Been fighting this for quite awhile and just can't seem to find the cause. My car used to vibrate bad at the 1000ft (feels like I broke a lifter) then clears right up. I cannot see this on the grid data logs so its not ignition related or engine for that matter. (It would show a flat spot or dip on the graph correct?)

We started running 1/8 only and the problem seemed to go away. Last year I switched from 29x10 to 28x10 slicks and the problem has come back around the 580-600 ft mark. Burnout and low gear, the car is perfect but once it shifts into high gear and gets out towards the stripe, it will vibrate for a split second. This is around 6400. I shift at 7000 and go thru around 6600-6700.
Here is the list of what I've done so far:

-checked wheels, tires and even pulled axles
-re-balanced slicks (then mounted new ones with no change)
-re-balanced front tires (spun balanced and checked a couple weeks in a row)
-checked over all the hiem joints in ladder bars
-made sure shocks weren't leaking
-checked pinion angle, re-scaled it and alignment
-new ball joints
-new u-joints (then had a new driveshaft made)
-even changed convetor

I did a bunch of work to the car over the winter and have only had time for a couple times runs so far this year. It was way worse than ever before. Only thing I can find is I can move the yoke up and down slightly with my hands in the back of the trans. I'm running a Reid PG case with roller tail shaft housing. We originally sanded the yoke down to fit the bearing (.002-.003 removed if I recall) and the yoke looks the same as it did but seems really sloppy now. I ordered a new roller bearing and hardened trans yoke this week hoping this may fix the problem.

Any ideas what else I can look for?

I picked up a vibration a few weeks ago. Somehow I knocked the bearing out of the tail shaft on the trans. Replaced it, now my vibration is gone.

Hopefully your new tail shaft will solve the problem.

Sounds like some rotating part is bent. Wheel, yoke, axle, etc.

Try putting the car up on stands and running the driveline in low gear with someone else in the drivers seat. Don't get under it but inspect everything that's turning to look for runout. I had a similar problem once and that's how I found it. Mine turned out to be a slightly bent driveshaft due to a very small dent.

Based on the vibration moving sooner in the run after the gear change, I'd be looking between the tailshaft and pinion gear. Was the driveshaft balanced to the rpm it's turning? What is driveshaft diameter?

Check your driveshaft for a lost weight. At very least have it rebalance for proper operation.

Hope the new roller bearing and yoke will cure the problem.

I'll go along with yoke, driveshaft or u-joint problem. Is the yoke engaged far enough or possibly too far in?

I'm always diagnosing vibrations in heavy trucks. Ride height (pinion angles), tire balance, something in the engine all vibrate differently. Majority of the time, I can say what's causing the vibration after going for a road test just by how it feels and what part of the vehicle I feel the vibration in.

I was told by a Navistar dealer to try a phone app called VibSensor so I'm not promoting it but it's an app that the dealers are told to use. I haven't been able to try it yet but based on the type of vibration, it may help pinpoint the source.

VibSensor is the first choice when searching in the play store. Sorry, I have no idea if it's available to apple products.

I had the old driveshaft re-balanced but it didn't help. I am not using stock stuff, they are 3" made by a local driveshaft company that everyone in the area uses.

I had new u-joints installed and no help.

Had a new driveshaft made last year, a little longer (don't remember the exact number) because I went from leaf springs to ladder bars and evidently moved the rear back a little and didn't notice. I'm thinking the old one being too short may have hurt the bearing.

Parts should be in this week. I'll find out over the weekend if it fixed.

A friend of mine, Gary Ellison developed a sound identification device to locate driveline/suspension noise. The device consisted on a small box that had wires leading to 9 sound sensors. Each numbered sensor was then placed at various points on the car and each wire/sensor was then numerically identified on the control box. With the sensors in place and the box inside the car you could drive the vehicle and by changing channels on the box identify where the sound originated. The device was incredibly effective in determining where the sound originated.

I believe that he patented the device but never manufactured duplicate units due to being severely injured in a car jacking incident.

Bob

check the gears set in trans.I had one do what yours is doing and found 1 tooth with a chip broke out.fixed it and vib went away.

Update:

New bearing and seal were installed in the tailshaft last week. I also installed the new hardened Strange yoke and front u joint.

The vibration hasn't gone away and just keeps getting worse and worse the more I run it.

-Buying new front and rear tires

-Pulling the trans to go thru it and send the converter out to be checked.

-Pulling axles and R&P to check all the bearings in the rear.

If that doesn't fix it, I don't know what else to look for.

Engine is fixing to fly apart?

Checked the filter after Fridays race, everything looks perfect there. Oil pressure yesterday was good, 35 at idle and 70+ going down track.

Went through the valves Sunday morning too.

Tom,when you changed convertors did you eyeball the flywheel for cracks at the bolts? Or missing weight if externally balanced?

quote:

Originally posted by Cashflow:
Engine is fixing to fly apart?

I wasn't going to post this, but I had a vibration exactly like this in an S10 I had a couple of years ago. And that is exactly what happened to it.

quote:

Originally posted by deadon1578:
Tom,when you changed convertors did you eyeball the flywheel for cracks at the bolts? Or missing weight if externally balanced?

Thanks for the input, I will inspect the flex plate tonight once the trans is out.

quote:

Originally posted by SuperProRacer:

quote:

Originally posted by SuperProRacer:

quote:

Originally posted by Cashflow:
Engine is fixing to fly apart?

I wasn't going to post this, but I fought a vibration exactly like this in an S10 I had a couple of years ago. No idea if it had anything to do with the vibration, but that is exactly what happened to it.

I hope not, no leaks and good oil pressure. It is a stock GM 350 block and its going way faster than I ever intended it to go. Dam thing went a 6.39 in the heat Sunday.

quote:

Originally posted by Tom Reyer:
Update:

New bearing and seal were installed in the tailshaft last week. I also installed the new hardened Strange yoke and front u joint.

The vibration hasn't gone away and just keeps getting worse and worse the more I run it.

-Buying new front and rear tires

-Pulling the trans to go thru it and send the converter out to be checked.

-Pulling axles and R&P to check all the bearings in the rear.

If that doesn't fix it, I don't know what else to look for.

Not going to help, but I have had bad luck with that roller tailshaft stuff.

Seems the bearing would somehow "c0ck" in the housing, would eat-away at the slip yoke. Yes, it vibrated going down track and got worse at higher speeds. I was running the correct slip yoke which is not cheap, and has a special coating on it they DO NOT remove!

Anyway, I got sick and tired of new tailshafts and slip yokes every 500-600 passes. Went back to a normal tailshaft and slip yoke, never had a problem after that.

If you actually did get the old roller bearing out and replaced it, you're the man! I couldn't do it, Trans Specialties couldn't do it. Still have two of them around here somewhere as reminders why NOT to use them!

Tom, I had the somewhat the same thing in a sbc a month ago. starts fine, runs great, good oil pressure, but vibrates like crazy 5000-5200. Above or below that smooth as can be. I developed a small rear main oil leak and when I went to fix it I found I had knocked out the thrust bearing and had .015-.020 crank end play. Might check that if you havent already
good luck
Scott Horsley