I'm getting a distinct wobble in the front wheels on my '87 GL. At about 20mph you can feel the wheel alternately being pulled to the right, then the left, and feel the car shake. Not so noticeable at higher speeds (I think because it's higher frequency), and it still tracks really good. When you hit the brakes, it feels like the rotors are really warped -- real pulsating feel through the pedal.

 

So, tonight, I'm going to look at the rotors, and maybe put a different set of rotors and wheels on it off the parts car. But I'm wondering, what could make rotors go bad like this? (if it is the rotors) It's the first time I drove it, and the previous owner had let it sit for over a year. The rotors are rusty, but I figured driving would wear that off pretty quickly. Is there anything else that could cause this feel?

I'm getting a distinct wobble in the front wheels on my '87 GL. At about 20mph you can feel the wheel alternately being pulled to the right, then the left, and feel the car shake. Not so noticeable at higher speeds (I think because it's higher frequency), and it still tracks really good. When you hit the brakes, it feels like the rotors are really warped -- real pulsating feel through the pedal.

 

So, tonight, I'm going to look at the rotors, and maybe put a different set of rotors and wheels on it off the parts car. But I'm wondering, what could make rotors go bad like this? (if it is the rotors) It's the first time I drove it, and the previous owner had let it sit for over a year. The rotors are rusty, but I figured driving would wear that off pretty quickly. Is there anything else that could cause this feel?

 

From your description of the problem, am I correct in assuming this feeling occurs even when you're NOT applying the brakes?

 

If my assumption is correct, check your ball joints... my Optima had a bent lower ball joint retention bolt, and it caused the exact symptoms you described.

Unless the rotors are vissably tweaked( you can see a bend in them an i have never heard of that happening) they wouldnt do that. and if it were the rotor it would get worse when you applied the breaks i agree to check ball joints but also check out all your other front and parts like tie rods and steering components.

wheel bearings...

had a few of em go with exactly these symptoms

Broken cord in a tire, check yer tires for lump or side-to-side variences in the tread lines (easiest when jacked up off the ground) just stick it in first and watch the tread.

 

while you got it in the air shake the tires top to botoom and side to side looking for and freeplay

 

Check your lugnuts.

 

wheel bearings growl on the road, especially notacable when turning.

 

A siezed axle will lumpa lumpa lumpa down the road.

 

Rotors rarely if ever shake without applying the breaks.

Thanks everyone for the suggestions. Here's the verdict...

 

The rotors are indeed warped -- after some driving you can see that they've worn the rust off in two quadrants, but not in the other two. So I'm going to swap on the good rotors from the parts car.

 

But that wasn't what was causing the vibration. I put a different set of tires on there, and it's gone. The tires were permanently flat. They had sat in the same spot with about 10psi in them for too long and developed a flat spot that didn't go away even when pumped back up to proper pressure.

Subarus warp their front rotors very easily. Mostly becuase people set their parking brake while their rotors are still hot. Our cars lock the front brakes with the e-brake, and if you set the e-brake with hot rotors, they will cool and warp with pressure being applied to only one section.

 

Good thing they're cheap tho. I can usually find new rotors on ebay for like $20 a pair. Or Napa for about $30each

 

-Brian

... e-brake with hot rotors, they will cool and warp with pressure being applied to only one section.

 

YIKES! Now THAT is a good tip to have.

 

How long does it take the rotors to cool down??

Long enough that you should just park it in gear if you suspect the brakes are near glowing. :-)

 

http://www.stoptech.com

 

More articles on brakes and brake systems than you could ever want.

 

Amusingly enough, both of my Subarus have developed odd vibrations in them. And, both times it was tires.

 

-=Russ=-