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Old 11-06-2004, 06:26 PM
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Have an odd vibration...need some help

I have a 95 2wd truck 5 speed.


At 45 mph there is a deep drone/ vibration very noticable, that comes on strong but goes away only to return at 65mph. Once you decelerate from 65 mph it vibrates until the vehicle is below 45mph. One a side note, when I raised the rear and brought it to 45 then 65 then decelerated, it still vibrated, going up and down, as opposed to how it performed on the road.


What I have done so far:

Ruled out the engine altogether, it vibrates coasting down a hill with the tranny out of gear. So obviously rpm of the engine isn't a factor.

With the tranny in gear I pulled and pried on the driveshaft/ u-joints etc., solid as a rock.

I ruled out the front end wheels/bearings/suspension by raising the rear of the truck off the ground, brought it to speed, and it vibrated....so it cannot be the front end as its stationary or the suspension as its not being put to use.


I ruled out the rear wheels/tires, one by having them rebalanced yesterday, two, by taking the wheels completely off the truck when the rear was off the ground, still vibrated when I brought it to speed.

I did notice that when I spun both tires by hand, there was a sound simillar to rolling a pencil on a desk with your hand, not too loud kinda quiet but noticable. Regardless the wheels spun freely, is this normal? I know the front bearings when I replaced those were quiet. Acutally I have another truck, simillar frame, I think I will see if those rear wheels have a simillar sound/ feel. I am thinking this might be the problem but need to be sure before I start tearing things apart.

What started this, this is the wifes truck, we purchased her another then when I drove this one, it vibrated the snot out of me, thinking that was odd, I checked the tires, sure enough one was very low, so I patched the tire then had it balanced, the major vibration that nearly shook my teeth out stopped but there is still a vibration...wonder if it could have done something to the drum brakes? Hmm...(thinking in print) I might have to check that next.

Any idea appreciated. Thanks

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Old 11-06-2004, 07:11 PM
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Probably rear wheel bearings, if that noise is any indication.........

Could also be the "U" joints, just because they feel solid, doesn't mean that they aren't dried out.
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Old 11-06-2004, 07:21 PM
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Yeah that sound I heard turning the wheels caught my attention. I just went out and spun a wheel on another truck to see if it made any unusual sounds, nothing. So I went back and spun the other trucks axles with the wheels installed this time and it sounded the same/


I did notice that on one side, it seemed the drum brakes were catching a little, in a rhythmic pattern. Suppose I will loosen the shoes on that side in the morning and see what happens, when I reset them.


Definitely odd...appreciate the reply
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Old 11-07-2004, 03:21 PM
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Well just in case someone reads this and has an idea or two....


...I loosened the rear brake shoes and drove it, still vibrates....so thats not it.


Since I know its not the engine or suspension or anything related to the front end for that matter. I had a brain storm...need input as I haven't done this, yet, if its not a good idea then, someone let me know. I thought about disconnecting the driveshaft from the tranny, rev it up in fourth gear or so and see if it vibrates, in hopes of isolating the problem to the tranny or driveshaft/rear axle. Anyone forsee a problem before I attempt this?

(I will mark the driveshaft and the tranny output shaft so its reinstalled correctly)

thanks
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Old 11-09-2004, 05:06 PM
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I dont really see the point in doing this. In neutral the driveshaft isn't spinning anyways. If its speed related, the only thing on the tranny it might be would be in the tailshaft (bushing). You probably wont notice the vibration if the driveshaft is out because the bad bushing isn't spinning anything (due to the driveshaft being out).

If its at a higher speed and isn't RPM related you are looking at tailshaft area, driveshaft, wheels, bearings, rear gears, pinion angle (although this is unlikely) etc.

Read the other post about vibrations at speed as it has a lot of ideas.
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Old 11-09-2004, 07:06 PM
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Quote:
Originally posted by poncho62

Could also be the "U" joints, just because they feel solid, doesn't mean that they aren't dried out.
U joints can fool a person sometimes
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Old 11-10-2004, 07:28 AM
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I would have replied sooner but I've been having trouble login in.


Siggy_Freud

I will assume you meant, the driveshaft won't spin in neutral if the rear is off the ground. True, but I figured if I removed the driveshaft, and put the tranny in gear, surely if the output shaft bearing were loose it would vibrate the shaft. I believe its the U joints now....how I missed it before I dunno but I did.


Crosley

I hope your right. I tested them again and placed myself at a better angle than previously and sure enough, one of the joints moved, ever so slightly. Since they aren't supposed to move at all I hope this is the problem. I will tear into it in the next day or so and hopefully have positive results to report.


Appreciate the replies
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Old 11-14-2004, 06:55 AM
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Well fellas I was gonna update the post but for some reason it wouldn't let me post. So I have a new username for now, at least until they fix the other one.



Well, it was the u-joints after all, appreciate the replies.
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Old 11-14-2004, 09:09 AM
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Quote:
Originally posted by 357f-150
Well fellas I was gonna update the post but for some reason it wouldn't let me post. So I have a new username for now, at least until they fix the other one.



Well, it was the u-joints after all, appreciate the replies.
I suggested a re-look at the U joints since I've seen many "good" joints that were bad
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