1G Violent shutter when braking at high speeds..

[uberstrafe]

Hey guys,

well i just took my car for a lil drive after installing a fidanza fly and sbr3500, and as i was just going to my buddies house to pick him up and get use to the new fly and clutch i forget to take off the the e-brake for a good 4 blocks (i know im a retard ). Anyways I took my car out on to the highway and picked up some good speed and when i hit the brakes decent the whole car shuttered violently (scarey as shit at that speed), it felt as if the rotors were made from jagged metal.

About a month i bought some powerslots for the rear and I didnt do a break-in on them, I didnt read the piece of paper that came with them. Didnt even come to mind that I would need to break them in. I also bled the front brakes while i had the wheels off during the clutch job.

So what I'm asking is could the ebrake or the rear rotors or a messed up bleeding job cause this shutter?

Thanks for your help guys!

P.S. I love the new fly and clutch its awesome!

 

[splattj]

You could have overheated and warped the rear brakes or just have created some hot spots leaving pad material deposits on the rotors.

Bleeding the brakes won't cause braking vibrations.

Does the steering wheel shake or the whole car? If it's not pronounced in the steering wheel but the car shakes you need to either replace or turn the rear rotors. If the steering wheel shakes when you brake, the front rotors probably have to be fixed.

 

[uberstrafe]

i didnt feel it in the steering wheel, so how do u turn the rear rotors?

 

[c5chris]

i didnt feel it in the steering wheel, so how do u turn the rear rotors?

Turning means you get a grinder and take off some material on the surface to make sure it is flat and even. I do not like doing this since brake shops charge too much for this service and you take off alot of mass from the rotor.

Buy new ones.

 

[splattj]

Turning means you get a grinder and take off some material on the surface to make sure it is flat and even. I do not like doing this since brake shops charge too much for this service and you take off alot of mass from the rotor.

Buy new ones.

You can usually have a machine shop turn them on a lathe for $20-$40 if you bring them in. Brake rotors have specific ranges stating how much material can be removed. A proper shop won't remove much material at all and will check the tolerances before they even mount your rotors on the machine. Make sure to ask the shop if they will do slotted rotors before you start working. You should be able to find a machine shop in your yellow pages.

 

[uberstrafe]

did they overheat because i didnt do the breakin process?

 

[Turbo Shogun]

A rear brake rotor at NAPA or Autozone will run you around $30-$40. Might as well buy a new pair, unless you can find a machine shop that'll do them for cheap and you're real tight on money.

 

[splattj]

did they overheat because i didnt do the breakin process?

No. They overheated because you drove with the ebrake on for 4 blocks. The break-in is to evenly heat and cool the rotors so that internal stresses can be relieved which helps prevent warpage and stress fractures.

 

[slugsgomoo]

No. They overheated because you drove with the ebrake on for 4 blocks. The break-in is to evenly heat and cool the rotors so that internal stresses can be relieved which helps prevent warpage and stress fractures.

right, but that shouldn't cause shudder in the fronts... sounds like repeated hard braking has left pad deposits.

Rotors don't "Warp" and you can read about it on any braking site (stoptech has a great writeup). Brakes actually work by coating the rotor with material from the pad, and using the two surfaces for friction. Un-even pad deposits cause a pulsing feeling that most people deem "warped rotors".

Turning means you get a grinder and take off some material on the surface to make sure it is flat and even. I do not like doing this since brake shops charge too much for this service and you take off alot of mass from the rotor.

Buy new ones.

Dude, that's a terrible idea. No matter how good you are with a grinder, you are *not* a lathe. The entire point of turning a rotor is to true the surface so that it is perfectly flat. Grinders aren't meant for that kind of work. A brake lathe will take off only a few thousandths, depending on how bad the rotors condition is. You cannot measure how much you are taking off otherwise.

There's no reason to waste money buying new rotors when the old ones are in decent shape and can be turned for $20-30 each. If you develop any kind of relationship with your machinist, you can probably get a better rate as well.

 

[splattj]

right, but that shouldn't cause shudder in the fronts... sounds like repeated hard braking has left pad deposits.

I didnt feel it in the steering wheel

Rotors don't "Warp" and you can read about it on any braking site (stoptech has a great writeup). Brakes actually work by coating the rotor with material from the pad, and using the two surfaces for friction. Un-even pad deposits cause a pulsing feeling that most people deem "warped rotors".

You most certainly can warp a rotor. It's just not the cause of pulsation in hardly any street cars. I would bet that you are right in this case about pad deposits, but I was just reusing his terminology to make things a little easier to understand. Besides, most of the machinists still consider them "warped."

Uber, you'll have to let us know if you get them sorted out.

 

[Omega]

If you have slotted/drilled rotors, you might have a tough time finding a shop to turn them. Go pick up a set of OEM rotors, you don't gain anything by having tricked out rotors... especially in the rear.

Slugs is right. Rotors generally don't physicly warp.. GT racers are a possibility. It's just a buildup of the brake pad material. The idiots that skim them usually take off too much... leaving you no choice but to buy new ones.

Another cause could be excessive rust on the rotors. If the car sits for an extended period of time with crap rotors, it can give you similar effects. If you put some more miles on it it clears up.

 

[slugsgomoo]

splattj: I suppose you're right, though i didn't really expect him to be breaking hard enough to make his rotors GLOW RED HOT.

Omega, why wouldn't a shop turn slotted or drilled rotors? I'm certainly not one to argue for them (frankly, they're a waste of time in this day & age) but I never had a problem turning any rotor for anyone when i was doing that kind of work.

It's not like the lathe cares that there's a difference in depth.

 

[Omega]

I found it difficult around me to have it done. I could only assume, the monkeys kept snapping tools froma taking too much material off at one time so they axed the option.

Shit, I had a shop tell me my BAER rotors were made from a material they couldn't turn down. I didn't push the subject, laughed and walked out.

 

[slugsgomoo]

I found it difficult around me to have it done. I could only assume, the monkeys kept snapping tools froma taking too much material off at one time so they axed the option.

Shit, I had a shop tell me my BAER rotors were made from a material they couldn't turn down. I didn't push the subject, laughed and walked out.

Aren't you glad you have those experiences before they do work for you? It helps you avoid shops you shouldn't be going to in the first place.

 

[wret]

Apparently some drilled rotors can be turned and some cannot. The other day I removed my rotors because of a pulsation, loaded them into a back pack and rode my bike about 6 miles to my mechanic. I didn't really think this out very well (Try riding any distance with 50 pounds of cast iron strapped to your back, in 90° whether).

When I got there, he looked at them and said he didn't think he could turn them because they were drilled. He said the cutting tool gets caught in the holes and jumps around. I glanced over at his 911 race car and asked, "How do you turn yours."

"I don't."

He agreed to try it, ran them very lightly at the slowest speed and after about three passes they were smoothed with no problems. I lucked out with my drilled rotors but I can't see how they could turn the slotted ones at least in any conventional way.

 

[slugsgomoo]

you might want to tell him to check his lathe- it is a fixed tool and the whole point is that it will cut through and not move, NO MATTER WHAT.

I took .01 off in one pass for a guy one time, because he wanted to salvage some extremely damaged rotors. It worked, but it sounded horrific. heh (we basically turned his rotors from "decent life" to "minimum spec")