Updating AHC system (1 Viewer)

[PADDO]

Paddo, 58 does seem low to me but I figure the AHC is doing a lot of work so maybe that was plausible. How did you measure the spring rate? I don't know how to do that so I would be curious to learn how. Using 90 instead of 58 would yield a spring rate of 123 lb/in for a 37% increase so the King Springs theoretically would still be good for the parameters I was using.

Measure spring rate? Support the spring, add weight and measure deflection. Repeat several times for an average. Noting the coil isn't perfectly linear so there will be some degree of progressiveness, that's why it's an approximation.

 

[Fuge]

I will try that when I take the springs off.

 

[Fuge]

The King Springs arrived about two weeks after I ordered them. Just got them installed yesterday. Pressures went from 8.5 to 6.4. I suspect it would be even lower but I had about 200lbs of gear and car seats in. So a drop of 2 is huge and it rides much better now.

 

[PabloCruise]

I just did some more digging, and it appears the LX450 springs that I tried in my LX470 had a spring rate of 150lbs/in. I haven't done the math to confirm this as I don't have all of the info needed at work with me.

It makes sense though, as I've read multiple places they aren't as stiff as the 100 series non-AHC coils. I'm still keeping my fingers crossed that after I add the rear bumper and drawer system that the 80 series springs aren't too stiff still.

How do you like the 450 springs?

Silly question, are 450 springs the same as 80 series springs?

 

[94SRUNNER]

How do you like the 450 springs?

Silly question, are 450 springs the same as 80 series springs?

No, the 450 springs were softer than the 80 Series spring

 

[OregonB]

I like this approach...my off-roading is limited to logging roads, washboard, and mud. I'll leave Moab and the Rubicon to the pros.
Like to keep my AHC until it croaks - any differences if I want to swap springs on the '05 LX?

 

[PabloCruise]

No, the 450 springs were softer than the 80 Series spring

Thanks! Anyone know how the 80 spring rates?

 

[PabloCruise]

@Fuge this is all good stuff. I'd like to throw a few data points into the mix:
I've previously measured LX AHC coils at between 90-95 lbs/inch - higher than the calculated 58lbs/in and in line and reasonable (in my view) with the published 170lbs/in for standard non AHC coils and Kings stated 130lbs/in.
I've found that 210lbs directly over the rear axle ~ 1 MPa increase in rear pressure
1 inch increase in rear height ~ 0.6MPa
1 inch increase in front height ~ 2.2MPa
@Ramathorn15 recent install of the Kings saw his rear pressure drop ~3.9 MPa and my own experience with these springs netted a drop of 2.5MPa. Averaging these gives a drop of 3.2MPa which if you multiply by my 210lbs per MPa you come out with something like 670lbs increase in capacity over standard coils. The objective always being to return and keep the rear neutral pressures in their design range, ideally the lower end of the range. And as we are measuring to one decimal place for pressures with a similar accuracy for height there's going to be some variations.
A few more pre and post King install pressure readings (with no other variables thrown in to confound) would help build out the data set.

I just did some more digging, and it appears the LX450 springs that I tried in my LX470 had a spring rate of 150lbs/in. I haven't done the math to confirm this as I don't have all of the info needed at work with me.

It makes sense though, as I've read multiple places they aren't as stiff as the 100 series non-AHC coils. I'm still keeping my fingers crossed that after I add the rear bumper and drawer system that the 80 series springs aren't too stiff still.

Am I reading this correctly?
470 AHC spring rate = 95 lbs/in
King = 130
450 = 150
100 = 170

 

[PabloCruise]

No, the 450 springs were softer than the 80 Series spring

Maybe the 80 series rear spring rate is same as 100 series rear?

 

[PabloCruise]

Does anyone know how the 200 series rear springs compare to 470/AHC rear spring rates?

 

[PabloCruise]

Am I reading this correctly?
470 AHC spring rate = 95 lbs/in
King = 130
450 = 150
100 = 170

Maybe the 80 series rear spring rate is same as 100 series rear?

Does anyone know how the 200 series rear springs compare to 470/AHC rear spring rates?

I spent some time with the helpful folks at Cruiser Outfitters @cruiseroutfit this morning and they shed some light on things...

Yes, 80 series rear coil is the same as 100 series rear coil.
Yes, 450 rear coil is softer than 80/100 rear coil.
200 rear coil is quite a bit different than 80/100 rear coil.

Hope this can help some future searcher...

 

[PabloCruise]

I spent some time with the helpful folks at Cruiser Outfitters @cruiseroutfit this morning and they shed some light on things...

Yes, 80 series rear coil is the same as 100 series rear coil.
Yes, 450 rear coil is softer than 80/100 rear coil.
200 rear coil is quite a bit different than 80/100 rear coil.

Hope this can help some future searcher...

I got a chance to compare the LX470 rear coil springs to the LC100 springs over the weekend - big difference!

 

[PabloCruise]

I got a chance to compare the LX470 rear coil springs to the LC100 springs over the weekend - big difference!

Darn - try again:

 

[longranger]

When I fist got my truck I loaded it fully (drawers, fridge, food, recover gear, luggage & camping gear for 5 PAX, fully loaded roof rack and boat with 100kg ball weight) and she sank down to LOW on the test run with myself and the kids.

The shocks and torsion bars in the LX are a lower load capacity than the LC ones as the AHC system holds a significant % of the vehicles mass. Where as on the LC the springs and torsion bars hold the whole vehicles mass as there is no AHC system in the middle.

So I did some checking and physically the LC springs are larger in DIA than the LX ones, so I installed them and no issues when fully loaded

If I fully unload the LX now the rear is bouncy, suggesting its over-sprung with the LC springs, but as I'm keen to install a rear bar shortly I think the extra weight will remove that issue.

This is VERY helpful — if you can, could you share the part number. There is also often a lot of talk about people installing so-caller “violet” springs that are stiffer and used on armored LCs, with at least one mudder suggesting they are Eibach springs, but without part numbers, or links. If anyone has part numbers/dimensions/etc., pls do share.

 

[longranger]

If we spend our lives listening to others what we should do. We will never be happy. I come to this forum to gather and share information.

Ultimately I make final decision based on information I gather.

I replaced globes for $600 from oversea. Look at other post I made. I am pleased with the decision.

Even more surprising is that I replaced all end links with new bushings as well as sway bar bushings. Rubber were almost dry.

Now I'm even more happy with the ride. Especially long trips we take few times a year.

AHC is awesome.

Can you post a link to your globe swap post pls? Can’t find it.

 

[longranger]

I would like to second Bamabrock's question. Does anyone know what the spring rates are or where to find that information? There is bound to be a way to do the math based on how much armor and gear a vehicle is carrying to figure out the appropriate spring rate that will get the AHC into spec. Does anyone know what this equation is?

I have a 99 LX with an ARB front bumper with winch, Slee dual swing rear, roof rack, slides and steel skids. I carry a recovery bag, small tool kit, xjack, and a few other odds and ends at all times. Best estimate is 1000lbs for all of that. My factory LX springs were shot when I bought the vehicle and the pressures were obviously way off when I put all the stuff on. To fix that, I turn the torsion bars and got the pressures in the front right. For the rear I replaced the springs with new factory LX springs and added 30mm spacers. That brought the rear pressure down to 7.1 but not quite in spec. The system works great now. Except when we load up the whole fam with camping gear. I think that is just too much weight for it. I can trick the system to go to high mode by getting everyone out of the car once off road and then hit the button. It will go up and stay up then. Best estimate for family, dog and camping gear is 800lbs.

The way I understand it is the springs and TBs are suppose to carry 60% of the weight the AHC is supposed to carry the other 40% plus up to 1200lbs of additional weight (people and gear). So if we call that the neutral position of the system, with my LX being slightly out of specs, it is putting more weight on the back AHC than it should. Which I feel then cuts into my 1200lbs of people and gear. The ride is not as good either. The computer system was supposed to operate with the TBs the way they were and not extra turns and springs that aren't squished with spacers. My goal would be to find a TB and spring combo that would bring the system back to how it was designed to operate while accommodating the extra static weight. If I can get the correct stronger TBs and rear springs, the AHC essentially wouldn't know I had added 1000lbs. Most of the variables are known I just don't know the equation or the spring rates. I haven't studied Mechanical Engineering since college 16 years ago so I pretty much don't remember any of it other than I know this should be a solvable puzzle with out using opinion, guess or trial and error. Come on smart people on here, show me your magic.

Agree that there should be a more rigorous way of finding springs for different LC/LX setups — and weight adds. Seems that folks with good/comfortable rides who are running constant gear loads (recovery gear, RTTs, etc.) have best info on what spring upgrades work best (especially if no torsion bar tweaks were made). However, these folks are probably enjoying their rides, instead of haunting “spring rate” threads on forums.

 

[Dannyboy lx470]

The lx 470 spring sits way lower from the picture.I guess thats why when you switch to land cruser suspension sits a bit higher.

 

[dfrelich]

Can you post a link to your globe swap post pls? Can’t find it.

Genuine Japanese Car Part Imports - Amayama

Sources for AHC Accumulator Globes

 

[longranger]

Genuine Japanese Car Part Imports - Amayama

Sources for AHC Accumulator Globes

Thank you! This is for the AHC on the LX470, correct? And also LC100 that had that option, right.

 

[planomateo]

Thank you! This is for the AHC on the LX470, correct? And also LC100 that had that option, right.

Yes, optional in LC from 2006-2007 vs standard equipment on the LX.