Lx570 pogo’ing, tundra coils a solution?

[TeCKis300]

I think a mild sensor lift would fix the pogo’ing that happens when going over speed bumps.

And, barring the availability of a slightly stiffer front coil, that may be the only solution…ideally I’d like a set of terrain tamers for the rear and for the front.

I think you had a list of spring rates for the various front coils available to us.

Did you ever figure out what the front coil’s spring rate was?

Haven't been able to find data on the front rates.

With AHC, the modification strategy is different from static suspensions. Going straight to heavier coils may not be the right solution.

I have run AHC bone stock with 2k payload and it worked great there except the system wouldn't go into high anymore, which is expected per the manual. I've incrementally upgraded with front spacer, rear spacers, bigger rear spacers, sensor lift, and now have a variable rate rear setup with airbags. The system is pretty flexible and has worked well for me in the stages of upgrade.

I'd start with a minor sensor lift and see if that changes any impressions. Easy, no cost change. And easy to revert. Take each sensor, critically mark current position, then shift by ~1/4". You'll want to look in this thread as I forget which way to shift the front axle sensor vs the rear axle sensors as one of them is in reverse

LX570 AHC height modifications (lift it!)

forum.ih8mud.com

It's very possible that you need replacement globes per @tbisaacs . It may be one of them is weak and pegging out lending to the pogo'ing. Why it doesn't seemingly happen in high is why I'm scratching my head, but there's merits to his suggestion. That incremental sensor lift may tell us more?

 

[1world1love]

Did you have a sensor lift while running excess weight? Because your hydraulic suspension has quite a lot of flexibility in handling weight…by lifting your car with them, you’re, essentially, stiffening up your ride by taking some pressure off your coils and adding a bit via the hydraulics.

My issue completely goes away when I have a “sensor lift” and gets extremely bad when I go into low. At neutral it’s only noticeable when going over speed bumps.

Also, there are no leaks in the system and it rises itself from low to hi in 24 seconds…which I think is faster than what’s expected by the manufacturer…

Is anyone running a heavier rig without a sensor I lift other than me? You guys might all be utilizing the hydraulics to get, in essence, a stiffer suspension to handle the excess weight.

Yes, I only did the sensor lift recently when I replaced the springs. Prior to that I was stock all around.

 

[1world1love]

And i

And re-reading your post makes me think that it is almost certainly your shocks.

When AHC is in high mode, the hydraulics are carrying much of the load. In extra high mode in CC, it is carrying all the weight.

But in low, all of the weight is on the shocks.

So if it is worse in low and gets progressively better as you go up, then it would point to bad shocks.

and I should clarify that here I don’t mean literally supporting the weight but rather the dampening.

 

[1world1love]

So riding in normal height and rolling over a significant speed bump, what roll do the shocks play?

I assumed that they would absorb the initial compression. Otherwise, why are they there? I thought that the shocks provide the baseline dampening and the accumulators allowed for refinement.

But it sounds like the accumulators handle the bulk of compression and rebound. So what do the shocks do?

 

[nwfl4runner]

maybe my brain is fried, but why involve a sensor lift if the ride is garbage? Aren’t we just dealing with either a leak, shot coils, shot accumulators, or blown bushings? If you were truly too heavy, you wouldn’t hit H to begin with?

 

[lx200inAR]

So riding in normal height and rolling over a significant speed bump, what roll do the shocks play?

I assumed that they would absorb the initial compression. Otherwise, why are they there? I thought that the shocks provide the baseline dampening and the accumulators allowed for refinement.

But it sounds like the accumulators handle the bulk of compression and rebound. So what do the shocks do?

The shocks are mostly the interface where the force is exerted on the hydraulic system so it can provide compression. Or vice versa, where AHC can increase pressure to lift the truck. Even in the parts diagram, Toyota refers to the shocks as “actuators”.

When you go over a speed bump, the shock compresses, it applies force on the hydraulic lines, therefore applying pressure back on the globes. If the globes weren’t there, or if you closed a theoretical valve between the shock and the globe, no compression would happen. The shock would just act like you had a bar of steel between the axle and frame.

There has been speculation that there is some damping going on in the front actuators, but I’m not sure that’s ever been proven, or to what extent it dampens.

 

[grinchy]

The easiest thing to check is tire pressure. Go put 45 lbs in all your tires and see if your pogo goes away.
It does? Good, lower pressures to the value that has the best ride and a freeway psi temp gain of 10% or so.
If not, bleed your ahc and reassess after bleed.

 

[1world1love]

The shocks are mostly the interface where the force is exerted on the hydraulic system so it can provide compression. Or vice versa, where AHC can increase pressure to lift the truck. Even in the parts diagram, Toyota refers to the shocks as “actuators”.

When you go over a speed bump, the shock compresses, it applies force on the hydraulic lines, therefore applying pressure back on the globes. If the globes weren’t there, or if you closed a theoretical valve between the shock and the globe, no compression would happen. The shock would just act like you had a bar of steel between the axle and frame.

There has been speculation that there is some damping going on in the front actuators, but I’m not sure that’s ever been proven, or to what extent it dampens.

Thanks. I think I need to look over that diagram more thoroughly

 

[1world1love]

The shocks are mostly the interface where the force is exerted on the hydraulic system so it can provide compression. Or vice versa, where AHC can increase pressure to lift the truck. Even in the parts diagram, Toyota refers to the shocks as “actuators”.

When you go over a speed bump, the shock compresses, it applies force on the hydraulic lines, therefore applying pressure back on the globes. If the globes weren’t there, or if you closed a theoretical valve between the shock and the globe, no compression would happen. The shock would just act like you had a bar of steel between the axle and frame.

There has been speculation that there is some damping going on in the front actuators, but I’m not sure that’s ever been proven, or to what extent it dampens.

I am an idiot for sure. I am not sure why, but I had it in my head that this was way more complicated than it is.

 

[AnyMal]

I am an idiot for sure. I am not sure why, but I had it in my head that this was way more complicated than it is.

The interesting thing with AHC is that it incorporates fluid dynamics, height lift pressurization, and gas chambers compression all in harmony. I want to thicken the fluid and see if it can handle more abuse. On someone elses LX lol.

 

[highfructose]

maybe my brain is fried, but why involve a sensor lift if the ride is garbage? Aren’t we just dealing with either a leak, shot coils, shot accumulators, or blown bushings? If you were truly too heavy, you wouldn’t hit H to begin with?

Going into hi stiffens the shocks…increases the pressure…which means it handles the excess weight I have better since it has the coils I already had plus more shocks too.

Going into low softens the shocks…reduces the pressure…which puts more weight on already overloaded coils…so I’ve got less shocks and still the same amount of coils…so it handles the excess weight worse.

An easy bandaid would be always run my shocks at a higher pressure…I.e. get a sensor lift.

An ideal solution would be to find coils for the front and rear that are designed for slightly augmented loads…

Another possible solution is coil spacers…which apparently will preload my coils and make them stiffer somehow. I don’t understand that option to be honest. Seems counterintuitive to me.

 

[highfructose]

The easiest thing to check is tire pressure. Go put 45 lbs in all your tires and see if your pogo goes away.
It does? Good, lower pressures to the value that has the best ride and a freeway psi temp gain of 10% or so.
If not, bleed your ahc and reassess after bleed.

I’m going to try this first. I forgot to include that from 40-43 SEEMED to improve things somewhat, though it might have just been in my head. I’ll try 45. if that gets me a little closer, maybe a 0.5-1” sensor lift too.

 

[grinchy]

I’m going to try this first. I forgot to include that from 40-43 SEEMED to improve things somewhat, though it might have just been in my head. I’ll try 45. if that gets me a little closer, maybe a 0.5-1” sensor lift too.

I just want to take tire pressure out of it. I had e rated tires that softened the sidewall over time, and led to similar symptom you are having. Never thought to check that a higher cold psi could be the fix.
I had already done a bleed and replaced accumulators (a while back) so didn’t suspect them.
I overfilled in an air up (38 instead of 35) and the change in ride was remarkable. Porpoise/ front back bounce eliminated.
These were 129 load tires, so run a lower psi naturally.

 

[highfructose]

I’m going to try this first. I forgot to include that from 40-43 SEEMED to improve things somewhat, though it might have just been in my head. I’ll try 45. if that gets me a little closer, maybe a 0.5-1” sensor lift too.

Going to 45 seemed to help a bit. Going into hi, again, completely eliminates the problem. They’re 275 60 r20 k02’s so I think max psi is 65. They’re around 2 years old.

I’ve never used tires at this high of a psi. Would bumping it to 47 or 48 not be advised? I need a stiffer ride…

 

[grinchy]

Going to 45 seemed to help a bit. Going into hi, again, completely eliminates the problem. They’re 275 60 r20 k02’s so I think max psi is 65. They’re around 2 years old.

I’ve never used tires at this high of a psi. Would bumping it to 47 or 48 not be advised? I need a stiffer ride…

First, you should check the tire pressure thread for recommendations. Here’s a random online calculator
Based on this, sure, run it up a couple more and see what you get.

 

[lx200inAR]

I'll preface this with saying I don't believe these RCTIP calculations are very meaningful, but you used the LCs OEM RCTIP rather than an LX, and they are fairly different (one reason I don't believe them...haha)

 

[grinchy]

I'll preface this with saying I don't believe these RCTIP calculations are very meaningful, but you used the LCs OEM RCTIP rather than an LX, and they are fairly different (one reason I don't believe them...haha)

View attachment 2902564

Yes, definitely get a recommendation from the tire pressure thread!
However my personal experience is I run more tlc pressures than Lx pressures. A D or E or F tire is not a P tire, and setting pressures assuming they will behave the same from the suspension’s point of view is only an approximation.
these are just places to start, and I wouldn’t be surprised that as the accumulators age (less pressure on the nitrogen side) that they can no longer offset the sidewall compliance of the lower psi and this leads to some porpoise.

 

[TeCKis300]

I likewise am running higher pressures than RCTIP for larger 35s. Where I was running lower than RCTIP for 33s.

My own interpretation is that for larger tires and taller sidewalls, that there warrants an added factor to RCTIP for load and sidewall stability. Same with heavier and heavier loads as I routinely go +8PSI when really laden or trailoring. That is beyond just having enough air to support the load which is what RCTIP only considers, but is unfortunately based off of factory pressures that probably didn't only include load. Because there's a myriad of other reasons, including specific tire sizing, wheel size, tire model and even personal preference that could be tailored for as well.

 

[AnyMal]

The whole thing is predicated on an assumption that every pound of pressure in the factory recommendation is to support load. The load profile of a P tire is actually very different than an LT. Thats why the manual may ask for 33 +6 @ 39 PSI to tow but on an LT you may be good just adding a third of that. Its way more complex than just a raw conversion so if it feels right on your rig to your experienced opinion then go with it. You will feel being out of range both over and under in pretty meaningful ways. No reason to deny your own observation.

 

[grinchy]

The only thing I worry about with PsI is too little. And by that I mean not enough air to control tire temperature and lead to a delamination. Rule of thumb for that is 10% cold to hot psi change. Beyond this little guidance it is what feels right.