40mph vibration

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bobthebuilder

10 Year 15 Year
Joined
Oct 16, 2007
Threads
27
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208
Location
Topton Pa
I know a vibration is pretty much impossible to diagnose via the 'net but I'll try anyway. I drove my truck home from CT on well worn Michelin tires and it was smooth up to about 75mph. I had my new Cooper Discoverer ATPs installed a week or two ago and now intermittently I have a strange vibration around 40mph. The whole truck vibrates like its having a seizure. The only thing that changed was tires. I went from 265/75 to 285/75. The tire shop said there weren't any issues balancing the wheels. Any idea where to start w/ this? The obvious solution is to drive faster or slower than 40 but that is the ideal speed for back roads around me.
Thanks gents
 
sounds like a balancing issue to me

Is it vibrating in the steering wheel or the seat of your pants?

Sometimes there are issues that pop up and throw you off, Diffs will create an issue sometimes. There is a whole set of threads in the FAQ on troubleshooting driveline problems in the FAQ
 
Thanks Romer. I'll check those out. The truck is stock, 187k etc. It just seems weird that it popped up after tire installation. Regardless, I will search for more possible solutions
 
bobthebuilder said:
Thanks Romer. I'll check those out. The truck is stock, 187k etc. It just seems weird that it popped up after tire installation. Regardless, I will search for more possible solutions
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I know what you mean, but been down that path to find out coincidences happen. I would have them recheck the balance first though
 
You can move the wheels/tires front to rear, etc. to try to isolate the vibration.

As Romer et al. noted, I expect your tire balance is off. I threw a wheel weight in the first 5 miles after a tire balance a year ago. I would have the tires balanced again.
 
What Western Flyer said above, I've had several of my cars roll off the shop and throw a weight off within the first few minutes of getting on the highway, and cause worse vibration than when I went in to get it fixed.

Also, I've had something similar happen before when I had my old old tires on. Drove fine till I had a guy look at the brakes. After getting back on the highway days later the whole truck felt like it would shake apart beyond 45-55 mph. Found out it was a combination of worn shocks + a possible wheel weight that must have come off somehow (only evidence I have of that besides the symptoms is the caked on dirt around the edges of where the weight would have been).

New tires later, I now can drive unwittingly past 75 mph and the only random vibration is due to worn shocks + bumpy roads/resonating surface etc.

Rotate the tires front to back, check the feel on the steering wheel when this happens before and after and you might be able to nail this to a tire weight.
 
I had a similar situation, and think it may be the same gremlins that others have. After a check of the wheels/ driveline try this.

Park your truck in a dark garage, open the hood and look at your spark plug wires. Can you see spark/ electrical current in them/ coming from them to the head? My wires had been getting so heated from laying on the engine they were cracked and shorting out/ not getting full spark to the plugs. Letting the cylinder fill with gas etc. And causing a short/ power loss/ vibration.

New plugs wires etc from Cdan, problem solved. It all "looked" good. The NGK in there were decent but had fouling after pulling them.

Only denso for me now. And some heat wrap on the wires. I think many have this problem and can't "see" it and assume driveline vibration.

My truck felt like it was going to fall apart so much vibration from the short. Slamming on the gas gave more spark etc giving the false assumption that it was driveline.

May not be it, but a dark garage will show it. Looked like a lightning show on the top of the engine.
 
Slamming on the gas at 40mph would help give just enough spark to the plugs to burn the gas and make it go away, but idling etc was always jumpy.

I never wouldve thought wires/plugs, maybe injector - but she runs like a seeing machine now. I bought all the bearings etc etc just "knowing" it was a birf, bearings etc bc it felt so driveline related.

Was the wires shorting out on the head. Tiniest little hairline splits from the heat. But man was I happy to get that out of the way.
 
FJC80 said:
Slamming on the gas at 40mph would help give just enough spark to the plugs to burn the gas and make it go away, but idling etc was always jumpy.

I never wouldve thought wires/plugs, maybe injector - but she runs like a seeing machine now. I bought all the bearings etc etc just "knowing" it was a birf, bearings etc bc it felt so driveline related.

Was the wires shorting out on the head. Tiniest little hairline splits from the heat. But man was I happy to get that out of the way.
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Thanks for sharing that. I have been putting off this bit of maintenance but I will try and get wires done sooner just to prevent anything like this from arising.
 
After driving the truck quite a bit today, I think it might be a combo or steering stabilizer (original), out of balance wheel and alignment. Sound plausible? The wheels are getting rebalanced next week
 
bobthebuilder said:
After driving the truck quite a bit today, I think it might be a combo or steering stabilizer (original), out of balance wheel and alignment. Sound plausible? The wheels are getting rebalanced next week
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If the steering dampener is shot, then yeah it is possible that any shimmying by the natural forces acting on the front wheels would cause some vibration. If you have big(ger) tires I understand it hurts vibrations more.
 
FJC80 said:
Silver horse, at the ACLU do you "defend evil" or fight against it? little confusing man!?
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FJC80 said:
Esp with the next line- hitlwr gave great speeches. That's funny man
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pretty sure there's a joke in both of those signature lines. I think you're reading into it way too much:rolleyes: For example; look at my 100% stock----->poser pic in my sig.
 
I get the "joke" about hitlers/"obaama" (sorry couldn't resist) speeches alright, but te ACLU line wouldn't make sense turned around, or atleast would make allot of people think maybe he does defend evil and hitler.

I'm pretty sure he had to of meant "defending against evil" , and then the hitler line is funny after that.

Other way around people might take you as a nazzi sympathizer

maybe he meant to write it that way, but i think it works against the funny aspect.

Sadly I'd say the majority of 'mericans don't even know what ACLU is or what they do.

thankyou for your constitutional defense by the way silverhorse

And now I have fully abused my thread privelages by threadjacking and owe everbody an ARB with winch. Forgiveness please
 
Don't forget to check the tire pressures. Once, when I got new tires, I got strange vibrations at different speeds. The tire jockeys had filled my tires to the 60psi, when I dropped them to 34psi, all was well.
 
Same problem

I had the same exact situation happen to me yesterday. I drove my 94' to Discount Tires at 75 mph with old, cracked, and worn Michelin 275/70r16's on and was completely smooth. I had General AT2's installed in size 305/70r16 and drove it around town a bit and all seemed fine. Got it up to speed at 45 mph and had a terrible shake/ vibration. It reminded me of a death wobble I had in an old AMC Eagle. It is really bad! Will update when I figure out what's going on
 
This issue was resolved for me with an additional trip to Discount Tire for a re balance. Very smooth now with no vibration.

My nephew had the same problem with a set of 33" Duratrack tires installed at the same shop. They did not balance one correctly, and it made his Jeep ride like s***e
 
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