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post #1 of (permalink) Old 10-20-2003, 09:11 PM Thread Starter
 
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Vibration

Alright, it's a new one.

At about 40-60 kmh, I get the most insane vibration.. It's most pronounced in 3rd gear, but still there if I skip 3rd and go straight to 4th.

U joints? It dissapears or blends in after 70kmh.

It's not there if I just rev the engine up to any RPM, it's not there if I put the clutch in, or if it's in nutral clutch out, it's not there in any gear, when the T-case is in nutral..

BUT.. it's not there if I'm in nutral going down a hill...
That's why I don't think it's a driveshaft?

Anyone got any ideas?
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post #2 of (permalink) Old 10-20-2003, 09:26 PM
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Re: Vibration

Transfer case input bearing possibly.

It sounds like a bearing somewhere in your drivetrain to me, but I couldn't tell you where exactly.
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post #3 of (permalink) Old 10-20-2003, 11:42 PM
 
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Re: Vibration

axle wrap, when you have the gas pedal mashed and you are doing 44 mph the axle has some wrap to it, so the pinion will point up a little extra. which might be enough to cause vibration. I only have vibration when I down shift.

but, this wouldn't explain violent vibration.
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post #4 of (permalink) Old 10-21-2003, 12:18 AM Thread Starter
 
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Re: Vibration

I've got a solid wrap bar..

Very solid..

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post #5 of (permalink) Old 10-21-2003, 01:04 AM
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Re: Vibration

I'm assuming you crawled under it and did a full inspection of the drive train, that's why I'm not mentioning that a broken tranny mount in my CJ-5 will do that exact same thing if the tranny shifts too far out of line.

It makes sense in my brain that if it were axle wrap it would be more pronounced in 1st gear, I'm thinking that would be the most torque the axle would see.

Did it start gradually, getting worse and worse, or all at once, like something broke or came loose?
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post #6 of (permalink) Old 10-21-2003, 02:19 AM Thread Starter
 
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Re: Vibration

It started out after I got off the ferry.. crazy vibration through all the gears, mostly under heavy load.

Then I got underneath and fixed the torque arm on the tranny (read: tightened it)

so off the line im all good, but now it's just that 40-70.. really bad in 3rd geaar.. but I'm guessing its less noticible in 4th only because the engine is bogging more.

I've got under and thrashed around the driveline and nothing..

I had a lot of noise from the throout bearing.. but now thats gone too..
Maybe the bearing's gotten worse? but then why not through all the gears?

Output bearing? or is driveline vibration from too much angle/bad U-joint only when theres load from the engine side? Not hte wheels driving the shaft?
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post #7 of (permalink) Old 10-21-2003, 02:28 AM
 
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Re: Vibration

</font><blockquote><font class="small">In reply to:</font><hr />
It makes sense in my brain that if it were axle wrap it would be more pronounced in 1st gear, I'm thinking that would be the most torque the axle would see.

[/ QUOTE ]

inertia is not the only force that you would over come, wind resistance can take allot of torque to push trough.
regardless it would be during any application of torque, and the frequency of the vibration would be a fundamental of the rotational speed of the drive shaft. in first gear the frequency would be very low.

in my theory, the vibrations would be most noticeable at the torque peak of the engine and would tapper off above and below that point.

but your motor/transmission mount theory has merit, they could be wrapping up instead of the axle.

...but, the cat lover needs for weigh the input and make his own choices on how to proceed.

cat dude,
does it vibrate when you are heavy on the gas, neutral on the gas, no gas but in gear( decelerating).
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post #8 of (permalink) Old 10-21-2003, 02:57 AM Thread Starter
 
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Re: Vibration

As far as I can tell..

It only vibrates between 1500, and 2000 RPMS in 3rd gear..
little lower in 4th gear.

between 40-70 kmh.

Doesn't do it coasting out of gear, or when I'm not on the gas (coasting in gear)


It's a vibration throught the Jeep. steeringwheel, seats, consoles.. everwhere.

and it gets better past 70kmh... but I can tell it's still a little there.


So I guess it would be described as a complete vehicle vibration while under power, at 40-70kmh.

I know my rear main seal/or/bearing leaks and my throwout bearing is jsut about toast. I'll be fixing these soon...

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post #9 of (permalink) Old 10-21-2003, 04:10 AM
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Re: Vibration

Ujoints can do funny things, easy to pull the rear shaft and check them out. Start with the easy stuff and work towards more complicated possibilities. Good luck and keep us posted! [img]images/graemlins/grin.gif[/img]
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post #10 of (permalink) Old 10-21-2003, 08:55 AM
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Re: Vibration

I had a vibration that acted similar to yours. Turns out the driveshaft u-joint at the pinion had no needles left and had beat itself pretty good.
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