Updating AHC system (1 Viewer)

[jjrowe]

I recently went through and updated my AHC system and thought I would share my findings. I purchased a 1999 Lexus LX 470 with 126k miles. Seemed like a good deal but I didn't research the AHC system well enough. After purchasing the car I noticed the ride was stiff over bumps and when I towed a ski boat the truck dropped into low mode. I checked the system with Techstream and found that the pressures were 7.1 in front and 7.0 in the rear. The actuators had a timestamp of 1999 and I was getting 6-7 graduations when going from low to high.

The first thing I did was replaced all the actuators ($1600 from cruiser parts) and flushed the fluid ($80), this greatly improved the ride. I then added 10mm spacers to the rear springs, but this had virtually no effect on the rear pressure. Finally I opted to change the rear springs to king springs KTRS-79 ($300 shipped from Australia). These springs are made for the AHC system but are heavier than stock to allow for the extra weight of towing the boat. Three turns on the TBs and front pressure is now 6.9 and rear is 5.0. The rear is a little bouncier than before but acceptable. The system still goes to low and high fine.

 

[LandCruiserPhil]

More info on the replacement AHC rear springs please

 

[SWUtah]

Based on what you have spent so far you could of installed a bullet proof OME 2" lift. I think anyone with a 100 series AHC system needs to look at changing out to OME when they start having problems, unless you like to tinker with your suspension and deal on going with these issues.

 

[jjrowe]

I thought about it but wanted to keep it stock. I started with a system that was tired but still working fine. I felt that ripping out the hydraulic system and having to cover up warning lights, having non operational buttons, messing with the stability control system, etc was a hack. Just my personal opinion. If I was off roading maybe but then I probably would just get a different truck. It "should" last for many years with the work I've done.

 

[TXLX100]

It's not a bad system and doesn't require continuous tinkering. My AHC is original and wasn't touched except for fluid for 15 years. And I've never personally seen the system leave anyone on the side of the road. As far as adjustable suspension systems go, it has to be one of the most reliable.

If you like the features, I say it's just as good as a conventional setup. But yeah, factory accumulators are $2k+ for a set. I'll probably dump the AHC on mine, but will miss the Low mode.

 

[Nishiki]

@jjrowe, how long did shipping take? Also, any other springs out there similar? I know I asked you elsewhere, but the 5.0 MPa is an excellent reading and I want to get there.

 

[OregonLC]

For both of you guys, I'm especially interested in how the modified system performs on washboards.

 

[jjrowe]

how long did shipping take? Also, any other springs out there similar? I know I asked you elsewhere, but the 5.0 MPa is an excellent reading and I want to get there.

Shipping took a few weeks. I actually bought mine through euro4x4parts.com but they require a bank transfer as payment, it would have been easier to go the eBay route. I could not find any other springs made for AHC.

 

[TeCKis300]

Great job! The KTRS-79 springs I was unaware of and would definitely like to hear more. Obviously they are higher in spring rate than the stock AHC springs, but I wonder how much less spring rate they are compared to say 80-series springs.

SWUtah, surely the OME is an option. No offense, but I don't really consider that on the same level as AHC and it'd be quite the downgrade. I liken it more as an option for someone that has a static OEM suspension hundy, which wouldn't handle added weight without mods either. For someone to go from AHC down to a standard suspension setup makes for a real loss of tangible capabilities. jjrowe here as refreshed and augmented the AHC now to have all the capabilities, yet augmented it for additional capacities. That's an awesome thing!

 

[SWUtah]

Great job! The KTRS-79 springs I was unaware of and would definitely like to hear more. Obviously they are higher in spring rate than the stock AHC springs, but I wonder how much less spring rate they are compared to say 80-series springs.

SWUtah, surely the OME is an option. No offense, but I don't really consider that on the same level as AHC and it'd be quite the downgrade. I liken it more as an option for someone that has a static OEM suspension hundy, which wouldn't handle added weight without mods either. For someone to go from AHC down to a standard suspension setup makes for a real loss of tangible capabilities. jjrowe here as refreshed and augmented the AHC now to have all the capabilities, yet augmented it for additional capacities. That's an awesome thing!

i love the AHC and AVS on my LX570. I also have loved the AHC on the other 3 - LX470's I have owned, great systems when they work. But that said unless you have owned a LX470 with the OME 2" lift with the Slee diff drop, you can't compare or have a valid opinion. I like the OME on my LX470 more the the AHC suspension. It handle great looks way better and is pretty much bullet proof. What I believe is keep the AHC as long as it works. When it gets old and starts to have problems, it's time to "upgrade" to the OME 2" lift with the diff drop and save money and have a new suspension.

 

[TeCKis300]

i love the AHC and AVS on my LX570. I also have loved the AHC on the other 3 - LX470's I have owned, great systems when they work. But that said unless you have owned a LX470 with the OME 2" lift with the Slee diff drop, you can't compare or have a valid opinion. I like the OME on my LX470 more the the AHC suspension. It handle great looks way better and is pretty much bullet proof. What I believe is keep the AHC as long as it works. When it gets old and starts to have problems, it's time to "upgrade" to the OME 2" lift with the diff drop and save money and have a new suspension.

I'm glad you've been able to experience all those nice setups. Though I don't need to have owned an OME 2", diff drop, etc. to have a valid opinion, thank you very much.

That'd be like saying that I don't really appreciate AHC for:
- drops 2" lower to aid loading/ingress (that's 4" on the OME!)
- load levels the rear when I'm trailering 6k (o wait, let me swap in OME heavy's cause now I'm sagging)
- adjustable suspension to coddle my family (or to imitate my Porsche when I'm alone)
- saves gas hauling at 80mph on the fwy (though gas is cheap now so OME's would be great for wasting more cheap gas)

 

[SWUtah]

I'm glad you've been able to experience all those nice setups. Though I don't need to have owned an OME 2", diff drop, etc. to have a valid opinion, thank you very much.

That'd be like saying that I don't really appreciate AHC for:
- drops 2" lower to aid loading/ingress (that's 4" on the OME!)
- load levels the rear when I'm trailering 6k (o wait, let me swap in OME heavy's cause now I'm sagging)
- adjustable suspension to coddle my family (or to imitate my Porsche when I'm alone)
- saves gas hauling at 80mph on the fwy (though gas is cheap now so OME's would be great for wasting more cheap gas)

Sounds like your good to go!

 

[Wilsil]

Good to know that there are springs out there for the AHC system.

 

[Jack90210]

The King springs are a great option that I didn't know I had.

OP, would you mind sharing where you ordered them from?

 

[jjrowe]

OP, would you mind sharing where you ordered them from?

There is a guy selling them on ebay. I got mine from euro4x4parts.com and they matched the ebay price.

 

[ntsaint]

Can you provide a link to the springs on EBay? can't find the particular one i need, and don't want to get it wrong.

 

[jjrowe]

http://www.ebay.com/itm/LEXUS-LX470...Parts_Accessories&hash=item540e5b2928&vxp=mtr

 

[ntsaint]

nevermind i see it's in your original post.

 

[ntsaint]

ha...see you replied right when i did. Sorry for my ignorance.

 

[OregonLC]

I'd be interested to see the spring rate comparison between those and the OEM LC springs.