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Still trying to solve vibration problem - Update Fixed!!!!

thegreatjustino

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Red Head Grease Monkey
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Jan 23, 2002
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15,624
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Stockton, CA
A while back I posted this thread trying to track down a periodic vibration/whooshing sound. After not messing with it for a while, I started trying to troubleshoot it again this weekend.

Here is what I have found: the vibration will just start arbitrarily while driving around town.

It sounds like it is coming from the bellhousing or transmission - I am leaning toward the transmission.

Once it starts, it continues if I put the transmission in neutral, if I put the transfer case in neutral, and if I just shut the engine off.

The only way it stops is if I come to a complete stop.

It never happens upon acceleration, so I don't think it is clutch chatter.

I am afraid to drive it on the freeway this way, but the one time I did and it happened, it eventually went away on it's own after about ten seconds.

Something is going on, and it does not sound good. Just trying to pinpoint the problem so I can fix it. I do have another NP435 here that I can swap in, but I REALLY don't want to pull the whole thing back apart if I can help it.
 
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rhinobuggie

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Apr 22, 2008
Messages
123
Have you tried pushing on the clutch pedal just a little , to see if its the throw out bearing
 

TBS-POPS

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Jun 16, 2007
Messages
1,388
Loc.
valley springs, ca
Crawlin68 had that problem and found out the collar that the throwout bearing rides on, on the front bearing retianer on the 435 had broke off and was float'n on the input shaft. might take a look through the clutch fork opening if ya can...
 

Larry B

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Medford
If you are up to speed and it is vibrating you could put the divider box in nutral and kill the engine. If you still have the vib it would have to be in the divider box, drive lines , rearends or wheel bearings. Because with the engine dead and divider box in nutral everything is completly stopped from the transmition forward. Things will still be turning in the divider box.
 
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thegreatjustino

thegreatjustino

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If you are up to speed and it is vibrating you could put the divider box in nutral and kill the engine. If you still have the vib it would have to be in the divider box, drive lines , rearends or wheel bearings. Because with the engine dead and divider box in nutral everything is completly stopped from the transmition forward. Things will still be turning in the divider box.

I've not tried putting things in neutral and killing the engine at the same time. I will give that a shot.

Has anyone had a similar problem with a rear end that was set up incorrectly? Shortly before I put in the NP435, I swapped in a slightly used third member. Just wondering if it could be something there. It wouldn't explain why the vibration sounds like it is coming from the bell housing/tranny area though.
 

Larry B

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Medford
You might put the rear axles up on blocks and see if it will come on with no load. With somebody outside it may sound much diff and you could watch for drive line vibs.
 
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thegreatjustino

thegreatjustino

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You might put the rear axles up on blocks and see if it will come on with no load. With somebody outside it may sound much diff and you could watch for drive line vibs.


I have driven around in four wheel drive with the rear driveshaft out. I still have the vibration problem with just the front driveshaft pulling.
 

nrramse

Sr. Member
Joined
Apr 20, 2008
Messages
522
I just swapped third members. I did not swap anything internally in the rear end. Unbolted one third member and bolted the other one in

I'm not a differential guy, but I think the ring and pinion wear together over time. When the 3rd member got swapped this changed the ring gear but not the pinion (if a 3rd member is what I think it is, which is the gear set inside the differential). My theory is that the difference in the two wear patterns is making the noise. Hopefully someone with more knowledge will chime in.

Newell
 
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thegreatjustino

thegreatjustino

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I'm not a differential guy, but I think the ring and pinion wear together over time. When the 3rd member got swapped this changed the ring gear but not the pinion (if a 3rd member is what I think it is, which is the gear set inside the differential). My theory is that the difference in the two wear patterns is making the noise. Hopefully someone with more knowledge will chime in.

Newell


On a Ford 9" the ring and pinion come out of the housing as one unit - the third member. It is different than a Dana axle where you take the carrier and ring gear out but the pinion stays with the housing.
 

69 Fl. Bronc

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Aug 8, 2007
Messages
911
I would put it on jack stands and see if you can find it that way. Safty first. Good luck
 

nrramse

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Joined
Apr 20, 2008
Messages
522
On a Ford 9" the ring and pinion come out of the housing as one unit - the third member. It is different than a Dana axle where you take the carrier and ring gear out but the pinion stays with the housing.

Oh okay - I see what you're saying. Thanks for the correction.

I had something done to my rear axle many years ago - I think it was a pinion bearing replaced. The shop that did it said I might hear some noise, but I never noticed it. I don't know if this is useful to you or not, but there it is.

I like LarryB's idea with putting it in neutral and killing the motor.

Newell
 

DirtDonk

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Bronco Guru
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Nov 3, 2003
Messages
47,355
At first it sounded like a possible rear output bearing on the transfer case, but then you said it did it even with the rear shaft out. So much for that...
Then I thought about a missing tooth on one of the diff gears. Might be worth an afternoon diff pull just to inspect it. First time it took me a couple of hours to fiddle around with it. You've done it before so it should take no time at all.
Nowadays I'm down to about 15 minutes on mine!

On the engine fan... Don't rule anything out! Those things are swingin' some serious inertia. Though you did say it does it with the engine off, so at least in your case it's ruled out. But I've seen fans make some wierd symptoms that felt like they were coming from somewhere else entirely.
And if it does it with the transfer case in neutral, then it "shouldn't be anything in front of the t-case since you isolated it all. Unless of course it's an engine mount...

Good luck.

Paul
 

Viperwolf1

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Did you check the outer axle bearings when you changed the diff?
 
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thegreatjustino

thegreatjustino

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Stockton, CA
Did you check the outer axle bearings when you changed the diff?

When I changed the third member, I went from 28 to 31 spline axles. I installed a brand new set of Mosers, so it's a slim possibility that it's an axle bearing.

I am leaning toward the rear end. I have three EBs here, so it looks like I will be swapping third members next weekend. Kind of frustrating, but I would rather swap third members than transmissions.

Thanks to everyone for the suggestions.
 

d.c.parris

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Aug 26, 2005
Messages
168
Loc.
cumming ga.
Crawlin68 had that problem and found out the collar that the throwout bearing rides on, on the front bearing retianer on the 435 had broke off and was float'n on the input shaft. might take a look through the clutch fork opening if ya can...

same thing happened to my bronco about 20 years ago would rattle for a few seconds then be ok for a while then would start again after i would change gears made a hell of a noise and vibration
 
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