Suspension/brake problem - slight shudder and left pull

PharmDZ

Hey everyone - I've had a chronic issue now with brake shudder and my car pulling slightly left (which becomes annoying on the highway when you have to keep the wheel slightly right or it'll veer off).

First off, the brake issue. I used to use hawk HP+ pads along with the stock rotors with Z1 stainless lines and motul RBF600 fluid at the track and autocross. After a few HPDE sessions I found that under braking at highway speed the wheel was shuddering pretty bad. I tried rebedding but ended up just getting a set of Z1 two piece rotors instead. This initially fixed the problem, but after another track session and a few autocross the problem resurfaced. I had also installed the Stillen brake ducting last year to help prevent over-heating issues. I then noticed my two piece rotors had the internal vanes running in the wrong direction, and replaced them with new Z1 two piece rotors. Since then I've been running EBC yellow stuff pads, and needless to say the problem with brake shudder is back yet again. I started noticing it again at highway speeds, and I really want to get this ironed out before racing season is here again. I did bed the pads in correctly. Should I try re-bedding them? I've read enough to know that warping shouldn't really be an issue, especially with the precautions I've taken to prevent the brakes getting too hot (and also never sitting on the brakes coming off the track when they're hot).

Onto the second issue... I had replaced my stock tires on the Rays sport rims with Hankook RS3's 275/35r19 square and since then have had some issues with the car pulling. I've had the alignment redone and rechecked multiple times and it isn't an issue. The shop who originally put them on even rebalanced the rims/tires. On the highway I have to drive with the wheel slightly turned to the right to stay straight or it'll veer off left (not violently, but it doesn't just track straight on a nice flat piece of highway like it should). Are there any other suspension parts I should be concerned with here? Or could it be an issue with the tires themselves? Seem to be wearing fairly evenly, but I don't want that to continue and mess up the tires as well. I do have adjustable front/rear camber arms and I am due for another alignment/corner balance in March. Just wondering if there is anything else I can investigate in the meantime.

Sorry for being long-winded. I just want to be 100% sure that the car is in working order before bringing it back out to the track and giving it the beating it deserves

FL 4Motion

Sub'd

Wish i could give you an answer. If you've rebedded the pads, then i doubt the brake shuddering is deposits/"warped rotors". What are your lug nuts torqued too?

Fat tires up front will tramline and pull the car around more but it doesnt sound like tjats the issue. Could you have a bent suspensipn component? Then again, with adj arms etc, even if there was a bent part, your mech could have aligned the car and evened everything out anyway.

What is your alignment settings btw?

PharmDZ

Thanks for the response FL. I do know that bigger front tires can track a bit, but like you said this doesn't quite seem like that since it's favoring one side. I'll find my alignment settings from last year. I know it was -2.2 front -1.6 rear, not sure on toe. Had a corner balance done with RT Tuning which made the car feel great. The car is going back to them in a few weeks and I'll have them give it a once over. Also, now that I forgot previously, my other set of rims, Enkei PFo1's with r888's did feel better in terms of the tracking and brake shudder. The rims I'm driving on now have never been curbed or hit any potholes though. Wouldn't think they're bent. But maybe something I can't see?

AdamRacer

I notice the same exact issue but my steering wheel vibrates and it'll only pull towards the left under braking. I keep thinking my rotors are wrapped since they are stock and haven't been turned either. As far as the pulling left under braking I'm not sure about that and would like to know as well.

Spooler

I am not sure on the 370z but on other models a common issue with pulling left while braking was due to the rack/pinion bushings needing to be replaced. I haven't even look under my car to see how they have the rack/pinion setup.

PharmDZ

The pulling for me is a constant thing. Doesn't pull any worse while braking though.

Rusty

Brake rotors. Take them off and put them on a brake lathe to check for run-out. You might have to kiss them alittle.

Tires. Sounds like you might have a radial pull. Did you try rotating the tires. LF to RF. RF to RR. RR to LR. LR to LF. Since you are square.

You said you have adjustable control arms. Which ones? And want is your caster left and right?

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boosted180

I have the same problem with brake shudder at high speeds under hard braking.

I haven't tracked my car in almost 2 years and hardly drive my car on the street, so I haven't looked closely into trying to fix this problem, but it's been there for quite some time.

At freeway speeds (70+mph), if I get on the brakes hard (like slowing down for an exit ramp), it shudders badly. Then if I get off the brakes and back on again, it's ok. It's almost as if the pads weren't properly seated and then after the initial hard braking, it's fine. Then if I speeded up again and got on the brakes again, no problem. And even the initial braking, it only vibrates and shudders if I brake hard.

I just want to get this taken care of now b/c I want to start tracking again.

Another problem I've been having is weird clunking, chattering, noises in the suspension (I think it's the suspension) that only happens at low speeds. Like driving around in the parking lot. It happens most noticeably after I've been driving fast and slowing down quickly and then steering. Not sure if it's related to the braking issue.

I have stock wheels and NT05's stock sizes. -2.25 camber front and -1.75 rear, and a hint of toe-in in the rear (don't remember exact number).

Sway bars with aftermarket end links, adjustable camber arms front and rear, Eibach springs, everything else stock.

I found that the ball joints on the control arms in the front are worn out and ordered new ones. Could that be causing the clunking noises?

I was going to resurface the rotors and see if that helps with the braking, but I don't think that's the problem since if it was warped rotors, the vibration/ shudder would happen all the time, not just on initial hard braking. I think the pads are not seated or something more along those lines??

FL 4Motion

I wonder if the brake shuddering a few folks inc the OP are describing might be related to the oem akebono calipers? Seems like everyone with the problem has or is currently tracking on the stock calipers. Perpaps one or bothhave warped somhow or the pistons are messed up in one of them?

With toe settings at 0 or slight toe in in the rear, the cars should be tracking straight at speed so it doesnt appear to be a toe setting issue, that was why i mentioned it earlier.

Could the left caliper be not completely releasing and cause the car to pull ever so slightly to the left perhaps?

These are some strange issues.

Rusty

I'm tracking with the Akebono's with no problems. I also run a Hard Brake heat shield between the pads and pistons.

Another thing too. Might have one piston hanging up in a caliper. But you could see that in pad wear.

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FL 4Motion

Yeah, it was a wag since im also running the stock akebonos with no issues and did so as well with the last nismo for 3 years but this is a strange problem and im curious as to the resolution so i thought id throw it out there.

PharmDZ

And pad wear does seem even/fine as I have changed the pads (and rebed them) often in the past. Been riding consistently on my EBC yellows lately though. I'll get my camber specs - I know they're around here somewhere. Also, since I had the corner balance/alignment done last year I wonder if it's still in spec now. I have SPC front arms and the eibach rear camber arms. I know they're not SPL, and I do put them through some abuse. I guess we'll see what it shows in March when I go for my re-alignment. I'll try a few of these things in the meantime. Thanks again for the input guys. If anyone has any other thoughts please let me know!

Robert Yuras

As far as the braking goes: I have the same left hand pull, regardless if I'm on my track pad setup or street pad. As previously stated, an initial threshold braking period, the car will pull; but a trail brake or slight set (medium braking) and it goes straight. I believe it could be contributed to the yaw control on the vehicle or possible the ABS unit firing in an odd manner. In the past these problems were normally associated with hanging calipers (as Rusty mentioned) or worn out brake lines. Doesn't sound like any of us have that issue. The problem really becomes aggravating when you're sailing off into a turn at 140 mph and trying to downshift WHILE keeping the damn wheel straight.

As far as the OP's pull while normal driving (and not braking): I'd get a soft tape and check the roll out on those tires. I've seen street tires be off by an 1" (The original Falken Azenis especially), which will obviously cause issue. I think it derives from different production run numbers of tires being mixed.

PharmDZ

So I can't believe it's taken me this long to figure out, but I think I finally know where the problem is coming from. A while back I had an incident where a shop had taken my Enkei PF01's off the car and thrown my Rays on forgetting that the right front PF01 left it's hubcentric ring on the hub. They bolted up the wheel and drove the car, and when they realized the ring was still on and the car was driving funny they took it back in and discovered the problem. I think the wheel bolting up over the ring and onto the hub caused some damage to both the hub and the inside of the stock Rays wheel. That's why I get the problem slightly when the PF01 are on (those wheels aren't damaged, but the hub may be slightly) but when the Rays are back on the shudder becomes MUCH worse. I took some pics, it's hard to see but the inside of the wheel that sits on the hub is nicked/bent up pretty good in spots. Either way, I ordered a new hub and we will see what happens.

Rangerz

I had a similar problem where the driver side wheel would shudder badly under hard breaking at the track. When i did the SPL bearing swap i had to pull my rotors off and the inside of both rotors had burn in deposits in the shape of the pad. I used some break clean and steel wool to clean the deposits off and the are back to being smooth a silk. Apparently after a session i sat with the breaks applied No No that i know is not ideal. I would check that first then maybe get them turned or replaced.

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