41 replies to this topic

[Muda]

If you murder curbing or drop a wheel you may experience knock back. Has nothing to do with the skills of the driver. If you are using return springs and have freshly greased pins it's more likely. Everyone should be left foot tapping before brake zones.

[Parity]

What is your running position in a typical SM race? ...

Depends on the number of cars. I have finished second twice...in a two car race.

[svvs]

I'm with Muda on this one...I left foot tap before every braking zone now.  It's a pain getting the size 14's over there, but well worth it.

[Alberto]

If you murder curbing or drop a wheel you may experience knock back. Has nothing to do with the skills of the driver. If you are using return springs and have freshly greased pins it's more likely. Everyone should be left foot tapping before brake zones.

Sorry, I didn't mean to imply that it was entirely skills dependent.  I'm usually back of the pack myself fwiw.

 

The harder you work the suspension, the more the hubs are stressed, the greater the probability of pad knockback.  add some rough curbing, the probability of pad knockback increases.

 

What I meant to say is that if your skills haven't progressed to the point where you are pushing the car the way a front runner does, the probability of stressing the hubs sufficiently to experience bad pad knockback in the Miata is lower.

[Muda]

Depends on the number of cars. I have finished second twice...in a two car race.

And you were on pole for one of them. 

[Parity]

Sorry, I didn't mean to imply that it was entirely skills dependent.  I'm usually back of the pack myself fwiw.

 

The harder you work the suspension, the more the hubs are stressed, the greater the probability of pad knockback.  add some rough curbing, the probability of pad knockback increases.

 

What I meant to say is that if your skills haven't progressed to the point where you are pushing the car the way a front runner does, the probability of stressing the hubs sufficiently to experience bad pad knockback in the Miata is lower.

I was poking fun at myself there. No worries. Fact is until recently I never saw knockback but we've been hitting the curbing harder. In the last NASA race I did notice the most folks tapping the brakes prior to braking zones.

[Glenn Davis]

Summit Point T10 can knock them back pretty good.  If you head into T1, braking at 275' and have the problem, you'll be taking the exit to the skid pad

[davew]

Canada Corner at Road America is notorious for knock back. I have seen several cars end up in the gravel trap or worse (in the side of someone elses car) due to no brake pedal. Later determined to be knock back related.

 

PUMP 'EM BABAY

 

Dave

[AW33COM]

Changing piston seals and torquing down the rotors (my original hubs came with bolts for the rotors) will help.  Brand new seals will spring back the pistons more than the old once, at least in theory. 

[Muda]

Rebuilding a caliper takes about 15 minutes and costs about $15.  I do it before every season.

[Lange]

Paul,

I had this exact problem a couple of months ago after a bad crash. Tried changing the calipers, master cylinder, pads, bleeding the brakes, finally changed the caliper mounting brackets and it fixed the problem, they had become slightly bent in the accident, just enough to not allow the front pads to engage properly.

 

 

 

Hope that helps.

[Tom Hampton]

Rebuilding a caliper takes about 15 minutes and costs about $15.  I do it before every season.

 

Here is a suggestion that this practice may not be prudent, at this time:

 

http://mazdaracers.c...ons/#entry34331

[Muda]

Here is a suggestion that this practice may not be prudent, at this time:

 

http://mazdaracers.c...ons/#entry34331

Don't see how that pertains to rebuilding your own calipers?  All about bad remans and poor quality replacement parts.  Got tired of bad remans even from the best suppliers.  Haven't had a problem yet.  Will continue with my practice.  Oh, and removing the parking brake hardware on the rears takes another 5 minutes.

[Tom Hampton]

Quote from Bennet:

Recommendation: Don't "rebuild" known good calipers unless you need to,
at least not as regards the main piston seal. Replacing pin boots and
dust seals are fine, of course. Your 15+ year old rubber from Mazda's
OEM supplier is almost certainly better than what China Inc. is selling
the rebuilders (including the rebuilders Mazda North American may be
selling at any moment in time).

 

however, he does go on to say:

 

IF you rebuild, for now I would suggest using Mazda's rebuild kits -
they are expensive, but I have "proven" (strong word meaning "I've
convinced myself") that they perform as well as the original parts, at
least as regards durometer, "blowout" pressure, and DOT4 fluid
compatibility.

 

Just passing on information from a known reliable source (Bennett).  Use (or don't) as you wish.

[Muda]

So, the alternative is to try and pick a good reman and not know what's inside?  Or hope Mazda picked a good one?  Or keep driving on that 3 season old burnt out POS because you're afraid of China Inc.'s quality control?  Thanks, but I'd rather inspect my own parts and assemble properly.  I don't use Cardone anything.  Buy good parts, assemble and test, inspect at the track and after each event, carry spares and react to any changes with appropriate caution.

 

It amazes me how many guys are out there running brake calipers for multiple seasons, never bleeding or replacing fluid and only examining the brakes when the pads are at 1/16".  And they wonder why they are locking up or have a soft pedal.  Surprised we don't have many more catastrophic failures.

[Parity]

So is Mazda the only decent source for rebuild kit or is there somewhere else?

[Tom Hampton]

I think Saul was pretty clear, Mazda rebuild kits are the only source that he has any confidence in. 

[steveracer]

And I don't recall them being expensive considering 1 kit does both sides. (Discovered after ordering 2 of each)

[Ron Alan]

Changing piston seals and torquing down the rotors (my original hubs came with bolts for the rotors) will help.  Brand new seals will spring back the pistons more than the old once, at least in theory.

Do you do this for a living or are you  just reciting what you've read somewhere? Nothing in this post makes any sense. Maybe you stayed at a Holiday Inn Express?

[Bench Racer]

   Some of us, don't express ourselves well.

 

In person I'm a nice guy and most likely Schabi is also.