Harsh riding '05 LX this can't be normal

[Ivan80]

Drove my wife's '05 LX today, and I cannot believe how harsh and rough it rides. The problem is most noticeable at slower speeds, and when you get to highway speed it's not too bad, but still...I can't believe a $66k vehicle would ride like this. In all seriousness, my 80 with 3" of lift and 35" Trxus rides better.

End of rant, now the facts:
Dunlop Grantrek, stock size, front PSI, 30, Rear 28. I don't know how many miles are on them, but they have less than %50 tread left.
AHC set to comfort. Ride height works, comfort/sport setting seems to do nothing for the harshness, although it corners marginally flatter in sport.
55K miles (purchased it at 35K miles, and it seems to have worsened since then)

I'm thinking tires, possibly. I would think michelins would ride better, but they need to be a lot better for this to be acceptable.

Is it possible that the wrong type of fluid in the AHC system would make it rock hard? I've never changed it out or added. I searched and found bad fluid causing sponginess, but not harshness.

Any ideas would be appreciated. Thanks.

[Trunk Monkey]

If you change the AHC settings does the vehicle raise and lower? Just thinking you may have an AHC issue that's stuck and not allowing the fluid to compress.

[Ivan80]

Originally Posted by Ivan80

AHC set to comfort. Ride height works, comfort/sport setting seems to do nothing for the harshness, although it corners marginally flatter in sport.

Yea, the height adjustment works. It's the fact that every bump can be felt, and it's the initial harshness, or impact of every bump that makes the truck ride poorly.

[hoser]

Something doesn't sound right at all. Check the AHC fluid graduations from Low to Hi mode. Tell us how much difference you read. Also, flush and change the AHC fluid. It is due at 60k anyway.

[Ivan80]

Thanks, the graduation marks are as follows:

Low setting: fluid at top-most graduation mark

Normal setting: 9 down from low

High setting: 4 down from normal, 13 graduation marks down from low

[hoser]

Those numbers are within normal limits. I don't have my FSM at the moment to further investigate this.

[Trunk Monkey]

Something simple, over inflate the tires?

[1loudLX]

something simple like reading that they're set at 30F and 28R?


Did you purchase the extended warranty or was it a CPO vehicle?? If you have the EW just drop it off and complain.

[Jim_Chow]

Originally Posted by hoser

Those numbers are within normal limits. I don't have my FSM at the moment to further investigate this.

I've heard of a case on club lexus where the high to low gradations met the 7 gradation spec easily, yet the accumulators were still flat. I suspect the accumulator globes are dead. I definitely notice a difference between sport and comfort. When going over speed bumps in comfort, you won't bounce up much, as if riding in one of those old caddie's. In sport, you will bounce up as if you were driving a sports car w/ firm suspension. Just because your AHC will raise and lower the vehicle properly doesn't mean it's working. The damping is controlled by the accumulator globes, and when those are shot, you the ride will be harsh as if there were no shock absorbers. Since you have a '05, get it done under warranty ASAP, 'cause if you're out of warranty, it'll run 'ya $2.5K for new globes.

[hoser]

I agree, there is a very significant difference between comfort and sport mode. Was there ever a time where you had to add a lot of AHC fluid to the reservoir? I would first test the damping force actuators.

If you don't already have the FSM or the Toyota TIS, this would be a good time.

[lancaster]

Same exact thing happend on our 03 LX. We needed new AHC spheres and sensors on all four corners.

Luckily it is still under CPO.

Good Luck

[dfrelich]

Have you tried deflating your tires a bit. Your tire may be over inflated?

I noticed a big difference in rides when I have over inflated tire vs at suggested pressure. Under inflated tires feels much more smoother but thats not wise though.

If not, then it could be air in your AHC? When i bled my AHC a few weeks ago, I had air bubbles in two of my corners. After the flush... my lx felt much more responsive at sports and smoother at comfort.

[Jim_Chow]

If the globes are shot, chances are, someone put the wrong fluid in the AHC resevoir. Anything but Toyota brand AHC fluid will destroy the globes. Otherwise, there's no way that new of a LX is going to develop bad globes. There are those on this board who have run theirs 120K+ miles w/o issues.

Oh, another thing I noticed...the tires can make a huge difference. I had old Pro Comp AT (LT-rated) tires on my 4runner @ 33psi (max rating of 50psi). They still had maybe 20% tread, but the ride was really harsh and the rubber was getting old and hard/cracked (I have a 2" OME lift w/ beefed up t-bars, ARB/Kaymar). Last weekend, I got new BFG AT's in the same 31" size, inflated to 40psi (LT tires, max of 50psi). The ride is plush in comparison, as if I were driving a new 4Runner or Taco. I'm amazed at the difference. The tires could be some of your difference. The Dunlops suck. The Bridgestone HT's suck offroad bigtime.

[Ivan80]

I noticed there are bubbles in the reservoir top of the fluid. Is this normal? The fluid is dark brown.

The truck has 55K miles on it and no CPO warranty(see sig line) and the tires are at 30f, 28r (see first post).

I'm thinking the Dunlops are a lot of the problem. I'm going to replace the tires in the next month, they're borderline anyway. And I'll R&R the AHC fluid.

[dfrelich]

Originally Posted by Ivan80

I noticed there are bubbles in the reservoir top of the fluid. Is this normal? The fluid is dark brown.

I do not see why there would be bubbles in the reservior. I would think it is containment that is like water and oil. It'll look like bubbles if water sits in the oil. This might be your case.

[Ivan80]

These are air bubbles. Uniform bubbles around the edge of the reservoir about the size of BB's.

[SWUtah]

Originally Posted by Ivan80

These are air bubbles. Uniform bubbles around the edge of the reservoir about the size of BB's.

My fluid has no bubbles and the fluid is almost clear, like new oil. Mine is a 2004 with 44K miles. I would take to the dealer and have it diagnosed

[Texasoil]

These vehicles DO NOT ride harsh. Try this test to check the 4 accumulators on the struts. At normal ride height, run the wheels up on a curb, first front , then rear, pointing to and from the curb, then drive off quickly (not racing, just smartly) the goal is to 'bounce' each end. If the accumulators are gone, it will bounce like there is no suspension, hard, rapid un-damped bounce--cause its only the tires giving. OTOH, if the 'bounce' is well absorbed, then the suspension accumulators are OK.

The 'shocks' are simple single acting hydraulic cylinders, just like a hydraulic jack. Nothing inside them effects the ride. All the 'shock dampening' is in the 16 position electronically dampening valves to which the accumulators mount. All the 'absorption' of shock is in the accumulators. When the OEM nitrogen leaks out, there is no place for oil from the 'jacks' to go when you hit a bump.

Recently had 2 more customers experience early failure (<18 months) of Dealer OEM replacements. OUCH!. >$4,000 parts and labor.

[aedgington]

A lot of people mentioned tire pressure, and it does make a big difference... did you check it?

The recommended pressure is on your info sticker on the driver door's inner area, or use the numbers 1LoudLX gave you. These #'s are probably about 5 psi lower than those Dunlops max value.

Dunlop GT AT20s are for freakin' Tundras and Sequoias, not LXs!

[SWUtah]

I keep my ride setting one click to the right of the middle (little more sporty) and run my tires at 30 psi all around but I have the Michelin LTX tires which are way better then the Dunflops. My ride is a little more sporty but not at all harsh.

[tom.]

Hi,
My problems are similar to Ivan80’s.
I have bought my car few months ago (50K, ‘02) and since then I try to resolve AHC suspension problem. The ride is harsh and it is only noticeable at slow speed on expansion joints/cracks, potholes. On highway speed and bigger road imperfections everything seems to be Ok.
I have changed accumulators, checked sensors, shocks pressure, set everything (t-bars, sensors, car height) to correct specifications, fitted new tires (pressure front 30, back 32), changed AHC fluid three times and suspension works like before. Maybe there is improvement in the difference between sport and comfort settings but it does not make any changes for road expansion joints/cracks at slow speed. I feel like suspension does not absorb this small road imperfections.
Does anyone have any ideas what can resolve this problem?
Thanks

[Jim_Chow]

Don't expect it to ride like a caddie sedan over small imperfections/cracks in the road. You will still feel those, regardless of what truck you drive in. The only way you wouldn't is if the vehicle had 4 wheel indep suspension with very soft springs/shocks. Anyways, you should notice a significant difference between comfort and sport if you drive slow with one side of the car going over a speed bump. Try it in both modes. In comfort, the bump should be a lot less noticeable while in sport, it'll be as if you had a stiff sport suspension.

[CivicFerio]

Car manufacturers have different taste when it comes to damper settings. My observation on Toyotas in general, is they have good high speed damping giving you more road feel. At the same time a moderate mid to low speed damping for better ride on dips and bumps, but gives floaty feel at higher speeds (80mph+).

My observation on the AHC system is that it stiffens up the mid-low speed damping the faster you go. It gives you the best of both worlds. Low speed comfort and high speed body control. Though I sometimes like feel it needs a tad less on the high speed damping to iron out the road imperfections.

I'm a big fan of KONI shocks and their damping philosophy. I wish Koni has made an FSD suspension on our land cruisers. Maybe I can talk to them at PRI next week.

Koni FSD info

Koni: FSD

[uHu]

Originally Posted by Ivan80

I noticed there are bubbles in the reservoir top of the fluid. Is this normal? The fluid is dark brown.

The truck has 55K miles on it and no CPO warranty(see sig line) and the tires are at 30f, 28r (see first post).

I'm thinking the Dunlops are a lot of the problem. I'm going to replace the tires in the next month, they're borderline anyway. And I'll R&R the AHC fluid.

There is definitely something wrong with your fluid. The color might even be from dissolving membranes in the spheres, and seals in the shocks and actuator valves.
I recommend you not only replace the fluid, but take off the shocks and flush them too. Remember to bleed well, also at the (pressure)accumulator (at the middle of the DS frame rail). It's easier if you avoid getting air into the pump/reservoir while changing the fluid.
And - the sooner the better.

[tom.]

I have heard that LC with AHC suspension rides better than Mercedes S, and if it is truth, I would like my car to be like that. My previous Toyota sedan drove smoother in conditions which I have described previously. I tried test with a speed bump and there was a significant difference between sport and comfort. When tried with two wheels going over bump together, it was much more rough but I think this is normal for all cars. Sometimes want to give up, but I have spend to much money … I need to resolve this problem.

Did anyone heard about any problems with ECU TERMINAL? Is there something like Harshness controller which controls the damping force? If so, how can I check them?

Thanks

[SWUtah]

Originally Posted by tom.

I have heard that LC with AHC suspension rides better than Mercedes S, and if it is truth, I would like my car to be like that.
Thanks

My SL rides alot better then my LX even over bumps. The SL's suspension is under 2700 lbs of pressure, very high tech and it works.

[scrappyslexus]

After numerous visits to the dealer they finally decided that the accumulators were shot. The dealership blamed it on AHC contamination which was bull because they did all the services. I pulled oil samples and the AHC fluid was fine. The accumulators just went. You may be able to get it repaired under warrenty. My truck was very bouncy, barely noticeable on a flat highway. I called 4 lexus dealers and took it to the one dealer that understood what I had them qouting on. i got it done for $2300. The job is simple but needs to be done correctly flushing system ,bleeding and draining shocks. Good luck.

[SWUtah]

Originally Posted by scrappyslexus

After numerous visits to the dealer they finally decided that the accumulators were shot. The dealership blamed it on AHC contamination which was bull because they did all the services. I pulled oil samples and the AHC fluid was fine. The accumulators just went. You may be able to get it repaired under warrenty. My truck was very bouncy, barely noticeable on a flat highway. I called 4 lexus dealers and took it to the one dealer that understood what I had them qouting on. i got it done for $2300. The job is simple but needs to be done correctly flushing system ,bleeding and draining shocks. Good luck.

How many miles did you have on your LX when you think they went bad?