My car now has a little under 8k miles and 10 track days on it. I am surprised by how bad my pad knockback has gotten (I have a Stoptech 14" 4-wheel kit). I never had an issue the first time at the track with the car, but now the knockback as gotten worse (I think it is a combination of my track mileage and the fact that I have become a better, more agressive driver with my car -- I know that it is not a BBK/Stoptech issue). I track a lot at Buttonwillow which has a lot of S-style curves which really work the hubs (causing the knockback).

I have learned to give my brakes a quick tap with my left foot while I am in straights to pump the brakes up, but it is one more thing now that I have to think about. I know that pad knockback is something that a lot of track hounds and sports car racers deal with -- but I am surprised that I have it with such a new car.

Are the hub bearing not packed well at the factory on our cars??? I am thinking of having a good race shop replace with bearings and pack the hell of them to see if that solves the problem. I just hate losing that rock hard pedal feel that I am used to with my Stoptechs.

I am just wondering -- has anyone ever replaced their hub bearings because of knockback?

If you are reading this and want to learn more about pad knockback -- here is a good article.

http://www.stoptech.com/whitepapers/knockback.htm

 

+1 on the knockback. I've got it pretty bad (35k miles and about 18 track days,) and like you, I've become accustomed to hitting the brake pedal with my left foot once or twice on straights leading up to braking zones that require a downshift (I don't bother on those that don't require downshifting, as they usually don't require threshold braking, and it doesn't bother me as much in those cases that the pedal goes below the throttle, because I don't need to heel-toe.)

I've replaced my left front bearing under warranty, and had hoped that it would help the knockback (thinking that maybe the knockback was caused by the bearing having gone bad.) Unfortunately, I experienced no change in pedal feel after corners after the replacement. Like you, I've considered discussing the problem with local race shops to get some input, but just haven't gotten around to it yet.

Let us know if you decide to upgrade your bearings, and how it goes for you.

 

Any progress on this?

I can drive all day and the pedal is right where I want it until I start doing hard cornering and then I notice that my pedal feels lower.

Chris

 

can you explain why the hub causes a lower pedal? or what you mean by 'knockback'

 

See the stoptech link in the first post.

Chris

 

thanks hy.

 

There has been cases where I have been able to rebuild the Hub assy on vehicles, but I have yet to hold in my hand a Z assy. The brgs as a rule are Rollers and sealed, although a sealed brg can be packed either with a syringe or by removing/replacing the cover.
If the brg can be pressed out or is held in with a snap ring, then a replacement can be bought at any good Brg house and POSSIBLY a better brg can be had.

If the brg was put into the hub, Logically it can be taken out of the Hub

 

True, but look at post #3 https://my350z.com/forum/autocross-road/234489-annual-maintenance-for-a-track-car.html Might be safer to replace the whole hub assy?!?!

 

What we see here is Hub/Brg failure and I have seen it first hand ---Very bad deal !!!!---I have though in the past rebuilt hubs when the Hub/Brg can only be bought as a unit at a very Hi $$$$ figure.
It is not recomended for the guy thay has just mastered changing his own oil, But if possible, for the guy that goes through brgs at a more than average rate. If it can be done ,and I will know once I get into one, it would be safe if done right and save a ton on money.

For all I know, assys may be cheap, for the Z ---But I started doing it a long time back when they were 250.00 + for cars and 500.00-700.00 for 4X4s

 

FYI MSRP on hub assy is 180.00 or so, Can be had for as low as 132.00

 

the hub/bearing assy can be had for $140 per side so thats not cheap when doing both sides but for those who track their cars it may be worth the peace of mind knowing you have a new hubs also.