Mike S.

I know...you guys must think I'm being a constant complainer lately, but something isn't right.

Setup/History: Car has ~40K miles, standard brakes. Front brake pads/rotors NEW, about 10 months ago. Nissan/Infiniti parts, installed at dealer. Rear pads and rotors NEW this past April.

My problem is a soft pedal/too much travel. There is PLENTY of pad left as the hardware is in great shape. I've complained to the dealer and they drive it and think its fine. However, here are some weird symptoms:

The pedal firmness seems to change with RPM, which makes me think its a vacuum leak/booster kind of thing. For instance..sometimes when I'm in a hurry I might not really let the car warm up. I might start it...high idle rpm...wait about 5 seconds and then put it in reverse to back out of my driveway. So, my foot is on the brake and the pedal actually feels firm (but the rpms up at say 1500). Then as I put it in reverse (and the ecu smartly lowers the rpms a lot BEFORE engaging reverse), I can feel my foot sink a decent amount as reverse engages.

In summary, my brakes are the opposite of "grabby"...something a 2012 G Sedan (non sport brakes) was just rake over the coals for over at cnet.com


Any help?

Dj1ofDet

iTrader: (5)

If your car is or isn't under warranty, I'd just drop it off at the dealer and have them diagnose it. When something's wrong with my Cadillac I can't figure out, a full diagnostic runs around $120. I can then take the report to a more reasonable repair facility, other than the dealer.

Mike S.

Yes, it's still under warranty.

Another thing, when the car is off, I can pump my brakes 3 or 4 times and get the pedal nice and hard (thats how it should be right?). Then, while my foot is resting on the rock hard pedal, I'll start the car and my foot will sink a good couple of inches.

CodeG

Your brakes may have air, just need to be bleed again.

JSolo

iTrader: (14)

I do believe the pedal will go further to the floor with the car running than when off. Has the amount of effort required to stop the car changed or brake feel changed recently?

When waiting at lights or similar, does the pedal slowly sink to the floor if you maintain a constant pressure (that is, enough force to keep the car stopped)? If so, that could be a sign of internet MC leakage. Brake Master Cylinder Troubleshooting

The above poster is right though. If the brake system has never been bled or flushed, now is a good time to do so. Your info doesn't specify whether it's an 09/10, or whatever year, but even so, it's something that's recommended at least every 2 years, more so if you drive/brake hard often.

da mayor

iTrader: (2)

have you changed the fluid yet?

Mike S.

More info:

Car is an 09 G37xS (so non-akebono).

The pads and rotors when replaced (both less than 10K miles ago) were done at an Infiniti dealer with Nissan/Infiniti parts. I hope the used OE parts but I guess I actually never asked.

I would imagine they would have bled the lines when doing the brake jobs (front and rear were done at two different visits).

I have however NOT ever had the lines flushed/changed.

The pedal does not really sink at a stoplight. The car stops, but there just seems like too much pedal travel. I swear when the car was new, the brakes were much more firm. I understand the car has 40k miles now, but new brakes should perform the same as a new car (unless of course older fluid is hurting it).

da mayor

iTrader: (2)

open the hood and check the fluid level

Mike S.

Yup fluid level is fine, just at the full line or maybe a touch over. Looks clean. Interior of the compartment is clean, no leaks from the MC or the steel lines or overflow from the cap.

Lou@Amplified

iTrader: (26)

I'm almost sure you need to flush and bleed the brakes, that should fix the problem

JSolo

iTrader: (14)

Mike, flushing/bleeding is not normally part of a brake job (though it should be) unless you pay extra for it. At 40K, it's the first thing I would do. Since you're not doing the labor yourself, bring it to someone you trust to do.

FWIW, i've test driven at least 6 or 7 g37's (mostly S models in coupe and sedan styles, few X and reg journey) in recent weeks, they all were 2008 or 2009 models, from 12K to 30K miles. They all seemed to have an initial amount of small pedal travel before the brakes started engaging. Might just be the nature of the beast. But, if you absolutely remember that not being the case, test drive a new car(s) and see how those are.

blackhawksfan81

http://www.infinitig37.com/TSB/ITB00-024e.pdf

Page 5 of this TSB refers to pedal feel.

JSolo

iTrader: (14)

There's a spec for pedal play.. Both of those #'s are very small, less than a half inch combined.

I still think the OP needs to test drive a car or two to see what those feel like.

From the 2010 FSM


Brake Pedal
Unit: mm (in)
Brake pedal height (H1) 171.5 – 181.5 (6.75 – 7.15)
Clearance (C1) between ASCD brake switch threaded end and the stopper rubber 0 – 0.6 (0 – 0.024)
Clearance (C2) between the stop lamp switch threaded end and the stopper rubber 0.74 – 1.96 (0.0291 – 0.0772)
Brake pedal play (A) 2.0 – 8.0 (0.079 – 0.315)
Brake pedal shaky fitting (B) 0 – 1.4 (0.0 – 0.055)
Depressed brake pedal height (H2)
[Depressing 490 N (50 kg, 110 lb) while turning the engine ON]
124.0 (4.88) or more

Mike S.

The last time I had my car in for an oil change (I get free ones at the dealer), I went home with a ~10k mile used G25 loaner. As I was pulling out of the parking lot, I felt like I almost was going to go through the windshield, that the the brakes were that much more touchy. I'm due to be back there in about a month or so. I'll ask them again, and probably pay for a flush/bleed of the system.

maxfinity

I just had my 30k miles service. I have the factory service plan. I don't think a brake flush is included with it but the dealer flushed my brake system anyway. My brakes grab so much better now. Makes the car feel new again. I suggest you have your brake system flushed.