Shudder during hard braking

While doing some enthusiastic driving yesterday I noticed that my car shudders a bit when I'm braking hard. I never notice it during regular driving, before or after.

 

I'm guessing my rotors are warped, but if anyone has other ideas about what can cause this I'm all ears.

 

Thanks!

what do the rotors look like? how many miles are on them. You guessed what i thought it was when i read the title. Look into getting your rotors turned.

Make sure all your lugs are torqued evenly. Other than that, it sounds like it may be time for new rotors.

if you are running stock pads, then they are the pads leaving deposits on the rotors. If tey are aftermarket pads, then the rotors are prolly warped.

While doing some enthusiastic driving yesterday I noticed that my car shudders a bit when I'm braking hard. I never notice it during regular driving, before or after.

 

I'm guessing my rotors are warped, but if anyone has other ideas about what can cause this I'm all ears.

 

Thanks!

 

Rotors just don't warp anymore. What you most likely have are pad deposits. These may be removed by hard braking several times or by turning the rotors. But it has to be GOOD turning job, otherwise the least bit of pad material will cause the shudder problem to return.

+1 for the pad deposits. It happens on any type of pad, not just factory pads.

 

Go for a new break-in run on the rotors and remember not to hold the brake down after you're done or you'll leave more deposits on it right away.

 

Or get a nice roloc wheel, jack your car up, and go to town on the surfaces of your rotors

sure its not just the ABS kickin in?

I am not sure whether it's rotors or deposit but if the wheel vibrates it's the front and if your ass vibrates it's the back, it might help narrow it down.

When ABS engages you can feel it in the pedal, and that definitely wasn't the case here. This was also on dry pavement. It felt a bit like an out-of-balance wheel, but it only happened when braking fairly hard.

 

I'll have to try the re-break-in and see if that helps.

 

I felt it in the wheel and in my seat, so maybe both ends are in trouble. But if it's one end, it's probably the front end.

Rotors just don't warp anymore. What you most likely have are pad deposits.

 

+1

 

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

 

- drew

Rotors just don't warp anymore.

 

 

well, then you havent driven a late model ford/lincoln/mercury product then.

 

Back when i was a tech. they used to come in all the time for brake viabratons and when i put the rotor on the lathe, i would have to machine the rotors 4-5 times just to get the thing true befor i did my final cut.

If the rotors were warped they would be vibrating more than just when you brake hard

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

- drew

 

That was a really interesting read, thanks for posting the link.

 

I made a half-assed attempt at re-breaking-in the pads yesterday and I think it actually worked. Will find out for sure tomorrow.

I had this problem and it was getting progressively worse. When I took it to the dealer, they rebalanced the wheels and it solved the problem. You might want to try this if you haven't eliminated it as a variable.

The problem is reduced now but not completely gone. I think it may have been gone for a while but it doesn't take much to bring it back.

 

I've dealt with out-balanced wheels before (yesterday in fact - snow/ice caked up on the insides of my wheels) and this is something different. Balance problems get worse as you go faster, but my car is smooth up to 80 or so, until I hit the brakes.

The problem is reduced now but not completely gone. I think it may have been gone for a while but it doesn't take much to bring it back.

 

Do you have the stock tires? And how many miles on the pads.

 

They seem to do it a little bit less as they wear, and for me the virtually stopped doing it once I put real tires on it that had enough grip to keep up with the ABS. The stock tires were setting off ABS chatter constantly,even on clean dry pavement. This seemed to aggravate the formation of uneven deposits. I was having to bed the brakes like every two weeks.

You know after thinking about this for awhile, I now remember the whole story at the dealer...Sorry about the earlier post. They discovered a warped rotor in fact. It must have been defective in the first place and once it experienced some heat it warped. This happened at around 10k on the car. They did a brake job (resurfaced the rotors) and this is what actually solved it. I was not too happy about it though. After that my brakes were screeching a lot on light braking. The kind of braking you do around town when pulling up to a stop. After a couple of thousand miles, I could not stand it anymore and took it back to the dealer. I demanded new rotors and pads, since by resurfacing them in the first place they robbed me of some rotor life. The squealing came back on the new pads but not as bad, and now I am just living with it again. The car has about 17k miles on it now, and I may go back for a third set of pads soon....

Stock everything, 30k miles.

Not sure if you are still covered under warranty, but it sounds like you need a brake job. Incidentally, at the dealer the technician confessed that subarus are plagued with brake problems. He said that they had to stop fixing them under warranty for the STI guys.

My 3/36 ended three weeks ago. The problem is pretty mild right now, I think I can continue improving it if I keep up with the techniques described in that articles.

 

Actually, 'stock everything' wasn't right, I'm on snow tires now - hence the "fairly hard" braking and "half-assed" re-break-in. I'll go back to stock in a week or three, then summer tires a few weeks after that when my new wheels arrive. Summer tires might invite more trouble, but on the other hand they'll also let me do a full-assed re-break-in. We'll see.

Stock pads lay down those deposits very easily, sadly...

 

Even after bedding. Until you go w/ AM pads, rebedding more often is your only option. (The good news is that will help rid you of the stock pads faster )

Stock pads lay down those deposits very easily, sadly...

 

Even after bedding. Until you go w/ AM pads, rebedding more often is your only option. (The good news is that will help rid you of the stock pads faster )

 

Agreed.