[ukrkoz]

How exactly do I know, if shake during braking is coming from the front or rear?
My assumption is, if it's front, steering wheel shakes side to side.
If it's rear, entire car shakes.
In my case, it's 98 Grand Marquis, which is old style steering without R&P. RWD.
Car had brake shake when I bought her, so front rotors were turned, followed by rear ones, with good results. OEM rotors. New pads.
Then, rather quickly, front started shaking again, so I replaced rotors. What did real well, until about a month or so ago. Shake returned.
But, steering wheel is rock solid, car simply jerks back for, like as if brakes are skipping.

So I have NEW aftermarket rotors in the front(maybe 5K miles on them) and, OEM turned rotors in the rear.

Makes me think it's the rear ones. Considering, they are rather price, being very large rotors for large car, I don't really want to hunch replace them.
So, if SW is rock solid, no wobble, and entire car jerks back/for, it's rear ones?

 

[Bondo]

and, OEM turned rotors in the rear.

Makes me think it's the rear ones.

Ayuh,...... I concur,..... Anytime I've had warped rotors turned, they warp again the 1st time ya get 'em hot,.....

 

[ukrkoz]

I'll just swap them out.. braking becomes interesting...

 

[Windows on Wash]

Almost nobody cuts them any longer and most of them are not indicated to be re-cut on a lathe. If it has the thin face that mounts on the spindle, don't bother.

 

[Joeywhat]

Check your calipers (and drums if you have them) for proper operation. Stop throwing new rotors at it, something is causing them to warp very quickly. Could be a stuck caliper, for instance.

While you have the calipers off to check, replace the guide pins and lube them up. The guide pin kits are cheap and it's good insurance. For a car that old if the calipers slide pins haven't been replaced then I'd bet a dollar that's causing the issue. Those pin boots degrade over time causing the pins to corrode and the grease to escape.

 

[huesmann]

Rotors very rarely warp. What usually happens is that your pads deposit material on them and they get glazed, which causes uneven friction surfaces. If you think your rotors are warped, take a sander and sand both surfaces of each rotor first.

 

[ukrkoz]

You ever tried to sand rotors? I did. As a slave punishment, it's a good idea.

Guides are good, everything is lubricated. I side with bondo. Some rotors simply are that way.

And yes, rotors do not warp.

 

[huesmann]

When I said a sander, I meant a power sander, not a sanding block.

 

[ukrkoz]

Yeah, that's exactly what I meant. Angle grinder. Blanchard grinding. Slave punishment. And, really does not much. And, toxic like nuclear plant sewer.

 

[Drachenfire]

Have you had the alignment checked?

 

[ukrkoz]

Twice. Has none to do with it. It's rotors shake. It's a BIG HEAVY car, rotors work hard to stop it.

 

[Windows on Wash]

Biggest issue I see with new brakes, is proper break in. If the brakes are done properly (i.e. pads, rotors, proper torque on the wheels, lubrication of the slide pins, and well functioning calipers), most people get on them too hard too early.


The Jeeps were notorious for under-sizing the brakes. My old 4Runner would get 100K out of a set of brakes.

 

[ukrkoz]

bedding was done as recommended by StopTech. I bed in rotors for years.
As noted, it's new rotors in the front and OEM turned in the rear. All 4 bedded in.

 

[Windows on Wash]

bedding was done as recommended by StopTech. I bed in rotors for years.
As noted, it's new rotors in the front and OEM turned in the rear. All 4 bedded in.

If the car is heavy and the binder undersized, you'll get unequal depositing. The only thing that I ever try to do is when I have to make a hard stop, I don't stop the car completely where it can transfer pad material irregularly. I just let the brakes slip slight like when at a light after a hard stop. Not much, but just stop a bit short of the car and let it slide.

 

[Drachenfire]

Can you get truck-grade rotors?

 

[ukrkoz]

I'll just get carbon ones from Cheron. Lighter. Cheron is, basically, MGM based anyway.

 

[ukrkoz]

It was rear rotors. Swapped them out yesterday. FWY commute to Seattle 33 miles. Much better.

 

[woodyg2060]

FWIW for years on multiple vehicles I've been running centric rotors that I buy from rockauto. Never had an issue. Make sure you lube pins etc. Theres a lot of crappy Chinese parts out there.

Sent from my SM-T387V using Tapatalk

 

[ukrkoz]

Certainly. Thank you.

 

[ratherbefishing]

Glad you got it fixed. But the way to check, assuming the e-brake works the calipers, is to apply the e-brake while moving. That will isolate rear from front.