Indexing helped a little but not much. I'm off to get a hose clamp...

 

WLF, I wound up raising the rear of the truck and putting jackstands under the axle tubes. You can put chocks on the front wheels if you want to. I marked both ends of the driveshaft in four places using a black marker. Each incriment was even with the centerline of one of the 4 cups on the U-joint so I know they were spaced evenly. I marked them 1 thru 4, with 4 being side that had the weights welded onto it .

Before I even tried the hose clamp I ran it up to 80 MPH to make sure I heard the rumbling noise and it sounded even louder up on the jackstands than it did while actually driving at 80 MPH.

I put the clamp right on the driveshaft itself rather than on the yoke or companion flange. I put the hoseclamp on the smooth part of the driveshaft tube, alongside the weld. After some trial and error I found the sweet spot at the 10: o'clock position on the front of the driveshaft. In this position there is no vibration at any speed! I push my luck and put a small 3/8 washer under the clamp now to see if it would get better and that little bit of weight was enough to make it rumble again although not as bad as before. After removeing the washer it went back to being velvet smooth again.

I repeated this whole thing with another clamp on the rear of driveshaft but regardless of where I placed the clamp it just got worse. Needless to say I left the front one where it was and totally removed the rear one.

Before I took it down off the jackstands I tried it out a couple more times to make sure it was'nt a fluke and it was flat smooth at 80MPH each time!

I cant tell you how good it is to have my truck back to being Cadillac quiet like it was before but now I think I notice the rearend noises more? I burned a 1/4 tank of gas just cruisng around yesterday.

I hope this helps you out somehow. Let us know how things turn out.

Good luck.

 

Will I have tried every combination in indexing. I have also used the clamp at every position in the clock trying to get rid of the noise and nothing works. I am now convenced this is gear noise. I do not and never did have any vibration or leaking of the tailshaft.
My next effort will be to try to dampin the gear noise since the drive shaft seems to be acting as a boom tube to bring the noise to the cab.
Any siggestions?

 

Le Pew,


The dealer took the shaft to a local place in Indy that does balancing. But, Ford said they wouldn't foot the bill even though the dealer said they new it was the problem. After 2 phone calls to the service rep and explaining that the 5" drive shaft was put on and new tail shaft, he wouldn't have another one put on. We agreedthat if it didn't fix the problrm that I would foot the bill on the balancing, but they would still be responcible for fixing it.
Low and behold that afternoon, after the balancing, took the truck out, no more rumble/vibration over 90 mph. Total bill was $109.00. A lot cheaper than a new drive shaft....

 

Sorry the hoseclamp did'nt give good results. I did have low frequency rumble that got worse at higher speeds but I'm a real happy camper now.

Did I mention that I think I'm hearing the gears more since the rumble has been eliminated? When I was looking around for someone to install the gears each mechanic said the gears would be totally silent but I have to believe that higher ratios are inherently more noisy? I think they are mechanically sound so I can live with a little noise I guess.


The yoke on mine has a vibration damper, maybe one is available for the companion flange on the pinion?
Is your driveshaft aluminum or steel?
Were you able to hear the noise while you had it up on jackstands?
Is your trans mount in good shape?
Are your transmision/pinion angles OK?
Did ya shake the yoke at the tailshft for loosesness?
Did you grease the U-joints if possible?
Did you check the axle bearings?

You already had the pinion done over recently so I know your gear lube is all squared away too. I really cant think of much else right now but I'll definetly chime in if something else comes to mind.

Good luck.

 

Thanks Ecm747x, there's a driveshaft shop called Universal in Rutherford and I've dealt with them in the past but I dont know if they do aluminum. I'll call them tommorow for details, they're only about 40 miles away.

Do you know how high in RPMs yours was balanced for? Some driveshaft specialty shops are claiming their products are balanced to 10,000 RPMs !!

 

LePew,


I was trying to think of what rpm they did the balance at when I was writing the previous post. I couldn't remember for sure but I know it was over 5,000 rpm. Just don't remember the actual #s'.

 

Thanks, that's encouraging to hear Ecm747x. I'm trying to do the tailshaft bushing and driveshaft balancing at the same time so one doe'snt trash the other. We'll see what happens I guess.

 

LE PEW
Yes to all. The only thing I haven't done is replace the front U-joints. I will do that this weekend. I have the aluminum driveshaft. I will have to check the condition of the dapener when I take it off.
Otherwise everything is new or at least checked.
Like you said, I think the higher ratio rears are just noiser then the others. I will have to decide what to do next.