spokewrench

I was just wondering if it is normal for a c-3 to vibrate somewhat more than
a more modern vehicle? I have replaced or rebuilt: driveshaft (balanced),halfshafts,all u-joints, new motor and mounts, new trans mount,
all new front end parts including wheel bearings, new rear wheel bearings, shocks,etc. and I still notice a vibration when cruising down the highway @
about 70 mph and 3000 rpms it seems to get worse when I step on the gas
and accelerate,but then once the speed is reached goes away again. I mean its
not real bad but more noticable than say my 1987 F-250 4x4 at the same speeds. Could it be I did'nt replace the harmonic balancer? do they go bad?
Maybe vettes are just a little more prone to vibration? Any comments would as always be appreciated, It was almost 60 degrees in N.J. today WAHOOO!
SPOKE_

JohnS_77

Have you checked your alignment? That might be causing it.

spokewrench

aligned front and rear.

Flareside

I don't think your C3 will ever feel as tight as a modern car. Assembly and construction techniques have come a long way in 30 years! My car drives pretty well on the highway, but it's certainly not as smooth as my new car or truck. Never will be...

dman535

My 12 year old BMW is much more confident at speed than my 77 Corvette is. Even with the addition of a 700r4 and the lowering of the engine rpms on the freeway its still a sensory stimulating ride. Not sure that I would want to see the 140mph mark in the Corvette.

PRNDL

Didnt get out today. I will try tomorrow and get back to you! I was surprised to find my vette feels steadier at 85 than it does at 60. Dont know if I would call it a vibration. The worst on-road experience is I78 westbound around Berkely Heights. The ruts in the road are so bad the vette is hard to keep in lane. Barely noticeable in the family car. MJ

TJRed76

I was setting my valves last night and could not get them right. I couldn't figure out why I could not find TDC.

I got to looking at my harmonic balancer and realized that the guy that owned the car before me had put the wrong one on. He had a magic marker line about 1/4 of a turn off from the factory mark.

I'm hoping that replacing it with a correct one will take care of my vibration.

Could it be that yours is not original also?

spokewrench

Thanks guys I'm starting to realize this is a 30 year old car and technology and even with all new parts its still 30 year old technology! MnJack I noticed
it feels much better above 80 mph as well, the worst vibration occurs around
68-75 mph. I thought it was wheel balancing but I had the wheels balanced
with that new technology that actually rotates the tire on the rim too match
the two together, and it still was the same!

Wrecked82

Berkely Heights! I use to live there - 1975 to 1978. Then I came back to TEXAS!

TedH

I would suggest a bent aluminum wheel. I was on a rear wheel dyno with my '80 L48 and the tuner mentioned that my left rear tire was clearly bent. Would cause a vibe/wobbling feeling at highway speeds; not noticable around town.

I've had that problem for several years at highway speeds and always appeared to come from left rear. Now I have to be able to afford a replacement...


[Modified by TedH, 5:57 PM 2/8/2002]

Steve Grodin

To say that the front & rear have been aligned and the tires balanced doesn't rule those out. It all depends on whether the folks working in those shops know what they are doing. My '74 doesn't have any vibration, but I've only had it up to 130 mph.

jimduchek

Harmonic balancers do go bad. Put the car in neutral when it's vibrating (or push in the clutch) at speed to take the engine out of the equation. If it is still vibrating, the problem is in your drivetrain. If it quits, the problem is the engine.

The usual bits to check are:
U-joints
alignment
wheel balance

The less usual bits to check are:
drive/half shaft balance
wheel bearings
Alignment of engine/tranny together
Alignment of engine/tranny to differential (this is hard to test and hard to fix and usually designates a bent frame.. When the driveshaft is spinning fast, it wants to be as straight as possible, and if the tranny tailshaft doesn't point EXACTLY at the front yoke of the diff, you'll get vibrations. To test, drop an empty block bolted to an empty tranny case into your car, and run a string from the front of the engine, through the block and tranny to the center of the diff yoke. If the string doesn't come out exactly in the center of the tailshaft opening, you have problems.)

Also, do you have wider wheels than stock? High speeds and very wide tires makes things more difficult and makes balancing not as good as it could be. (remember, a tire could possibly be heavier towards one sidewall than it is towards the other, a balance just balances it along the circumference but not through the width as well)... wider wheels definitely contribute to tracking along ruts in the road.

My $0.02.

Jim

Wrencher

Mine gets a little "buzzy" over 4000 rpm, but I just atribute it to a less than perfect balance job. Suspension wise, it's fine.

Hans

1971 454

My 71 runs very smooth on the highway. It is almost compariable to my 97 Audi A4 (as long as the higway is smooth)! My biggest complaints are the squeaks and rattles when driving around town. Jim's comment about pushing in the clutch at speed is definetly a good first step.

bn7035

My 81 with 52,000 miles has no vibrations. At highway speeds there is no vibrations at all. I do have road noise and quited it down some by insulating the floor boards. If alignment was properly done, I would check rims and tires. Occassionally you can get a bad tire. With any older vehicle getting it to drive like new can be very difficult if not impossible at times. Thats one reason I love my C-3. I'll never finish working on it and for the money I could have bought a Z06. :crazy:

corvettemaster

My '81 doesn't vibrate at highway speeds neither. My biggest complaint was mentioned above, the rattling while driving through town. But I just think that might be the t-top locks, or a loose trim piece. :confused:

BubbaJJ

My 75 does the exact same thing. It vibrates at about 70 then smoothes out. I think I have a tire balance problem or I have U-joints or wheel bearing problems.

Chuck Gongloff

I "chased" a similar problem a few years ago, and it turned out to be a bent rallye wheel. Could also be a tire with a shifted belt, etc. Check the front suspension, ball joints, tie rod ends, idler arm, bushings, etc. Just got done rebuilding the front end of the 69 this winter. I had a little shimmy at about 60 MPH. That's now gone with new front end parts. Both my 63, and now the 69 are solid as a rock at any highway speed. I took a few test "blasts" up to about 100MPH with the 69 and it's great. Chuck

mrvette

I hate to tell you guys, but in fact my 30 year old shark is stable as a rock at 130+ mph....and no vibrations....
now having said that I notice one thing was overlooked......it's bugged me a bit from time to time...the exhause pipes going through the frame near tranny...they rub the frame a lot....any engine vibration will shake hell out of the frame....and you notice it right under your butt.....
not to mention in the shifter...

of course a slipped harmonica balancer will toss engine balance off, notice the balancing holes in the outer fly weight.....

other than that, the obvious has/have been mentioned allready...driveshafts....
and wheels/tires///true and balanced.....
seen lumpy tires??? sometimes tire shops try to palm that off as normal...
bullpoopie....tires are supposed to be round, not friggin square like some morons try to claim....


I would not short the capabilities of an old shark in good shape just for being a 30 year old design...it's modern enough to keep up without splitting too many hairs....

GENE

Larry B.

I have found, over the years, that vibrations that seem to be difficult to find usually ends up being tire balance. Computer balancers are only an aid for the shop to get you in and out fast. Most machines only balance at 55-60 mph and not too good at that. If you have someone in your area that does "on car balancing " you should take you car there. You will never be happy with computer balancing again. Of course this takes a skilled person and computer balancing can be done by a trainee. I have never been happy with a computer balance. One car that I put new tires I took back three times after a short test drive and each ime they put a different amount of weights in a different place resulting of course in vibration at different speeds. The last time I complained about vibration at 66mph . When the manager(some kid about 22) said " hey, the speed limit is 55" I aksed for a refund and took the car acroos town, had the new tires balanced on the car for $16 each. PERFECT at any speed. :D


[Modified by silvervetteman, 5:27 AM 2/9/2002]