CHEVY6000VHO

iTrader: (2)

Please explain this..... Since u-joints are designed to work at an angle, then why would you set your front DS section equal with the tranny slope??? The u-joints angles there would be 0.
That is just part of the reason all of this is confusing me now.
If I turn the diff nose down any more than what it is, it will be even more out of phase than what it is set at now.
Anyone else care to answer my questions in my recent previous post about what you are setting the pinion angle to be parallel with? Tranny output or first DS output?
This crap is unreal.
Until I get my angles corrected and vibration issues eliminated, no mods are going to be done.......
I would have thought there would be a driveline specialist at this site.

Jim

CHEVY6000VHO

iTrader: (2)

This shudder began by just adding 2" shackles.
I have since then added a 1" lowering hanger. I now have a total of a 3" drop in the rear.
Like I said, the only thing that seems to take the vibration away is raising the carrier bearing up higher. Though I am not liking what it is doing to the u-joint angles at the tranny. My front DS now has a 1-1/2* downward slope, the tranny has a 4.5* downward slope. Thus placing a 3* angle in those u-joints. The carrier bearing can go up another 1-1/2", but I can't imagine what the angle would look like then.
What do I need to do then? At this point, I cannot bring the carrier bearing back down to stock hidth. It will not come down that far anymore.
I wish I never cut out the original carrier bearing bracket.....
When I only put 2" shackles, I originally shimmed the pinion down more with 2* shims, the vibration could be heard going that way, and it had a low speed shudder. So I swapped the shims around and the noise went away, but the shudder was still there. So, this has me to believe that shimming down is not working for me.
Hell, I don't know what to do.

Jim

jblack6527

so you are saying here that your rearend housing yoke is lined up perfectly with your tranny output shaft? If so, then what I say you should do (and this is solely my opinion) is set the angle of the front u-joint (at the tranny) to 0*. Since there is only one u-joint in the first shaft, when you move it and make it angled, there is nothing to cancel out the harmonics of the joint. So set the first u-joint angle to 0, and set the angle of the rearend yoke to between 1-3* down, and try that.

Dock Rocker

Since you live in Houston there has to be a drive line shop, take it there!. If Jackson MS has one the houston must. They can fix it in a matter of hours. If you are not going to do this then get a DS loop. IF you are driving it eventually the drive shaft will give out and f up all sorts of stuff. You also need to check the runout on your pinion yoke. Mine was worn and gave me a bad vibe.

BigCountryx

iTrader: (3)

Couldn't you space the carrier bearing down using a block between the bracket and the bearing to bring it down lower, "IF" that is what your after? You may have to press out or drill the factory bolts and add your own longer bolts.

Still seems that with 3 u-joints one would have to have a working angle of 0*

CHEVY6000VHO

iTrader: (2)

I had a custom carrier bearing bracket made for full lateral adjustment.
I spoke with a Belltech engineer today. He said I will need to raise the carrier bearing until the low speed shudder goes away, then adjust the pinion down until the high speed vibration goes away.
He also said that if it takes more than 5* of a shim to get the pinion corrected to rid vibration, then a carrier bearing relocator is needed. Basically he said the u-joints need around 2 - 2-1/2* of angle to work without any vibrations at all. Basically, when you guys are using big shims, you are creating more than the maximum of 3* working angle on the u-joints at the pinion and or after the carrier bearing.
He said I'm on the right track, but he also said I cannot allow the tranny u-joints to go more than 3* when raising the carrier. Mine will, so he said I will need to shim the tranny mount with a 3/4" spacer.
Oh well, I dropped it off at the shop that made my custom carrier bearing bracket. He said he would fix everything. He said I should have let him in the first place........ I now agree totally!
This will be the first and last truck I ever lower!!! I promised myself!

Jim

Last Call

iTrader: (4)

I hope you get it all worked out bro... I know how stuff like this can be.

CHEVY6000VHO

iTrader: (2)

Update:
The shop placed a 4* shim to pinion down the diff. He also lowered the carrier bearing bracket back down. That ridded all the hard acceleration vibrations, but there is still a low speed (10-20mph) shudder under normal driving. If you place a load on the truck by applying the brake at 15mph, the truck will shudder/ shake quite a bit consistantly until you let off the gas or brake.
He will try to figure out what is doing this tomarrow.
I will say this, it hooks up a lot harder now! Hopefully he will figure out what is causing this shudder at low speed.
Anyone else ever have this low speed shudder/ shake or know what could be causing it?

Jim

CHEVY6000VHO

iTrader: (2)

The driveline shop I took it to thinks the small 10-20 mph shudder is fine. I said I don't think so. So he decided to keep it longer to play around more with the carrier bearing area. He wants to start over in that area and bring it back down to stock hidth. We also found that his design of the custom carrier bearing bracket would not allow removal of the front DS section without taking apart the u-joints at the tranny. He actually welded in the custom carrier bearing bracket to the truck frame.
I guess I may have wasted my money on the custom carrier bearing bracket.
Guys........I'm pretty much fed up with all of this vibration crap!
If I knew where an expert driveline shop in Houston was, I'd take it there.
These guys that have my truck do a lot of drops, lifts, and custom fabricating, but they said they never encountered a truck that just was lowered 3' in the back having this many issues.
Any help or guidence at this point to where to take itto next would be appreciated!
I'm actually thinking about canning this truck all together because of this.
That is, if they don't figure it out after redoing the carrier bearing bracket.

Thanks,

Jim

1slow01Z71

iTrader: (36)

PM Mister P over on ls1truck or sss.com he had ALOT of problems with driveline vibrations and I believe he finally got it figured out after taking it to a professional shop in DFW. Might pick his brain a bit.