Anyone had any issues with driveshaft vibrations after installing rear drop shackles? I put 2" drop shackles in and now have a driveline vibration. I tried shimming the t-case up an inch which is more than I want to go but vibration still there. Also tried putting the drop shackles at the - 1" whole still no luck. It looks like the u joint at the t-case becomes almost straight with the shackles in. Truck is a 06 extended cab. Anybody else had this issue?
Lowered truck vibrations
- Thread starter Tothemax
- Start date
leaf pack 100% stock?
you may need to shim the axle, not the t-case. set the pinion angle so it matches the angle the t-case output is at with no shim under it.
you may need to shim the axle, not the t-case. set the pinion angle so it matches the angle the t-case output is at with no shim under it.
yes the leaf pack is stock with overload still in. was trying to get the truck so that I didn't have to drag a jack to the track to get the front down. trying to make it able to 4x4 at will. wont shimming the rear to get the pinion that high make to poor rear traction. my end goal is more function than looks.
I didn't need to start shimming my axle untill after I removed my overload on more than a 3" shackle. You have problems elsewhere.
Not every truck is the same nor is every "butt". Some are much more sensitive to angle change than others.
If that was the case, there would be a lot more guys on here with just a shackle asking about vibration problems.
Who's to say they didn't search the issue and put shims in the truck? Or who's to say they just didn't care or notice? 2" drop is a 4" longer shackle. That ain't no "little bit of movement" and translates to pinion change. Shorter the drive shaft, more amplified it becomes. Axle pads may be welded on at just a bit more angle than the last or maybe he's seeing a little more axle wrap than someone else and now the change in pinion angle is amplified by the wrapping.
What else ya got cummins boy? Lmao
well I was able to use my adjustable traction bars to pull up 2 degrees on the pinion. that for the better part solved the vibration and noise I would get around 60 and up. I know I cant leave it like that because is got the leaf springs over (pre loaded). now the front leaf spring bushing squeak. I have new pro comp 2.5 degree aluminum shims siting in my shop. I need advise on the best way too use them. I know what way they need to face but I'm not sure if I put them right on the diff pads or between the lea and overload. if they go on the diff pads the centering pin wont be long enough to go into the diff. plus I was would like to remove the over load springs. can I pull the overloads out and put the shim under the spring pack with lets say a 6'' long 2.5 wide .250 thick mild steel plate under it with 5/16 hole in the center so that I can tighten everything together with a new center pin?
sorry for the book and thanks for input
sorry for the book and thanks for input
Having that centering pin right is crucial whatever you have to do to get it right. I bought new center pins when I removed my overload because they were too long and didn't have enough threads to go down tight. There is a large part of the pin that is shouldered and not threaded. The shim needs to be in between the leaf pack and axle pad or it's not going to work.
2 piece or 1 piece driveline? I've yet to hear of any real notable vibrations in lowered trucks with 1 piece drivelines, but those dang trucks with the two piece are always having issues.
I've been at almost every step of low and sitting at a 4/6 now and have had a smooth driveline since stock, every truck is different.
2 piece or 1 piece driveline? I've yet to hear of any real notable vibrations in lowered trucks with 1 piece drivelines, but those dang trucks with the two piece are always having issues.
I've been at almost every step of low and sitting at a 4/6 now and have had a smooth driveline since stock, every truck is different.
Last edited:
Buy some longer pins. Pair of socket head allens work well. I made spacers to go under the Allen head so it would hold the shim centered and center it's self in the axle hole. The u-bolts do all the holding of the axle on the springs so I prefer steel shims as they don't compress or deform like aluminum ones can.
Putting them under the overload will make one end of the overload very close to the spring pack and the other end quite a ways away.
Btw, stock spring pins are a grade 2 bolt. They do this in the event of a crash, the pin will sheer and let the axle slide up the pack or come off. They also have a higher chance of breaking under a large shock load and not having the u bolts tight enough. I don't like that lol