resurrecting this post...finally getting around to cleaning up my rusty brake components this weekend and doing a Google I came across this

Little pricey at $30-$40 depending on retailer but seems like a good concept. I plan on using a wire brush attachment on my Bosch since its free

 

I have an attachment like that for a power drill. Works well. It was cheap

 

I may have finally solved the judder issue. First a little history. Bought 2010 Journey Coupe new. I think it probably had a little judderfrom the start which got worse over the years. Above 50 mph the front end judder when braking only. Mostly from the front right, there is minimal pedal vibration, mostly feel it through the seat and a little through the steering. Makes a loud rumble also, the faster you go when braking the more it shakes, especially going downhill.
This past year I decided to attack the problem, have my own lift, tire changer and corghi balancer so could try a lot of things. Also do my own alignments using small magnetic digital level attached to the rotors for camber (rear only) and smart strings for the toe.
First the brakes. Replacing rotors and pads twice did nothing. Rotor runout reduced to less than .002 using dial indicator and set screws in the rotor hat.
Replaced lower control arms, sway bar links, strut cartridges, right upper control arm, hub bearing assemblies, right front brake caliper, inner and outer tie-rod ends. The car handles great with all these new components but if anything the judder is worse.
Pressure bled brakes. Could not get all the air out of the right front line the first time, but read on to learn how I finally got all the air out.
Ok, so now I tried shimming and adjusting everything I could. There was some play in the steering rack bushingpassenger side, shimmed the bushing with brass shim stock. Side to side play in the sway bar eliminated by moving the collars inward slightly with a hammer. New gaskets where the struts contact the body. Shimmed the brake caliper sliding pins-brake pedal noticeably firmer but judder same or worse.
Turned attention to the ABS. Disconnected harness to ABS pump and went for test drive. No change in judder. This is where I started thinking outside the box. The G37 uses a split circuit brake system. The rear brake line coming off the master cylinder goes into the ABS pump/module then splits into 2 lines-one to the LF caliper and one to the RR caliper. Likewise the master cylinder front line feeds the RF and LR calipers. This is why the bleeding sequence is RR, LF, LR then RF. The system is designed this way as a safety feature for something called change mu braking. The solenoids inside the ABS module are supposed to keep the LF and RF line pressures equal, but it is easy to see how a bad solenoid or an old master cylinder might cause unequal pressures.
So this is my latest test. I switched the RR and RF lines coming off the ABS module. Now the same brake circuit feeds the LF and RF calipers, and the same brake circuit feeds the LR and RR calipers. This is the way brake systems used to be designed before ABS. Went for a quick test drive at just to make sure it was safe. Didn’t get up to speed but I did notice the car brakes very straight. It braked straight before but there would be a slight twitch at first, which is now gone.
The problem with doing this is if there is RR wheel slip, the ABS will now apply braking to the RF wheel and vice-versa. Potentially dangerous so I probably will turn off VDC next time I go out. In my experience VDC mostly works by cutting power instead of selective braking so I think it should be ok.
Finally, I pressure bled the brakes but with the ABS harness disconnected. Got all the air out. The fluid flowed noticeably slower than with the harness connected.
Test drive tomorrow will let you know how it worked.

 

Original reason for dual brakes was to retain some braking power if a line failed. ABS just puts extra stuff on the circuits.

Interesting read on all the stuff you did. Sounds ABS module is at fault.

 

Back to square 1. Switching the RF and RR brake lines had absolutely no effect on the judder. Running out of ideas at this point. I’m beginning to think it is a design flaw with the G37. The dual wishbone suspension creates a large positive scrub radius which amplifies any vibration. This could be why the wheels have so much offset, to reduce this large scrub radius. 43 mm of offset maybe isn’t enough though. Seems that dual wishbone suspensions worked better when cars had spindles, it allowed smaller scrub radius. Perhaps this is why most cars use Macpherson struts where the top mount acts as the top ball joint and the strut rotateswhen you steer. The projection of the steering axis is farther outboard, minimizing scrub radius.

 

I don't think the suspension design is your problem. You've checked run-out on the rotors but you haven't indicated that you checked the wheels for either radial or axial run-out.

Did you swap left and right front wheels to see if the rumble followed, indicating a wheel or tire problem?

 

Well I don't think the break in will fix pedal vibration with already warped rotors. But it is a must do when you put in new rotors and pads. You mentioned "slight" pressure, I always light up my brakes, going as far to almost lock them up going 50. Slight pressure might not get you to smell the brakes if you are making a few passes back n forth, meaning not getting enough pad to transfer on the rotor

 

These days, rotors normally don't warp. The pulsation is caused by uneven pad deposits on the rotor. Several HARD stops in quick succession will usually remove the deposits. Heck, it costs nothing to try it.

 

I used to bang my head every time I saw somebody write "my rotors are warped".

Lately, I just let it go. It's like yelling at the wind.

 

You guys must not tell people to "roll their windows down" either, right

 

Old habits die hard. What verb do you recommend?

 

I actually did replace one of the wheels and tried it at different positions. No change in the judder. From what I've gleaned from this and other threads, when you torque the lug nuts you induce a mild sinusoidal pattern in the hub flange which gets transferred to the rotors. At the factory the rotors are probably turned on the car, and this is probably what the dealer does to address this problem. But the problem always comes back, sooner if you remove a wheel.
So why don't other cars get the judder as bad. Probably due to the large positive scrub radius I mentioned before which is characteristic of the dual wishbone suspension. Also the G37 and 370Z have notoriuosly poor brake cooling.
I love my G in all other aspects so I'm just going to tolerate the judder. I suppose getting 2 piece floating rotors would solve the problem but I'm not going to spend $500 or more on that, if they're even available for the non-sport model. BTW I previously had a 2008 G37 sport model that suffered the same judder.

 

I still think you are off-base with your suspension comments.

Lug nut torque is hardly enough to flex the hub or rotor hat; besides, they're not far enough out to induce any significant warping in the rotors. Big rigs, maybe. Cars, don't think so.

I'm still mulling over your situation. Hope to offer another suggestion...

 

If he didn't use OEM rotors and pads and used some other cheap shyt made in china that might be the root cause of his problem?

I'm on my third Infiniti and only had brakes replaced once at the dealer on my 06 G35 6 speed at 86k miles. New pads and they turned the rotors on all four wheels. Was perfect when I drove it out and those same pads and rotors were still on the vehicle when I traded it in at 171796 miles.
On my recently traded in 2012 G37S with 94444 miles I was still on the original pads and rotors with about 5mm left on the pads.
Never experienced any brake judder.
Perhaps he is just over his head and needs a brake pro?

Telcoman

 

yea just strap on some centric rotors and akebono pads. I have had great luck with that combination (at low price too) on multiple cars...Just make sure you break them in the right way.