Hey guys.

After I did my DJM 5" flip in the rear the angle of my drive shaft was pointing up a bit in the rear from the front.

I figured I didn't have the angle correct & even noticed a slight "vvvvvvvvvrrrrrrrr" vibration when I hit 60+ and gave it gas or let off the gas.


So, last week I took it to a shop who had a proper garage lift and had them loosen the U bolts & axle plate from the flip kit to bring the drive shaft down to a more straightened angle.

As soon as the guy looked at it he saw it was sticking up too much & got to work.

They straightened it quite a bit but I still get a slight "vvvvvrrrrrrr" vibration when I accelerate around 40-50. I can't here it much but can feel it in the pedals.

They told me that it is as straight as they can get it without my drive shaft getting shortened. Because bringing it down more was pushing it forward into my tranny.

I have never heard anyone having these issues. Any ideas as to what might be going on here with the slight vibration?

It is driving me nuts & I don't want to keep getting on it, the way I drive and take off if I'm going to efff something up!




thx

 

Sit it in the ground, or support the suspension up so it supports the vehicles weight. Loosen the u joint caps, and see if there is enough room to remove the shaft. If you can get the shaft out, it is not too long. It sounds to me that you need to shim the axle so that the front of the rear end is pointing down more.

Basically you want the output shaft of the tranny, and the pinion of the rear axle parallel. When they are parallel, there is no vibration. They suggest pointing the nose down a few degrees so it straightens its self out under acceleration.

 

I was under the impression you DIDN'T want your DS perfectly straight.

 

The angle of the driveshaft doesn't matter. It's relationship to the rear pinion and transmission output shaft are what matters.

A 1 piece driveshaft is relatively easy to understand conceptually. The transmission output shaft and rear end pinion should be at equal and opposite angles. For example, if the trans points down 2 degrees the rear should be pointing up 2 degrees. And the angle on the U joint at the 2 ends of the driveshaft should not be more than 1 to 1.5 degrees ideally. Now some people may not set their rear end pinion at exactly the angle above since the rear end will rotate up at WOT so they compensate by pointing the rear down a tad in relation.

DANA has an outstanding PDF article on driveline angles which covers all this in great detail including for 2 piece shafts and other complex configurations.

 

I didn't mean perfectly straightened. At the angle my axle was at, the u joint connection was pointing up quite a bit then the shaft came down as it ran up into the tranny.

They were able to bring it down, but it still comes out of my tranny and the shaft runs up at an angle, the u joint is still pointed up a little, but not like it was.



talking about this here?

https://docs.google.com/viewer?a=v&q...ms1tG1rA&pli=1


off to read more


think I might need to shim it?

http://www.stylintrucks.com/articles...ion_shims.aspx

hey texasglock, did you have to shim? You put in the DJM kit too didn't ya?





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ah... http://djmsuspension.com/works/djm-flip-kits/

Axle locating brackets in most flip kits have a built in angle, by having unequal length legs in the “U”. This works pretty good most of the time, but not all trucks are created equal and often you need to adjust the pinion to get rid of a pesky vibration. You can buy pinion “shim kits” that come in 2, 4, and 6 degree packages that need to be installed between your axle locator bracket and the leaf spring. Better that that, DJM makes their flip kits with adjustable axle locator brackets. You have the ability to rotate your axle to the proper angle and then lock it in place. This is the best way to deal with pinion angle.

so, anyone know how the efff I do this?

 

Vegas, I have the BT flip, and it came with shims. I don't recall what degree though. I've seen most here recommend the DJM due to the fact it is adjustable as you posted.

 

VegasJ by losing and tightening the nut you shown on the front and the back.

For example tighten the front and loosening the rear will bring the pinion down.
doing the opposite will bring the pinion up.

On a leaf spring truck there is usually a slight difference of say 1 or 2 degress down ward so that the pinion can rotate upward under acceleration and as the suspension cycle's upward in it's travel.

On a side note when is the last time you opened up the rear end and inspected it??? Have you ever changed the gear oil??? Just asking in hopes that you have been taking care of it so the gears don't fail.

Once you get the angle set up if your still having vibration problems, have your drive shaft checked out. If you tightened the caps on the yoke to tight you can actually crush the yoke bearing caps. If the U joint is worn you could also have a vibration.

HTH

 

been a while probably on the gear oil. Maybe since the 30,000 mile service?

I'm at 73k now.

 

Now problem. Just wanted to rule out gears going bad or something else failing internally. Since it just started after the flip I would think something just needs adjustment.