Ls'92 Strange Vibration At Speed :))

[wwest]

Two SEPARATE problems...

1. The front caliper is stuck resulting in overheating.

2. A u-joint in the rear driveshaft or a CV joint in one of the "half-shafts" at the rear is failing resulting in the vibration.

[90LS400Lexus]

Hi. No, it seems to stay the same in the curves. I would like to go ahead and replace the motor and transmission mounts, as well as the tires sometime within the next 6-7 months. Maybe those CV joints too. How costly are these to replace on these cars? Is it a labor "intensive" job? Thanks.

How strange... my vibration is between 35-50 mph and worse the colder it is outside. Its terrible at 39-41 mph, just as it was on my 1990 LS. I feel most vibration through the steering wheel and very little on the shifter. Same vibration at any engine RPM and even if its in neutral. Its like a rotational vibration... it comes and goes within 1/2 second intervals.

Lexus tech told me it was a bad tire... they are 5 years old, so it would not suprise me, but the tread is still excellent. I am going to replace them soon... at least the two.

I know its very annoying.

"1/2 second interval"...

That would seemingly indicate a rotational function that "wonders" in and out of synchronization...

That might result from slightly different tire circumference L/R.

Front halfshaft CV's for FWD.

Rear drive axle CV's for RWD.

Or even L/R or R/L tires.

Does the vibration lessen with slight left or right turn....long sweeping curve..??

[Neofate]

lexus '92 263k

when I'm driving around the city it's ok,

but when I get up to around 80-100klm/h I start to feel under the car a strange vibration at steady speed

and when I start to brake it isn't smooth as it was before.

while at the speed I did put tranny in neutral and switched engine of and the vibes were still on- so it's not the engine

- first I was thinking it was the engine runnig on 6 cylinders or misfiring...

any ideas???

Driveline u-joints.

I'm sure you've gotten this answer -- but I'm just going off your main post, and the reply.

If it is your U-Joints, you jumped from A to Z in a genius way !..

First off -- At that speed I a few things come to mind,.. Every describes problems differently so need to list them all.

A) Wheel Balance -- (Cheap, be an easy check) --

B) Rotors,.. Warped rotors are a definite cause of break stutter -- Though if the stutter only occurs at that speed, it does make this a unique problem. Still wouldn't hurt to pop the wheels off and and Mic them.

C) Driveshaft -- Considering the location you are describing,.. any considerable imperfections/warps or loose parts in the driveshaft can cause similar symptoms.

I'll hush now, and go read the rest of the posts that probably have already answered this problem in detail :)

[Neofate]

Well it sounds like I was in the right ballpark -- With Rotors and the Joints have an effect on the driveshaft.. good information.

The only way I could possibly fathom a single caliper, and only ONE caliper becoming considerably hotter than the others on a consistent basis is improper function (obviously),.. more specifically it is locking up. When you apply the breaks it doesn't fully release that caliper, thus you get a vibration generating from the caliper that is still apply some resistance to that rotor, connected to that axle, connected to the hip bone, which is conencted ;) -- You get the idea.

But, the experts here think it is likely a dual problem.

Calipers aren't fun to buy -- But, if a caliper COMPLETELY seizes on you, it can and usually does cause a wreck, especially at 100Kph. I would have this examined and tested, if not just replaced for the safety aspect. Your life isn't worth trying to make sure you don't 'waste' money on a caliper. You could always grab a used caliper from a junkyard or refurbished caliper -- Should work just as good as new, and not cost you an arm and a leg.

I would like to go ahead and replace the motor and transmission mounts, as well as the tires sometime within the next 6-7 months. Maybe those CV joints too. How costly are these to replace on these cars? Is it a labor "intensive" job? Thanks

Depends on where you take it,.. a good , friendly, indie can replace your motor and trans mounts quickly, and for under 200$ if they are nice, a bit more if they mark up labor and parts more -- Not sure where lexus would go with this.

Tires,.. obviously non labor intensive, can be done in minutes literally.. likely a 15-1hour wait.. unless you just get it all done at once (best option).

Now the Constant Velocity joint (Lexus uses these? Fantastic.. I thought it was just a U joint for the RWD.. but again I'm not well versed on these cars yet) -- Anyhow.. this joint is expensive (to me).. new. From other vehicles I remember they run about $500.00 new from a dealer. Though, getting a rebuilt unit can cost considerably less, and I wouldn't dissaprove of it. If you have the money, go with the cheapest 'new' joint you can -- But if your running tight on money, a rebuilt unit (imho) will do just fine. The labor, as you asked, is not intensive (relatively).

Think of a bad CV joint as a popping sound if the outer portion is bad, and a pluuuning sound if the inner core is bad. They last anywhere from 10-15yrs before you really need to get them changed out.

[wwest]

Well it sounds like I was in the right ballpark -- With Rotors and the Joints have an effect on the driveshaft.. good information.

The only way I could possibly fathom a single caliper, and only ONE caliper becoming considerably hotter than the others on a consistent basis is improper function (obviously),.. more specifically it is locking up. When you apply the breaks it doesn't fully release that caliper, thus you get a vibration generating from the caliper that is still apply some resistance to that rotor, connected to that axle, connected to the hip bone, which is conencted ;) -- You get the idea.

But, the experts here think it is likely a dual problem.

Calipers aren't fun to buy -- But, if a caliper COMPLETELY seizes on you, it can and usually does cause a wreck, especially at 100Kph. I would have this examined and tested, if not just replaced for the safety aspect. Your life isn't worth trying to make sure you don't 'waste' money on a caliper. You could always grab a used caliper from a junkyard or refurbished caliper -- Should work just as good as new, and not cost you an arm and a leg.

I would like to go ahead and replace the motor and transmission mounts, as well as the tires sometime within the next 6-7 months. Maybe those CV joints too. How costly are these to replace on these cars? Is it a labor "intensive" job? Thanks

Depends on where you take it,.. a good , friendly, indie can replace your motor and trans mounts quickly, and for under 200$ if they are nice, a bit more if they mark up labor and parts more -- Not sure where lexus would go with this.

Tires,.. obviously non labor intensive, can be done in minutes literally.. likely a 15-1hour wait.. unless you just get it all done at once (best option).

Now the Constant Velocity joint (Lexus uses these? Fantastic.. I thought it was just a U joint for the RWD.. but again I'm not well versed on these cars yet) -- Anyhow.. this joint is expensive (to me).. new. From other vehicles I remember they run about $500.00 new from a dealer. Though, getting a rebuilt unit can cost considerably less, and I wouldn't dissaprove of it. If you have the money, go with the cheapest 'new' joint you can -- But if your running tight on money, a rebuilt unit (imho) will do just fine. The labor, as you asked, is not intensive (relatively).

Think of a bad CV joint as a popping sound if the outer portion is bad, and a pluuuning sound if the inner core is bad. They last anywhere from 10-15yrs before you really need to get them changed out.

First, I have experienced a stuck caliper, right front, on a '91 LS400 and it was due to the little rubber boot covering the top "slide pin" having failed, completely disappeared. As a result the slide pin lost all of the lubricating grease and the caliper became stuck in place. Lexus simply replaced the slide pin and boot, minimum cost.

It is my understanding that the vibration has nothing to do with braking so for me that would rule out warped or uneven thickness rotors. And since CV joints are tradionally more robust, reliable, vs u-joints I would check/replace the driveshaft u-joints FIRST, before doing anything else. If replacing the u-jopint doesn't resolve the problem then I would look next at the CV joints in the rear halfshafts.

Motor and transmission mounts seem to me to be a "wild goose chase". Replacing the (old, worn, "flaccid") mounts would undoubtedly somewhat subdue a vibration caused by driveline u-joints but eventually you would find your driveshaft lying back down the road apiece.

[Neofate]

Good advice. I don't know the condition of her Caliper, can only go by what is told. I've experienced a caliper 'locking or seizing' and it shattered the Wheel into pieces (alloy), and would have been a nasty wreck if I wasn't simply pulling onto a somewhat unbusy road at the time. This is the only reason I mentioned if it 'could' be a potentially dangerous caliper, it would, obviously, be wise to get it taken care of. If it is just locked tighter than the others then it is a different story, but anything is possible.

It is my understanding that vibration of the type spoken in this thread is generally not considered generated from brake components, but vibrations are resonated from brakes all the time. (Vibrations while you are *not* braking, eminating from the brakes.. are not common.)

I agree with you on the CV vs U Joints. CV joints are more expensive because of their more robust design, they are a different joint (in my understanding ) than U joints entirely. Engineering wise.

As for motor mounts -- All I know is what a mechanic that I respect has told me,.. That on a somewhat higher milage car, new motor mounts will generally always make a marked improvement. *Though not to say this is your problem*

I tend to think this is eminating from your driveshaft as well, or a component that is directly connected to it in some manner. The specific described vibrations just scream , hey check around the drive shaft. ;)

Best of luck.. and let us know what ends up being the resolution.

[90LS400Lexus]

Thanks.... well I may get the u-joints replaced anyway, as well as engine/tranny mounts in good time.

What has me the most frustrated is that the Lexus tech said he checked all of these and they were fine and swears its the tires and a wheel on the left rear. It just seems to me like this is not the problem, but who knows. The tires are still very good tread-wise, so I hate to change them, but the vibration is so annoying, I may go ahead and out on new tires soon, but if its not the tires, I will be very unhappy, because we all know tires are not cheap. <_<

[andre]

IT IS OFFICIAL - SEIZED CALIPER VALVE :((

waiting for repair kit to fix it...

[wwest]

Thanks.... well I may get the u-joints replaced anyway, as well as engine/tranny mounts in good time.

What has me the most frustrated is that the Lexus tech said he checked all of these and they were fine and swears its the tires and a wheel on the left rear. It just seems to me like this is not the problem, but who knows. The tires are still very good tread-wise, so I hate to change them, but the vibration is so annoying, I may go ahead and out on new tires soon, but if its not the tires, I will be very unhappy, because we all know tires are not cheap. <_<

Move the rear wheels/tires to the front....??

[eatingupblacktop]

IT IS OFFICIAL - SEIZED CALIPER VALVE :( (

waiting for repair kit to fix it...

One suggestion, when replacing the caliper, check for amount of pads left and make sure the rotors are clean of any deposits. Also the heat you were describing has most likely boiled some of the brake fluid...I would replace the fluid as well.

[wwest]

IT IS OFFICIAL - SEIZED CALIPER VALVE :((

waiting for repair kit to fix it...

Seized piston maybe.....??

[90LS400Lexus]

Thanks. ASAIGAC I will move them.... If no change I will assume its not the tires and something more. I really want this vibration to stop, as its getting very unpleasant to drive this car. If I let my hands off of the steering wheel, I cannot even feel the vibration. I really cannot feel it when I touch the door panels either... it is most pronounced through the steering wheel.... which is why I find it hard to believe its the rear tire/wheel like the Lexus tech said it was. I am wondering now if he really even checked it.

Move the rear wheels/tires to the front....??

[andre]

Seized piston maybe.....??

yes, piston,

you are wright :)