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Need Diagnosis Shop in Colo Springs....More Truck Vibration!

jeff in co

jeff in co

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Colorado Springs
I'm about at the end of the rope on this truck and it's vibration. I've done just about everything I can think of and I still get a driveline vibration from 60 MPH on up. The faster I go, the more vibration I get. I need a reliable, honest shop that can put it up on a lift, run it and fix it once and for all. Engine, Tranny, Tcase, driveline or axle.

Some details and what I've done for entertainment:
2-1/2" lift (springs in front, blocks in back)
With factory driveshaft terrible vibration so dropped T-case and actually pretty good up to 75.

I wanted to get rid of the tcase drop and get it into the proper position again so saved a LOT of money to do SYE from JB Conversions. Installed kit and ordered a new TW CV driveshaft. Installed and the vibration began all over again. Checked the angles and I was about 3 degree difference. Bought a shim to bolt to spring pack the next day and now I'm 1 degree down from the driveshaft (14 degrees to 15 degrees). Still had vibration but a slight improvement.

Tried shimming 1 degree more so it was parallel with driveshaft....no change.

Rebalanced brand new driveshaft as a check, it was definitely off (from what local shop said)...they rebalanced...slight improvement.

Replaced motor mounts, replaced T-case mount (with new rubber ones)....no change.

Thinking maybe some of the bearings from the Tcase might of been worn (I used a second one to do the swap so I had 2 t-cases)....I took the whole case apart, swapped just the SYE shaft and sprocket to other Tcase, reinstalled....no change.

Took wheels off and put on jackstand. Brought to 65 and still vibration.

Rearend was rebuilt last year with new GM gears from local diff shop. Transmission was rebuilt last year as well.

Everything feels tight grabbing onto the driveshaft but it is so annoying. I thought CV shaft was the end all to any truck vibration. Now, still frustrating. Don't know if its in a bearing in the tranny, in the engine, in the tcase, in the driveshaft or in the axle.

Sorry for vent.....getting tired of taking this truck apart so many times!
 
Have you read on using hose clamps for driveshaft balance? I have had to do this on my own stuff that was driving me crazy with vibe problems. Usually can get them to nearly perfect or better.
 
I can certainly try but after getting a new driveshaft and then re-balancing that driveshaft, I would expect it to be balanced. Worth a shot I suppose, but ultimately I'd like to just take it into a shop, say you get up to $500 to fix this, and be done. I have other projects to take on and it's hard to move forward on those ones until I can get it 100% drivable....especially after spending close to $1000 for the whole SYE & CV Driveshaft combo.......
 
Your sure its not the engine that might have the vibration ?..
I have seen bent fan blades or bad harmonic balancers make some pretty annoying vibes that "seem" to come from the drive train..

Seen more than one engine with a bent flex plate or one that belonged on a different engine that was externally balanced cause this type of issue also..

Having it up on a lift or jack stands will let the axles droop,and change the driveshaft angles,so it will be hard to tell if it would be just as bad as when the weight of the vehicle is on the springs and tires...about all you can tell by running it with it jacked up off the ground is if the shafts are dented or bent probably..
 
I took the rear wheels off as well as the brake drums and then sent the axle back down on jack stands. That way, it would be operating at the typical running gear angles. I could hear it vibrating while driving on jackstands, but couldn't really tell exactly "where" it was coming from. I keep trying things "hoping for success" but so far, still there.

The truck came with a t-case drop when I bought it so it's been in that position for several years (I'm guessing). Wondering if that long term location did something up front with the engine or tranny??

Vibration is there with power applied or off the throttle....either way with no change in vibration. :(
 
If its the engine,you should feel the vibration in neutral with the RPM's at the same speed as when you get the worst vibes driving it..

Letting the truck sit on the stands with the tires & drums off will get the angles close to what they are when driving it...I hadn't thought of that..

It is weird that dropping the T-case with the factory shaft seemed to make the best results..you'd think a new CV shaft would allow for a lot of "misalignment" and still cancel out any vibrations compared to a stock drive shaft....
 
wait, your running a drive shaft with a CV at the T-Case?

If that's the case your pinion should be pointed up at the T-case.

cv_angle.gif
 
Yes, this is the setup I have. Driveshaft is 15 degrees to the horizontal, pinion is at 14 degrees to the horizontal....
 
Jeff,

How does the t case oil look? I know you were just in there, but is it possible there is an issue with the output bearing?
 
Well, the t-case oil is new from the first tcase. I made the swap only a few days later so maybe 300 miles on it. Output shaft bearing on tcase was new from JB conversions.
 
Last edited:
There may be a slight chance I partially blocked that little lube channel for the output bearing but when I felt inside, it seemed like there was adequate oil in there. I also felt the bearing pretty good and didn't feel any movement. The second assembly I did leave that channel clear so should be lubed well.

I could change that I guess again...
 
Had friend in Ca who was having a similar issue. We went through everything. Just as you have done.

Believe it or not, a rear tire was out of balance and the blocks in the back enhanced the vibration. We figured this out by removing the blocks. It was the only thing we had not tried. The vibration was all but gone. Took the wheels and tires to Robbie Gordons shop and balanced them at a real 75mph.

Put the blocks back in and all was good.
 
Bum deal is that I already tried that... :(

I went to Discount tire a week ago and had them rotated and balanced. I asked how bad they were and they said tires were still pretty new (maybe 5,000 miles since purchase) and didn't need much of any adjustment. Certainly nothing significant they said.

When I jacked up the truck I took the tires and drums off....and then placed the axle on the jack stands. I then brought the truck up "carefully" to 65 mph in my garage standing still. Unfortunately, vibration was still there and certainly was not any axle wrap or movement from accelerating.

It's a hard one to figure out......

I certainly welcome any other ideas!
 
I read that, but it did not register. Getting old sucks.

Have you tried running it up to speed without the drive shaft? Get up to speed slowly as no load will be on it at all. This would eliminate the drive shaft back if it is still there.
 
Don't have a definite answer, but did you watch them balance the driveshaft?
I have not balanced one personally, but I did a lot of work for a friend of mine who owns a machine shop and has a balancing machine.
I watched him build and balance many driveshafts. The welded on weights on the upper end look a little strange. Not necessarily wrong, just unusual. It was not unheard of for him to put on more than one washer, but it was seldom. And usually they were all on the same line.

I'm quite sure they have much more sophisticated machines than what he had. But he would clamp the shaft in the machine, lock one end, and then spin it up with a belt lowered from above.
He would lift the belt, aim a strobe at the shaft and look for a mark or something to indicate where the light spot was. The strobe fired everytime the shaft moved up or down, so the shaft seemed to stand still.
Usually he would make a chalk mark and spin it again. Then he would select a washer from a pile, weigh it, and tape it to the shaft where the strobe showed the correct spot was in relation to the mark.
If it needed more weight, he would replace it with a heavier washer, or move the washer.

When he had it right, he might use a slightly lighter washer to allow for the weld bead, then tack the washer in place.

When he had that end dead on, he would lock it and repeat it with the other end unlocked. Sometimes he had to put weights on each end, sometimes only one.
But I don't remember ever seeing two washers at an angle to each other on the same end. If he was working on a used shaft that he had rebuilt, he always removed all the old weights.

You might want to see if there is anyone else that does driveshaft balancing.

And you need to watch it spun up on a machine. If its true, it will run true with no vibrations.

One other idea. It will take three people, with their heads on straight.
Its dangerous if everybody does not do their job.
You drive the truck down a four lane highway with good pavement. Your job, is to drive the truck at a speed that causes plenty of vibration. Thats all, just Drive The Truck.
Two friends follow you in another truck or car.
The driver of that truck only drives his truck. He MUST NOT look for vibrations. The passenger is free to watch for vibrations, record them, whatever.
The follow car follows you for a while, pulls up alongside and paces you, then pulls ahead.
After a few minutes, you change lanes, and the follow car drops back along the other side.

The two drivers must drive only. Especially the chase car. If he starts looked for problems, he will find more than he can handle. If its the shaft, the vibration will usually be centered in the truck. You will see both rear tires moving the same amount.
If its an axle, brake drum, tire, many other things, you will see more on one side than the other.
If its a front end problem, more of the vibration will be more in front.

Just a thought.
 
If you have a Go pro or camcorder, zip tie it to the crossmember with the lens capturing the driveline and the diff. See what happens
 
ktmoutfront said:
I read that, but it did not register. Getting old sucks.

Have you tried running it up to speed without the drive shaft? Get up to speed slowly as no load will be on it at all. This would eliminate the drive shaft back if it is still there.
Click to expand...

This was my next idea....I'll give it a shot.
 
Another thing to check for--if the exhaust pipes touch the frame or body anywhere,that'll transmit a heavy vibration at certain RPM's...
I recently replaced the front pipes on my diesel,and man,with one touching the frame just slightly on the right side,it sounded like I had installed solid steel engine mounts!..I had to heat the pipe up and pry it away to gain 1/2" of clearance..

A van a friend had sounded like it needed a rear end,it had what seemed to be noisy pinion bearings--the ring & pinion looked good,no excess backlash,so he replaced the pinion and diff carrier bearings--and it sounded exactly the same..it was like a high pitched whirring noise with a grinding vibration..

Only other thing he had done to the van was replace the rear leaf springs,and he did remember there was some kind of plastic or teflon "shim" between the spring pads on the axle tubes and the springs..
He decided to go through the agony of taking the u-bolts back off,and installed some new ones from a spring shop--and ta-da,the noise vanished !...
 
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