VIBRATION ISSUES - I'm at a loss

[Houston Ben]

Hi all,
Been having a vibration issue for some time now that I keep thinking I had nailed down, but it rears its ugly head again. The vibration feels like it is in the front as the steering wheel, sun visors, and side mirrors shake.

When I first got the truck, it was stock (possibly original) suspension. There was some vibration but thought it was the bad brakes, wheel balance, worn components, etc. So....I started replacing items (a lot needed to be replaced anyway).

Replaced:
-rear diff with true-track
-axels with new bearings
-rear drum brakes
-front rotor/pad/bearings(already warped )
-upper/lower control arms (CPP/Moog)
-tie rods
-sway bar
-CPP steering box
-drop spindles
-beltech 2/4 drop

Things I have tried:
Truck has a 5.3 w/6L80
-Cut floor and installed high hump to help driveline alignment
-put shims under rear leafs to point pinion down due to wearing out u-joint (had driveshaft built by shop)

Just installed:
-2010 camaro wheels with new Nitto 20" (from 15" wheels) with alignment.
With this installed, the vibration became worse, which I think is due to the lower profile tires transferring more vibration.

Only thing I can think of next is:
-Re-check driveline angle and post here to see if correct (can't seem to calculate this correctly)
-Exhaust is hard lined attached to body (form person before me). Could cause vibration I guess, but vibration is bad.
-Motor mounts, but engine is dead still when in park and revving up.

Most everything is new on this truck and I still have this damn vibration.

Any help or ideas to fix this would be greatly appreciated!

Ben

[Houston Ben]

Ok, Just checked under my truck.
It appears my u-joint at my trans is trash as there is grease coming out of it and there is a little play in it. The rear by the pinion seems ok.

I took the angle finder to the bottom of the trans, DS, and pumpkin snout where the pinion gear goes into and I get as follows form my garage floor:
Trans: 1-2 angled up
DS: 5 angled down towards the pumpkin
Pumpkin: 2 angled down

What about the use of a double cardan joint?

With the grease on the u-joint, I believe they are bad, but I don't know what is needed to correct the driveline angle.

Any help is welcome!

Ben

[mongocanfly]

One thing I see is your driveline angle...your engine and trans needs to be down 3deg...your pinion needs to be up 3deg...the bad ujoint can also play into this...
https://m.youtube.com/watch?v=Idk3BVDVHq4

[geezer#99]

And you need to measure the angles in the right spots.
On the ears of the yoke.
Couple pics in here to show you where.

https://www.dragzine.com/tech-storie...mproving-hook/

[homemade87]

The reason your front u-joint is trash is your angle is up on the trans as mongo has already stated. Your trans should be angled down 2 to 3 degrees . Also stop measuring to the floor . The floor has nothing to do with your drive line . What you are trying to do is get the center lines of the trans and the diff parallel to each other , this way the 2 u joints are at the same working angle .

Put and angle finder on the yoke of the diff and see what it is . If it is up ( lets just say 3 degrees could be more or less ) then put you trans down 3 degrees . This should get you real close and see how it does .

[Houston Ben]

Hi all,
Thanks for the replies. I think I confused everyone on the garage floor, I was just stating that it might not be perfectly level as they are usually at a small angle towards the driveway.

So the trans needs to be 3 down. Thought I was told opposite which is why it was up. I was also told to have pinion angle down 1-2 degrees to allow for warp up form the leaf springs.

I will put the angle finder on the yoke and see what it measures and report back when I get home from work.

thanks again!

[homemade87]

Originally Posted by Houston Ben

Hi all,
Thanks for the replies. I think I confused everyone on the garage floor, I was just stating that it might not be perfectly level as they are usually at a small angle towards the driveway.

So the trans needs to be 3 down. Thought I was told opposite which is why it was up. I was also told to have pinion angle down 1-2 degrees to allow for warp up form the leaf springs.

I will put the angle finder on the yoke and see what it measures and report back when I get home from work.

thanks again!

Ben , It does not matter if the truck has a rake or not . As long as the weight is on the suspension you are still only concerned what is happening between the engine angle and the rear diff angle only . Just put them at the same angle to create a parallel line to each other .

As far as engine angle its not necessarily going to be 3 degrees . The rear is pretty much set at what its going to be with out doing shims on the springs . So it easier to measure the rear angle and try to match the trans angle to it if possible . It may be anywhere from 2 to 5 . As long as the trans and diff are at the same working angle .

As far as as your 1-2 degree difference . What you dont want is zero degrees . This will allow the rear to wrap up above the the parallel line which is not good as your front joint has already experienced . Dont worry about this you will have enough if you get your angle where they need to be .

[mongocanfly]

And you can always stick a jack under the front or rear to get your frame level and then measure your angles if you want to...and checking the angles is alot easier with the driveshaft out...
On a side note..the truck im working on now had all the angles at 9deg...from the factory...but I changed everything to 3deg...

[Houston Ben]

Thanks all,
Just so I am clear, the transmission should angle down towards the pinion and the pinion should angle up towards the trans at the same or close to the same angle correct?

I do have shims on the pinion as the angle was up a ton, but I cant remember how much as this was a few years ago.

Thanks again all!

[homemade87]

Originally Posted by Houston Ben

Thanks all,
Just so I am clear, the transmission should angle down towards the pinion and the pinion should angle up towards the trans at the same or close to the same angle correct?

I do have shims on the pinion as the angle was up a ton, but I cant remember how much as this was a few years ago.

Thanks again all!

That is correct .

[andyh1956]

Crankshaft / trans centerline angle + rear axle pinion angle- divide this by 2 should = 3 degrees or less on driveshaft.
Adjust as necessary.
More than 3 degrees (like On A Jeep or Blazer) will require double CV joint w/ pinion at same angle as driveshaft.

[Houston Ben]

So here are the angle measurements

Transmission measured on the yoke up 1-2 degrees




Drive shaft slop towards pinion 5 degrees



Pinion angle pointing down 1-2 degree


Using the Spicer driveline operations angle calculator Operating Angle 1 is a 6-7 and Operating Angle 2 is a 3-4.

So I believe I need to drop my trans 3-4 degrees, does this sound right?

Thanks all!

Ben

[mongocanfly]

im not sure how you dropped the rear...but if you used shackles to drop it that can affect the pinion angle

[mongocanfly]

can you pull back and show where your getting the yoke/pinion angles?

[Houston Ben]

Hi Mongo,
Yes, I used shackles and hangars. The pinion was pointing 6-7 degrees up so I put 6 degree shims in to bring it down.

[mongocanfly]

ok...youll need to get your pinion up around 3deg (maybe try a 3deg shim) and then drop your trans to 3 deg and that part should be good...all this doesn't mean itll fix your vibration but its a step in the process...vibrations can come from a lot of things

[Houston Ben]

Thanks Mongo,
Most everything is new on this thing (needed replacing anyway) which is why this is really driving me crazy!!

This has to be a big source of the issue as the u-joint is bad and grease is coming out of it. Also, looks like it vibrated so much some trans fluid mad it out of the slip yoke entrance.


Looks like I got work to do!

[homemade87]

Originally Posted by Houston Ben

Thanks Mongo,
Most everything is new on this thing (needed replacing anyway) which is why this is really driving me crazy!!

This has to be a big source of the issue as the u-joint is bad and grease is coming out of it. Also, looks like it vibrated so much some trans fluid mad it out of the slip yoke entrance.


Looks like I got work to do!

Looks like you found your problem or at least the biggest source . That is so far out I am surprised it did not beat up the trans tail housing . I would at least take a hard look at the bushing , maybe go ahead and replace it and the seal .

Looks like you are on the right track now .

[tucsonjwt]

If all else fails, I would take it to a driveline shop and have them remove the driveshaft and make sure that it is properly balanced. My 83 had an out of balance drive shaft which caused a bad vibration. In my case, it was due to the previous owner installing a Gear Vendor overdrive unit and not getting the shortened driveshaft rebalanced.

[Houston Ben]

Thanks Tucson (i'm originally from Gilbert!), The DS is pretty new, had it built.

I was able to lower the trans to the 3 down mark. Took it out and much smoother so far. Was only able to really cruse at around 50-55, but I previously felt it there and it seemed gone. I got up to 70 at one point, but not enough time to get the feel of it. Will do that tomorrow and let you know.

The trans side u-joint does shake a little, is it safe to drive on until I change it out or is that a no-go?

Ben

[mongocanfly]

If its got any slop in it you better change it before your new driveshaft winds up looking like a pretzel....

[Houston Ben]

Copy that, thanks Mongo!

[Tom]

A long time back my 98 started vibrating. I had numerous tire balances, 2 sets of tires worn out and replaced in this time frame, replaced pretty much all suspension, u joints., got frustrated and took the truck to the dealer for diag. They put sensors in it and drove and said it was my driveshaft. Had driveshaft rebuilt, still vibrated. It got to the point I was sure my wheels were bent. Took it to different tire shop with road force machine. He said no bends just un-balanced tires. So I paid him to balance them so he didn't just do all that checking for free. Ride home with first time in over 2yrs that I didn't feel vibrations. THE FREAKING WHEEL BALANCE. After multiple balances and different tires over time. Something to consider......

[Houston Ben]

If it still persist after the u-joint replacement, I will take back and have them rebalance!

Thanks Tom

[Houston Ben]

Finally was able to find a U-joint for my driveshaft, or rather two u-joints. The guy who built my DS used a combination u-joint, but used grooved caps from a second u-joint. The u-joint that was in my DS had no markings on it so I had no idea what brand it was.

Spent an hour at autozone in the back measuring all brands they had to include moog and no luck. Got back online and looked at Oreilly's and the precision brand look to be to correct brand. After measuring everything I went to Oreillys and still couldn't find the right combo. I found one that would match up, but didn't have the grooved caps. The let me go around back and finally found the caps needed and will reinstall tomorrow. I had to use precision 459 with precision 534g caps.

Man what a pain, but I am glad I found the correct combo.