I don't know if anyone else has tried this or if it will pertain to everyone, but I decided to try something to fix the vibration problem I was having. I don't know how severe everyone else's is but I would say that mine was a 5 on a scale 1-10. Anyways I went and bought 2 longer grade 8 bolts with locking nuts and, I made 3 spacers outof 2"wide x 1/4" thick flat stock steel 8" long. I drop the midship bearing down and put the spacers in place and bolted everything back together, which lowered the midship 3/4". I can tell a difference, I would say that most of it is gone, I am going to get my tires rotated and balanced this week, I hope it will completely take it out. If after rotation and balance is done, and if it still has a little I may take one out to see if it helps, if not I may add another.

 

i was thinking abotu doing this. do you have any lift on the rear of your truck?

 

I am going to be doing this also because I put 4" blocks in the rear. What I wish I had done was checked the angle of the drive line before adding the blocks then I would have known how thick to make the spacers. I might be able to take a piece of pipe to find the old angle. I didn't have any vibration unyil the lift.

 

sounds good.......i had suggested this same fix in another thread because that is what they do to lifted/lowered trucks to reduce driveline vibration. they ususally recommend 1/4" of shim for every 1" of lift or drop. seemed like alot of people schrugged my post off. hmmmm.....

glad you got it fixed.

 

No, the height is stock. I have a 3500 dually, not sure if the srw's are the same but I believe that the problem we all are having is because I feel like the midship is in the wrong location...ie.. If you look under your truck you will notice that there is about a foot or a foot and a half of drive line past the midship.This puts your pivot point well behind the midship, and at a pretty sharp angle. Dropping the midship 3/4" will just about align everything up in a strait line. I have installed alot of drive lines at work and they use a slip joint at th midship which puts your universals right up next to the midship . With the universals a foot or so behind the midship I can see where you might get a "wobble" effect in the drive line. The best way I can explain it is take two ratchet extensions and put a swivel in between the two , as long as you hold it stationary at the swivel you can use it, but if you try to hold it away from the swivel it will "wobble" around. just my .02

 

Here is an update so far. I had tires rotated and balanced today, vibe is totally gone, I talked with the guy at the shop I have known for years and he said the same thing, as far as where the midship should be placed in relation to the universal joint. I told him the setup I had now that everything was pretty much in line , so we also decided it would not be a bad idea to add another 1/4" spacer (4 total), because when you are driving down the road you are actually pulling on the drive shaft due to tire rotation, centrifical force.etc..... putting more angle on universals. I hope you get the same results as I have , I am very happy so far, they might shrug off this post, but it may be the answer to alot of the problems so many are having, as for me mine are fixed.

 

OK, dumb question. What is the midship ?

 

Its the center carrier bearing attached to the frame where the drive shaft from the trans is connected to the drive shaft from the axle.

 

K Gotcha, so this would be for the lwb trucks ?

 

Yes, I cannot say for the swb trucks, I would imagine they have a one piece drive shaft.

 

here are some pics

 

Dodge has a TSB out on this since 03-04. It relates to shiming the center bearing and the rear end.

 

I did the same thing except I only used one spacer.
I found that if I used more than one spacer the driveshafts would completely be straight with no load and that would end up causing flat spots in the needles bearings inside the U joints.
You want some angle between the 2 shafts while unloaded.

 

What was causing the flat spots? Mine had 1 spacer on each side, looked like half of a washer, but you also have to consider that driving down the road that the angle will be greater due to axle torque,rotation etc.... I Will watch it for now, if I start having a problem I will look into changing something, thanks for the info.

 

Anyone know if Megacabs have the midship? I wonder if this is the cause of my shutter at launch or my vibration at 60mph?