Vibrations

[Ronw435]

Well was hoping to get some input on what the vibrations on my truck could be. I have a vibration that is pretty much constant unless your doing about 70. And even then I can still feel some. I have replaced the tires, one bent wheel, new u-joints, new trailing arm bushings, axles are straight. Drive shaft still has the weight on it but im not saying that it could still not be that. The Mucnie 318 trans does whine quite a bit, especially in first and even has a little whine in third. My truck is a 65 with 283 tot. When in neutral and sitting still I get no vibrations from the engine at all even if I let the clutch out in neutral. Engine runs great and has about 450 miles on it. Clutch, pressure plate, and tob at also new. I can feel it in my seat and also on the steering but not as if there is something going on in the suspension. All new tie rod ends and pitman arm. Truck runs very straight down the road.

I guess my question is could the bearings in the transmission be bad enough to cause a vibration? I think I might as well get the drive shaft re-balanced as it is the cheapest of the options. Trans rebuild is about 560.00 as long as everything inside is keepable!!


Thanks for any input.

Ron

[Arekusu]

Hi Ron -

Since I'm on a roll with replying today, I thought I'd try for some input with your situation as well.

I think you're on the right track with the driveshaft re-balance, if anything it's usually a cheap job and one less thing to worry about later.

I'm assuming you verified everything was tight on the suspension? From the A- arm nuts on the top and u clamps on the bottom, pitman, and idler arm, transmission mounts at the bell housing? Are your trailing arm or panhard bar bushings kaput?

Are the engine mounts shot or loose?

Is this a constant vibration the gets more refined and diminishes at speed? Or do you get more of a sine wave of vibration throughout the truck until 70 mph?

These are hard to diagnose over the internet. I personally would go through the truck one time and ensure all suspension nuts and bolts are tight; as well as checking all the suspension rubbers / mounts for wear and denigration. In my experience vibration is usually due to something being out of alignment or loose, but you said all your wheels were balanced , drive shaft may need a re-balance. Drive-shaft for me always got worse / vibrated more the faster I spin it; suspension bushings complaining at me seem to have a slow pulse vibration / sign wave until a certain speed that it just nulls itself out.. transmission bearings I'm not familiar with on vibration.

On to the topic of the 4 speed... ya that could be it as well. $500.00 for a rebuild to me sounds like parts only, labor cost not included (unless you know a guy or are doing the work yourself). I'm thinking more like 800.00-1000.00 for a rebuild and that's you dropping the transmission and bringing it to them. At that price point I'd start looking into a world class T-5 transmission with the S-10 tail housing adapted to it. I don't think the main shaft needs to be changed, but check out some of the treads on here for more info. I did that swap first after I first got my truck and it was nice until I wanted more power, swapped in a 350, and blew up the NON world class S-10 5-speed.

Good luck with the vibration chasing, let us know what you find.

Alex

[sawman]

just adding more to look for,when your driving if you let off the throttle or put in n does vib slow down or stop?,did you check ujoints?,most vibrations are from mounts loose or wore,ujoints,bolts loose bell housing/transmission,tires not balanced,bearings,check the easy stuff first,

[Keith Seymore]

Originally Posted by Arekusu

These are hard to diagnose over the internet.

Alex

This is true. That's why I usually try not to get involved even though I fixed vibration problems for GM for many years.

Having said that, the trick is all about "divide and conquer". If you can separate between engine related symptoms vs vehicle speed related symptoms, and driveline vs tire/wheel, etc. then you can know for sure what it is NOT so you can focus without distraction on what it might be.

If you can follow this thought process you can fix anything:











Memorize these; internalize them, love them - you'll be glad you did.

K

[Ronw435]

GREAT INFORMATION!

Thanks a lot for the charts.

Ron

[Ronw435]

I have checked all the things that you guys have said. I took the truck completely apart and put it back together. I replaced the things that were bad and left the others alone. I dont get any movement what so ever out of the front end. New motor and bell housing mounts. When you let off the throttle and put it in n it doesnt change.
The Muncie 318 is a 3 speed with short tail shaft. I did replace all the mounts and bushings. I am hoping that balancing the drive shaft will help.

Thanks for the info guys I really do appreciate it.

Ron

[sawman]

did you check to see if shaft going into rear end gets warm or has movement,wheel bearings,i once hasa problem like this could not find the problem forever,had the tires balanced problem was front tire came apart on inside,drive it awhile the get out check everything by hand see if any spots are warmer than others,feel front hub/rear/ujoints

[BR3W CITY]

^there is some good wisdom in that. I've found that a laser spot-thermometer (cheap) or an infrared camera (expensive) is an easy way to find the problem. Lets face it, the MAIN cause of failure in ANY device is heat (doesn't matter if its mechanical, electrical, computational electronics, fluid, thermodynamic etc etc etc).

If you find that after a short drive, your rear end or bearings are disproportionately hot, then you have a target area to aim for first in troubleshooting.

I didn't see in your response if you had addressed how it changed at speed. So your vibration goes away at 70, but is constant when it does occur? To me that almost indicates something like a wheel having a separated lug or a band that is debonding from the tire.

[Ronw435]

I will check the shaft, which I am assuming were talking about the drive shaft. I am going to put it on jack stands today and run and see what I can see. I will check the before and after temp on the drive shaft. I replaced the tires this week. I also replaced both u-joints. The rear end was supposed to of been rebuilt when the PO put 3.08 gears in it. I dont hear any noise coming from the rear. The vibration seems to start around 40 and gets better but does not go away at 70. I am going to check the temps today.
Thanks for the replys.
ron

[patrickk1]

Are your driveshaft u-joints in phase? Sometime people put them back together incorrectly. This would cause vibrations.

[Ronw435]

I am having the drive-shaft balanced and lengthened today so I would hope they put it in phase. When I took it to the shop they said that the input yoke was not going in the transmission far enough which would let it wobble, especially if it is out of balance also. Upon inspection of it out it looked like the three stooges welded it up. Instead of a nice flowing weld it had about ten spots where they stopped and started. I think it might of been Curly that did it but I wouldn't swear by that........ So hopefully I have found my source of vibration. I just hope the rear tranny bushing is not toast. Was going to rebuild the tranny next so we will see how it is after the lengthening and balancing.

Thanks everyone for the input. Will follow up after I get it back in.

Ron

[BR3W CITY]

Originally Posted by Ronw435

the input yoke was not going in the transmission far enough which would let it wobble, especially if it is out of balance also.

Instead of a nice flowing weld it had about ten spots where they stopped and started.

I can believe that. When I did air ride setups on s10 and cars running 2peice driveshafts, you'd chase vibrations all over depending on if the custom was running the truck aired up or down at at the time.

Starting and stopping a weld isnt' the end of the world as long as those points were fully penetrated, but the concern is obviously that there are multiple points which the extra material would have to be balanced against.

Most of the custom DS's I've had made always have the balancing weight on the side opposite of the weldment (for shafts welded on a rotating fixture), or two places if welded static (one pass for each hemisphere).

[Ronw435]

Well all is right with the world. Replaced the transmission and had drive shaft balanced. Vibration is gone. And transmission is a lot quieter now.Thanks to all who gave their input as it was greatly appreciated.

Thanks again
Ron

[Keith Seymore]

Well done -

K

[Ronw435]

Yeah the nice thing about it all is that I had been looking all over for the short shaft transmission. I could find long shafts but not the original short shaft for the truck. I have been driving by a house that had a 65 Chevy sitting and thought "what the heck I will ask if maybe they were going to put an automatic in it". Stopped and he said I have several transmissions in the garage. Low and behold there was one connected to a 292 six. Said what would you take for it and he said make an offer. I said how about 100.00. And he said SOLD. Put in in the truck and it is great except for the fact that there is something wrong with the speedo gear as i no longer have a speedometer. But I have been driving with a GPS for speed as the original speedo was off by about 12 miles an hour. I am going to try and see inside to see if the gear has maybe slipped back enough to not allow the gear to engage. Either way no more vibration!!!!!!!

[Ronw435]

Well took the truck on a 200 mile trip. I am still getting a pulsing vibration that is most pronounced at about 60. You can feel it in your seat as well as the steering wheel. It is not constant but is about a 2 second pulse then 2 second off then 2 second on.....etc.
Any ideas?

[cg285]

. alignment never causes a vibration
. worn suspension components don't cause vibration
. vibration from a transmission is not likely (converter/clutch issues are engine related and go away when in neutral at speed)
. verify if it is truly a rotating vibration vs something like a bad mount where there is no isolation from the frame/crossmembers

makeup a fixed pointer and position it by each wheel, rotate the wheel and check for run out at the bead (not the edge of the wheel). shouldn't have more than about .060 +-. if you do take the wheel off and check the axle the same way and verify axle or wheel.

if it were i, i would support it on 4 jack stands and mimic the action while feeling for the vibration but do not try that at home. that method would be only for trained professionals on a closed course.

[Ronw435]

I was wondering if my exhaust pipes could be transferring the vibrations from the engine. The engine seems to be running fine, but the rubber in the mounts for the exhaust system seem pretty hard. Its a 2" stainless system with two glass packs. Was thinking of removing the mounts and get some that hang with the heavy strap. The ones I have not are welded to the exhaust with a rod going through the rubber that is bolted to the frame.

[Keith Seymore]

Originally Posted by Ronw435

Well took the truck on a 200 mile trip. I am still getting a pulsing vibration that is most pronounced at about 60. You can feel it in your seat as well as the steering wheel. It is not constant but is about a 2 second pulse then 2 second off then 2 second on.....etc.
Any ideas?

Go back to the chart and start over.

Also (discussion regarding "oscillating" disturbances):

Originally Posted by Keith Seymore

In the biz, a "pulsating vibe" is called a "boom/beat".

It results from two disturbances, very close in frequency but slightly out of phase, such that the amplitudes gradually add and subtract over time. That's what results in the pulsating effect. The closer the two frequencies are the slower the boom/beat.

At any rate - it means you have two disturbances going on, like 4th order engine firing being very close to second order driveline, for example.

Fix either one of the disturbances (or dramatically change the frequency of one) and the pulsating effect will go away.

Originally Posted by Keith Seymore

Driveline imbalance is a "first order" of propshaft rotation disturbance (one "kick" per rev). U joints are a "second order" of shaft rotation (two "kicks" per rev).

Imbalance by itself usually results in a cabin "boom" (low frequency sound; almost more like a pressure that you sense) or a vibration that you feel, and normally is pretty steady. Large cabin volumes, like a crew or a Suburban, definitely are more sensitive to this. The boom/beat, or the phasing in-and-out, is a result of the driveline finding some other disturbance that is close to it in frequency.

[BR3W CITY]

Exhausts can transfer vibration, but usually when the are hard mounted. Only on big-motor stuff has the exhaust really transfered anything through to the cab/frame in my experience...and most of those also had hard motor mounts etc, making everything a bit amplified.

Now with that said, I have had bad exhaust mounts allow just enough play that the exhaust goes bouncing all over the place within the mount. It makes kind of a clattering noise like folding up a ladder everytime you hit a bump or the frame moves a bit.

[Mackie]

As "Fate" would have it you're likely not in an area with hills but I isolate engine related noise/vibration from chassis/running gear issues by getting up to speed on a downhill then pop it in neutral to let the engine fall to idle while maintaining road speed . Condition goes away it's engine ( or in your case exhaust) related.

[Ronw435]

Yes Mackie I did just that, I have pushed the clutch in to let the engine idle at 65 and it is still present. I wish there was someone near me that had the same bolt pattern and would allow me to try there wheels to see if it is coming from the wheels. Although that is a lot of work.......lol. Going to keep driving her to see if it gets worse.

[cg285]

another thought. has your driveshaft angle been changed somewhere down the line?

[patrickk1]

Originally Posted by cg285

another thought. has your driveshaft angle been changed somewhere down the line?

This! Have you checked the driveshaft & pinion angle? I would have checked that before replacing anything.

[Mackie]

OK Ron, you can rule out exhaust or engine issues. I'm chasing a slight but annoying vibration also and I'm about to try a cheap driveshaft test/fix that uses hose clamps.

http://www.demandaam.com/technical-s...haft-balancing

Other methods involve running the vehicle while on a lift or stands to eliminate the trial and error road tests. Then hold chalk close to the spinning shaft to get a witness mark for the heavy spot and put the screw part of the clamp 180* off.

Use this method as a temp. or permanent fix or just as a test to identify the source of the vib. then have the shaft balanced at a specialty shop.