Driveline vibration --HELP

77 Bronco

347, C-4, d-20 transfer case. With the drive shaft removed I have a vibration with the vehicle in gear- but not in park.

SO- what do you think? seems to get worse with rpms..

no one has an opinion?

Little more info please.
When you say the driveshaft is removed, do you mean the rear and you're driving on the front only? Or is it that you just put it in drive and let the output shaft spin without the truck going anywhere?

Also, when did it start? After some work? Come on slowly or all at once?
Is the truck new to you, and has done it all along, or have you had it awhile so could monitor the vibration's progress?

If just running it stationary, then the vibration would have to be coming from the transmission output section or the transfer case. If it was anything from the torque-converter forward to the engine, it would vibrate in park too.

Have you towed it recently? Made any modifications? Done some wicked burnouts with that 347 engine? Could be the rear output section of the t-case I suppose. Or it could be one of the bearings.

What is the frequency and modulation of the vibration? Low and deep, or high and shallow? Somewhere in between?
Any funny noises accompanying it?

Paul

Check your engine and tranny mounts and cross member. I'd be willing to bet they are amiss somewhere.

Little more info please.
When you say the driveshaft is removed, do you mean the rear and you're driving on the front only? Or is it that you just put it in drive and let the output shaft spin without the truck going anywhere?

YES-stationary and vibrates when reved- it does not do it in park

Also, when did it start? After some work? Come on slowly or all at once?
Is the truck new to you, -(truck is new to me but had huge swampers on it that I sold- they masked the vibration)

If just running it stationary, then the vibration would have to be coming from the transmission output section or the transfer case. If it was anything from the torque-converter forward to the engine, it would vibrate in park too.



What is the frequency and modulation of the vibration? Low and deep, or high and shallow?

It seems to be a pulsing vibration- not steady. goes away when driving if I back off the gas, but seems to speed up if I give it a little gas -it increases in frequency.

Thanks guys


one transfer case bolt is loose on the cross member. the other is tight. I can not get to the bolt on top to tighten that bolt

Worn u-joints maybe?

It has to be the input side of the tranny, if you are not allowing the output to turn. It would rule out anything from the trny output shaft back.

Time for some tranny love..sorry, couldn't resist.

Does it still do it with the trnsfer case in neutral?