OME springs with AHC

[miraloiza]

Hi has anyone had success with OME springs and torsion bars and AHC shocks. My understanding of the AHC shocks is that they control the height which is normally the springs role. The springs used for the AHC are very soft which to me means the shocks are very hard on the down stroke to make up for the soft springs. I believe that the springs are used to control the rebound which means the shocks are quite soft in their valving during rebound.
If normal or heavy duty OME springs are used then the suspension would be overly hard on compression but would bounce up quite fast when rebounding as the AHC shocks don't have much rebound valving. The AHC would not lower either with OME springs unless the AHC shocks are driven down with hydraulic pressure.
I have AHC suspension and while being good on road, is absolutely lousy when they are put to the test. After several hours driving with three small kids and 300Lt of fuel they default to low and as others have said will only raise when the key is turned off and back on. The more load you have obviously the harder the AHC shocks become and couple this with corrugations in Australia, the suspension just does not work and then sinks to low.
I am contemplating either taking it all out and installing new torsion bars and rear springs with OME or Ralph shocks or possibly trying just springs and torsion bars but with spring rates obviously soft to standard.
Has anyone had any luck combining the two as I can only see it working if the AHC shocks are modified in the rebound and compression dampening valving.

 

[Jim_Chow]

Hi has anyone had success with OME springs and torsion bars and AHC shocks. My understanding of the AHC shocks is that they control the height which is normally the springs role. The springs used for the AHC are very soft which to me means the shocks are very hard on the down stroke to make up for the soft springs. I believe that the springs are used to control the rebound which means the shocks are quite soft in their valving during rebound.
If normal or heavy duty OME springs are used then the suspension would be overly hard on compression but would bounce up quite fast when rebounding as the AHC shocks don't have much rebound valving. The AHC would not lower either with OME springs unless the AHC shocks are driven down with hydraulic pressure.
I have AHC suspension and while being good on road, is absolutely lousy when they are put to the test. After several hours driving with three small kids and 300Lt of fuel they default to low and as others have said will only raise when the key is turned off and back on. The more load you have obviously the harder the AHC shocks become and couple this with corrugations in Australia, the suspension just does not work and then sinks to low.
I am contemplating either taking it all out and installing new torsion bars and rear springs with OME or Ralph shocks or possibly trying just springs and torsion bars but with spring rates obviously soft to standard.
Has anyone had any luck combining the two as I can only see it working if the AHC shocks are modified in the rebound and compression dampening valving.

I clarified my response a bit more: You can put in heavier t-bars/coils, but they can't be so heavy that the AHC pressure is too low. The pressures at the shocks have to be in a certain span. If it's too high, then you crank the t-bars (or use stiffer coils) or use heavier bars. If too low, you have to use a t-bar/spring w/ lower spring rate. If you carry heavy loads all the time, stiffer springs will work. But if you carry heavy loads some of the time, light loads some of the time, it won't work. If you just stuff stiff coils in the rear, the AHC won't lower. Coils does the opposite of what you want. When you want the AHC high, coils don't provide sufficient spring since they aren't compressed as much. If you want the AHC in low, you want softer coils.

Do a search on what Dinibli did w/ his LC Sahara w/ ARB front/rear bars, aux tank, trailer, full gear. He spent a great deal of time researching the alternatives. The solution for a part-time heavy load w/ AHC is airbags rather than OME or custom coils. This still allows the AHC to function both when the rig is empty and also when the rig is overloaded and towing a trailer.

 

[hoser]

I am using standard OEM (not OME) 80 series springs in the rear with AHC and it carries the loaded 100 fine but probably oversprung on an unloaded 100. You'll either have to put some trim packers on one spring or find two drivers side (or two passenger springs) as the spring lengths are different. You also might want to adjust the rear AHC sensor to get the optimal balance between 80 series spring and AHC shock.

Dinibili's solution with his airbags sounds like a good way to go but also much more costly.

 

[dinibili]

The quickest solution to this problem is pulling the rear coils out and replacing them with Firestone Airbags. $1200 plus 3 hours work. The vehicle will then work a treat, loaded or near empty. If you have a front bar and/or winch you will need to have the torsion bars reset by Toyota to bring the pressures of the AHC in the front into spec.



Donald

 

[miraloiza]

How does your rig handle corrugations? My front end is probaly out of spec with pressures so thanks for the advice. I'll get this checked as I have wound up the torsion bars, not for height but for resistance to bottoming. I can get the AHC to ride nice on the corrugations but when I come up to a washout it would be nice to have my rig not bottom out. I find I have to go a lot slower than my mates with OME suspension or maybe I treat mine with more care. Corrugations are a problem when fully loaded. I have a 170Lt sub tank, plus camping gear etc...

 

[miraloiza]

How does your rig handle corrugations? My front end is probaly out of spec with pressures so thanks for the advice. I'll get this checked as I have wound up the torsion bars, not for height but for resistance to bottoming. I can get the AHC to ride nice on the corrugations but when I come up to a washout it would be nice to have my rig not bottom out. I find I have to go a lot slower than my mates with OME suspension or maybe I treat mine with more care. Corrugations are a problem when fully loaded. I have a 170Lt sub tank, plus camping gear etc...

 

[miraloiza]

How does your rig handle corrugations? My front end is probaly out of spec with pressures so thanks for the advice. I'll get this checked as I have wound up the torsion bars, not for height but for resistance to bottoming. I can get the AHC to ride nice on the corrugations but when I come up to a washout it would be nice to have my rig not bottom out. I find I have to go a lot slower than my mates with OME suspension or maybe I treat mine with more care. Corrugations are a problem when fully loaded. I have a 170Lt sub tank, plus camping gear etc...

 

[dinibili]

Corrigations, all day, every day are not a problem. I would suspect that winding up your front suspension without regard to the AHC pressures will have upset the system. Have you fitted any other gear front bar rear bar etc other than the extra fuel.
The max load the vehicle will carry comfortably is 530kgs. Any more than this represents a problem.

I would suggest you put the vehicle over a weigh bridge when loaded and weigh both front & rear axles. You will probably get a surprise. The vehicle knows when it is over loaded and acts appropriately.

 

[hec4x4dk]

Hi

OME T-bars and stiffer springs can work with AHC. Mine has such a setup and I am very happy with it.

Other treads has more info on this, but principle is to use the stiffer springs to increase height and/or carry more load. To have the AHC system function as it was built, it needs to be tricked into thinking the increased height is the standard height, as the AHC also is responsible for damping the movements.

More if required...

Regards...

Henrik

 

[CrusrDug]

Hi

OME T-bars and stiffer springs can work with AHC. Mine has such a setup and I am very happy with it.

Other treads has more info on this, but principle is to use the stiffer springs to increase height and/or carry more load. To have the AHC system function as it was built, it needs to be tricked into thinking the increased height is the standard height, as the AHC also is responsible for damping the movements.

More if required...

Regards...

Henrik

How much do you tow and what is the tongue weight? I had a towing experience this weekend and experienced the AHC dropping into low. Had to stop, turn off and turn on to get back to normal. I was towing a 5500# boat but not sure of the tongue weight. I am guessing it is around 4-500lbs with the trouble I was having.

 

[ats4x4dotcom]

OME t bars and intermediate springs will work fine with the AHC, and if you want lift, cut 6mm off the front adjuster threaded shaft, and re install them fully shortened, and move the rear the maximum the bracket will allow with the coils fitted.

The AHC shocks are a very good shock absorber in quality on the Cruiser.

 

[ats4x4dotcom]

How much do you tow and what is the tongue weight? I had a towing experience this weekend and experienced the AHC dropping into low. Had to stop, turn off and turn on to get back to normal. I was towing a 5500# boat but not sure of the tongue weight. I am guessing it is around 4-500lbs with the trouble I was having.

The shocks or "AHC" is designed to lift a max of 270kg, so if you add more than 270kg, you need a spring that keeps the AHC from requiring more than 270kg lift.

[270kg is aprox 594 #]

 

[hec4x4dk]

I have towed a 2T caravan, having at least 250kg on the tounge (wich may not be recommended, as heavy loads are on the moving parts of the trailer coupling). I have had the cruiser loaded to 3600kgs++ and no problems with the AHC - as it is adjusted to handle additional weight above what the normal springs (standard, not for AHC use) take. I am sure it will tow anything I can possibly (legally) throw after it.... the standard AHC will not, however, as 500kgs will sag it leveaing it at low (leaving me with the remainder 400 kgs of possible load up to standard total useless...)

Regards...

Henrik