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Discussion Starter · #1 ·
Please, I am about to go bonkers. I have researched all the past post concerning vibration and I have a long laundry list also of things I have tried. Will provide details if anyone is interested,(want to keep post short).
My vibration comes in at 60 MPH and gets worst with a increase in speed, also seems to be worst when speed is stablizated.
My question is since this feels like what I call a tight vibration, (close frequency) could the pinion bearing be the problem. When I did my frame off a couple years ago I did replace the pinion seal very carefully. However I could have screwed something up. Any and all comments would be very much appreciated. I am grabbing straws now guys.
Thanks for your help in advance.

Jesse Robertson

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Jesse66Original
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I had the same problem. Vibration at 60. I replaced wheels, you name it.

Check the axle faces where the wheel bolts up with a dial indicator gauge to look for run out. I think that some one slammed it against the curb, probably while in a four wheel drift. I remember doing that when I was a kid in my mother's car. Man was I busted! I am looking for a new axle now for my '67. That was the problem. Could be a place to look if you haven't checked them yet.

Chuck

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Chuck Bonasera
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Jesse. This may not be your problem but would not hurt to check. Years ago I had a nova with a 4 speed. I developed a vibration that just about drove me nuts! I was to the point that I was going to change the clutch. When we put it on the hoist, the transmission bolts to the bell housing were loose. Tightened them up and the problem went away!
 

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You could be missing a weight on the driveshaft.

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1970 Chevelle SS396/M20/4.10 My 70 SS396
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1970 Chevelle SS454My 70 SS454
1968 Oldsmobile Cutlass convertible
1982 Oldsmobile Cutlass 350 Olds,TH350(daily driver)
Chris Corwel,TC Member 785
 

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Check the u-joint at the rear. If it is loose in the drive shaft or on the yoke, even a small amount it will do this.

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Discussion Starter · #6 ·
Thank each one of you for your comments, some I have already tried but I am open to any suggestions. I was really hoping that someone out there in T/C could tell me if a incorrect preload/torque on the pinion bearing would give this particular type of vibration/feel. It really reminds me of what a bad/worn u-joint would feel like in the old days when I was young and had a limited cash flow and would drive it forever. It is that kinda quick/fast vib. Hard to explain how it feels, but it is like I should be able to indentify it and cannot not, that's the flustrating part.
Thanks again everyone that responded.

Jesse

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Jesse66Original
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Jesse,

I have one question before I go into a long explanation. Did the problem start after you replaced your CARRIER or your ring and pinion? If they were not replaced, were they out of the car prior to the vibration?

Starting at 60MPH, does the vibration tighten up the faster you go? Is it a Wah-Wah-Wah-Wah sound?

If any of the symptoms fit, let me know. It took me years and a lot of money to finally trace the problem in my car with tons of expert advice.

I can't tell you how many times some EXPERT would tell me, "Your So and So needs to be replaced!" and after spending lots of time and money and the problem was still there, the Experts would say, "Well I would have sworn that was the problem"!

I replaced the exhaust system, (used soft rubber hangers to isolate any vibration) tires, wheels, rear axles, drive shafts, yolks, U-joints, torque converter, internal shafts in my transmission, new ring and pinion, motor mounts. Are you getting the picture?

I was limited to how fast I could go not by horsepower but by how bad the vibrations got. The frequency of the vibrations got so severe at about 80 MPH that the car felt like it was going to explode.

Bottom line! The Moroso Brute Strength series four Carrier had been manufactured out of balance. It was like it had a heavy spot on the outside of the casting.

At slow speeds, you didn't notice it. At about 3000 RPM, it started and got worse with speed.

When I replaced the Moroso unit with a Eaton unit, the problem went away.

I have since been told that sometimes the ring gear can also be manufactured out of balance, or have a heavy spot in it, and can cause similar problems, hence my initial question. If a ring gear has a heavy spot and by chance it is bolted up to a bad carrier where the heavy spots might meet, you've got problems.

Jesse, I'm not saying that this is your problem, but something you might consider.

Please let me know how things turn out.

Argus
 

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The Moroso unit is made by Eaton.Just stating fact.That's pretty interesting..

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1970 Chevelle SS396/M20/4.10 My 70 SS396
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1970 Chevelle SS454My 70 SS454
1968 Oldsmobile Cutlass convertible
1982 Oldsmobile Cutlass 350 Olds,TH350(daily driver)
Chris Corwel,TC Member 785
 

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Discussion Starter · #9 ·
Hello Argus,
Thanks guy for going in such detail about my vib problem, I really appreciate the help.
To answer your questions, when I did the frame off I only pulled the axels to have the wheel bearings replaced, after installing the differental that is when I replaced the pinion seal only. So really the rear end had the least maintenance of anything on the car. I have had the car since new and the entire rear end with the exception of the axel gear thrust washers, wheel bearings/seals,pinion seal, has 143,000 miles on it and when I was younger I dumped the clutch from a dead stop many many times. Yes you are correct the so called EXPERTS are slowly breaking me. Yes you were much deeper into the replacement process than I am. I am also limited as to how fast I can go by the vibration, anything over 60 mph I feel like it is not healthy for my car due to the increase in vibs. I really do not know what to do next. I do not have the experience to determine if the rear end is just tired and causing all this.
Once again thanks ever so much for sharing your experience with vibration.

Jesse

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Jesse66Original
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Have you thought about the rear extension bushing in your tranny? My Muncies' bushing was bad and I had the same vibration you have, just an idea.
 

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Jesse.

Do me a favor and e-mail me if you resolve this problem. I am having the same problem on my 71 Elco. My top speed is 60 mph, at that point it feels as if I am leaving parts behind..

Thanks
[email protected]

Tim
 

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Jesse. I just did a search, and there is LOTS of information there for you to go through. One in peticular that caught my eye was one started by "pony breaker" his problem seems very simular to yours.Give it a try.
 

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And the drive shaft. Most shops cant balance these thigns past 2500 rpm, so when you start spinning it at 3000, a vibration could defintely start. Why dont you call Denny at www.dennysdriveshaft.com , tell him I sent ya and ask the pro your pinion question.

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Jesse,

I gave your problem some more thought. If I understand your post your problem started after you replaced the pinion seal and rear axle bearings.

If you didn't center the rear u-joint in the pinion yoke this could cause a bad vibration.
I had this happen to a Chevy truck many years ago. There was just enough wear in the yoke that the u-joint could move off center maybe .025. It was enough that it really
vibrated bad if you were not paying attention, and got it off center, when you tightened things down. (1) are the u-joints centered in the yokes? (2)Is there any chance that you you could have a bent axle? Could you or someone else have hit a curb or pothole right after your restoration? Bent axles will do it too!

I know how I hated the fact that it took me years to find and eliminate my vibration problem. If by process of elimination we can help you find yours, GREAT!

Just a few more questions. (3)Did you have any vibration problems prior to your restoration? (4)Did the vibrations start immediately after the restoration? (5)Did they start small and become more intense as time progressed?

Here is something to try that will help figure which end of the car the vibrations are coming from.

Jack up the rear of your car and put the axle tubes on jack stands. Put the car in first gear and slowly bring RPM's up to the speed where the vibration starts when you're on the road. Go beyond that speed by about 1000 RPM's and hold it. (6)Is the vibration present? Now pull the stick into neutral. (7)Is the vibration still there as the RPM's spool down?

OK now, you have seven questions to answer.

When you can reply to these, we will move on from there.

Argus
 

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Jesse,

I think Argus is on the right track. I had a Camaro with a 12 bolt. I changed the pinion seal as you have done. That thing vibrated so bad, you could barely stay in the car. I replaced everything from the front to the rear, U joints, drive shafts, motor mounts, trans mount, trans tail shafts, axles, you name it. I never got into the rear end, but I think that is where the prob is. The pinion yolk had some wear, I changed it, but the vibration stayed. However, something had to cause that wear. It looked as though the u-joint wallowed out the yolk. By taking the pinion nut off to replace the seal, you can take the preload off of the pinion. I would suggest servicing the differential. New carrier bearings and pinion bearings will most likely fix the prob. Check the yolk also, since you have a vibrations, you may have damage to this as well.

Good luck and let us know what you find.

David
 

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Discussion Starter · #17 ·
You guys have been great with all the good responses. Thanks to all. Argus I will try to answer your questions, I have had the car since new and it was a daily driver until I placed it on 4 jack stands in 1986. At that time I cannot recall it vibrating, it was a long time ago. I started a frame off in Nov of 1998 and finished in May of 2000. Since there had been very heavy maintenance complied with I was satisfied to get it to where it would drive down the road. Then I only drove mostly to car shows with other cars so I never noticed the vibration until late this summer. Here is what the sequence of events that have all been down hill so far. My original intent was to repace the tail shaft housing bushing and front slip yoke, the guy at the drive line shop told me to bring my shaft in so he could check it out. Well he said it was bent and ask if he could apply heat to it. He did so and installed two new u-joints and a new slip joint. I installed it and the car vibrated worst than ever. I then had a new shaft made at another shop with new joints and used the same slip joint. It vibrated about same, I then rotated the shaft 180 drgrees and still no change. Had the tires and wheels checked, had the Muncie M-20 gone through completely,
went into the rear end and changed axil thrust washers, did find the spider and axil gears worn but could not find new GM gears, installed old ones, replaced all exhaust system hangers, had tires and wheels checked again at a different place on a Hunter 9700 machine(simulates road conditions), the machine rejected atire and wheel, replaced them and no change, had a friend drive it while I road in the trunk (like the drive in movie days) and it does shake like hell, I do not know what that proved. So I do not for sure know when all this started, I only noticed it in August this year. The rear joint fits very snug in the pinion yoke. The car has been run on four jack stands on three ocassions, rear tires on, tires off, drums on, drums off, at 2800 RPM it still shakes the same. On numerous road test say running at 70, car shaking, kick it out of gear, shut the motor off and it still shakes down to about 50 mph or so. I believe I have beat this subject to death and I am sorry folks. But with everyones help from T/C I shall find it someday. If I was sure the pinion bearing or something else in the rear end was the problem I would go there but I am just not sure about that. Once again thanks to all of you for the great responses.

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well jesse that was a very informative post,it about narrows your choice down to the rearend,i read it twice and that is what it points too and only one way to find out even though i know you don't want too but it sounds like you need to pull the rearend apart and go through it. it's about all that is left. you will probably find the pinion bearings bad or the gears not meshing correctly. well let us know what happens.JIMK
 

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Jesse,

After reviewing your post and giving this my best SWAG (Scientific Wild A** Guess) I would say that you have a problem within the rear end.

My recommendation would be to make an appointment with a shop that specializes in rear end work and have them go through the entire thing. Find a shop that does bench work where they will work on the rear end on the bench not in the car. Now is the time to decide whether you want to change your gear ratio or buy a different carrier or axles. After 140,000 miles of hard usage you could say that you are due.

Eaton makes a great Carrier and if you can find OEM gears for the thing GREAT.

This will not be a $1.98 repair, of this I'm sure you realize. Bite the bullet and have it done right the first time and cry but once.

Understand this is just MY opinion, I could be wrong, but worse case scenario you will end up with a great rear end.

Best of luck,

Argus
 

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like argus said a shop would be best and biggearhead is pretty close to you in ky. he really seems to know his stuff so when i am ready i am transporting mine to ky. for a pro job. if you find his profile you can e-mail him and he will be willing to help i'm sure.JIMK
 
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