Drive Shaft Vibrations Solved Step-by-Step

i understand and figured that this change would make a difference, wasnt sure which way though. but it is much worse than it was before i flipped them. and if it is both high and low speed meaning the pinion and the CB are at bad angles i'll be looking at a different degree shim correct?? guess i just need to drive it do the old washer routine.

 

It's worse now because you have a double wobble going on, but you're also not stressing the heck out of those u-joints. Your pinion is good, at 0.45 down. It's the CB operating angle I'm messing with. Yours is 0.6 down, I'd like to try closer to 0.2 down or so. You need to bring the CB, lessee....which way is that....down. You need to drop your CB down just a hair to bring the two shafts closer in line with each other, which of course will alter the rear pinion angle from 0.45 down to probably closer to 0.30 down. Don't mess with your leaf shims any more, you're done with that hassle. Don't forget to retorque your rear axle u-bolts in a few days, by the way.

 

okay, just went bizurk with washers and shims under there. replacing, driving, removing, driving. basically i went from no shims on the cb all the way up to around 5/8" or so with no noticeable difference in the vibration. i'm using 1/16" washers for step ups, in combination with a 1/4" spacer and the toytec 3/8" spacer so i dont have a million washers stacked up. is it possible that i need to use something thinner for super fine adjustment and that maybe i just missed the sweet spot somewhere? i tried one less and one more than what i had in there when i did the measurements and like i said there was no difference. it really vibrates, it feels like its more vibration but im probably crazy, when i decelerate. im just wondering if there is something else that making these changes is affecting that is either wearing out or broken and needs to be replace. i know nothing about this suspension and drive shaft stuff except for what i've learned and taught myself by adding the lift and screwing with the CB and axle shims.

 

Say what? NO, as in NONE, difference in the vibes when making up to a 5/8" CB adjustment? That's not right. And MORE vibes when you DEcelerate? Huh. How you say....WTF? Rear drive line shimmies are usually more pronounced upon acceleration, when everything is all torqued up, and at the ever-so-familiar set speeds of 30-40 and 55-65 mph. Deceleration issues usually come from the front end, when the front end gets loaded up as the vehicle's weight shifts forward. What does your truck do when you stomp on it (floor the accelerator all the way up through 65mph, like on a freeway onramp somewhere safe), versus coming to a stop from speed (like on a freeway offramp when no one is behind you safely). Try to do the tests in as much of a straight line as possible. And your 1/16" washers are fine, it's not that super critical. Ultimately a double cardon driveshaft will solve all this nonsense, they just cost a grand or so. Spending a little time with $100 worth of parts in the driveway is a good first option until you get so pissed off the $1000 driveshaft seems like a bargain at 3x the price.

 

oh man thats bad news! yeah not getting any difference still. i can feel it in the steering wheel and then it feels like it goes to the driveshaft?? idk man. but i sure as hell dont have $1000 to put into a new shaft. i'll take the lift off before i do that and cross my toes that its still okay! but heres what i've gotten to today.
1st pic is zeroed on transfer case
2nd pic is on rear pinion flange
3rd is front shaft
4th is rear shaft.
Am i measuring from the wrong spot or do i literally have something else wrong with this thing!? and if so why would changing the orientation of the rear shim affect the vibing up front soo much??

 

it could be my imagination about the more vibration during deceleration. i have noticed the more you step on it the less vibration there is, havent stomped on the brakes to see how that goes however. and as far as getting up to 65 i've just been weary because i dont want to have a blow out on something. im bummed out. haha!

 

I plugged your numbers into my pdf, attached. Not too surprising that the numbers change day to day, has to do with the rear leafs binding when you park.

Ideal world would have the far right number (pinion flange) be closer to -0.2 rather than -1.2, means your 3.5deg shims might want to be 2.5deg shims. PM me your address and I'll send you a couple of 1.5deg shims you can stack together to make a 3.0deg set and see if that makes a difference, or you can reverse one 1.5deg shim on top of your 3.5deg shim to make a 2.0deg shim. The shims have ridges on them that specifically allow stacking without shifting around.

Ideal world would also have first shaft (6.4) and second shaft (6.7) be a touch closer to the same number. You can imagine that when you lower your CB, the first shaft angle increases and your 6.4 number would get bigger, while at the same time your second shaft angle decreases and your 6.7 number gets smaller, thus moving both numbers closer to, oh, 6.5 or so.

My numbers were very close to yours and I had vibes. I had to: 1) pin the rear leafs (replace the stock bolts (qty 4 total) that connect the leaf springs to the truck frame with nyloc nuts that won't rattle loose and juuuuuuust snug them tight by hand, DO NOT TORQUE the crap out of them, you want them loosey goosey); and 2) get my rear pinion flange angle to -0.5deg; and finally 3) get my first and second shaft angles to be within 0.2deg of each other (with the second shaft being down (bigger number) from the first shaft) by Cb shimming. Vibes cured.

Then I had to buy a double cardon driveline to accommodate my 42gallon gas tank and all that work was for nothing. Good learning experience though.

 

ok, i know for a fact that i tightened the hell out of the bolts that attach the leafs to the frame. where can i get some of these nyloc bolts you're talking about?? i'll go ahead and change those as well because that maybe an issue. i'll pm my address now. thanks a million by the way man, you're really helping my head stay attached to my body!! this is frustrating as im sure you know. just really hoping that A) i can keep the lift on and find a fix and B) i dont have to get a new shaft to keep the lift on haha!
thanks again.

 

Nyloc nut info is on my post #76 this thread, they're M14 x 1.5 metric, and I forgot about that leaf shackle so you'll need qty6 total. I'll pick some up on my way home tonight and include them in the shim box to you, UPS tomorrow. Tighten until the metal frame brackets just begin to bend inward. Seems scary loose, but works great.

 

hey, you're the vibration unicef! thanks man! i really appreciate that, you didnt have to do all this.

 

Does anyone know of a place in the So. Cal area that can make double cardon driveshafts for our trucks?

 

Bayou, still no answer for you? I saw you post the same question awhile ago, was hoping someone from SoCow would answer. I called my San Jose shop and they said there's about 7 or so shops scattered around Hollyweird, Pomona, a good one in Garden Grove, one in Ontario, etc. They wouldn't recommend one over any other, said they've worked with pretty much all of them on a referral basis and have had good success, so depends on "the shop nearest you" I guess. You want a shop that will crawl under your truck and measure from front trans/transfer flange to CB, then CB to rear pinion flange, and explain to you where on the second shaft they're putting the cardon section. If you can spare the truck for a day or two they can use parts and sections off your old shaft, otherwise, full penny for a complete replacement. I did a quick google search and came up with a dozen or so, randomly called one in Azusa wherever that is and the guy knew what I was talking about, so shouldn't be too difficult to find a shop close to home.

 

Thank You TscotR214, I will google and see what I can come up with. I appreciate your response, I was starting to think my threads were not getting through. Anyway you are a greaat help, Thank's man.

 

TscotR214, went to Deaver this morning and got my custom leaf pack along with 2.5 degree shims, had to push the CB bracket forward about 1/2" to compensate for the shims moving the pinion in line with the CB, so I benefited in two ways, got ride of the vibes and pushed the yoke a little farther into the tranny. Finaly got ride of the 1 1/2"block and the other leaf pack. Vibes are GONE AT ALL SPEEDS,,,,,,,MAN WHAT A Blessing!! Thank's again for your help. Now I can work on the small stuff finaly.

 

Deaver in Santa Ana, off 1st St? I know them, good folks. Glad they set you up right! Congrats! So, kick down the info for other folks. Did they: Option A -- align your rear pinion with your front trans flange (trans and pinion flanges are parallel, drive shafts are whacked angles), or did they: Option B -- align your rear pinion with the rear drive shaft (trans and first shaft are whacked, second shaft and rear pinion point nice and straight, directly at each other). See attached pdf for diagrams.

 

Bayou, 2wd or 4?

 

Nate, he's a prerunner like yours, check out his truck info on his tag.

 

Jeff at Deaver suspension took measurments of my leaf pack and three weeks later he installed them. I told Jeff I had some vib problems, he went into his shop and showed me different shims he made for that problem. Seems as though he just knew what I needed this guy is realy into his work and you can tell by the way he studies what he is doing. Anyway he picked out the shims and put them on a beautiful set of Deaver leaf packs then all of a sudden option B fell right into line. Is their such a thing as right place right time, this truck now rides like a dream, no vibs, sits even all around, no block, Damn, I feel like a beer. It's not a cheap way to go, but considering I was begining to look for a double cardon drive shaft, I guess you pay either way. I did not have a clue this would work but I don't mind, Jeff did a hell of a job and he knows what he is doing, it just worked out. Damn! I feel like a beer.

 

I have read through this a while ago (about 6pgs at the time) I just lifted my truck and put in the cb drop also. I only have a vibe at takeoff 0-10mph. I haven't had a chance to get measurements yet as the weathers been crappy in ny. Any rough guesses would be great. Thanks

 

Sounds like you just need a little shim work. I think the low speed shudder is a pinion angle being off.