C4 Vibration

My 94 convertable starts to vibrate around 65 mph.

Feels like it is in the back of the car. Can feel it through the gear
shift, so could it be drive shaft? Car is just at 100K.

Recently acquired the car, first vette, so no history on the car and not
sure where to start looking.

Is this a common problem, or do I just go through the check the tire
balance, rim straightness, etc. routine?

Everything feels tight. No clunking on acceleration or deceleration, so at
this point I don't suspect U-joints.

Ideas anyone?

Thanks!

Alex

Alex wrote:
> My 94 convertable starts to vibrate around 65 mph.
>
> Feels like it is in the back of the car. Can feel it through the gear
> shift, so could it be drive shaft? Car is just at 100K.
>
> Recently acquired the car, first vette, so no history on the car and not
> sure where to start looking.
>
> Is this a common problem, or do I just go through the check the tire
> balance, rim straightness, etc. routine?
>
> Everything feels tight. No clunking on acceleration or deceleration, so at
> this point I don't suspect U-joints.
>
> Ideas anyone?
>
> Thanks!
>
> Alex

Welcome and enjoy!

Sixty-five is a typical speed for a C4 tire
balance problem to raise its ugly face.

You 'to-do' list looks good. Add the following:

Assuming you have the orginal factory wheels,
check to see if some well-meaning grease
monkey rotated wheels front to rear.

The original tire sizes were 255/45 on the
front and 285/40 on the rear.
--
pj

"PJ" > wrote in message ...
> Alex wrote:
>> My 94 convertable starts to vibrate around 65 mph.
>>
>> Feels like it is in the back of the car. Can feel it through the gear
>> shift, so could it be drive shaft? Car is just at 100K.
>>
>> Recently acquired the car, first vette, so no history on the car and not
>> sure where to start looking.
>>
>> Is this a common problem, or do I just go through the check the tire
>> balance, rim straightness, etc. routine?
>>
>> Everything feels tight. No clunking on acceleration or deceleration, so
>> at
>> this point I don't suspect U-joints.
>>
>> Ideas anyone?
>>
>> Thanks!
>>
>> Alex
>
> Welcome and enjoy!
>
> Sixty-five is a typical speed for a C4 tire balance problem to raise its
> ugly face.
>
> You 'to-do' list looks good. Add the following:
>
> Assuming you have the orginal factory wheels, check to see if some
> well-meaning grease monkey rotated wheels front to rear.
>
> The original tire sizes were 255/45 on the front and 285/40 on the rear.
> --
> pj

if you have option z07, the tires are the same size front to back.

regards,
charlie

"charlie" > wrote in message
...
>
> "PJ" > wrote in message
> ...
>> Alex wrote:
>>> My 94 convertable starts to vibrate around 65 mph.
>>>
>>> Feels like it is in the back of the car. Can feel it through the
>>> gear
>>> shift, so could it be drive shaft? Car is just at 100K.
>>>
>>> Recently acquired the car, first vette, so no history on the car
>>> and not
>>> sure where to start looking.
>>>
>>> Is this a common problem, or do I just go through the check the
>>> tire
>>> balance, rim straightness, etc. routine?
>>>
>>> Everything feels tight. No clunking on acceleration or
>>> deceleration, so at
>>> this point I don't suspect U-joints.
>>>
>>> Ideas anyone?
>>>
>>> Thanks!
>>>
>>> Alex
>>
>> Welcome and enjoy!
>>
>> Sixty-five is a typical speed for a C4 tire balance problem to
>> raise its ugly face.
>>
>> You 'to-do' list looks good. Add the following:
>>
>> Assuming you have the orginal factory wheels, check to see if some
>> well-meaning grease monkey rotated wheels front to rear.
>>
>> The original tire sizes were 255/45 on the front and 285/40 on the
>> rear.
>> --
>> pj
>
> if you have option z07, the tires are the same size front to back.
>
> regards,
> charlie
I thought they started to vibrate when you put them in gear? May be
why they were called "Shakers" in days gone by. ;-)

On Sep 16, 9:21 pm, "Alex" > wrote:
> My 94 convertable starts to vibrate around 65 mph.
>
> Feels like it is in the back of the car. Can feel it through the gear
> shift, so could it be drive shaft? Car is just at 100K.
>

Sounds like tire balance, but, 100k is about right for u-joints to go
out. It happened to my '91 and the symptoms were vibration at high
speed, squeaking at low speed, and a weird wandering feel from the
back end. There was no clunking.

Like PJ said, clean the inside of the rims first.

Alex wrote:

>My 94 convertable starts to vibrate around 65 mph.
>
>Feels like it is in the back of the car. Can feel it through the gear
>shift, so could it be drive shaft? Car is just at 100K.
>
>Recently acquired the car, first vette, so no history on the car and not
>sure where to start looking.
>
>Is this a common problem, or do I just go through the check the tire
>balance, rim straightness, etc. routine?
>
>Everything feels tight. No clunking on acceleration or deceleration, so at
>this point I don't suspect U-joints.
>
>Ideas anyone?
>
>Thanks!
>
>Alex
>
>
Low aspect ratio tires are very prone to a sensitive balance.
Clean the rims inside, and have a tire place check the runout of the
tire/wheel combo.
U-joint "could" be the problem, but generally you will also have the
clunking, & noise symptoms also.
But 100K is around the time frame generally for u-joints to start
showing wear symptoms.

--
Ric Seyler
Online Racing: RicSeyler
GPL Handicap 6.35

http://www.pcola.gulf.net/~ricseyler
remove –SPAM- from email address
--------------------------------------
"Homer no function beer well without."
- H.J. Simpson

> My 94 convertable starts to vibrate around 65 mph.
>
> Feels like it is in the back of the car. Can feel it through the gear
> shift, so could it be drive shaft? Car is just at 100K.
>
> Recently acquired the car, first vette, so no history on the car and not
> sure where to start looking.
>
> Is this a common problem, or do I just go through the check the tire
> balance, rim straightness, etc. routine?
>
> Everything feels tight. No clunking on acceleration or deceleration, so at
> this point I don't suspect U-joints.

I'd like to hear from someone with a late model C4 that has
absolutely no vibration at 65-75mph like my 2003 C5. I've fought with
vibration in that speed range since my 1996 C4 was new, it's about
115K now. It seems like there's a body resonance that is always there
but strongly magnifies any problem. Mine seems to be towards the
front. Wheel balancing and tire changing make a difference but don't
eliminate the problem. The last round after the vibration got worse
replaced a worn ball joint which helped a lot. I drive the C4 to work
twice a week and the 65-75mph vibration is worse in the first few
miles and calms down as the tires warm up. It's almost as if the
tires take a set when they sit like old nylon belted tires did. This
is the same for Goodyear GSC's and Firestone Firehawks.
That being said, there are a lot of things about my C4 that I like
better than the C5. By all means, have the items mentioned elsewhere
in this thread checked in case there is something that needs attention
but don't worry about a little residual vibration. Nothing I've ever
driven is as comfortable cooking into a turn as a C4. Enjoy your new
vette.

> wrote in message
ps.com...
>> My 94 convertable starts to vibrate around 65 mph.
>>
>> Feels like it is in the back of the car. Can feel it
>> through the gear
>> shift, so could it be drive shaft? Car is just at 100K.
>>
>> Recently acquired the car, first vette, so no history on
>> the car and not
>> sure where to start looking.
>>
>> Is this a common problem, or do I just go through the
>> check the tire
>> balance, rim straightness, etc. routine?
>>
>> Everything feels tight. No clunking on acceleration or
>> deceleration, so at
>> this point I don't suspect U-joints.
>
> I'd like to hear from someone with a late model C4 that
> has
> absolutely no vibration at 65-75mph like my 2003 C5. I've
> fought with
> vibration in that speed range since my 1996 C4 was new,
> it's about
> 115K now. It seems like there's a body resonance that is
> always there
> but strongly magnifies any problem. Mine seems to be
> towards the
> front. Wheel balancing and tire changing make a
> difference but don't
> eliminate the problem. The last round after the vibration
> got worse
> replaced a worn ball joint which helped a lot. I drive
> the C4 to work
> twice a week and the 65-75mph vibration is worse in the
> first few
> miles and calms down as the tires warm up. It's almost as
> if the
> tires take a set when they sit like old nylon belted tires
> did. This
> is the same for Goodyear GSC's and Firestone Firehawks.
> That being said, there are a lot of things about my C4
> that I like
> better than the C5. By all means, have the items
> mentioned elsewhere
> in this thread checked in case there is something that
> needs attention
> but don't worry about a little residual vibration.
> Nothing I've ever
> driven is as comfortable cooking into a turn as a C4.
> Enjoy your new
> vette.


I had the same problem with a 75 vette at one time.
I found a place that still balances the tires while they
remain on the car.
that balances the rotor and all.
they solved my problem...

g'luck
--
'Key
=====

In om>, " > writes:
>> My 94 convertable starts to vibrate around 65 mph.
>>
>> Feels like it is in the back of the car. Can feel it through the gear
>> shift, so could it be drive shaft? Car is just at 100K.
>>
>> Recently acquired the car, first vette, so no history on the car and not
>> sure where to start looking.
>>
>> Is this a common problem, or do I just go through the check the tire
>> balance, rim straightness, etc. routine?
>>
>> Everything feels tight. No clunking on acceleration or deceleration, so at
>> this point I don't suspect U-joints.
>
> I'd like to hear from someone with a late model C4 that has
>absolutely no vibration at 65-75mph like my 2003 C5. I've fought with
>vibration in that speed range since my 1996 C4 was new, it's about
>115K now. It seems like there's a body resonance that is always there
>but strongly magnifies any problem. Mine seems to be towards the
>front. Wheel balancing and tire changing make a difference but don't
>eliminate the problem. The last round after the vibration got worse
>replaced a worn ball joint which helped a lot. I drive the C4 to work
>twice a week and the 65-75mph vibration is worse in the first few
>miles and calms down as the tires warm up. It's almost as if the
>tires take a set when they sit like old nylon belted tires did. This
>is the same for Goodyear GSC's and Firestone Firehawks.
> That being said, there are a lot of things about my C4 that I like
>better than the C5. By all means, have the items mentioned elsewhere
>in this thread checked in case there is something that needs attention
>but don't worry about a little residual vibration. Nothing I've ever
>driven is as comfortable cooking into a turn as a C4. Enjoy your new
>vette.
>
>

Same experience with my '89. I think you've got it right.
First 8 miles on the freeway on winter mornings are the
toughest (I hold it at 62 mph while warming up.) Definitely
worse with tires that have 'noise reduction' belts.
(Yokohama dB2s front and ES/100's on the rear). Adding
the convertible frame brace to my coupe helped.

The 'soft ride' suspension seems more sensitive to older tires
with hardened tread.

Probably gets worse when 'Dad' rides in a C4 --
definitely a shakey character -- when he's around
L98 or LT1 engines, he rattles around a lot and gets
very noisy. {{--0(

Yeah, the C4 is more fun than the C5 for freeway
on-ramps and off-ramps.

--
pj

> wrote in message ...
> In om>,
> " > writes:
>>> My 94 convertable starts to vibrate around 65 mph.
>>>
>>> Feels like it is in the back of the car. Can feel it through the gear
>>> shift, so could it be drive shaft? Car is just at 100K.
>>>
>>> Recently acquired the car, first vette, so no history on the car and not
>>> sure where to start looking.
>>>
>>> Is this a common problem, or do I just go through the check the tire
>>> balance, rim straightness, etc. routine?
>>>
>>> Everything feels tight. No clunking on acceleration or deceleration, so
>>> at
>>> this point I don't suspect U-joints.
>>
>> I'd like to hear from someone with a late model C4 that has
>>absolutely no vibration at 65-75mph like my 2003 C5. I've fought with
>>vibration in that speed range since my 1996 C4 was new, it's about
>>115K now. It seems like there's a body resonance that is always there
>>but strongly magnifies any problem. Mine seems to be towards the
>>front. Wheel balancing and tire changing make a difference but don't
>>eliminate the problem. The last round after the vibration got worse
>>replaced a worn ball joint which helped a lot. I drive the C4 to work
>>twice a week and the 65-75mph vibration is worse in the first few
>>miles and calms down as the tires warm up. It's almost as if the
>>tires take a set when they sit like old nylon belted tires did. This
>>is the same for Goodyear GSC's and Firestone Firehawks.
>> That being said, there are a lot of things about my C4 that I like
>>better than the C5. By all means, have the items mentioned elsewhere
>>in this thread checked in case there is something that needs attention
>>but don't worry about a little residual vibration. Nothing I've ever
>>driven is as comfortable cooking into a turn as a C4. Enjoy your new
>>vette.
>>
>>
>
> Same experience with my '89. I think you've got it right.
> First 8 miles on the freeway on winter mornings are the
> toughest (I hold it at 62 mph while warming up.) Definitely
> worse with tires that have 'noise reduction' belts.
> (Yokohama dB2s front and ES/100's on the rear). Adding
> the convertible frame brace to my coupe helped.
>
> The 'soft ride' suspension seems more sensitive to older tires
> with hardened tread.
>
> Probably gets worse when 'Dad' rides in a C4 --
> definitely a shakey character -- when he's around
> L98 or LT1 engines, he rattles around a lot and gets
> very noisy. {{--0(
>
> Yeah, the C4 is more fun than the C5 for freeway
> on-ramps and off-ramps.
>
> --
> pj

My LT-4 has 145K miles on it and it is silky smooth down the road at all
legal speeds, a few body rattles going slow on rough roads but not bad at
all. Who can say why some cars do better with mileage than others.

I had an RX-7 that the drivetrain would shake when cold but would smooth out
when warmed up, felt it through the gearshift too. I checked the driveshaft
U-joints and they were tight and smooth but changed the shaft anyway and the
problem went away immediately. I'm thinking it might be the driveshaft!
Also had a car that would shake only at a certain speed in top gear and no
other gears, turned out to be the harmonic balancer on the crankshaft funny
though at that rpm in other gears it wouldn't shake, harmonics through a
vehicle can be very complex.

And oh I don't think I would trade my C4 for a C5 even with low mileage I
have a neighbor with a '98 and have smoked him several times so much so he
won't even try me anymore.

Butcher
'96 LT-4 CE (with aftermarket exhaust and intake)