Wide tires and front end shaking
 

Looking at a C4 and test drove this morning. The car has new tires on GS wheels, also brand new. Car is located in older neighborhood so the roads are bumpy/lumpy. On smooth paved roads the car behaves fine, but as soon as it enters the uneven paved roads, the whole front end does a vibrating dance...I thought the front end was coming apart. Then I would enter a stretch of smooth road and the car acted fine.

I believe tires are 285 in front and 305 in back. they have 11.5 rims in back. I have never experienced this type of behavior before, but I never had a car with such wide low profile tires either. Is this common or is there mechanical problems? The owner is fairly meticulous mechanically and with new tire/wheels the facility should have caught any problems inferring he did have an alignment.

Thanks, the car is a daily driver with 3 prior owners. This behavior is holding back the sale.

The wide tires will make the car follow the ruts in the road a lot more than stock. If the alignment was done recently, most shops wont do it if there are problems with anything. Try bouncing the front end and see how long it takes to stop. If more than twice it may need new shocks. If they are bad, this will tend to make the car skitter around on rough roads.

Good luck with it.

Like mentioned, the wider front tires will make the car wander and follow imperfections in the road more so than a narrower tire. However, it sounds like something else may be upsetting the suspension. Worn out shocks or loose wheel bearings could the culprit. I would also check to see if the alignment is correct.

If it does good on a smooth surface but not on a bad surface it's called the sports car syndrome. :D Can't stand driving mine on a crappy road.

Typical of car owners is the lack of attention to shocks. Pretty paint, wheels etc. Ask how old their shocks are and a blank stare comes over their face. (Same goes for brake fluid)

My guess is the shocks are beyond gone.

My 93 vett. 100x miles was the same when I bought it, shook terrible on rough roads, or hitting a bump at speed, fine rest of the time. I rebuilt the whole front end, new ball joints, tie rod ends (use only Moog) and new steering rack, fixed the problem. If you let it go on a car with new tires they will soon be ruined by a worn out front end.

If the steering wheel shook a lot, sounds like the top was not secure.
My 94 tracks and responds to bumpy roads well with the top on.
When I remove the top it is like the front end will come off of the car on
bumpy roads. 285's up front and 315's rear.

look at the camber if its alot of camber it will cause this syndrome
just eye ball the wheels to see if there plumb. alot out or in may not be a problem just may need an alignment. was the car tracked?

If it only shakes when you hit a bump, its a ball joint problem.

Were you driving with the roof panel off? Makes a huge difference in these cars, and yes it will shake and vibrate, make the wheel jump about in your hands and you'll see the cowl moving and generally behave bloody awful on rough roads (compared to more modern cars). It's why aftermarket braces and x-braces from the vert are a popular add-on ;)
Yes ask about its suspension and alignment. Mine had a brand new front spring, shocks all round and a professional alignment at a well known Corvette specialists when I bought it, yet still drove like crap with the top off. My main reason for keeping it on..

if you are new on C4, you have to consider that probably you'll never obtain a today -car confort,squeek,vibrations are common on these 25 years old car.Generally a worn out front end produces lot of shaking and noises.Early C4 use a strong/stiffer rated spring set up,even if you put in new shocks,the car reacts very rough on bad paved roads.As told,C4 main frame has torsional reactions that translate into interior vibrations and squeeking of 25 years old plastic molding.Restoring your C4 front end require a multi-step approach based on your budget:

1) replace shock abosorbers with good Bilstein.smooth out your front end- entry level
2)replace tie rod and ball joint-use Moog only- reduce heavily shaking noises and worn out play-it's a good restoration level+shocks absorbers
3)replace bushing- urethane for sport handling ,rubber for confort-you have to dismount entire front end,very hours spending/professional work,the best +previous steps
4)replace hub bearing (only Delco avoid other China made items)complete front end restoration to an excellence level,you have changed almost everythings
5)replace front leaf spring with a new one only if this is worn out

Agreed...It's the nature of the beast, however in your case you may have some symptoms of failing tie rods, ball joints, control arm bushing, etc. You'll have to get in there and check it out.

I rebuilt my front end this summer with new shocks, tie rods, ball joints and control arm bushings and it still rides real rough over big bumps. Over moderate sized bumps it does ok, but when you hit some real bad roads it doesn't like it. Just the nature of the car i guess.

Good luck :thumbs:

Sometimes a road force balance can help.

Chrome and/or heavier wheels hurt. I think this was one reason they moved to 8.5" wheels for the LT cars.

Uneven wear can cause this at higher speeds.

These are in addition to points previously made.

:cheers:

Thanks everyone for the replies. Got the car home. The previous owner had Chevy do a multi point inspection a few months ago, and Firestone did an alignment check when they installed the GS wheels and tires.

Back in my neck of the woods, car feels great. It was those lousy city streets after all. Going to switch back to the CE wheels and stock sized tires (tires are brand new) that also came with the car. Those 315 in the rears are impressively massive.