack and fiddling with the suspension modes, I have been able to get it going to regular ride height. I am about to swap coils with the OE 80 series coils but have not yet done so.

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Fraserbluff, just curious, are you running the two airbags with a T-connection or individually? I realize the shared T-connection would allow for better articulation but was wondering what benefits running them individually offered? Better on-road handling I'm guessing.

Seems like you guys know what you are talking about regarding the ride height system. Anyways, I pulled the fuse for the ride height control when it's at L and it stayed at L at any speed. I really like the ride at L. I suspect it will do the same for H. Just wondering if it will do damage to the suspension if I keep it at L.

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