Odd Vibration- Possible Transmission Problem?

[90LS400Lexus]

That is my problem. I do not want to put any more $$$ into this car and still have the vibration. If I cannot soon get rid of this- I will probably sell the car and buy a Mercedes-Benz. :whistles:

If I wanted a car plagued with vibrations, I would have bought a Yugo.

[99lsguy]

Pachocco1,

Is this what your talking about?

(This is 99 LS manual - but could be similar?)

Man, I wouldn't think there should be any play in them <_<

repl.pdf

[pachocco1]

That document is a gold mine.

Notice the two indentations. ( north - south )

One definitely has play and might be installed incorrectly or is faulty.

Also, another point of interest.

I devised a litmus test of sorts for this situation.

It calls for a 6 by 2 by 1/2 inch piece of soft wood.

(measurements do not have to be exact)

With the car raised enough to access the differential area,

Lodge the wood (sandwich style) between the sub frame and the differential.

It should reduce any play in the whole driveline to about nothing.

Take a quick test drive. Hit the appropriate speed range where noise/vibration is present.

In my case, it took it out almost completely.

My long-term concern here is whether this is the root cause for the problem.

I do think several other components contribute to this problem. (Tires, wheel, bushings wear)

Thank you so much 99lsguy!!!!

I will post any results from this.

[99lsguy]

The propeller shaft...ie drive shaft could have worn bushings also.

Here's the troubleshoot for it......

pst.pdf

[99lsguy]

And here's the components..

Notice the adjustment washers above the center crossmember. Check them too!

comp.pdf

[pachocco1]

90LS400Lexus,

I also share your grief with the ride.

A few questions...

Did you ever get that tranny flushed?

What kind of tires do have?

Does your notice specifically shake all over but is heard (low frequency) from the rear of the car?

Have you done something that I have not? ( see prior post) such as bearings, axles, torque converter?

While there at the Lexus dealer did you ask them to look into your problem?

I have sunk a considerable amount of time and money in this car but am still looking at a good payback if the engine and tranny stay sound for about 2 years.

pachocco1

[90LS400Lexus]

90LS400Lexus,

I also share your grief with the ride.

A few questions...

Did you ever get that tranny flushed?

What kind of tires do have?

Does your notice specifically shake all over but is heard (low frequency) from the rear of the car?

Have you done something that I have not? ( see prior post) such as bearings, axles, torque converter?

While there at the Lexus dealer did you ask them to look into your problem?

I have sunk a considerable amount of time and money in this car but am still looking at a good payback if the engine and tranny stay sound for about 2 years.

pachocco1

I did have the transmission "serviced", which according to members here- is only a drain of about 3-4 quarts and a refill. I had that done because they told me when I had my oil changed that it was dirty. I was also experiencing that "vvvvert" sound when I would rapidly shift out of lock-up mode at 35-50 mph speeds and someone said that theirs did that and it was because of old fluid. That problem has seemed to have went away. Just the vibrations continue.

I have BFGoodrich Touring T/A tires ($99. each) on the car. They only have about 3500 miles on them. I have noticed an occasional "wobble" at 1-15 mph speeds if I accelerate slowly. Perhaps a bad wheel or tire - which is also cause of 35-up vibration? Between 16-34- it is smooth. The vibration starts at about 35 mph on the dot and evenly vibrates the entire passenger cabin. At times it is worse than other times. It seems to vibrate the whole car the same. I can feel it in the steering wheel and when I touch the door panel I can also feel it. It does not have a side to side vibration in the steering wheel. I do not recall it doing this until I had the rear struts changed and then it was so gradual, I did not even realize it until it was annoying. I have heard that they should have done another alignment, but they did not, because they do not have that capability. I have been planning on taking it to the other place I take my cars (other than dealer) and have them check the alignment. I really can hear a faint rumbling type sound I think at times, when the vibration is going on, but really cannot say for sure. I have even shifted it to "N" at about 55 mph when it is vibrating to see if it stops vibrating, but it does not stop. Shifting to "N" while moving is probably a no-no, but I have to figure out what is going on here. It seems to do it the worst at 55 mph.

Here is something I noticed today. When I first start my car of the mornings- when it is idling fast- it will have that "out of round" feel to it, as if the engine is "out of round". When holding the steering wheel while it is doing this- it feels IDENTICAL to the vibration I get when I hot 35 mph- that lasts up to about 70 MPH. That is why I was thinking possibly bad motor mounts, but someone here said that they doubt that. Hopefully we can figure this out soon.

[pachocco1]

I have followed the mount path. (tranny and engine)

It lead me to the tires. Replaced.

which lead to the wheels. straightened. 2 were bent.

Which lead me to the differential. Replaced.

...knucklebushings...

...driveshaft...

...differential mounts(3)...

...rear sub-assembly mounts...

So I am running out of options here.

Points of interest.

Temperature sensitive also!

On a rack, the vibration seems to come from the diff.

I have put a little peice of wood between the diff and the car frame. it reduce

the vibration significantly.

There is one side mounted diff bushing and two vertical mounted bushing holding the diff. You can see them from behind the car. I had these replaced recently and it also reduced the overall vibration. But it is still there none the less. When examining the left vert. bushing, I notice that it has a slightly different form to it. Two 1/2 inch indentions in it appear at opposite sides. The other side appears to be a solid rubber mount. With a long screwdriver, I pried at the center bolts of both mounts. The right solid one did not move much at all with a good degree of force. The left one however, moves very easily, but only in the direction of the indentations (pressed in at north -south).

There are numbers on the side of the mounts. It starts with a

6 - 0 - 1 - 2 covering about 1/4 of the bushings circumference.

My question here

is there a top or bottom (and thereby installed incorrectly)?

is this left mount deffective ( indentation are not supposed to be there)?

could somebody check there car to verify this?

BTW, Damn I am sick of this also!!

Ok now, my mechanic has finally solved the problem.

It appears that the assurance I was given that a remanufactured driveshaft would be up to OEM new specs was unbalanced (pun).

After focusing on other areas, my mechanic returned to the driveshaft as the possible culprit.

While another 91 was in his shop, he did some process of elimination with the problem areas.

Removing both axle assemblies (to eliminate the wheels as well) and still having the vibration.

Removing driveshaft produced no vibration at all (not tranny). Leaving just the differential and driveshaft.

Taking a driveshaft from the other LS400 (known to be in fine working order) and installed. No more vibration.

Course of action-

1 Buy a new driveshaft. or

2 Find a driveshaft shop to balance your existing one use a high speed DYNAMIC method and a quality guarantee. I emphasize that because, like our wheels, the rotational forces in the driveshaft have just as much negative effect as bad wheels. My remanufactured one was supposed to be high speed DYNAMIC balanced but was not. My mechanic demanded only a new part be used at this point. I am working out a refund with the driveshaft supplier.

Points of interest-

The remanufactured shaft had only 1 weight on one base of the two shafts. The OEM on had tiny and large weights all over both. (little rectangular pieces of metal tack welded on).

The shaft alignment was spot on for both.

The root cause is unknown. (How do they come unbalanced?)

[90LS400Lexus]

Thanks for that information!! Can you describe the vibration your car had and at what speeds? Did it seem worse at any other speeds? My cars seemed to have gotten progressively worse when I had the new rear struts installed. I did not recall it doing it before, but only shortly after. I know that they did not do another alignment. I have heard that this could be my problem.

I know that it is getting worse and worse and more and more irritating.

It does not seem like the tires is causing it. It seems like the entire cabin is vibrating as if a severe thunder is rumbling the car. The vibration does not seem any worse at any other part of the car. It seems the same throughout the cabin. It starts at the moment the car hits 35mph and not a mph lower.

I am 99.9% sure now that it is not my transmission.

Whats even worse is that my starter is doing that "sticking" deal in the mornings when I first start it and I am afraid that my starter is going out, or will go out if this keeps going on.

How much did the new driveshaft cost? How much did they charge to install?

Thanks again!!!!

[pachocco1]

Cost- 700 newlexusparts.com plus markup if applicable

Labor- 120

Could be done DIY but I do not have the time nor garage resources.

My air suspension was replaced by the previous owner. When worked on the Lexus dealer noted that all mounts were collapsed and needed replacing. I wonder if that could have a part to play in it as well.

I would sugguest replacing the differential mounts(3) first. They cost about 150 or less. Then if not satisfactory then the whole thing.

My vibration started at 38 till 60 or so. Then the whole car would shake including the center console (very annoying as well). I used to get a very defined hum in the rear of the car at 40-45 till I got the diff mounts replaced. That sound went away once those were replaced but the vibration (although not as prominent) was still present. I will post a long term evaluation as well.