I think the key would be comparing ahc springs to used non-ahc springs that have some miles on them, new non-ahc springs would offer a very very stiff ride.
Coil springs for AHC
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I think that's a perfect application for air bags in the rear springs.
I have both LX AHC and used non-AHC LC springs in my garage right now. I've also got a press with a force gauge. If there's a simple way to mount those up in an "unlikely to kill somebody" arrangement I'm happy to provide some spring rate values.
Well, I've run 3 used options so far
With my stock rear bumper and stock AHC coils (with 180k miles) the ride was good, pressures were out of spec.
I added some used LC AHC coils and the pressures went into spec, honestly didn't notice a ride difference.
Added a rear bumper and swingout (around 150lbs) and used LC stock rear springs. Pressures at the low end of spec and ride is slightly harsher. I notice the springs top out and kind of make a slam noise if I'm unloaded and on a rough forest service road going around 30 mph. Loaded up with tools l, bags and people it doesn't do that.
I also noticed my N to H time basically doubled after adding the springs and TB out of a land cruiser. Ride is ok for me, a little harsher but not really that noticeable. When I go to L it basically will only go so far because the LC springs support the truck fully. That part doesn't really matter to me
Unless you are adding at least a steel bumper I would go with spacers, king springs, or AHC springs from a land cruiser.
I now have added about 100 lbs additional with sliders and I have a basic platform and gear in the back that probably adds another 120 lbs.
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Will I still be able to use the spacers with the bags? The bumpstop gets removed so what keeps the upperend of the spring in place? I guess there is a deep spring perch up there much deeper than the 30mm spacer?
I didn't compare, but I replaced my old LX470 springs with new LC AHC springs. I did not notice much difference at all, but it got my pressures in spec.
I mostly did it because the LC AHC springs were cheaper than the LX springs.
I'm not sure. There's good info out there on the bags though. Search around and I'm sure you'll find someone that's crossed that bridge.
And the globes probably wouldn’t do their job
Does anyone have Toyota documentation about paint colors on springs? I thank CivicFerio for his post, but is there anything published by Toyota similar to what user uHu posted on Jan11, 2020 that covers a stock 2004 LX470?
I recently had my springs replaced and they installed 482131-6A730 and 48231-6A740 according to the work order. The parts labels are torn off. However, the spring installed on the RH has GREEN paint on it, and the LH has YELLOW. According to the above post the -6A740 is GREEN and s/b LH. If so, mine are backwards. I would like to have some airtight documentation in hand to, (a) know if they are wrong, right and if the marks are in fact definitive from Toyota, and (b) be able to show the installer to get them swapped.
(FYI: Measured ride height in rear is equal. I've been adjusting my front TBs and ride heights are FR = FL = 19 3/16, and the rears RR = LR = 20 1/4. Techstream pressures Front 6.4, Rear 6.3. So I should probably back of the TB. Have never adjusted the ride height.)
thanks in advance. Sorry if the info was posted elsewhere and I missed
Might be a good time to also do a little AHC system maintenance. Once you check the graduation marks and do a fluid flush and all that, measure the distance from the center hub to fenders on all four corners. Should be about 19.75" front and 20.5" rear stock. Cross-level the front, if driver side is lower, tighten driver-side torsion bar 2 clicks and at the same time loosen passenger torsion bar two clicks. The vehicle should be within 10 mm. Drive side can be the taller of the two. 30mm socket. Might have to soak with PB the day before. Drive after each adjustment and then re-measure.
One full turn of TB is also equal to about ⅛” to cross-level.
I think it is IMPORTANT to use Scanguage or Toyota Techstream to see the pressures in the AHC system, two sensors front and one rear. Take values after moving vehicle from normal to low to normal setting, wait 60 seconds, leave the engine running. Field Repair Manual states that rear pressure needs to be taken with the temperature sensor disconnected. The temperature sensor is closest to the firewall on the pump assembly beneath the reservoir on the passenger side of the engine compartment. It has two wires. The center connector with 3 wires is the pressure sensor, forward with 2 heavier wires is pump motor power. It is debatable if you need to disconnect or not, take readings both ways and see.
6.9 Mpa (+-0.5) is what you are shooting for in the front. And 5.6 - 6.7 is going to be the goal in the rear. A quick note: 210 lbs over the rear axle is going to increase the rear pressure by +1Mpa in pressure. I usually take three readings and average them out. If you don't have the front dialed in, it will have some influence on the rear. Each rotation of the torsion bar in the front is about 0.2 Mpa from what I have found. If you decide to go the 30mm rear spacer route in the rear, that is equal to about 0.3-0.5 Mpa.
Having all of this done, you can really dial in your rear springs ... I think for you the best bet is going to be a set of King KTRS 79 springs which are 25% stiffer than the stock AHC but not as stiff as the non-AHC springs. This is going to be good for a full 3 Mpa. Cheap and easy.
The idea is to find a balance, especially if you are going to be having more weight. If the pressure goes too high, the AHC will default into Low or won’t lift into Hi. NOTE: Driver-side spring is just a hair taller. So measure the new springs before you throw them in so you know which side is which. This is normal. Airbags are also an option that fits inside the springs, they provide good flexibility but it wasn't my first choice. EDIT - As Suprarx7nut has mentioned it seems King Springs are identical in height.
With a front bumper, winch, and a tired set of TB's ... it is possible that they may need to be re-indexed.
Also when you are playing around with the computers ... if it comes up that reserving steering angle is required, disconnect battery lead for 20 minutes with wheels straight. lock to lock the systems measures at 1150 degrees I don’t know why this comes up for some people.
Perform the graduation check once again when you are all done. Everything should be good to go.
One full turn of TB is also equal to about ⅛” to cross-level.
I think it is IMPORTANT to use Scanguage or Toyota Techstream to see the pressures in the AHC system, two sensors front and one rear. Take values after moving vehicle from normal to low to normal setting, wait 60 seconds, leave the engine running. Field Repair Manual states that rear pressure needs to be taken with the temperature sensor disconnected. The temperature sensor is closest to the firewall on the pump assembly beneath the reservoir on the passenger side of the engine compartment. It has two wires. The center connector with 3 wires is the pressure sensor, forward with 2 heavier wires is pump motor power. It is debatable if you need to disconnect or not, take readings both ways and see.
6.9 Mpa (+-0.5) is what you are shooting for in the front. And 5.6 - 6.7 is going to be the goal in the rear. A quick note: 210 lbs over the rear axle is going to increase the rear pressure by +1Mpa in pressure. I usually take three readings and average them out. If you don't have the front dialed in, it will have some influence on the rear. Each rotation of the torsion bar in the front is about 0.2 Mpa from what I have found. If you decide to go the 30mm rear spacer route in the rear, that is equal to about 0.3-0.5 Mpa.
Having all of this done, you can really dial in your rear springs ... I think for you the best bet is going to be a set of King KTRS 79 springs which are 25% stiffer than the stock AHC but not as stiff as the non-AHC springs. This is going to be good for a full 3 Mpa. Cheap and easy.
The idea is to find a balance, especially if you are going to be having more weight. If the pressure goes too high, the AHC will default into Low or won’t lift into Hi. NOTE: Driver-side spring is just a hair taller. So measure the new springs before you throw them in so you know which side is which. This is normal. Airbags are also an option that fits inside the springs, they provide good flexibility but it wasn't my first choice. EDIT - As Suprarx7nut has mentioned it seems King Springs are identical in height.
With a front bumper, winch, and a tired set of TB's ... it is possible that they may need to be re-indexed.
Also when you are playing around with the computers ... if it comes up that reserving steering angle is required, disconnect battery lead for 20 minutes with wheels straight. lock to lock the systems measures at 1150 degrees I don’t know why this comes up for some people.
Perform the graduation check once again when you are all done. Everything should be good to go.
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Are the King springs different left v right? I couldn't tell a difference in markings or height on mine.
Good question, my stock springs are very slightly different. I will measure my Kings before I install them, but I also have a feeling they are identical.
IndroCruise
SILVER Star
Maybe I have misunderstood the written words but for abundant clarity please do not assume that adjusting the front torsion bars will do anything for 'ride height' when the vehicle is operating with a healthy AHC system. It won't happen. AHC = Active Height Control and it means that when operating, a healthy system will self-adjust to the heights set by the Height Control Sensors, regardless of torsion bar adjustment.
'Ride height' is adjusted only by using the Height Control Sensor adjusters. It should be done after cross-levelling and before measuring AHC neutral pressures -- because incorrect heights mean that AHC pressures are not comparable with FSM specifications. More height = more AHC pressure because more weight is carried by the AHC system. Less height = less AHC pressure. Change in HI/LO graduations at the AHC tank (which signify 'globe' health or otherwise) are only comparable with FSM specifications when AHC pressures are within the FSM-specified range. Within IH8MUD, a user-specified ride, or operating, 'height standard' has been adopted: Front: 19.75 inches or 500 millimetres: Rear: 20.50 inches or 520 millimetres. These do not come from Toyota/Lexus. They have been found to be reasonable approximations for most purposes and are easier to measure than the FSM height specifications -- see attachment.
Different to a conventional suspension, the torsion bar adjusters serve only two purposes:
1. 'cross-leveling' the front of the vehicle, done according to the attached FSM extract using same turns on each adjuster in opposite directions with engine "OFF", mainly to ensure that the both torsion bars are carrying equal shares of the vehicle front load and to ensure that the vehicle does not have a built-in lean -- it does not matter what the actual measurements of these 'static heights' are in this step but it is important that they are equalised,
2. adjusting front AHC neutral pressure (under correct conditions) after vehicle ride or operating height has been set correctly, by using same turns on each adjuster in the same direction, clockwise when looking up at the bolt to transfer vehicle weight from the front AHC system to the torsion bars and thereby reducing front AHC pressure, or, counterclockwise to transfer weight to the front AHC system from the torsion bars thereby increasing front AHC pressure. (Measurements must be made with the engine and AHC "ON" and after the suspension has settled but the actual adjustment wrenching should be done with the engine and AHC "OFF" for safety).
[Note: 'cross-levelling' cannot and should not be attempted with the Height Control Sensor adjusters. This will result in confusion and frustration. When the vehicle is stationary or with front wheels straight ahead, the Electronic Control Unit (ECU) averages the readings between the Right and Left Height Control Sensors and does not differentiate between them. The Gate Valves in the Control Valve Assembly are open in this condition and there is no difference between Right and Left AHC pressures -- so different front Height Control Sensor positions cannot result in different Right and Left heights. Instead, if the Height Control Sensor readings are widely different, the ECU will put the system into 'fail safe mode'. Then a harsh ride will be experienced because the adaptive damping is fixed at Step 8 of 16 Steps.]
I have GREEN on the left side and YELLOW on the right side. GREEN spring is longer. I am not the first owner, can't say it is like that from the factory.
IndroCruise
SILVER Star
If it is helpful, various supplier catalogues, for example, Toyota parts catalog - https://toyota.epc-data.com , show the following part numbers:
48231-6A730 LHD Rear Coil Spring with AHC, Right Hand Side (Passenger side in USA)
48231-6A740 LHD Rear Coil Spring with AHC, Left Hand Side (Drivers side in USA)
These Part Numbers can be checked by inserting your VIN into the various catalogues.
What about the colour patches – which colours go with which springs?
This eBay Seller in Florida USA provides a picture of 48231-6A730 Right Hand Side (Passenger side in USA) showing a yellow paint mark:
Lexus LX470 Rear Coil Spring Passenger Side 48231-6A730 1998-2007 OEM | eBay - https://www.ebay.com/itm/Lexus-LX470-Rear-Coil-Spring-Passenger-Side-48231-6A730-1998-2007-OEM/283907342747?epid=1522195790&hash=item421a32419b:g:K7YAAOSwAa9e3qmY
This is consistent with the report by @medtro at Post #153 above in this thread.
For what it is worth, I understand that the rationale for a slightly longer spring (~15 millimetres) on the Left (Driver’s side) of LHD vehicles is to compensate for both the driver and most of the fuel load being on the Left (Driver’s side) in LHD countries.
Is this “airtight” evidence as requested by @Hulio? No, probably not – my lawyer friend would tell me that it is “hearsay” and it is not “cogent and compelling” without documents! However, this is not going to the Supreme Court and it is enough to challenge the Installer – ask him to confirm that he has the correct springs in the correct places, given what other Owners and other Suppliers have to say. If it is wrong, he may be willing recognise and correct the mistake without any further fuss.
Alternatively, a Parts Sales person who really knows his/her stuff at a different Toyota Dealer may be able to explain what colour patch goes with each different spring by Part Number. That would be tighter "evidence" if it is required.
For those interested in KING KTRS-79 springs, in my Right Hand Drive part of the world (where these springs are manufactured) the springs come in pairs, both of equal length and bar diameter. Are they the same for LHD parts of the world? It would be best to ask the manufacturer directly – phone and e-mail contact details can be found at Post #115 above in this thread. At the time of this post it is 3:42pm Sunday at the Kings Springs factory, just South of Brisbane in Queensland, Australia, so make time zone allowances for phone calls.
It is of no use to @Hulio but of possible interest to RHD others, my 2006 RHD Japanese-built, Australian-delivered, AHC-equipped Landcruiser with additional rear subtank (and I believe similar RHD LX470’s in Australia) was manufactured with 48231-6A770 OEM springs, length 485 millimetres, purple colour patch, same Left and Right. I know this because I still have these springs following removal and replacement with KTRS-79 springs, also length 485 millimetres and same Left and Right.
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I could not either on my king 79s
Thank you for the confirmation.
Thanks for the great writeup/refresher on AHC, FSM attachments and the ebay color reference. Yes, miscommunication on my part regarding ride height. I mentioned the torsion bars and ride heights to indicate that those were not way out of spec, in case that with the springs reversed the rear cross levelling could be affected. And my Front Pressures are to the low end of the spec at 6.4, so I could probably take a few turns out of both TBs and recheck. I have not adjusted any Height Control Sensors yet as they are pretty close: FR 0.0, FL -0.2, R -0.1 and wanted to wait until I had the rear springs replaced first.
Now with this info I'll return to the installer and see what they say about colors and reversing them. I will also ask them to ensure that the longer (740, hopefully Green) is on the left.
just throwing in my recent experience. I was having a spongy ride and problems when loaded up heavy (2 kids, fridge, 4 bikes, all kinds of stuff). It would lower down and not raise up. I replaced with some King Springs and its not stiff at all, rides ****ing great! Even with rear bumper and drawers.
Answering my own post since I found a photo.
TLDR: At least one spring with green paint is 48231-6A740, which is LH side for my VIN, US LHD 2004 LX470 with AHC.
Click on the camera icon and enlarge one of the photos:
Not sure about the label which here says 'RR'. All other documentation says this is LH side.
And at the bottom of coil number two is a barely visible little green patch.
Sorry, for being anal, just wanted to document what I found.
