Vibrations ... The saga continues...

[IMNCARN82]

I'm still having problems searching for the source of some vibrations I'm getting through the pistol grip.And basically throughout the car at high speeds.80-90mph.The only thing that has ever done anything has been to jack up the back of the trans.(TKO-500) I've trimmed the hump to get it up some,But am considering cutting the top off and re-fabbing.I've tried adjusting the 4-link rear countless times.Adjusted the pinion angle both ways.Measured to 1/16" c-c on the wheels.U joints are good. New front tires,The rears could be replaced.Need to have all new tires all the way around at once.4 wheel alignment,Frame alignment,Balance,Ect..?  Nothing I do helps.Getting frustrated with it. Can't afford much either. There's got to be something I can do.  Not sure where to start anymore.As I've looked it all over from the front to the back.Too many times.   Now I'm wondering if the rear-end is o.k.  Is there supposed to be a little play in the Suregrip? When it stops I get a little "ping" in the shaft.  Anywayz...   I know with a question like this comes more questions. I'll try and answer as best I can.      I really need some help.           

[dodj]

I had an annoying vibration a couple years ago. I had the d-shaft balanced, wheels ballanced - still vibrations. Then I put the rear on j-stands and started it up and put it in first at idle and let the rears spin. The passenger side wheel slightly wobbled. Brought it in to work and put it on a lathe and sure enough the axle was slightly bent. Replaced it and - no vibes. 

[IMNCARN82]

I think the housing was damaged at one time. Not sure. I know one axles are slightly different. When I re-did the bearings,Cleaned it up. Different colored kinduv.  When I jack it up and spin it back and forth in Neutral there is some play there.  I was told not to re-install the little thing that goes in between the two axel ends.Where they meet. A small pin thing. FWIW.     I'll try getting it going slightly up on jack stands...
Might be time to think about new axles/housing.   Also... Can a center section go bad?    Thanks for the ideas!   R/T

[KEISLERGENE]

I would bet if you raised the back of the tail on the trans the vibration will go away.

We have 3 different spacers in our kits to do this.

[IMNCARN82]

I have three large washers on each side. Approx. 3/8" -1/2"  I need to cut the hump and re-fab the top. How many spacers would you recommend?   There were none in my kit.  Thanks for the help!  R/T

[73EStroker]

I was told not to re-install the little thing that goes in between the two axel ends.Where they meet. A small pin thing.

If you are running a Mopar 8-3/4 rear, with the stock tapered wheel bearings, you need the spacer between the axles. If you are running the green ball bearings then you do not need them.

[IMNCARN82]

Thanks,That's what I thought.Just double checking. Guess I'll cut the hump.

[IMNCARN82]

peeled the hump back to allow full access.Slipped another two washers each side for a total of 5 per.Approx. 3/4". Not a lot of change. I'll try spinning the wheels up on stands. Maybe another couple washers.  

[bigblue73]

Hey Robert -
Have you determined if the vibration is RPM driven?  The RPM driven problems caused by drive train angle issues will be present in all gear at a certain RPM range.  Other could by bad tires.  This area is hard to swallow but the higher priced tires are indeed truer with respect to runout or the amount of weight that they need balanced.  Since you are in the rear end, checking with bearings.  Did or have you changed the rear end oil?  Did you add the sure grip additive back if you changed it?  What are you running for lube in 8 3/4?

[IMNCARN82]

Hey Tony!  :wave:It seems rpm driven. It's worse the harder i accelerate. New oil in the 8 3/4. It's 90w gear oil.What's sure grip additive?         Yeah,Good tires are a must. I'm headed there.     The trans. is full.   It's got GM syncromesh in it.   No matter what I adjust it's still there.  FWIW when I spin it up on jacks in N there is a slight chatter type noise in the trans.  Seems normal though.   I'm gonna' rotate the shaft 180*,And have it re-checked.    Raising the rear has helped a little... Now it's up around 3500rpm's on up.  The faster i go the worse it is. As for the other vibe,through the whole car. It's only while cruising above 40-50mph. It kinduv' oscillates.   New rear tires and all 4 new balance.   R/T

[ChallengerHK]

Hey Robert -
Have you determined if the vibration is RPM driven?  The RPM driven problems caused by drive train angle issues will be present in all gear at a certain RPM range. 

This is what I was thinking too.

[73440cuda]

I just went through all this, and finally found out my pinion yoke was worn/bad, I had about 1/16'' play on my drive shaft in the pinion yoke.  Replace the yoke and all is well.

[IMNCARN82]

The pinion yoke ehhh...   Hmmmm there is some play there. How hard is that to replace?  Driveline angles have been dialed and re-dialed.Even over-kill just to see.The 4-link allows for lots of adjustment. Hey Drew,Thanks for the therapy call. We need to go for a cruise!!!

[drewcrane]

The pinion yoke ehhh...   Hmmmm there is some play there. How hard is that to replace?  Driveline angles have been dialed and re-dialed.Even over-kill just to see.The 4-link allows for lots of adjustment. Hey Drew,Thanks for the therapy call. We need to go for a cruise!!!

Get that dude going and we can check out our bad vibes together 

[cwestra]

Hey Tony!  :wave:It seems rpm driven. It's worse the harder i accelerate. New oil in the 8 3/4. It's 90w gear oil.What's sure grip additive?         Yeah,Good tires are a must. I'm headed there.     The trans. is full.   It's got GM syncromesh in it.   No matter what I adjust it's still there.  FWIW when I spin it up on jacks in N there is a slight chatter type noise in the trans.  Seems normal though.   I'm gonna' rotate the shaft 180*,And have it re-checked.    Raising the rear has helped a little... Now it's up around 3500rpm's on up.  The faster i go the worse it is. As for the other vibe,through the whole car. It's only while cruising above 40-50mph. It kinduv' oscillates.   New rear tires and all 4 new balance.   R/T

If you say it's RPM related then shouldn't you be looking at something in front of the transmission and not in the rear axle and drive shaft area?  The drive shaft will spin proportionally to MPH, not RPM.  If it is really RPM related then you should be able to reproduce the problem in every gear at the same RPM.