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Immense grinding/scraping/vibration after swap to new disc parts

cudak888

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Gentlemen:

I come to you today from the parking lot of a mini storage, a few blocks away from the alignment shop where I just had my new front end aligned.

The front end is fresh with all new parts, Bendix rotors, and Raybestos pads - and until this point, I've never driven it except at 2mph from one driveway to another.

Well, I hit the brakes to the worst grinding, grating, and vibration any one could humanly expect at 2mph. Also hear circular scraping too after braking. It's not drivable.

Took a look underneath and everything looks good, so I'm left to guess this is a pad/rotor incompatibility. Would make sense, as it gets worse with a hard braking application, and improves when released. Sound right? Or am I overlooking something?

FYI - alignment appears spot-on. Have no reason to suspect it. -0.5 camber, +6 caster.

-Kurt
 
Rusty rotors? Hung calipers?
 
Sounds like you never bedded in your new brakes. The following is very similar to what I do after a brake job:

http://brakeperformance.com/bedding-in-rotors.php

Didn't bed them in - but if I did the 45-mph stop described there, I'd probably lock the front brakes and set the car into a spin. Hitting the brakes normally at 25mph locks it up.

Rusty rotors? Hung calipers?

Rotors are new and were machined before installation. Calipers may be hanging, but I'd expect the problem to go away under braking if so - but it only gets worse.

-Kurt
 
Hub bearings loose? Caliper misaligned? Brake dust shield need some clearancing?
 
What shape are your Flex lines in? That would cause your brakes to lock up.
 
Hub bearings loose? Caliper misaligned? Brake dust shield need some clearancing?

Possibly, don't think so. Caliper misalignment is possible; might be hanging on the anti-rattle rubber bands. Had to pry the dust shield in one spot (see below) when I installed all the new equipment.

What shape are your Flex lines in? That would cause your brakes to lock up.

Brand new and checked for binding. (P.S.: I do note the dust shield's position - this was the only place it rubbed and was taken care of after the pic).

32807572054_6a4d43de18_b.jpg


-Kurt
 
Possibly, don't think so. Caliper misalignment is possible; might be hanging on the anti-rattle rubber bands. Had to pry the dust shield in one spot (see below) when I installed all the new equipment.



Brand new and checked for binding. (P.S.: I do note the dust shield's position - this was the only place it rubbed and was taken care of after the pic).

32807572054_6a4d43de18_b.jpg


-Kurt


Something you didn't mention was the pads. Is it possible that one, two or maybe all the pads are installed backwards? You may be hearing the metal pad backing rub against the rotor. Not knocking anyone but it can happen especially if you are in a hurry, it's at night, tired and you want to get the car together. I'm speaking from experience.
 
"Rotors are new and were machined before installation."

Why were new rotors machined?

I would take it all apart, clean everything, reassemble with caliper grease where required.

Edit: Deleted my comments on flex lines since you have replaced them.
 
Something you didn't mention was the pads. Is it possible that one, two or maybe all the pads are installed backwards? You may be hearing the metal pad backing rub against the rotor. Not knocking anyone but it can happen especially if you are in a hurry, it's at night, tired and you want to get the car together. I'm speaking from experience.

No offense taken, great point. I know the outers are correct and doubt that I got any reversed, but that's actually a really good point, as I found it easier to prop the inner pads on the caliper adapter first and then and slide the calipers over both rotor and inner pad.

"Rotors are new and were machined before installation."

Why were new rotors machined?

I would take it all apart, clean everything, reassemble with caliper grease where required. Also, replace the flex lines if they are more than (5-10 yrs old) and flush the brake lines with fresh fluid designated for your car. Flex lines can look fine from the outside, but swollen on the inside. Swollen lines will open and allow fluid into the caliper. However, the swollen lines will trap pressure in the caliper when you release pressure on the pedal. A swollen line, if not too bad, will allow trapped fluid (pressure) in the caliper to slowly flow back into the brake system.

Regarding the machining: Been told in the past that it's a good idea. Then read your comment and did some additional Googling to find out (now) that it's an old wives' tale. Lesson learned.

Everything that moves has caliper grease on it. But it also has those anti-rattle rubber bands, which I'm starting to have my doubts about...they sit right on the area where the caliper slides.

Fluid is new (entirely; flushed entire system after doing the disc-to-drum swap; MC is new too), brake hoses (all three), 3/4 of the hard lines, etc.

-Kurt
 
FYI: Don't know how much time I have to fiddle with it today, but going this course:
  • Check inner brake pads for position. If OK, move to...
  • Check rotor/spindle bearings for play. If OK, move to...
  • Remove anti-rattle rubber bands. I have a suspicion that I should only be using one rubber band per caliper, not two. Reassemble. Test car. If no change, move to...
  • Inspect for caliper pistons hanging
-Kurt
 
I wonder what this is...

ndshmw.jpg


I don't know if that's the brake pad pulled forward, or if it's one of the alignment shop's tools jammed in there...but I'll know in 15 minutes.

And I'm DAMN glad I didn't try some kind of stupid stunt like trying to bed the brakes...at 45MPH...with this.

-Kurt
 
Last edited:
Possibly, don't think so. Caliper misalignment is possible; might be hanging on the anti-rattle rubber bands. Had to pry the dust shield in one spot (see below) when I installed all the new equipment.



Brand new and checked for binding. (P.S.: I do note the dust shield's position - this was the only place it rubbed and was taken care of after the pic).

32807572054_6a4d43de18_b.jpg


-Kurt

I also see a wear mark at the base of the hub. When you have the front off the ground are you spinning the hub to hear possible metal to metal?
 
PROBLEM IDENTIFIED:

ndshmw.jpg


I don't know if that's the brake pad pulled forward, or if it's one of the alignment shop's tools jammed in there...but I'll know in 15 minutes.

And I'm DAMN glad I didn't try some kind of stupid stunt like trying to bed the brakes...at 45MPH...with this.

-Kurt

What the heck is that?
 
PROBLEM IDENTIFIED:

ndshmw.jpg


I don't know if that's the brake pad pulled forward, or if it's one of the alignment shop's tools jammed in there...but I'll know in 15 minutes.

And I'm DAMN glad I didn't try some kind of stupid stunt like trying to bed the brakes...at 45MPH...with this.

-Kurt
Looks like the upper part of the dust shield is pushed over against the rotor
 
Looks like the upper part of the dust shield is pushed over against the rotor

Ding, ding, ding. You also have ESP:

2qx44g3.jpg


Looks like I'm Idiot of the Week. (Good thing it's the end of the week). Rotor is nicely chewed up on the other side. I will say - if nothing else - it's really easy to install the pads reversed on these calipers, if you're rushed and not paying attention...

Looks like I have a new rotor and pads to buy. I reassembled the junk parts as-is to get the car back down for now.

-Kurt
 
That really sucks. They should have been designed to be "Murphy proof".
 
You going to check the other? Seem you can't catch a brake. Pun intended.








Ding, ding, ding. You also have ESP:

2qx44g3.jpg


Looks like I'm Idiot of the Week. (Good thing it's the end of the week). Rotor is nicely chewed up on the other side. I will say - if nothing else - it's really easy to install the pads reversed on these calipers, if you're rushed and not paying attention...

Looks like I have a new rotor and pads to buy. I reassembled the junk parts as-is to get the car back down for now.

-Kurt
 
That really sucks. They should have been designed to be "Murphy proof".

Hopefully, fellow DIY'ers will come across this thread before they attempt this, thus nullifying Murphy's Law.

You going to check the other? Seem you can't catch a brake. Pun intended.

Hahaha. Between these rotors (really feel a bit terrible about ruining one - took SO LONG to get the brake issue resolved), the strut rod roll pin, the tie rod ends, and everything else...I've really had the rough end of it. I will NEVER do this again piecemeal. Cass at Dr. Diff has a new dedicated customer for however many more I do in the future...

Believe it or not, the ONE THING I didn't check on the road was the inner right rotor surface. I did check the inner LEFT rotor surface, and that one is A-OK. It's also the caliper I did first.

-Kurt
 
Ding, ding, ding. You also have ESP:

2qx44g3.jpg


Looks like I'm Idiot of the Week. (Good thing it's the end of the week). Rotor is nicely chewed up on the other side. I will say - if nothing else - it's really easy to install the pads reversed on these calipers, if you're rushed and not paying attention...

Looks like I have a new rotor and pads to buy. I reassembled the junk parts as-is to get the car back down for now.

-Kurt

Man, don't kick yourself. I did it myself. I run KH brakes on my 68 GTS. I just finished a long day with the car on the rack. I pretty much thrashed to get under car stuff done to include the front brakes. I had the calipers on and off throughout the day trying to get the brake hose brackets fitted up. When I pushed the car out I could hear something dragging. Pushed the car over to the assembly room to work on the interior. The following week I was able to get it back on the rack. There and behold there it was on the passenger side caliper. Had the outside pad backwards. I was fortunate that I didn't score the rotor.

Like I said, it happens.
 
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