Driveline Vibration Part 2

Ok I going to solve this problem once and for all...I hope.:ugh2:

The only thing original on the truck since the old setup is the rearend and drop kit but playing with the pinion angle seems to change the vibration intensity.

Right now its set at maybe -1* on the trans/eng and the rearend is -3to4* pinion angle.

The vib is really noticable now at this setting at the speed of 65-70mph and the faster you go I guess the harmonics of it change and it smooths out.

Look at the crappy way DJM adj. pinion angle...

http://i129.photobucket.com/albums/p...xle/gen004.jpghttp://i129.photobucket.com/albums/p...xle/gen003.jpghttp://i129.photobucket.com/albums/p...le/shoc002.jpg

I am having the same problem, i am just trying different shims looks like i need the 2* shims

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Originally Posted by murdered_outgmc

I am having the same problem, i am just trying different shims looks like i need the 2* shims

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Well at least I can say Im not the only one with this problem. Only thing is mine doesnt use shims.:ugh2:

Whats ur lowering setup?

I would take off that clamp style flip quick and weld some perches on there. That thing is gonna spin and break stuff.

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Originally Posted by tanz45

I would take off that clamp style flip quick and weld some perches on there. That thing is gonna spin and break stuff.

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X2, thats a pretty 'ugly' flip kit... :spit: Make sure you know your angles for sure (dont guess).

hey man any progress lately??? i finally had time this morning to throw mine up on 4 cylinder blocks on the garage floor and measure out my pinion angle. currently my Transmission is sitting at -2 degrees and my rear end is at a positive 5 degrees. i want the driveline angle to be at -2 degrees so im 5 degrees out of wack on the rear end and already have a 4 degree shim in there. im hoping this is whats causing my vibrations which is only muliplied by that fact that i have 4:56 gears and the shaft is turning pretty fast. do you have any idea if CalTracs allow you to adjust pinion angle? or how the heck your supposed to compensate for being so many degrees off. thanks bud hope all is well with the truck!

The Ideal setup is to cancel out all the angles to 0 total and keep the ujoints within 4*.... So if the trans is pointing down 4*, you want your rearend pointing up 4*, this creates the same angle front to back, and keeps the ujoints in phase with each other. This is also on a stock height vehicle.

Now comes the problem, everyones truck is lowered and these angles become more severe, and the above statement doesn't always hold true. You can usually start out by shiming the tranny mount up to reduce the angle up front. I like to get it to around 2-3*pointing down, now you need to shim/correct your rearend angle to around 1-2* degrees pointig down to help with wheelhop and correct angles under load. The rearend will roll up a few degrees with leafspring flex under load. These angles are within range to keep nasty vibrations away during acceleration and during cruising speeds. And usually once you get all of this set go ahead and change the unjoints again due to any failure that might have happened before to bad alignment....

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Originally Posted by DBRODS

The Ideal setup is to cancel out all the angles to 0 total and keep the ujoints within 4*.... So if the trans is pointing down 4*, you want your rearend pointing up 4*, this creates the same angle front to back, and keeps the ujoints in phase with each other. This is also on a stock height vehicle.

Now comes the problem, everyones truck is lowered and these angles become more severe, and the above statement doesn't always hold true. You can usually start out by shiming the tranny mount up to reduce the angle up front. I like to get it to around 2-3*pointing down, now you need to shim/correct your rearend angle to around 1-2* degrees pointig down to help with wheelhop and correct angles under load. The rearend will roll up a few degrees with leafspring flex under load. These angles are within range to keep nasty vibrations away during acceleration and during cruising speeds. And usually once you get all of this set go ahead and change the unjoints again due to any failure that might have happened before to bad alignment....

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makes perfect sense to me. i can probably shim the trans to 0 degrees but as far as getting the rear end to a -2 degrees i would need another 5 degree shim on top of the 4 degree one i have thats 9 degress that doesnt even seem right to me that a drop kit put stuff so far out of whack like that... any suggestions on getting the rear end to a -2 degrees? i know your pretty good with rear suspensions. and i mentioned cal tracs because i heard you can use them to adjust and hold a solid pinion angle and i need a set any how. im just trying to determine other options that having huge shims under my rearend. thanks! hell i wish i had the setup you guys did on rickys truck thats badass. to bad you dont market the setup id buy it in a heart beat cuz my truck squats and almost touches the roll pan off the ground when i really hammer it.

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Originally Posted by Wtfan18

hey man any progress lately??? i finally had time this morning to throw mine up on 4 cylinder blocks on the garage floor and measure out my pinion angle. currently my Transmission is sitting at -2 degrees and my rear end is at a positive 5 degrees. i want the driveline angle to be at -2 degrees so im 5 degrees out of wack on the rear end and already have a 4 degree shim in there. im hoping this is whats causing my vibrations which is only muliplied by that fact that i have 4:56 gears and the shaft is turning pretty fast. do you have any idea if CalTracs allow you to adjust pinion angle? or how the heck your supposed to compensate for being so many degrees off. thanks bud hope all is well with the truck!

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Man I cant see how ur 5 degree pointed up, it needs to be pointed a few degrees down.

My trans is at 0 degree and my rearend is at 3.5 degree down. The vibration is still there and it not bad at all. Just at 70mph and after that its gone.

I installed a belltech flip kit that uses shims which made the adj. alot better.

Wheelhop is still there and I dont get it why, I never had a problem with it

Get some pics of that reareand.

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Originally Posted by DBRODS

The Ideal setup is to cancel out all the angles to 0 total and keep the ujoints within 4*.... So if the trans is pointing down 4*, you want your rearend pointing up 4*, this creates the same angle front to back, and keeps the ujoints in phase with each other. This is also on a stock height vehicle.

Now comes the problem, everyones truck is lowered and these angles become more severe, and the above statement doesn't always hold true. You can usually start out by shiming the tranny mount up to reduce the angle up front. I like to get it to around 2-3*pointing down, now you need to shim/correct your rearend angle to around 1-2* degrees pointig down to help with wheelhop and correct angles under load. The rearend will roll up a few degrees with leafspring flex under load. These angles are within range to keep nasty vibrations away during acceleration and during cruising speeds. And usually once you get all of this set go ahead and change the unjoints again due to any failure that might have happened before to bad alignment....

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I have a ? for you what shocks are u using with ur drop? It's probaly 4 link'd right and are u using traction bars

Are you meaning the trans angle on the pan or the yoke?

I get what ur saying but for some reason its not helping me out.:(
I cant lower my trans angle only raise it due to me using the factory crossmember.

Thanks

Measure on the yoke...thats the best spot. Raising your tranny in the rear will lower your angle on the yoke. Yes I have a 4link out back with KYB gas adjust shocks. Basically the ujoints follow a eliptical path as the rotate, thus they speed up and slow down. If you don't have the front one matching the rear one they will travel at different speeds and that is what causes the pulsations/vibration/harmonics. Which also causes FAILURE.


Yes Caltracs and Long bars will help out with pinion roll.

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Originally Posted by Kros383SS

Man I cant see how ur 5 degree pointed up, it needs to be pointed a few degrees down.

My trans is at 0 degree and my rearend is at 3.5 degree down. The vibration is still there and it not bad at all. Just at 70mph and after that its gone.

I installed a belltech flip kit that uses shims which made the adj. alot better.

Wheelhop is still there and I dont get it why, I never had a problem with it

Get some pics of that reareand.

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i know i dont get it either... so you went to a belltech huh? can you take a pic or 2 of your setup if you get a chance?? i didnt get shims with my kit from what i remember.

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Originally Posted by Wtfan18

i know i dont get it either... so you went to a belltech huh? can you take a pic or 2 of your setup if you get a chance?? i didnt get shims with my kit from what i remember.

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Sure can, give me till friday. I had a box of shims so I played with it awhile back but its still there.

Here's the deal. Everything is diffrent except the rearend since I did the swap and its still there, soooooooo my next plan of attach is to pull the axles and spin it up and see. Also check carrier bearings and pinion bearing. Hopefully there is nothing wrong with the carrier or gears.

But.....having violent wheel hop is also another issue, im leaning towards shocks. Im running the Doesch tech shocks. What are you running for shocks.

Setting pinion angle does nothing for the vib or wheel hop.:(

well sorry to hear that bro i figured mine out, my buddy and i goofed and put the shims in wrong. :argg: lol. so i changed them around this weekend and shimed my trans to 0 degrees. my rear end is now -1 degrees and has 0 vibrations till about 110 or so. im hoping a set of caltracs will fix that issue and it will be done with. good luck with yours.

Was the vibe present before the swap?

Checked the tires/wheels for out of balance?

Have you put it on jackstands yet????

Compared to Wtfan, your pinion angle is in the money. Sounds like if you shimmed your tranny UP to the 3* to match teh rear, then they would be parallel but opposite....like they should be. I think you have another issue other than the pinion angle.

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Originally Posted by r6z4o6

Was the vibe present before the swap?

Checked the tires/wheels for out of balance?

Have you put it on jackstands yet????

Compared to Wtfan, your pinion angle is in the money. Sounds like if you shimmed your tranny UP to the 3* to match teh rear, then they would be parallel but opposite....like they should be. I think you have another issue other than the pinion angle.

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Hey whats up, are you in Hutto... I drive through Hutto everyday atleast twice.

Yeppers, offa 1660 north. I get on Chandler road and zip to Georgetown to get to work everyday. Where is your shop located at????:naughty:

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Originally Posted by r6z4o6

Yeppers, offa 1660 north. I get on Chandler road and zip to Georgetown to get to work everyday. Where is your shop located at????:naughty:

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I live in Round Rock off Sam Bass and my shop is in Circleville..just north of Taylor off 1331 next to the Lake. Right across the street from the water treatment plant..

Quote:

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Originally Posted by r6z4o6

Was the vibe present before the swap?

Checked the tires/wheels for out of balance?

Have you put it on jackstands yet????

Compared to Wtfan, your pinion angle is in the money. Sounds like if you shimmed your tranny UP to the 3* to match teh rear, then they would be parallel but opposite....like they should be. I think you have another issue other than the pinion angle.

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truck on jackstands with no rim/tires or drums....still does it, did it before the swap

not much left to check other than axles and the carrier assembley itself, maybe bearings

damn man sorry this is giving you such a hard time. mine feels much better but at 105-110 the vibs are unbareable so im not in the clear yet haha. keep us posted.