Brake job, now brakes pull the car left
 

At 35,000 miles I had what seems to be the common vibration fate of the stock 4-pisont sport brake system.

I had the stock rotors turned when the brake shop said they could be, so that saved me a bunch of cash. I used brand new Hawk HPS pads all around, using care and TLC in applying the Hawk included grease to the backs of the pads, shims, and any metal-to-metal touching points, also making sure not to get any of the stuff on the pad itself. With a familiar friend in the garage, we bled all four corners per the factory manual specificaitons (RR / FL, then RL / FR) and added new fluid to the master resevoir after every corner completed. I never let the resevoir level get as low as 'low' always filling it back up to the very top for each corner bled.

The braking vibration has been a thing of the past which was the beast I was initially after.

Now and after about 2000 miles I'm sure the system is fully broken in; the car pulls left under hard braking. :shakes head: Most of the times I also feel the steering wheel try to pull in the left direction, and under a "panic" braking condition I can just about lock up the front left wheel while the front right has less braking power. The last interesting symptom is measured with my IR temperature gun, where the FL rotor will always run about 25% hotter than the FR. The RR runs 25% hotter than the RL.

This weekend I was having to hammer it down for a lot of turns for mountain roads. When the car hunkered down it often wanted to vear toward the center of the road and became quite the choire and just another thing I had to manage and monitor while driving spiritedly.

So far my only trials have been with re-bleading the FR/RL corners thinking there is some kind of air in the lines. I've now bled the lines 3 times to no avail. My next best guess could be something gone foul with the master, or perhaps a flexible brake line got damaged. I've thought of getting aftermarket SS lines but really dont know if that would help or just exaserbate the issue.

Any clues?

Did you follow any kind of "bedding in" process after you had the job done?

First, check your tire pressure in all of your tires....

if they are good, than chances are you either have a air pocket in your lines, or a caliper seized.. if they worked for 2,000 miles Im willing to bet you may be low on tire pressure...

I did follow the proper bed in with the hawk pads to the t.

the pulling has happend sice the first day out, only its worse and noticable in a real hard situation so 2000miles ive learned to live with it. i was just hoping breakin was still present even after bedin so i gave it 2k. now im tired of the problem.

Stange thing i can do is; if i press the brakes all the way to the floor for a few seconds standing still then take the car for an agressive stop the pulling seems to be better temporarilly.

ive bled the lines of the weaker fr/rl corners four times to no avail.

You bled both sides of the calipers right? It's definitely not the master cylinder as that gives equal pressure to the front brakes, seems as though you have something weird going on with the right front caliper. I would unbolt the caliper and check the pads at this point and look for uneven wear - this telltale sign of a sticking piston (which also would generate the shudder in the first place).

Yup. Outside then inside of each caliper.

To me that seems like a logical step. I'll go ahead and take a look at this later on today. Thanks

I had something similar happen on my truck. Worse at high speeds. I sort of ignored for awhile.

But when I went to fix it, it was defiantly a stuck piston. So if it's pulling to the left it's going to be the caliper on the right with the stuck piston. Well, that was my case. I assume brake systems could play various types of games on you. The pad was wore down to the wear indicators on the left side while the right was hardly wore. Being older truck I just replaced both calipers.

But yea check for uneven wore pads, then bleed hole system again, and check tire pressure.

For a truck with a floating caliper (what most cars and light trucks have) it would be a stuck caliper slide pin, not a stuck piston. But in this case with sport package the caliper is fixed, base is sliding.

Oh ok. Same principle I assume.

More or less, just could have saved yourself a few bucks in that case and just got the slide pins :) Although sometimes they seize up in the bracket so you have to replace that too (but not the caliper). I've had a stuck piston on my truck calipers a couple of times, you know that is happening because you'll smell burning as the pad drags on the rotor generating a lot of heat. I can usually fix that with a $2 piston seal.

Yea. But also that same caliper had a burnt look to it. Plus I also get 45% off with my account at O'Railly.

to me sounds like the brakes were not bedded properly due to lack of pressure caused by air bubble in the brake lines.

i would remove all the pads and clean the pad surface using sand paper, bleed the brakes, and re-bed. should work. :)

UPDATE:

Thank you for all the heads up. At this point I think things have gotten slightly better for my brakes but there is still something a bit wrong here.

I took the following steps to help resolve:


1. I broke down the front right caliper but noticed nothing out of the ordinary. All four pistons were able to be pushed in/out by hand without much binding - rules out any caliper siezure. I checked the wear even-ness and rotor for antyhing out of the ordinary but found symetry and evenly worn parts everywhere indicating no binding.

After doing this the problem was still apparent.

2. I bled the rear-left outside then inside followed by the front-right outside then inside calipers. I noticed no trace of airbubbles nor pedal feel changes.

After doing this the problem was still apparent.

3. I got real mad about this whole spiel and stomped on the brakes all the way to the floor with both feet about ~10 times while the car was running by stationary. The funny thing is, this seemed to partially do the trick! :confused: its not 100% perfect as the car still drifts slightly left, but its about 75% better than before to the point where I dont get surprised then I press the pedal hard anymore.

Do I maybe have a collapsed or kink in one of the brake lines?

Any thoughts?

The only thing I can think of that's remotely possible is maybe the brake line needs replacing? Pretty inexpensive part and worth a shot.

I also wonder if there could still be some air in the ABS module? Seems I remember Reading something of this due to it's hard to get air out of the ABS if it gets in there. Just thinking out loud.

Find a nice big open space and stomp on the brakes as hard as you can from about 40 mph a few times. When they pulled the caliper to get the rotor off they may have not supported the weight of the caliper and left it danging by the hose which could have done some damage. New stainless lines might be a good idea.

Caliper issue.

Have you checked the tire pressure ? And how new/old are your tires ?

I know it sounds dumb but if your 7/8 psi off it could pull the car.

If not that I say a bad line.

Update:

I just replaced the factory lines with aftermarket stainless ones built by Forged Performance; plus sucked out -all- the fluid and filled it with fresh Motul Dot4. Seems the problem is much much better now; to the point where I'd have to say its just about perfect. One things I did still notice is that the after a few hard stops I get out to check the termperature of my rotors with an IR Heat-gun. i find the left front is still running about 5-9% hotter than the right front, but the rear rotors now equalize in temperature.

So I'll have to give it a few days, but so far so good and the car brakes a bunch better than before. I'll probably give it just a few days and bleed the brakes one last time before I call it quits.

Either I had some air or a kink in the lines.

:tup:

Well, It's been about a year since I had to deal with this issue. To date I've done the following:

Car now has 52,xxx miles, with about 20k on the brakes.
Changed the lines to stainless and the fluid to Motul.
Bled the brakes from the caliper side of things about a half dozen times.
Bled the ABS unit one time

By now I've learned to just live with the problem, where under normal driving/braking theres not much issue. Still though, under severe braking I am able to get the front left tire to almost lock while the right is still operating at about 90%. You can imagine the car does tend to wonder/vere to the left. For the past I've burned into my brian - countersteer under hard braking - if there is such a thing. My best car buddy drove my car the other week and said he hated how my brakes react and recommended I bleed them again.

So now I'm back on top of this. Could there be a problem with the master brake cylinder not applying even pressure to both halves of the system? its about the only thing I have left to check. Also now since I have a bunch of miles on these pads; I'll probably check again for un-even wear for a stuck caliper.

Any other ideas? I found some online place which sells rebuild kits for calipers so thats a good avenue. What about master cyl rebuild kits?

Can't be the master cylinder, because it applies equal pressure to both sides of the brake circuit.

On most cars, the brakes are split in diagonals. LR with RF and LF with RR. This is so that if something happens to one corner, you still have "even" braking. Since your issues were originally with the LF and RR, I'd say you've got an issue with something after the split.

The master cyl has two outputs connecting to the ABS unit. Are both outputs in series and paths linked inside of the ABS module? If this is the case, then you are right the master has nothing to do with the issue; otherwise I do notice the master has two outputs on it.

I just bled all the pipe fittings from ABS module back to the master cyl (8 fittings total) and no difference in braking distribution. I almost want to unbolt the ABS module and level it out or even shake it a bit; bleed one more time. I'll check into this.

Another thing I notice is the F-to-R conenctor which appears to be on top of the passenger wheel well. The service manual: http://www.nicoclub.com/FSM/370Z/Coupe/2010/BR.pdf , page BR-22 is showing a physical connection labeled A or 2. I'll have to check this piece out to see if any air might possibly be trapped inside.

I'm not sure if it has helped yet, but I bled all four fittings on this connector. its located passenger side front wheel well behind the rear plastic mud guard.

http://i886.photobucket.com/albums/a...403_201254.jpg

It sucks that your are still having this issue. I feel the problem is in the caliper because you say the problem goes away when you press hard on the break, essentially setting all calipers in a uniform position. But over time the issue returns, a caliper becomes unset with the rest. As to what part is causing it I have no idea and I doubt it would be easy to notice by inspection.

2011 Nismo, actually the optosite happens. When I press the brake really hard, the front left wheel will lock before the right, and the car will tend to rotate slightly left. Light duty breaking does not always reveal the issue.

After bleeding the above connecter I think things have gotten a tad better.

I called some places and searched online, but then I totaly scored a win! I must have the best (alas RedNeck) Pawn Shop in the state just a few miles from my house. They have so many pro mechanics tools its not even funny. I picked up a ($350 - new) brake line pressure tester built by KentMoore model J-39729 for a mear twenty-five bux! What a steal. It looks the the former owner/technitian also modified these also with an on/off bleeder valve. - NICE!

Its a little old/rough, but for accasional usage I think will do just fine. I just finished cleaning it up and re-doing all the NPT fittings with new teflon and air pressure tested them acurate to 125PSI. What do you think? I'm hoping the end fitting will screw into the calipers.


http://i886.photobucket.com/albums/a...404_123404.jpg
http://i886.photobucket.com/albums/a...404_123408.jpg
http://i886.photobucket.com/albums/a...404_123421.jpg
http://i886.photobucket.com/albums/a...404_123358.jpg

Nice Find

This is what I meant about pressing hard on the break. I wasn't clear in my first post.

*UPDATE*
I think I've confirmed the problem using the above brake line guages, but just wanted to post the scenerio observed.

Rear brakes: With the car running, both guages are able to hit ~1300PSI. Both gauges react at almost the same time, in the same way/fassion. Smooth pressure rise on the guages.

Front brakes: The FR (which I believe has always been close to the worst or problem) measures fluid pressure much slower than the FL. With the engine running, the line pressure will reach ~1300 PSI on both sides, however the rising rate of the left is greater/faster than the right. Under gental brake engagements, the FR sometimes does not measure at all or takes up to 2 seconds to even poll a reading, while the FL is as-soon-as the pedal is pressed.

More observation on FR: If the brakes are pumped hard a few times, the presure seems to be get better; both FR/FL will pressure rise at the same pace after being pumped. If the brakes are left to sit for maybe 30 seconds, the FR will then start to delay in rising pressure.

Summary, RR, RL, and FL all react the same - pedal and instant pressure. FR has a slight delay of 0.5 to 2 seconds depending on pressure applied, and if pumped.

Solution: Bleeding isnt helping at all. I've literally bled about 1Q of fluid through this thing in over a year and nothing has improved.

Should I try rebuilding FR caliper? SHould I rebuild both FR/FL at the same time? Am I missing something? Right now I am thinking that since/if the FR caliper is seized, that is it retracting/reacting slowly and causing pressure to be lost inside. I'm kind of thinking a piston resisting it's new place is heading back inside of the caliper; where re-presurizing requires time for the piston to move back out in play. Does this sound correct?

Those tools look really useful, nice find!

They are being connected at the bleeder on the caliper, right?

If so then whether the caliper piston moves or not is irrelevant, the pressure within the caliper should be equal on both sides. Now, if there is a pinched line or hose somewhere leading to that FR then you would have the result you indicated, slow pressure build up in the caliper.

Chris, You could be right.

I'll try and check the brake line pressure before the calipers to rule them out - I'll take the calipers out of the loop. I'll have to come up with some adapters or bypass a line or so, but I dont see this being much trouble tapping in just before the calipers for a good test.

In google searching, seems either a restriction somewhere upstream or a faulty caliper are both culprits.

Did you measure at both the inside and outside FR bleeder? It would have to be some kind of debris within the caliper if there was uneven pressures side to side. Other than getting crud inside or a stuck piston due to a bad seal (usually) there isn't much that can go wrong with a caliper.

Is there an update to what was wrong with the car pulling to the left?

I have a 2010 Nismo and I have steering wheel and seat vibration at certain speeds, and under braking. The car pulls right as well. Here is what I have don't to try and fix the problem:

New tires
Road force balance
New rotors and pads
New brake fluid & several bleeds

To answer any obvious pieces of advice:

I've ensured tire pressure is always the correct pressure
I've had several alignments and tire balances.
The old rotors/pads had this problem and now have been replaced.
Rotors/pads were imbedded properly.
Pads have even wear as far as I can tell.

What is next in figuring out how to fix the steering wheel/seat vibration under braking and not braking? As well as the pulling right under braking.