Lumpy350z

I recently upgraded the brakes on my 06 base model Z to track brembos and am having trouble getting any proper brake pedal feel. I installed the track brembos which I rebuilt, SS lines, and Hawk HPS pads with brand new rotors. I unfortunately did end up allowing the master cylinder to bleed almost dry. After having trouble getting what I first thought was air out of the system even using the Motive power bleeder I ended up taking the car to the dealer where the master cylinder was bench bled and then everything else was bled.
Now the problem is that the brake pedal is still not right. When I press the pedal it seems to barely do anything for the majority of the pedal travel and then only starts to really bite and stop the car near the bottom of the pedal. Does anyone have any suggestions or idea as to what the problem could be at this point? I am currently planning on taking the car back to the Nissan dealer who seems sure there isn't air left in the system on Monday. Could it be related to the Hawk HPS pads? Any help would be much appreciated!

dkmura

iTrader: (64)

Depending on whether you properly bed in the Hawk pads, you may have glazed the surface. Take out the pads and inspect them, If glazed over, use a #200 grit piece of sandpaper and a sanding block to get the glaze off. Also take a good look at the rotors and see how worn/glazed they are too.

But my guess is you still have some air stuck in the brake lines, so try bleeding them AGAIN after they get a bit of heat in them. Might take some time, but between checking and eliminating glaze and getting ALL the air out, your brake pedal should be firm and easily modulated at the top of its travel.

Lumpy350z

Thanks dkmura! I appreciate the input I will definitely check out the pad and rotor surface. I did not have a chance to bed in the pads myself before resorting to taking the car to the dealer to get air out of the master cylinder, and they told me that they bed the pads in. I never told them what pads they were so could it be possible that they did not bed them in correctly and instead glazed the pads?

dcains

iTrader: (15)

The Z is notorious for being difficult to bleed if you let the system run dry. Best bet is a pressure bleeder and a good amount of fluid and patience.

terrasmak

iTrader: (8)

Exactly , after letting air into the system it takes multiple days of bleeding to get it out

Lumpy350z

Okay, so while bleeding again I noticed that on the rear calipers on both sides the inside pad was not contacting the rotor and the outside pad was pressed firmly against it.
I am assuming this is definitely not normal and could be the cause of my low brake pedal? I had my girlfriend press the pedal and the pad does not contact the rotor until she pressed the pedal fairly far in. I don't have time to compress the rear calipers right now, but will do it later and reinstall the pads.

dkmura

iTrader: (64)

You've definitely got more air in the lines. The rear calipers are not moving due to a lack of pressure in those lines. Use a clear hose when you're bleeding the rears to see if any air bubbles are being drawn out.

JBJ

I definitely feel your pain Lumpy. I let my system run dry when I rebuilt my Brembos. A mistake I won't make again. As DK said, I had air in my brake lines I couldn't get out. I did a lot of research and here is what I read and ended up doing to knock the air bubbles out.

First buy a Motive Bleeder. Well worth the money. And you don't have to use your girlfriend.

I read to use a rubber mallet and beat the air bubbles out of them. I did.

Drive down a dirt road with wash board on it to help knock the bubbles loose.
(I know that sounds kinda dumb, but I was desperate).

And go drive the **** out of it. Lots of hard braking.

I'm not really sure which one worked, but I eventually got the bubbles out after a couple of days like terrasmak said.

For the record, I'm relatively new to the Z and certainly don't have the experience that dkmura and terrasmak have, but the above methods did work for me. Hopefully the guys with more experience will correct me if any of the above info is a bad idea. But something above did eventually work.

Hopefully we'll see you at a SCCA or NASA event next year since you're getting your Z set up for the track from what it seems.

Lumpy350z

Thank you for the advice everyone! It is all greatly appreciated! Update time. I compressed the calipers and reinstalled the pads, the rear pads are now both sitting flush with the rotor as they should be, and the pedal feel has improved as the take up before the pads contact the rotor is gone. I am not sure as I have not driven another Z with brembos but I feel as if it could still get a little tighter. I took the car out a little earlier and drove it very hard on a local backroad that was free of traffic. Did many hard stops and the car seems to have considerable braking force.

Currently all bleeding as ceased as the adaptor cap on my power bleeder has stopped holding pressure.

I have been bleeding all the calipers with the motive power bleeder and using clear hose. I have not been able to get any air bubbles out for the last 2-3 bottles of fluid I have put through the system so I am not sure if there is any more air left in there or not.

Been using the Motive Power bleeder the whole time for all bleeding. Works great, except adaptor for the master cylinder is not holding pressure anymore. However, I am no longer getting any bubbles out of the calipers when I bleed em. Tried the rubber mallet method too myself haha.

I am trying to set my Z up for track use and will hopefully be attending some SCCA and or NASA events!

dkmura

iTrader: (64)

Well, you've got more than five months to get ready for any SCCA or NASA events in the Rocky Mountain region. Glad your brake issues are getting resolved anyway.

Lumpy350z

At this point the pedal still feels sort of ineffective initially with some take up before the car really starts to slow down, but if I give it a quick double tap it becomes incredibly firm almost like an on/off switch. Is this normal for a Z with brembos, or should it be this firm always?

Sorry for all the noob questions haha, just trying to get an idea of what I should be expecting out of the brake pedal.

guitman32

iTrader: (15)

The motive alone is not that great at getting hard stuck air bubbles free. Alternating between the movie and pedal has been most effective for me.

GreyZ

iTrader: (2)

yup, the motive is good, but to get mine the last little bit, I had to pedal bleed a quart through. I ran my master cylinder dry aswell and ended up using 3and a half quarts (quarts, not pints) of brake fluid to get it firm. Theres definitely nearly zero pedal travel though. Im not positive I could get my pedal to hit the stop if I tried right now.

dkmura

iTrader: (64)

This is an important distinction for any brake system with fresh pads and "within spec" brake rotors. You should be able to get an immediate response (and reach threshold braking) from the first instant you touch the brake pedal. For Brembos in particular, your description indicates you still have air stuck in the system that is compressing.

Lumpy350z

Well, after spending more time messing with it. Bled the master again and then everything else the pedal is just about where I would like it to be. I will probably do another bleed in a week or two after I drive the car around some more and see if any more lingering bubbles work their way through before I put some good brake fluid in.

Thank you so much for all your help everyone, I appreciate all your responses!