Harsh Vibration at high speeds

ZEN_OWT · Jun 30, 2024

I’m getting a harsh vibration that I can feel in the steering wheel, seat and basically the whole car. It starts at 75 mph and then intensifies as I get to 80 and 85. It becomes very uncomfortable to drive at 80.

I had my tires road forced balanced twice and they said that is not an issue. I have stock suspension. Only change was 285/70/17 tires. My car only has 5,500 miles, tires have 5,000 and I rotate at every 3,000.

I have cleaned all components under the car. Even cleaned the engine bay.

The shaking occurs even if I take my foot off the gas, so I doubt it is engine related.

I got under the car to check for loose components. Everything seems in place. But I can rotate the stabilizer bar with my hand. I’m guessing that is normal because the ball joint allows for play?

Any thoughts? Could it be air in the stabilizer? Something slightly off in the alignment?

Anyone else experience this? Appreciate any insight.

LWA55DAL · Jun 30, 2024

There could be a million different reasons so hard to guess by reading the description, but I would guess that because it is only at a high rate of speed it is likely drivetrain related, if you feel it throughout the vehicle. The drive shaft balance is one item that could cause this, but you also have the transfer case and differentials. Since you have ruled out the tires I think you likely need to focus on the drivetrain. Now - getting to the actual root of the issue is the challenge and not an easy one. I would look and see if you have leaks at any of the seals around the diffs or transfer case. If you have a significant amount of shaking taking place then more than likely you are going to see a seal leak as a result. This will at least help narrow down the problem. It could also be the joints in the drivetrain. You might want to see if they have play in them as well. At the speeds you are talking about you are at the upper end of what the vehicle was designed to accomplish.

ZEN_OWT · Jun 30, 2024

LWA55DAL said:
There could be a million different reasons so hard to guess by reading the description, but I would guess that because it is only at a high rate of speed it is likely drivetrain related, if you feel it throughout the vehicle. The drive shaft balance is one item that could cause this, but you also have the transfer case and differentials. Since you have ruled out the tires I think you likely need to focus on the drivetrain. Now - getting to the actual root of the issue is the challenge and not an easy one. I would look and see if you have leaks at any of the seals around the diffs or transfer case. If you have a significant amount of shaking taking place then more than likely you are going to see a seal leak as a result. This will at least help narrow down the problem. It could also be the joints in the drivetrain. You might want to see if they have play in them as well. At the speeds you are talking about you are at the upper end of what the vehicle was designed to accomplish.

Thanks for this. I have zero leaks. I can even feel it as low as 70 mph. I don’t consistently drive at 85, but the 70-80 range on freeways in socal should be normal for the car. So something is up. Appreciate your response.

LWA55DAL · Jun 30, 2024

You may want to check the diff fluid levels as there have a couple of VERY isolated incidents where they weee not filled all the way. If you do find they were low you likely want to document it for the dealer as I would want a replacement. Any chance you know if your vehicle was subject to the transfer case replacement? There is a thread on here to verify you have the newest version. I think it need to end on a “B”. The dealer should be able to tell you if it was replaced and if so - I’d best those clowns did something wrong.

Tinerfeño · Jun 30, 2024

Transfer box or differentials very seldom cause vibrations.
Drive shafts (prop shafts) are possible cause, but if the vibration doesn't change with engine load I would rule these out.
General vibration (which is not power related) is often caused by suspension bushes. Possibly also by alignment problem.

Tinerfeño · Jun 30, 2024

Tinerfeño said:
General vibration (which is not power related) is often caused by suspension bushes.

One loose bolt may be enough.

Catpaw4x4 · Jun 30, 2024

nmoeder said:
Thanks for this. I have zero leaks. I can even feel it as low as 70 mph. I don’t consistently drive at 85, but the 70-80 range on freeways in socal should be normal for the car. So something is up. Appreciate your response.

There may not be "visible" leaks - look for any "sheen/shine" on the undercarriage. I was at 6200 the transfer case was low by 50%. A leak didn't reveal itself on the driveway until after an off road once on an intermediate difficulty trail. Could actually see 2 drops formed on the box.

ZEN_OWT · Jun 30, 2024

Good idea. I just check transfer case. It’s dry. No other evidence of sheen anywhere. I look all around in other spots too.

Catpaw4x4 · Jun 30, 2024

nmoeder said:
Good idea. I just check transfer case. It’s dry. No other evidence of sheen anywhere. I look all around in other spots too.

Great to hear!!

Mudnut · Jun 30, 2024

Have your checked wheel balance? 5k on tyres could cause wear, or missing wheel balance weights. Next rotation have them checked.

DaBull · Jun 30, 2024

nmoeder said:
Good idea. I just check transfer case. It’s dry. No other evidence of sheen anywhere. I look all around in other spots too.

Hi nmoeder, I would have it aligned as there is a possibility the alignment may be putting vibrations into the
suspension at higher speeds. Just one of many things to check.
DaBull

Skydance · Jun 30, 2024

Did it happen before the tyre change? If not it would certainly be the tyres. I once had my tyres balanced several times, turns out that one my tyres had a flat spot.

JP4 · Jul 1, 2024

nmoeder said:
I’m getting a harsh vibration that I can feel in the steering wheel, seat and basically the whole car. It starts at 75 mph and then intensifies as I get to 80 and 85. It becomes very uncomfortable to drive at 80.

I had my tires road forced balanced twice and they said that is not an issue. I have stock suspension. Only change was 285/70/17 tires. My car only has 5,500 miles, tires have 5,000 and I rotate at every 3,000.

I have cleaned all components under the car. Even cleaned the engine bay.

The shaking occurs even if I take my foot off the gas, so I doubt it is engine related.

I got under the car to check for loose components. Everything seems in place. But I can rotate the stabilizer bar with my hand. I’m guessing that is normal because the ball joint allows for play?

Any thoughts? Could it be air in the stabilizer? Something slightly off in the alignment?

Anyone else experience this? Appreciate any insight.

Have you mentioned whether or not a proper alignment has been done after the new/upgraded tires?

DenisM · Jul 1, 2024

I'd suggest you have the caster settings checked.... to ensure you're not getting front wheel shimmy at higher speeds.

DaveB · Jul 1, 2024

I have seen one case where the tyre pressure monitoring system was not replaced correctly and was loose in the wheel.
Not bouncing around just hanging loose.
Not sure if that is possible on the ones used in the Grenadier.
Also saw one where a balance weight had to be put opposite the TPMS unit for balance at higher speeds.

Max · Jul 1, 2024

An on-car wheel balance might bring something to light...tyre balance would show itself much sooner than 70/75mph

ZEN_OWT · Jul 2, 2024

Thank you to everyone for your help. Problem is solved. It was the roof rack. I guess after it settled in it really started to vibrate.

I have the Bison Gear rack. I love it. The issue is that I did not have the wide panels between the first and second bars in the front (see first picture). If I opened the safari windows, the vibration went away. I put my hand up there thru the safari windows and felt the front bar was vibrating like crazy, even though all the bolts were tight. [Credit the Mossy Ineos in San Diego who actually figured this out. Very smart and experienced techs across many types of offroad vehicles.]

So the solution was to move some panels around and make sure that I had 3 of them in the front connecting the first two bars (see second picture). Once I did that, everything was good. And when I felt it at high speeds, the first bar was not moving and stout. I guess it needed that extra strenght in the front.

Hopefully this will help others. I'm going to reach out to Bison to suggest maybe they reccomend that panel placement in their installation guide.

Thanks again everyone.

lightning · Jul 2, 2024

Wow you were lucky l think, to find the cause.
That might have never been discovered unless you took off the roof rack for some reason.

GN4HIR · Jul 21, 2024

Wow, interesting. I was thinking about the Bison rack. Still am.. but your experience is really good to know.

ZEN_OWT · Jul 21, 2024

I would still get the bison rack. I love mine. Issue is solved with those plates at the front.

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