Author Topic: New EBC rotors/pads install and BAD shudder! Help!  (Read 236 times)

Offline Rubber_Snake

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New EBC rotors/pads install and BAD shudder! Help!
« on: October 07, 2019, 01:00:24 pm »
Okay, so I ordered a new set of EBC rotors and pads from Murph.  Went about R&R.  No issues during install.  Everything went on clean and exactly as before. 

I went to seat the pads.  I started off slow and made some light, initial brake applications.  As I increased speed, I could feel a shudder, maybe even worse than a shudder.  It's as if there's a fracture in one of the rotors that's catching the edge of the pad as it rotates through.  I pulled over and looked over the front end and can't find anything wrong.  Not finding anything unusual, I proceeded to continue more brake applications.  The more I tried to seat the pads, the worse the shudder got.  It's almost like a "clunk clunk clunk" as the wheel makes each rotation. 

I double and triple checked all of the bolts for the calipers, the axle, the pinch bolts, fender bolts.  I put the wheel on in the correct direction and the ABS ring on the correct side.  When I bolted the new rotors, I snugged them in a star pattern like a wheel on a car.  I used the original gaskets that were between the original rotors and wheel hub.  The spacers for the axle are correctly in place.  The pads are lined up properly with the pins and springs.  I placed the rotors with the EBC labels visible on both sides. 

When I spin the front wheel while on the center stand, the pads ARE rubbing a bit.  The wheel doesn't spin very freely.  I suspect that my calipers could use a rebuild, but I can't see how that would cause the clunking sound.  The rotors seem true, not bent in any obvious way.

Did I miss something? 

Any advice or help would be greatly appreciated.

Ray

UPDATE.  So, while continuing to work on this, I wanted to test for warping.  I put a zip tie around the front lever and the grip to maintain a constant pressure.  As I rotate the wheel, there is strong resistance until I get to one spot and the wheel turns much easier.  It would seem as either the rotor is warped or there's grease on it (which there isn't, I cleaned the rotors before and after install). 

What should I do from here? 
2009 GTR 1400 ABS, 48k miles, AMSOIL synthetic 10W-40 (since new), AMSOIL synthetic 75W-90 final drive (since new). Helibar Horizons, Symtec heat demon grips, V-Stream windscreen, Mountain Runner Flash, Brian’s low fuel eliminator farkle, ST2 smart brake module and smart turn system, Two Brothers Black Series M5 w/P1X decibel killer.

Offline VirginiaJim

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Re: New EBC rotors/pads install and BAD shudder! Help!
« Reply #1 on: October 07, 2019, 01:37:45 pm »
Had the same thing happen with me..although I believe of my own doing.  EBC rotors and pads but forgot to monitor the fluid level in the master.  Had too much initially.  Even after I lowered it, still had the shudder.  Tried everything, new pads and rotors again.  Uncounted bleedings.  Finally after living it with it for a few years decided to rebuild the calipers with new seals.  That fixed it.  May not be your issue but it certainly was mine.  I believe I had a seal sticking.  I broke the calipers apart to put in the new seals as it was easier that way.  Good luck.
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Offline gPink

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Re: New EBC rotors/pads install and BAD shudder! Help!
« Reply #2 on: October 07, 2019, 04:27:22 pm »
My foggy memory is trying to recall something about the rotor to wheel gasket....maybe it'll come to me.
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Offline Rubber_Snake

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Re: New EBC rotors/pads install and BAD shudder! Help!
« Reply #3 on: October 07, 2019, 06:49:06 pm »
I was able to locate a dial indicator to see if the rotors were bent. The dial indicated a .005 variance, so I don’t believe that’s my problem.  I still come back to my homemade constant brake pressure test.  As I rolled the wheel with constant pressure on the lever, there is medium resistance for about 80% of the rotation, followed by hard resistance and then light resistance.  Every rotation is the same, it gets heavy and then it gets light, then back to medium for the other 80%. 

Could it be that one of the rotors is thicker/thinner in that spot?
2009 GTR 1400 ABS, 48k miles, AMSOIL synthetic 10W-40 (since new), AMSOIL synthetic 75W-90 final drive (since new). Helibar Horizons, Symtec heat demon grips, V-Stream windscreen, Mountain Runner Flash, Brian’s low fuel eliminator farkle, ST2 smart brake module and smart turn system, Two Brothers Black Series M5 w/P1X decibel killer.

Offline jwh20

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Re: New EBC rotors/pads install and BAD shudder! Help!
« Reply #4 on: October 11, 2019, 03:30:15 am »
I was able to locate a dial indicator to see if the rotors were bent. The dial indicated a .005 variance, so I don’t believe that’s my problem.  I still come back to my homemade constant brake pressure test.  As I rolled the wheel with constant pressure on the lever, there is medium resistance for about 80% of the rotation, followed by hard resistance and then light resistance.  Every rotation is the same, it gets heavy and then it gets light, then back to medium for the other 80%. 

Could it be that one of the rotors is thicker/thinner in that spot?

Runout, at least not 0.005" of runout, is not going to cause this "shudder".  The more likely cause is either inconsistent friction characteristics along the surface of the disc or a thin or thick spot as you have noted.

You can rule out the thin/thick hypothesis by measuring the thickness at a number of points around the surface of the discs with a micrometer.

As far as friction characteristics, is it possible that some contamination ended up on the rotors?  Could something have been spilled on the rotors that corroded them?

Offline Rubber_Snake

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Re: New EBC rotors/pads install and BAD shudder! Help!
« Reply #5 on: October 11, 2019, 01:01:05 pm »
Runout, at least not 0.005" of runout, is not going to cause this "shudder".  The more likely cause is either inconsistent friction characteristics along the surface of the disc or a thin or thick spot as you have noted.

You can rule out the thin/thick hypothesis by measuring the thickness at a number of points around the surface of the discs with a micrometer.

As far as friction characteristics, is it possible that some contamination ended up on the rotors?  Could something have been spilled on the rotors that corroded them?
Thanks Jdub. 

The rotors are new and clean.  I do not suspect any contamination.

This morning, I measured both rotors with a micrometer.  I believe my hypothesis is correct.  The right rotor was consistent with measurements of .1990~.1993” around the entire rotor.  The left rotor was inconsistent, giving me the following measurements as I went around:

Suspected low area (which is about the length the caliper):
.1982”
.1974”
.1972”
.1976”
.1981”

Suspected high area:

.1980”
.1985”
.1990”
.1990”

And the rest of the rotor as a went around:

.1987”
.1985”
.1985”
.1985”
.1984”
.1983”
.1983
.1986”
.1984”
.1986”

So I guess I’ll contact Murph and see what he thinks. 

Any thoughts from the resident pros?

Ray

« Last Edit: October 11, 2019, 06:00:40 pm by Rubber_Snake »
2009 GTR 1400 ABS, 48k miles, AMSOIL synthetic 10W-40 (since new), AMSOIL synthetic 75W-90 final drive (since new). Helibar Horizons, Symtec heat demon grips, V-Stream windscreen, Mountain Runner Flash, Brian’s low fuel eliminator farkle, ST2 smart brake module and smart turn system, Two Brothers Black Series M5 w/P1X decibel killer.

Offline jwh20

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Re: New EBC rotors/pads install and BAD shudder! Help!
« Reply #6 on: October 11, 2019, 02:42:25 pm »
.1990 - .1972 = 0.0018"  that's a HUGE delta.  I believe the spec is 0.0005".  So you're more than 3X the limit.