uh oh - I'm gettin some bad vibrations

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disallow
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uh oh - I'm gettin some bad vibrations

Postby disallow » Sun May 23, 2010 7:46 am

Hey Guys,

Last night while driving home, my wife and I heard a 'thump'. It happened while we were slowed down from highway speed driving through a small town. We both thought it was one of our kids dropping their bottle or juice cup in the back seat. However, it wasn't that, as they both still had their drinks in hand.

We were also carrying bikes using a hitch receiver bike rack. The bikes were still secure and hadn't moved at all.

After the 'thump', I seemed to notice a vibration which seemed to be synchronized with tire revolution, though I'm not 100% sure. I could actually see the bikes bouncing up and down as though we were going over an uneven road surface. Got worse as I picked up speed, so I pulled over.

This is what I checked:

1. Tires - no visible damage, all inflated to correct pressure.
2. Lug nuts - all present and accounted for and tight.
3. Suspension/Steering - both Tie Rods were nice and tight. Upper ball joints secure, stabilizers appeared to be tight. Steering wheel to full lock both ways, didn't notice anything unusual.
4. Visual inspection of driveshafts - no issues apparent.
5. Airlift 1000 - at 12psi, didn't blow out.
6. Rear Suspension check - no issues apparent.

So I drove the rest of the way home, about another 50 miles.

Now I was hypersensitive to all bumps and anomalies, but the vibration seemed to be less apparent. Occasionally I thought I felt pulsating or something in the steering column, and the odd vibration throughout the vehicle, but we made it home. Maybe a little worse than normal with the bump steer.

I was thinking about crawling underneath again today, check for the following:

1. U-Joints - my U-joint at the rear diff is new, but the other rear is not. It also appears my front driveshaft has been replaced in the past 3-4 years, but I will check them for play as well. I actually have all of the u-joints (1 rear and 2 front) so i can change them if needed.

2. More thorough inspection of suspension/steering components.

3. Check tires off the vehicle for slipped belt/cupping/roundness issues - I have Cooper Discoverer ATRs on the truck, never been super happy with them. They appear to be wearing 'funny' even though there are no apparent alignment issues and I've resolved the rear end sag with the airlift bags. At least one of them makes a 'whump-whump-whump' noise on smooth pavement which in my experience is a roundness or cupping issue. The tires have about 50k km on them.

So.... anything else I should check? Any input would be appreciated. I'm heading out of town this week and my wife is nervous...

t


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Tech
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Postby Tech » Sun May 23, 2010 10:16 am

sounds like you checked all the obvious things. I can tell you from experiece from the driver and the tech perspective, that those bike racks do make alot of ppl think they're truck is blowing up. Unless you have the thule with the proper stepped achoring pin, or shim the reciever, they thump alot. And because they are attatched to the chassis, the vibration transfers right through the truck. Sometimes the air/wind/veh speed combo can make the thing oscilate. Maybe have someone rock the rack while you're inside and see if it sounds the same. I'm uber sensitive to noise/vibration/harshness and I HATE driving with mine on...

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Postby fat_frog » Sun May 23, 2010 6:15 pm

One of the weights flew off of a tire?

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Postby disallow » Mon May 24, 2010 3:11 pm

fat_frog wrote:One of the weights flew off of a tire?
That could have totally been it.

No way to find out now, I had new tires put on yesterday. I was never happy with the Cooper Discoverer ATRs that came new with the truck when we bought it in 2008. They have about 50000kms on them now, and were cupped really badly and had a roundness issue. The wear on the inside of the rears was due to rear end sag. This was resolved when I installed the Airlift 1000, I highly recommend this mod.

Some of the bad wear is obviously from bad shocks and perhaps alignment issues, so I will be sure to get that resolved over the next couple weeks. I have some Bilstein rear shocks to put on, but the bolts were too rusty last time I tried. I have a compressor and impact tools now, so hopefully I will have better luck.

Also saw the recent post by pawjr74 that showed his lift project, and the condition of the factory shock on the front. Looks like I should plan to do those ones too.

Picked up Bridgestone Dueller A/T REV02s, LT265/75/16s. Bought from Costco, total bill came to just over $1000 canadian including sales tax. They are E rated, and 10-ply tires. They are surprisingly forgiving right now, and very quiet. Will report back once I have about 5000mi on them.

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Postby Spamcan » Mon May 24, 2010 4:58 pm

I'd bet on the wheel weight flying off as well - thump when the weight hit the wheel well. Especially if the vibration gets worst with speed. Almost every wheel will at least have 1 weight. If there's one without a weight...bet that's it. Costco will re-balance, but enjoy the wait.

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Postby disallow » Mon May 24, 2010 5:14 pm

Spamcan wrote:I'd bet on the wheel weight flying off as well - thump when the weight hit the wheel well. Especially if the vibration gets worst with speed. Almost every wheel will at least have 1 weight. If there's one without a weight...bet that's it. Costco will re-balance, but enjoy the wait.
Didn't wait at all at Costco... in and out in an hour.

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Spamcan
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Postby Spamcan » Tue May 25, 2010 8:12 am

Nice, not too bad a wait. Did they find a weight missing - was the vibration resolved?

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Postby disallow » Tue May 25, 2010 8:15 am

Spamcan wrote:Nice, not too bad a wait. Did they find a weight missing - was the vibration resolved?
They didn't say anything about a missing weight. But yes, the vibration seems to be gone, and the ride is a smooth as glass. I love new tires!

t

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Postby Spamcan » Tue May 25, 2010 9:16 am

Nice...love it when you can just enjoy the ride...


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