Heavier springs rate that works with AHC (1 Viewer)

[AnyMal]

Did you notice any particular symptoms of being slightly undersprung for your weight?

I ask because I think have a sort of pogo’ing effect going on due to perhaps being overloaded in the rear of my lx. I have a fair amount of tools and parts back there…plus a Wilco swing away hitch and carrier. I noticed lately that I have almost no “rake” between the front and the back.

I’m trying to figure out if I’m undersprung for the amount of weight back there.

Curious. Your AHC is not raising the rear into rake with the car running either? Are you sensor level/lifted?
What PSI are you running on the KO2s? Im assuming E load? Maybe you need to drop the pressure instead.
You shouldn't be overloaded even with 1000 lbs in the back but perhaps off balance instead, yet you do have a front bar.
That given you should still be within factory front/rear balance outside of any rear levering effects on the rear axle.

My first step here would be to go get weighed front and rear. Also considering your rear bias load, staggering front and rear pressures to start off.
If it is porpusing instead of pogoing that may be influencing it. A true level pogo may indicate spring sag which would be analogous to under-springing.

 

[TeCKis300]

Agreed, with the added detail, I don't think it's due to the cantilevered weight.

@highfructose , does putting the dampers in sport make any difference?

 

[AnyMal]

Agreed, with the added detail, I don't think it's due to the cantilevered weight.

@highfructose , does putting the dampers in sport make any difference?

Was wondering the same thing. Fructose, is your AHC dial creating any perceptible difference?

 

[1world1love]

Yeah, if I use comfort at highway speeds it can be quite an interesting experience and I could imagine that you might get something like a porpoising type effect with the right load.

Seems like the heavier I got the more squirrelly comfort mode got.

I always use sport unless I am wheeling and then I’ll use comfort.

 

[TeCKis300]

Yeah, if I use comfort at highway speeds it can be quite an interesting experience and I could imagine that you might get something like a porpoising type effect with the right load.

Seems like the heavier I got the more squirrelly comfort mode got.

I always use sport unless I am wheeling and then I’ll use comfort.

Yup, definitely have experienced this too. With a heavier vehicle and wheel/tire package, there needs to be more compression damping to control the suspension/tires. Otherwise the tires are skipping down the highway on bigger bumps, loosing contact with the tarmac and leading to a squirrely ride. Adjusting tire pressure down can help to a degree.

We're obviously using AHC outside of its original parameters so the built in response curve doesn't completely fit. Fortunately, we have that fancy damping switch to continue to dial in the response. The LC guys likely experience this too with larger and heavier tires, but the static stock shocks can't compensate leading them down the road of needing completely revamp the suspension.

 

[AnyMal]

Yep. My aim has always been to work around Normal mode.

All the testing and playing around is strictly in normal damping behavior. If the ride is too harsh or handling too mushy in that mode, i know where to look for issues.
The more i do load it up (and the more comfortable the ride becomes) with say 5 large passengers, the more i dial it up to combat the newfound compliance.

Only in Comfort with a full load is when i start to get a bit of bounce due to high AHC demand with springs "compressed". And thats not on rough roads or potholes, only road undulations. Neither on brake application release as AHC is doing its job marvelously.
I would roll with that all the time since im usually 1-2 occupants max, but it dives a tad bit too much at that point since all the weight is up front.

Not to also beat a very dead horse, but tire pressure is key. Dead horse of "right" pressure aside, heavy rear loaded vehicles should be running rears higher a la OEM LX 470 32/33 as well as all Toyota towing recommendations of 39 PSI for rears as a somewhat similar comparison (although that has a lot to do with lateral stability).

In the scenario of lets say 1,500 lbs max cargo capacity from the rear seats back, it would be a distribution of about 45/55 front to rear bias by a very rough approximation. Say you were needing to run 40 PSI for that load accounting for something like a 20% overage or whatever you liked, that would look something like 38/42 PSI front and rear. None of these number are precise but you get the point.
The more weight on the rear axles, the higher the rebound rate of the tire needs to be to overcome the compressed spring rate acting on it. Otherwise all things equal i would presume that the rear bounces on the axle instead of the tires properly actuating the shock and AHC rebounding that shock to the road with internal damping. Im not clever enough to think through this with all the physics involved, but this is my best guess at the dynamics.

Long story short rear weight bias is something AHC handles incredibly well, leading me to think this is something else and as always I'm gonna be a stickler for tire pressure. It continues to blow my mind just how much influence it can have on everything. Somewhere in the ether is the perfect harmony of tire physics, wheel weight momentum, offset leverage, AHC pressure, and spring rates. Add to that load is constantly changing and we are starting to have some fun.

 

[1world1love]

Yep. My aim has always been to work around Normal mode.

All the testing and playing around is strictly in normal damping behavior. If the ride is too harsh or handling too mushy in that mode, i know where to look for issues.
The more i do load it up (and the more comfortable the ride becomes) with say 5 large passengers, the more i dial it up to combat the newfound compliance.

Only in Comfort with a full load is when i start to get a bit of bounce due to high AHC demand with springs "compressed". And thats not on rough roads or potholes, only road undulations. Neither on brake application release as AHC is doing its job marvelously.
I would roll with that all the time since im usually 1-2 occupants max, but it dives a tad bit too much at that point since all the weight is up front.

Not to also beat a very dead horse, but tire pressure is key. Dead horse of "right" pressure aside, heavy rear loaded vehicles should be running rears higher a la OEM LX 470 32/33 as well as all Toyota towing recommendations of 39 PSI for rears as a somewhat similar comparison (although that has a lot to do with lateral stability).

In the scenario of lets say 1,500 lbs max cargo capacity from the rear seats back, it would be a distribution of about 45/55 front to rear bias by a very rough approximation. Say you were needing to run 40 PSI for that load accounting for something like a 20% overage or whatever you liked, that would look something like 38/42 PSI front and rear. None of these number are precise but you get the point.
The more weight on the rear axles, the higher the rebound rate of the tire needs to be to overcome the compressed spring rate acting on it. Otherwise all things equal i would presume that the rear bounces on the axle instead of the tires properly actuating the shock and AHC rebounding that shock to the road with internal damping. Im not clever enough to think through this with all the physics involved, but this is my best guess at the dynamics.

Long story short rear weight bias is something AHC handles incredibly well, leading me to think this is something else and as always I'm gonna be a stickler for tire pressure. It continues to blow my mind just how much influence it can have on everything. Somewhere in the ether is the perfect harmony of tire physics, wheel weight momentum, offset leverage, AHC pressure, and spring rates. Add to that load is constantly changing and we are starting to have some fun.

When I’m fully loaded and at around 38 psi cold, and in sport, it is spot on for me. I feel like I have great control and feedback and nothing is too squishy. The ride is super compliant.

 

[AnyMal]

When I’m fully loaded and at around 38 psi cold, and in sport, it is spot on for me. I feel like I have great control and feedback and nothing is too squishy. The ride is super compliant.

Now thats its winter here, im having a fantastic time on 36 PSI. Its usually a more consistent ambient temp all day VS the summer 40 degree fluctuations and scorching pavement. Targeting 38 at temp.
The C load A/T 3s are breaking in VERY nicely.

 

[highfructose]

Bumper and winch ballast is already installed. Very pleased with the Ironman bumper. I was able to do a slight modification to it and use my arb recovery points.

The Wilco is currently configured as such in the picture. I measured and, with the hitch riser, the rear of the hitch carrier is equivalent to the lx’s departure angle. I’ve got a slightly higher riser I’m going to install soon so I can fit my hilift and an axe under the hitch carrier as pictured though.

The Wilco is heavy, but it’s not the thing probably weighing me down.

I’ve got a lot of tools I like to carry around…plus a starter, cv, alternator, more power puller, and various other recovery gear…which I’m going to pull today. Most of that stuff I really don’t need to carry every day. It was just convenient to leave it back there.

If airing up doesn’t solve the problem I’ll probably purchase the terrain tamer springs and see if that fixes it…or perhaps do air springs for road trips where I would bring all those extra parts and recovery gear.

I need to check and see if you made a thread explaining air springs.

View attachment 2887483

View attachment 2887484

It seems like you would need to have a significant amount of weight on the carrier to cause that. Possibly more than the safe weight rating of the carrier itself. I have had my carrier loaded with a few bags of concrete and never had that issue.

Sounds like he is carrying a fair amount in the cargo space which is mostly centered over the rear axle.

Is It possible that his rear shocks are shot?

Also curious - @highfructose What AVS setting do you normally use?

Yes. Lots of weight in the cargo area in a toolbox behind the 3rd row.

Other than the Wilco, a hilift, and a hitch riser, there’s no weight in the hitch carrier section.

No noticeable change whether I’m in sport or comfort mode.

Is there a way to troubleshoot whether my rear shocks are bad?

 

[AnyMal]

No noticeable change whether I’m in sport or comfort mode.

That’s numberwang!

 

[nwfl4runner]

Yes. Lots of weight in the cargo area in a toolbox behind the 3rd row.

Other than the Wilco, a hilift, and a hitch riser, there’s no weight in the hitch carrier section.

No noticeable change whether I’m in sport or comfort mode.

Is there a way to troubleshoot whether my rear shocks are bad?

Replace your globes yet?

 

[teejnut]

Just got the TT springs direct from TT. I can measure them if that would be helpful for anyone. Will get some comparison pics with stock springs when I do the swap.

 

[grinchy]

Just got the TT springs direct from TT. I can measure them if that would be helpful for anyone. Will get some comparison pics with stock springs when I do the swap.

Yes please do!

 

[1world1love]

Just got the TT springs direct from TT. I can measure them if that would be helpful for anyone. Will get some comparison pics with stock springs when I do the swap.

Yeah, I wish I had gotten measurements and pictures of both before my install.

 

[LEXCRUISER]

Got my Terrain Tamer springs in. Before I have them installed, should I also get the airbag?

 

[TeCKis300]

Got my Terrain Tamer springs in. Before I have them installed, should I also get the airbag?

How much weight are you carrying? Either installed or added maybe with towing? AHC is plenty capable up to about 1800lbs payload. As you'll be installing TTs, I'd guestimate that to have maybe another 300-500lbs headroom.

Can't hurt to install airbags if just to future proof. It wants about 5PSI even if you're not needing it just so it stays in place, and that's going to add a tad more spring rate.

I have mine at 18 PSI to handle 1200lb tongue from my 8k trailer (~4800lbs rear axle weight on scales with WD bars).

Outside of that, I also use it to level the car front to back and side to side when car camping.

Adding Airbags to AHC

Picture is probably too subtle to show but it's part of the why - adding airbags creates the ability to level the vehicle side to side and front to back for backcountry car camping. In the pic, I have the right side jacked up 2" with about 25 PSI in the right rear bag. Secondly, while AHC has...

forum.ih8mud.com

 

[radman]

Got my Terrain Tamer springs in. Before I have them installed, should I also get the airbag?

I’ve actually been meaning to ask this (and sorry if it’s been asked before), but those who have gone with the TT - could you have just gone with the airbags instead (on stock springs)?
What benefit does TT give you over adjustable bags?

 

[1world1love]

I’ve actually been meaning to ask this (and sorry if it’s been asked before), but those who have gone with the TT - could you have just gone with the airbags instead (on stock springs)?
What benefit does TT give you over adjustable bags?

I guess I view airbags as a good solution for temporary loads such as a trailer or 10 bags of concrete. Uprated springs seem like a good solution for permanently increasing safe payload capacity.

I am pretty much always near gvwr. If I planned on towing a heavy trailer, I would probably do both.

 

[grinchy]

Looking back into these shocks. Did anyone ever figure out the spring rate and length?

 

[LEXCRUISER]

TT springs vs Stock