minor vibrations above 75mph

[matus]

Hi to all ,

I ve checked lot of threads here related to vibrations but none of them seem to me to be describing the same problem like I have with my 100 cruiser. Therefore I have decided to post a new thread with my problem.

My issue occurs when I drive above approx 75mph (120kmh). When accelerating above 75mph vibrations are not that strong but you can feel it in the seat and distributes little bit throughout the whole interior.
When I try to drive constantly (all speeds above 80mph) vibrations get little more intense.

And when i release the foot from throttle and let the car decelerate the vibrations get pretty intensive and kind of noisy.

What is strange to me is that the intensity of vibrations is the same when I try to accelerate either from 75mph or 100mph higher. It is still the same level of vibrations. The only difference that changes the intensity of vibrations is constant speed or deceleration.

Below 75mph the car runs very smooth

Until now I had my wheels re-balanced, both prop shaft re-balanced (one U joint was replaced but vibrations remain), both diffs checked for free-play, front wheel bearings checked.

The next thing I plan to do is change tyres (winter tyres) but I do not think this might solve this issue.

I was thinking if transmission or transfer case may have any effect on this....

Do any of you have any ideas what and where to look next?

Thank you for your comments

P.S car has 220k miles on tacho, year 1998, UZJ 100

 

[Julian Stead]

It would probably be easier to just drive at 70mph. There isn't a one answer solution to vibrations, just wait and see what it is like after different tires are fitted.

 

[DirtDawg]

What’s the need to run at such high speed? The speed limits only go to 70 around here so I usually only go 80 max, and at that speed I get a little more vibration than at lower speeds. These are 10+ year old vehicles, you can’t expect them to run like glass at 90mph. There is more than linkely some play in your pinion or tcase or somewhere that is causing your issue. Mine rides pretty smooth at 80, I don’t expect much more from it, considering it’s an huge AWD SUV.

 

[matus]

Hi,
I of course I do not expect it to be 100% smooth. I do not daily drive it in such high speeds but from time to time when I enter the highway it is not comfortable to drive with such vibrations.

The reason why I would like to identify the cause is to prevent eventual damage that of something that might cost me more .

 

[Julian Stead]

Hi,
I of course I do not expect it to be 100% smooth. I do not daily drive it in such high speeds but from time to time when I enter the highway it is not comfortable to drive with such vibrations.

The reason why I would like to identify the cause is to prevent eventual damage that of something that might cost me more .

I think you would be wasting more money now trying to rectify, as all components will have some wear that will have negative effects on vibration. If you are lucky enough that it is one component that will eventually fail then that would be your cheapest repair. If you are finicky and want it to drive like new then be prepared to spend a lot on a major refresh. I have done a good refresh on mine, but I still wouldn't call it perfect, you just have to draw the line and at some point realise that it is 20 years old. A vibration over 70mph is a minor concern compared to the cost you might have trying to chase it down. I am not trying to put you off the repair, but don't think that there is a one answer solution. First step would be to get your driveshafts checked out and balanced, and get your new tires road forced balanced.

 

[a_traut_man]

I don't believe you had an alignment listed, have you done that in addition to the balancing? An alignment issue could be causing your vibration, especially if it intensifies under braking.

 

[DirtDawg]

Road force balancing helped me get rid a lot of vibrations.

 

[matus]

I left the car in service where they performed tyre balancing (not road force as this method is probably not known in my country ), but anyway I will try to change the tyres for new winter tyres so I hope to see some result there.

Mechanic said that both front and rear driveshafts were balanced as one of the U joint was replaced due to little freeplay. He also claims that they have also checked the wheel bearings but you never know ...

Wheel alignment was the first thing I have done before I gave the car to service.

The strange thing for me is that the vibrations do not sound the same by acceleration and deceleration. I assume if there was a worn bearing or bad tyres etc. the symptom would be the same when accelerating or decelerating.

But anyway thank you for your comments and replies. If the tyre change will not solve the issue I will stick to what Julian Stead wrote.. I will not try to eliminate the vibration at all costs. Sooner or later the vibrations will probably get worse and maybe than it would be easier to identify the case.

If this happens I will post a reply with the result

 

[RND1]

Do you have a lift and if so is the caster in spec?

 

[matus]

No it has the factory AHC suspension without any changes.
The only modifications were Safari snorchel, winch in the front.

 

[matus]

Hi.. I finally got time and took the carvon the lift. Removed the rear wheels and noticed that vibrations aee coming from rear axle. It occured between 80-100 kmh and then above 120khm.. any ideas what might cause the rear axle to vibrate? Bend axle,rear brake discs, diff or....?

Thank you for your advise

 

[Spike555]

A bad u-joint. You do not say which u-joint was replaced, only that one of them was.
I would replace the rear most u-joint and see if there is any change.

Wheel bearings will not cause a vibration.

With the tires removed and the vibration still there it has to be a u-joint. Nothing else back there to do that that I can think of.

 

[matus]

Hi,

Actually it was that U joint nearest to the rear diff how about bushings?

 

[Spike555]

Hi,

Actually it was that U joint nearest to the rear diff how about bushings?

Bushings won't make any difference with the tires off and the truck on the lift.
Replace the rest of the u-joints. Even if they seem good, replace them anyway.

And make sure they all get greased at every oil change.

 

[matus]

Hi I decided to change parking brake shoes due to wear and I have noticed that a brake disc is rubbing against the part of an axle. See attached picture. Unfortunately I did not have time for testdrive this may be a source of my vibrations. I wonder what is bend when there was a contact... I hammered that part little bit to avoid contact.

 

[RyanStl]

My steering wheel earlier this year starts shaking when I hit 60 MPH or more. I got my tires balanced and problem was solved.

 

[trdcorolla]

My 100 started to have these vibrations right before 80mph. Never noticed it before. I did remove the flux capacitor recently, i'll put it back to see if that makes the vibrations go away.

 

[matus]

Hi an update from my side. I have been testing the car whole weekend and after installing new parking brake shoes (but parking brake still not adjusted) major vibrations disappeared. Now there are minor vibrations that occure above 140kmh. Those are coming from transfer case. When I touch transfer case shift knob I can feel it. And then above 160kmh those vibrations disappear. I will probably neer use those speeds as the consumtion is really high. I just want to be sure that the condition of the car is perfect.
I think now it is time to check propellers and let them balance again or do you think it may also be the mounting braket for transfer and transmission?

 

[matus]

Hi Finaly got rid of vibrations.. I had to replace all bushings on rear arms. Tested today by 160 kmh and no vibration also by decelerations.. I am now enjoying the real comfort on highways

 

[trdcorolla]

Thanks for the update, did you replace the bushings on both the upper and lower rear control arms?