whats to blame?

[blumule]

my 69 shortbed has had a slight vibration for awhile now and it has finally developed into an obvious problem. you can not only feel it there is obvious noise coming from diff mostly at the back side of pumpkin and trans output seal is leaking. which is the culprit? drive shaft itself? rear diff? axles? tranny? whats the best method to isolate without throwing money into parts.its a 1 peice drive shaft 2 wheel drive.

[Craigerf100]

the obvious sign of drive shaft is the clank you hear and feel when you put her into gear. as im sure you know already , specially automatics. if its bad you can tell by looking at the yoke and sometimes you can feel the play if u try and turn the drive shaft.

but what kind of vibration noise? explain it.
i mean if its a vibration and the noise comes from the truck vibrating so much then it could simply be one or more of your wheels out of balance. is it only at certain speeds? do you have rear rotors? and why do u suspect it being the rear differential, besides the leak?

[blumule]

its a 3 speed on column. its been a speed related vibe for awhile. only now its becoming more obvious. you can feel vibe in the ds by hand but you can hear a knock inside diff at back of housing. my question is, is the ds causing the knock in diff or diff causing ds to vibrate. wheels and tires were road force balanced and afterwards vibe seemed worse. is this related ? who knows when it comes to other people performing work for you. very frustrating.

[Craigerf100]

well ive heard road force balance is the best way to balance your tires. so it could be the Drive Shaft. as for the knock. i have no clue. hopefully a differential expert sees this and replays i take it its a 9"?

[blumule]

yeah its a 9. how much axle flange runout is acceptable. ive swapped several axles and all of them have anywhere from .010 to .015 runout. can a machine shop straighten them?

[blumule]

yeah its a 9. how much axle flange runout is acceptable. ive swapped several axles and all of them have anywhere from .010 to .015 runout. can a machine shop straighten them?

[Donnie]

I just sent a LONG DESCRIPTIVE post to Blu Mule------where is it, It was sent just a few minutes ago..NOT SHOWING????????? Donnie

[Donnie]

IT should have shown up before " IT's a 9 inch " post?????????????????????????Donnie

[Craigerf100]

[BobbyFord]

Axle runout is not going to increase with age unless you frequently mash curbs. Most gradually increasing driveline vibrations can be traced to spinning things that normally wear out, such as driveshafts (u-joints), tires, etc.

[blumule]

sorry i missed donnies post. oh well. all i know is sumpin aint right. hopefully it will continue to get worse and be obvious,

[bluef250]

Check the u-joints.

[Craigerf100]

looks like we all are leaning to your ujoints

[blumule]

U joints are new.I'm having driveshaft looked at today.I'm still leaning towards those axles.there is obvious runout there. Problem is ive switched 2 other sets of axles all with the same issue.how much is acceptable I don't know.I'm sure everyone here who jacked up there rears would see the same thing. Ill get it one step at a time and more money. I love these ole trucks and hate em at the same time.

[ultraranger]

If changing axles and U-joints didn't help the problem then another possibility is the driving pinion bearings/races may be going bad. You may or not be able to tell by grabbing and wiggling the drive shaft flange on the 3rd member but if it does have any give in it, then it's obvious something ain't right there.

Another possibility is the bushing in the tail housing of the transmission may be worn out. A drive shaft is a good conductor for transmitting noises away from the source of where a problem may actually be coming from.